CONCRETE PLACING AND SCREEDING APPARATUS AND METHOD

Abstract: A concrete placing apparatus is provided for placing uncured concrete on a support surface, such as an elevated deck of a building. The apparatus comprises a base unit (16) and a movable support (18), with a conduit assembly (14) extending therebetween. A supply end of the conduit assembly is positioned at the base unit and is connected to a supply line (20) for uncured concrete or other material, while a dispensing end (14c) of the conduit assembly is supported by the movable support and extends outwardly therefrom to dispense uncured concrete or other material through a discharge outlet. The movable support is movable arcuately and/or radially relative to the base unit to dispense the concrete in a generally uniform manner over a targeted area. The apparatus may further include a screeding device (72) at the discharge outlet to grade, level, compact and smooth the concrete as it is placed.

Description: CONCRETE PLACING AND SCREEDING APPARATUS AND METHOD CROSS REFERENCE TO RELATED APPLICATION The present application claims the benefit of U.S. Provisional application, Ser. No. 60/172,499, filed Dec. 17, 1999 by Philip J. Quenzi et al., which is hereby incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION This invention relates generally to concrete placing devices and, more particularly, to a low profile concrete placing and screeding apparatus for placing concrete in floors of buildings or in other areas where overhead obstructions preclude or limit the use of a boom truck. It is known to use a pumping truck and pipe or a boom truck to place concrete at a targeted site. The boom truck, which comprises an articulated boom and pipe apparatus, where the pipe sections are pivotable about one or more generally horizontal axes, may be used to reach areas which are at a greater distance from the pumping truck or which are at a different height, such as an upper floor of a building or the like. However, it is difficult to use conventional boom trucks between floors of buildings because there may not be enough clearance between the floor and the overhead structures to reach the entire floor with the boom. The boom of the boom truck may also not be sufficiently long to reach distant areas of the targeted floor, thus requiring additional pipes to carry and place the concrete at those areas. An additional concern with boom trucks is that these trucks are typically too heavy to be driven onto raised or elevated slabs in order to be able to reach upper floors or levels of buildings. In areas where boom trucks cannot reach or where a pumping truck is available while a boom truck is not, a movable pipe or multiple sections of pipe may be connected to the concrete pump and extended therefrom in order to reach the targeted area. Although such systems are capable of reaching remote areas from the pumps, it is difficult to manage the large and heavy pipes in order to properly place the concrete. Although several devices have been proposed which provide a mounting base for a movable pipe assembly to pivotally extend therefrom, it is still difficult to manage such devices, since the base must be manually moved once the pipes have spread the concrete at each particular location. Additionally, after the pumping truck or boom truck has placed the concrete at the targeted areas via pipes or a boom, a screeding device must be positioned at the targeted areas to compact and smooth the concrete before it cures. Typically, the concrete may be placed in a targeted region of a floor and then the screeding device may be positioned at this region to smooth and pack the concrete while the placing system is moved to the next targeted region. This may require further movement of the placing apparatus in order to make room for the screeding apparatus, prior to placing the concrete at the next, typically adjacent, targeted location. Accordingly, there is a need in the art for a low-profile placing apparatus which is easy to manage and/or maneuver in areas where there is low overhead clearance. The apparatus must be capable of reaching areas of a construction site which are remote from the location of a pumping truck. Additionally, the apparatus must be of relatively low weight, in order to be operable on raised or elevated slabs so as to be able to place concrete on upper floors or levels of buildings. There is also a need for an improved, more efficient method and apparatus for screeding the poured and/or placed concrete in such remote, difficult to reach areas, especially where overhead clearance is low, or on raised, elevated slabs. SUMMARY OF THE INVENTION The present invention is intended to provide a concrete placing and screeding apparatus which is especially useful and operable in areas with low overhead clearance, or on raised, elevated slabs, or in other locations where the support of high weight apparatus is difficult. The apparatus is easily maneuverable to place the appropriate amount of concrete in each targeted area. Additionally, a screeding device may be implemented with the placing apparatus, in order to combine the placing and screeding operations. According to a first aspect of the invention, a concrete placing device for placing uncured concrete at a support surface comprises a base unit, a conduit, and a movable support. The conduit comprises a supply end and a discharge end, wherein the discharge end comprises a discharge outlet and is generally opposite the supply end. The supply end is mounted to the base unit and is connectable to a supply of uncured concrete. The conduit is operable to dispense the uncured concrete through the discharge outlet. The movable support is operable to movably support the discharge end of the conduit at a position remote from the base unit. Preferably, the conduit is an extendable tube which is extendable and retractable relative to the base unit. Preferably, the base unit comprises a base portion and a swivel portion rotatably supported by the base portion. The supply end of the extendable tube is mounted to the swivel portion, such that the discharge end of the extendable tube is movable arcuately and/or radially relative to the base unit. Preferably, the concrete placing device further comprises a screeding device positioned at the discharge end of the conduit. In one form, the movable support comprises a wheeled vehicle, preferably having four wheels. In another form, the movable support comprises an air cushion device. In yet another form, the movable support comprises a plurality of wheel trolleys which are rotatable about a generally closed path via a drive motor and drive member such that the trolleys and the movable support are movable in a direction generally axially relative to the wheels of the wheel trolleys. According to another aspect of the present invention, a concrete placing and screeding apparatus comprises a movable support, a conduit having a supply end and a discharge end, and a screeding device at the discharge end of the conduit. The supply end of the conduit is generally opposite the discharge end and is connected to a supply of uncured concrete to be placed. The conduit is supported by the movable support. According to yet another aspect of the present invention, a concrete apparatus for placing and/or screeding uncured concrete at a support surface comprises one or both of a concrete supply unit and/or a screeding device, as well as an air cushion support unit. The concrete supply unit provides uncured concrete to the support surface, while the screeding device is operable to grade and smooth the uncured concrete on the support surface. The air cushion support unit is operable to support one or both of the concrete supply unit and/or the screeding device. In one form, the concrete supply unit comprises a conduit having a supply end for receiving uncured concrete for discharging the uncured concrete on the support surface. Preferably, the conduit is extendable between the extended and retracted position relative to a base unit. The extendable conduit may be a telescopingly extendable tube, which is mounted to a pivotable base unit. The extendable conduit may otherwise be an articulated tube which comprises at least two sections which are pivotable about a joint, with the supply end of the conduit being mounted to a generally fixed base unit. The conduits, support units and/or base units are operable to move the discharge end of the conduit and/or the screeding device both arcuately and radially with respect to the base unit. According to yet another aspect of the present invention, a concrete placing apparatus for placing uncured concrete at a support surface comprises an extendable conduit having a supply end and a discharge end, at least one air cushion support unit, which is operable to support the extendable conduit, and a base unit which is operable to support the supply end of the extendable conduit. The extendable conduit is operable to receive a supply of uncured concrete and discharge the uncured concrete to the support surface via the discharge end of the conduit. In one form, the base unit is substantially fixed, and may be secured via two or more adjustable cables. Preferably, the extendable conduit is an articulated conduit having at least two sections pivotable about a generally vertically axis relative to one another. In one form, the articulated conduit may comprise at least three sections, with at least two air cushion supports supporting two of the sections of the conduit. In another form, the conduit may be flexible in a horizontal direction, while substantially precluding upward and downward flexing, such that the conduit may be bent or pivoted relative to the base unit about one or more generally vertical axes. In another form, the extendable conduit may be telescopingly extendable to radially extend and retract the discharge end with respect to the base unit. The extendable conduit may further be arcuately movable with respect to the base unit. Preferably, the extendable conduit is mounted to the air cushion support with a trunnion which allows for pivotal movement of the extendable conduit about a generally horizontal axis, while also allowing pivotal movement of the conduit about an axis extending generally along the extendable conduit. Accordingly, the present invention provides a placing and/or screeding apparatus which is easily maneuverable and which may be easily implemented in areas where a boom truck cannot reach, such as remote areas of buildings or areas with low overhead clearance, or raised or elevated decks or slabs where weight may be a concern. The air cushion devices function to movably support the concrete supply and/or a screeding device and spread the load of the units over a larger area via a cushion of air, such that the pressure exerted by the movable units on the support surface is substantially reduced. The air cushion units also facilitate movement of the conduit and/or screeding device over areas which are already covered with uncured concrete, such that concrete may be placed or smoothed in those areas without disturbing the already placed uncured concrete. The conduits are preferably extendable and may be extended and retracted relative to a base unit, such that the discharge end of the conduit and/or the screeding device may be moved throughout the targeted area to place or screed concrete in substantially all locations within the targeted area. These and other objects, advantages, purposes and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRA WINGS FIG. 1 is a plan view of an embodiment of the present invention as it may be used to place concrete; FIG. 2 is a perspective view of the embodiment shown in FIG. 1, with the apparatus in a retracted state: FIG. 3 is a side view of the apparatus of FIG. 2, and further includes a crane assembly mounted at the base unit; FIG. 4 is a plan view of the embodiment of FIGS. 1-3, shown in an extended state; FIG. 5 is a hydraulic schematic of the embodiment shown in FIG. 3; FIG. 6 is a perspective view of an alternate embodiment of the present invention in a retracted state, with a screeding device positioned at a discharge end of the pipe assembly; FIG. 6 A is an enlarged view of the screeding device shown in FIG. 6; FIG. 7 is a perspective view of the embodiment of FIG. 6, with an alternate screeding device, shown in its extended state; FIG. 8 is a side view of the wheeled embodiment shown in FIG. 7, with an operator control positioned at the lead vehicle, shown in its retracted state; FIG. 9 is a plan view of the apparatus of FIGS. 6 and 7, as the apparatus is used to place and smooth concrete within a given targeted area; FIG. 10 is a hydraulic schematic of the embodiment shown in FIGS. 6 through 9; FIG. 11 is a perspective view of another alternate embodiment of the present invention with a rotatable screeding head positioned at the discharge end of the tube assembly, shown in a retracted state; FIG. 12 is a side view of the embodiment shown in FIG. 11; FIG. 13 is a top plan view of the embodiment shown in FIG. 11 ; FIG. 14 is a hydraulic schematic of the embodiment of the present invention shown in FIGS. 11 - 13; FIG. 15 is a perspective view of another alternate embodiment of the present invention, with the base and lead units comprising a two-fan air cushion device, shown in its retracted state; FIG. 16 is a similar perspective view as FIG. 15, with the apparatus shown in its extended state; FIG. 16A is a perspective view of the base unit of FIGS. 15 and 16, with the pipe assembly pivotally mounted to the base unit and casters positioned around the base unit; FIG. 17 is a plan view of an alternate embodiment of the embodiment shown in FIGS. 15 - 16, with each air cushion device comprising four lift fans, shown in its retracted state; FIG. 18 is a sectional view of the base unit, taken along the line XVIII-XVIII in FIG. 17; FIG. 19 is a sectional view of the lead unit taken along the line XIX-XIX in FIG. 17, with the pipe removed from the lead unit and a directional fan positioned thereon; FIG. 20 is a hydraulic schematic of the embodiment shown in FIGS. 15 though 19; FIG. 21 is an alternate embodiment of the present invention shown in FIGS. 15 - 20, with a screeding device positioned at the discharge end of the tube assembly, shown in its retracted state; FIG. 22 is a hydraulic schematic of the embodiment shown in FIG. 21; FIG. 23 is a plan view of an embodiment comprising an air cushion lead vehicle and screeding device, showing that the air cushion device may be movable over areas where the concrete has already been placed; FIG. 24 is a perspective view of another alternate embodiment of the present invention which has a lead unit which comprises a plurality of wheel trolleys which are movable in a generally axial direction to move the tube assembly arcuately relative to the base unit; FIG. 25 is an end view of the lead unit shown in FIG. 24 as viewed from the line XXV - XXV in FIG. 24; FIG. 26 is a perspective view of the embodiment shown in FIG. 24 in its extended state; FIG. 27 is an end perspective view of the embodiment shown in FIGS. 24 though 26; FIG. 28 is a side view of an alternate embodiment of the invention shown in FIGS. 24 - 27, with the base unit comprising an air cushion device, shown in its retracted state; FIG. 29 is a perspective view of another alternate embodiment of the present invention which comprises a screeding device positioned at the discharge end of the tube assembly, shown in its retracted state; FIG. 30 is a hydraulic schematic of the embodiment shown in FIG. 29; FIGS. 31 through 34 are plan views of the present invention and show a portion of the process for placing concrete in a targeted area; FIG. 35 is an upper perspective view of another embodiment of a placing apparatus of the present invention, with multiple movable air cushion support units supporting an articulated tube assembly; FIG. 36 is a top plan view of the placing apparatus of FIG. 35; FIG. 37 is a perspective view of a base unit useful with the placing apparatus of FIG. 35; FIG. 38 is an enlarged view of one of the joints of the articulated tube assembly with the tube assembly in its extended or straightened orientation; FIG. 39 is a perspective view of a mounting trunnion useful with the air cushion units of the present invention; FIG. 40 is an end view of one of the air cushion support units of FIG. 35; FIG. 41 is a sectional view taken along the line XLI-XLI in FIG. 40; FIG. 42 is a perspective view of the placing apparatus of FIG. 35, as implemented on an elevated support surface; FIGS. 43-48 are plan views of the present invention and show a portion of the process for placing concrete in a targeted area; FIG. 49 is a perspective view of yet another embodiment of the present invention, with a flexible tube assembly being supported by multiple air cushion support units; FIG. 50 a perspective view of another embodiment of the present invention, with a telescoping tube assembly supported by an articulating, wheeled base unit and a steerable wheeled movable support; FIG. 51 is a side elevation of the embodiment of FIG. 50; and FIG. 52 is a top plan view of the embodiment of FIGS. 50 and 51. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now specifically to the drawings, and the illustrative embodiments depicted therein, a placing apparatus 10 for placing concrete 12 in a targeted or designated area comprises a tube assembly, 14, a base unit 16, and a lead unit or movable support 18 (FIG. 1). Concrete placing device 10 is a low profile device and is thus usable in various locations, such as on different levels or floors of buildings or the like which may have low overhead clearance. The tube assembly 14 is preferably extendable and retractable, and is connectable at a supply end 14a to a concrete supply tube 20, which is connectable to a pumping truck 22 or other means for supplying uncured concrete through the supply tubes 20. Supply end 14a is preferably adapted to be connectable to a conventional supply hose or pipe, such as a 5 inch or 6 inch diameter concrete supply hose or pipe. The extendable tube assembly 14 places the concrete 12 via a discharge outlet 14c at an outer end 14b of tube assembly 14. Outer end 14b of tube assembly 14 is movably supported by movable support or lead vehicle 18, while supply or inner end 14a is preferably pivotally supported at base unit 16. Concrete placing device 10 is operable to extend and retract the extendable tube assembly 14 and to pivot the tube assembly relative to the base unit 16, in order to move discharge outlet 14b of tube assembly 14 both arcuately and radially relative to base unit 16 while concrete is being dispensed therefrom. The terms tube, pipe, conduit and the like are used herein to describe any means for conveying uncured concrete or the like from a supply of uncured concrete to a discharge outlet of the placing apparatus, and may include cylindrical pipes/tubes, open channels or troughs, hoppers or bins, or any other form of conduit, unless otherwise noted, without affecting the scope of the present invention. Although described herein as an apparatus for placing and/or screeding uncured concrete, the present invention may otherwise place or dispense other materials, such as sand, gravel, or the like, onto a support surface. WHEELED UNITS Preferably, base unit 16 and lead unit or movable support 18 both comprise a four wheeled vehicle, as shown in FIGS. 1 - 4. Base unit 16 and lead unit 18 both comprise a frame 16d and 18d, which houses a power source 28 (FIG. 5). Preferably, the power source 28 of each vehicle is an hydraulic pump which is interconnected with a reservoir 38 and a plurality of solenoid controls 40. A plurality of electronic controls 42 are provided to actuate one or more of the solenoids 40 to pressurize one or more hydraulic fluid lines and thus control driving the wheels, steering the wheels, and/or extension and retraction of one or more of the tubes of tube assembly 14, as discussed below. Power source 28 preferably is operable to drive or rotate each of the wheels 24 independently of the others via an hydraulic motor 44 at each wheel (FIG. 5). Each pair or set of wheels is rotatably mounted to an axle 26. Each pair of wheels on a given axle may be turned or steered together to change the direction of base or lead unit 16 or 18 Because both the base and lead units 16 and 18 are four wheel drive and are steerable by both axles, the units may be easily maneuvered into the desired area, even when there may be obstructions, such as vertical support columns or the like, present in the area. The lead vehicle 18 may be driven outwardly from base unit 16 to extend the tubes and then driven arcuately relative to base unit 16 to pivot tube assembly 14 relative to base unit 16. Lead unit 18 may be remotely controlled via wire or radio controls (not shown) or may further comprise an operator seat or station 30 and controls for an operator to sit or stand on the lead vehicle and drive or otherwise control it while also controlling the placing of the concrete, as shown in FIG. 8. Alternately, the lead unit 18 may be controlled via a programmable control, such that the unit 18 is driven along a planned pattern relative to the base unit 16, without any manual intervention required. Preferably, both base unit 16 and movable support 18 further comprise a swivel portion 16a and 18a, respectively. Swivel portions 16a and 18a are rotatably mounted to respective base portions 16b and 18b, such that each may be rotated 360° relative to the respective base portions of base unit 16 and movable support 18. Swivel portions 16a and 18a each preferably comprise a pair of upwardly extending supports or trunnions 16c and 18c, which further include a notch or groove for receiving corresponding pivot/support pins 14d and 14e, respectively, on tube assembly 14, as discussed below. As shown in FIG. 3, base unit 16 may further comprise a crane device 36, which is operable to lift and move sections of the supply hose or pipe 20, thereby easing the process of disconnecting and reconnecting supply end 14a of tube assembly 14 to the supply tube 20 when base unit 16 is moved to a new location. Crane member 36 comprises an extendable arm 36a, which is pivotally mounted to a base portion 36b, which is further mounted to swivel portion 16a of base unit 16. The base portion 36b is preferably mounted to trunnion 16c on swivel portion 16a and thus pivots with tube assembly 14 relative to base portion 16b of base unit 16. Extendable arm 36a may then be raised or lowered via an hydraulic cylinder 36c to lift or lower sections of the supply tube or pipe 20, which may or may not be filled with concrete at the time. Hydraulic cylinder 36c is preferably operable via the hydraulic pump 28 positioned on base unit 16. Tube assembly 14 is preferably extendable and comprises a plurality of nested or telescoping pipes or tubes, 15a, 15b, 15c and 15d, which slidably engage one another to extend and/or retract the tube assembly relative to base unit 16, as best shown in FIGS. 2 - 4. An innermost tube 15a, which also comprises the supply end 14a of tube assembly 14, preferably further includes a pair of cylindrical support pins 14d extending laterally outwardly from either side of tube 15a at supply end 14a. Inner tube 15a is pivotally mounted to a swivel portion 16a of base unit 16 via support pins 14d being received in the grooves of trunnions 16c. The pins 14d may pivot about a horizontal axis to allow for raising or lowering of one of the units relative to the other in areas where uneven terrain is encountered by placing apparatus 10. Additionally, because the pipe 15a is mounted to swivel portion 16a of base unit 16, the pipe assembly 14 may pivot or swivel about a vertical axis relative to base portion 16b of base unit 16. The tube assembly is thus preferably mounted to base unit 16 via a two axis mounting structure. However, other means for mounting the tube assembly to the base unit may be implemented, without affecting the scope of the present invention. Preferably, the tubes are nested within one another and slidable relative to each of the other tubes to telescopingly extend and/or retract tube assembly 14 in response to actuation of one or more controls on either the lead or base unit 18 or 16. Preferably, as best shown in FIG. 4, three of the tubes 15a, 15b and 15c of telescoping tube assembly 14 are positioned between base unit 16 and lead unit 18 such that they extend and retract in response to relative movement of the base and lead units 16 and 18. The telescopic pipes are arranged so the concrete passes from the smallest pipe 15a at the concrete inlet to successively larger diameter pipes toward the discharge end 14b. This provides an "accumulator" effect and reduces surging due to the periodic concrete pump cycle. The third tube 15c preferably includes a pair of cylindrical support pins 14e, which extend laterally outwardly from either side of tube 15c toward an outer end thereof. The support pins 14e of outer or third pipe 15c are preferably pivotally mounted within the grooves or openings of trunnions 18c of swivel portion 18a of lead unit 18, in a similar fashion as base unit 16, such that pipe assembly 14 is also pivotable or rotatable about both a vertical axis and a horizontal axis relative to base portion 18b of lead unit 18. Preferably, a fourth, outermost tube or pipe 15d is positioned outwardly of lead unit 18 and is further extendable and retractable relative thereto via a powered extending device 32, such as an hydraulic cylinder or the like. The discharge outlet 14c is positioned at an outer end of outer pipe 15d, and is preferably directed generally downwardly to facilitate placing of concrete at the desired locations. Extending device 32 preferably comprises a conventional hydraulic cylinder 32 and a rod and piston assembly 33, as is known in the art. An outer end 32a of cylinder 32 is fixedly mounted to a bracket 17a on outer tube 15d while an inner end 32b of cylinder 32 is slidably mounted on the next inner tube 15c via a bracket or collar 17b. A third bracket 17c is provided at an inner end of outer tube 15d and fixedly secures cylinder 32 at the inner end of the outer tube 15d. An end 33a of rod 33 is then fixedly mounted at an inward end of the next inwardly positioned tube 15c such that extension of rod 33 relative to cylinder 32 causes outward movement of outer tube 15d along inner tube 15c, as hydraulic cylinder 32 moves longitudinally outwardly with respect to tube 15c, while the sliding collar 17b slides along tube 15c. Brackets 17a and 17c support cylinder 32 and push outer tube 15d outwardly along tube 15c as cylinder 32 is moved outwardly via extension of rod 33. Preferably, hydraulic cylinder 32 is powered by power source or hydraulic pump 28 positioned on lead unit 18. The other tubes 15a - 15c may be extended and retracted by driving the lead vehicle in a generally longitudinal direction with respect to the tube assembly 14, and/or may be extended and retracted via one or more hydraulic cylinders, as discussed in detail below. Although not shown, concrete placing device 10 further comprises a valve or the like in tube assembly 14 to control the flow of concrete therethrough independently of the controls of the pumping truck 22, as is known in the art. In the illustrated embodiments, the tubes 15a - 15d are retractable such that placing apparatus 10 is approximately 17 feet long from supply end 14a to discharge end 14b of tube assembly 14. Preferably, tube assembly 14 is positioned on lead vehicle 18 such that tube 15c and outer tube 15d extend approximately 8 feet from their connection point (at support pins 14d on tube 15c) on lead vehicle 18 when tube 15d is fully retracted. The tube assembly 14 is then extendable a total of approximately 31 feet such that the placing apparatus 10 spans approximately 48 feet from supply end 14a to discharge end 14b when extended. Inner tubes or pipes 15a, 15b and 15c extend such that lead unit 18 may travel approximately 24 feet from its initial, retracted position, while outer pipe 15d is further extendable via hydraulic cylinder 32 approximately 7 additional feet from pipe 15c and lead vehicle 18. Referring now to FIG. 5, concrete placing apparatus 10 preferably includes at least one open loop, closed center hydraulic system for operation of all of the fluid motors and fluid cylinders on each of the base and lead units 16 and 18. FIG. 5 shows the hydraulic system for the lead unit 18, with the solenoid and cylinder for the crane 36 of the base unit 16 shown in phantom. An hydraulic pump 28 is provided which draws hydraulic fluid from a reservoir or tank 38. The pump 28 may be powered by a battery or diesel or gasoline powered internal combustion engine (not shown). The pump 28 provides hydraulic fluid under pressure through an hydraulic line 28a to a bank or series of hydraulic control valves 40, which are also positioned on the respective units 16 or 18. Each of the control valves 40 includes a series of individual, three position valves which may be shifted to open, close or reverse the hydraulic fluid flow through the appropriate motor or cylinder via actuation of an electronic control 42. Each of these valves further includes a flow control valve which may be adjusted or opened or closed to vary the speed of the hydraulic fluid flow through the valve to control the speed of operation of the respective mechanism. Fluid is returned to reservoir 38 via a return line 28b. As shown in FIG. 5, a first control valve 40a may control the drive motors 44 for individually driving the wheels 24 of the respective unit via hydraulic lines 45a and 45b. Hydraulic line 45a provides fluid to a first port 44a on each motor 44, via a counterbalance valve 46 and hydraulic line 48a, for driving the wheels in a forward direction, while hydraulic line 45b is connected to second ports 44b on motors 44, via counterbalance valve 46 and hydraulic line 48b, for driving the wheels in a reverse direction. A dual counterbalance or load control valve 46 is provided in the hydraulic lines 45a and 45b which is generally a dual piloted relief valve with pilot pressure for one line being supplied from the opposite port of the motor. This provides counterpressure to the lines in order to prevent the vehicle from excessively accelerating or running away when driving the respective unit downhill. For example, if the vehicle is travelling forward, pressurized fluid in line 45a travels through a forward portion 46a of load control valve 46 and into the forward ports 44a of motors 44 via hydraulic line 48a. If the unit begins travelling downhill rapidly in the forward direction, the pressure at the forward ports 44a would decrease toward zero, as the motors rotate at a faster rate than the fluid is being provided by pump 28. This drop in pressure causes a corresponding reduction in pilot pressure to the outlet or reverse ports 44b of motors 44 and in the reverse hydraulic lines 48b, which function to return the fluid toward reservoir 38 when the vehicle is being driven in a forward direction. When the pilot pressure is reduced to or near to zero p.s.i., the load control valve is at its maximum setting and thus provides back pressure to the reverse line to slow down the rotation of the wheels and thus prevent the machine from travelling too fast or getting away. Additionally, a traction control valve 50 may also be provided at each axle 26 to divide the flow of fluid to the left and right wheels of each axle in order to prevent a wheel from spinning freely if it encounters an area with poor traction. Each traction control valve 50 comprises a solenoid operated bypass valve that is normally open. When poor traction conditions are encountered, the solenoid valve may be energized to split the flow and variably adjust the lines to prevent slippage of one of the wheels. A third traction control valve (not shown) may also be provided to divide the flow between the front and back axles, in order to further improve the traction of the vehicles. A second hydraulic solenoid valve 40b is also provided to control the steering system 52 via a pair of hydraulic lines 54a and 54b. As shown in FIG. 5, this may be accomplished via a pair of hydraulic cylinders 56a and 56b at opposite axles of the respective unit. Each steering cylinder 56a and 56b comprises a double ended piston and rod assembly 58. Each rod end 58a and 58b of the respective rods connects to a corresponding wheel control arm 59a and 59b (FIG. 4) at an opposite end of the respective axle. Preferably, rod ends 58a of a front cylinder 56a are connected to control arms 59a positioned rearwardly of the front axle, while rod ends 58b of a rear cylinder 56b are connected to control arms 59b positioned forwardly of the rear axle, such that the cylinders are operable to pivot or steer the wheels at each axle in a generally opposite direction to the wheels of the other axle. Alternately, the control arms may be positioned outwardly from their respective axles, such as forwardly of the front axle and rearwardly of the rear axle, to accomplish the same steering effect. This approach is operable to turn or steer all four wheels together to facilitate a tighter turning radius and thus improve maneuverability of the base and lead units. The steering cylinders are equipped with piston mounted bypass shuttle valves (not shown), which open when the cylinders reach full stroke in either direction. This allows the wheels to be resynchronized at full steer in the event of cylinder leakage. As pressurized fluid is supplied through one of the lines 54a, the piston/rod assembly 58 in the front cylinder 56a moves along the cylinder to move control arms 59a and thus cause the wheels on the front axle of the vehicle to pivot together relative to their axle. A connecting hydraulic line 60 connects one end of front cylinder 56a to an opposite end of the other, rear cylinder 56b, so as to cause a corresponding movement of the piston/rod assembly 58 within the other cylinder 56b, thereby moving the control arms 59b and causing the wheels on the rear axle of the vehicle to pivot in tandem with the first wheels, but in a generally opposite direction. This is accomplished by positioning the control arms toward opposite ends of the vehicle with respect to their axles, such as one set being forwardly of the rear axle while the other set is rearwardly of the front axles, as is known in the art. Although described as having a front and rear axle, clearly the units 16 and 18 are drivable in either direction. A dual counterbalance or load control valve 62 is further provided to prevent unwanted steering caused by one or more of the wheels hitting obstructions as the vehicle travels along the ground. The counterbalance 62 is operable in a similar manner as load control valve 46 discussed above with respect to the wheel drive system. Although shown as providing steering to each axle simultaneously, clearly the present invention may be operable to steer the wheels on only one axle at a time, or to provide a "crab" steer mode, as would be obvious to one skilled in the art, without affecting the scope of the present invention. With respect to the lead unit or movable support 18, a third solenoid control valve 40c may be provided to provide pressurized fluid to hydraulic cylinder 32 in order to extend or retract outer pipe 15d relative to movable support 18. Solenoid valve 40c may provide pressurized fluid to outer end 32a of hydraulic cylinder 32 to cause extension of the piston/rod 33 via an hydraulic line 64a, while a second hydraulic line 64b is connected at inward end 32b of hydraulic cylinder 32 to allow fluid to return to reservoir 38 as piston/rod assembly 33 extends from hydraulic cylinder 32. Solenoid control valve 40c is also operable to pressurize hydraulic line 64b, such that the piston assembly 33 is moved in the opposite direction to retract outer tube 15d relative to movable support 18 and the inner tubes 15a, 15b and 15c. With respect to the base unit 16, an additional solenoid control valve 40d may be provided to control extension and retraction of the hydraulic cylinder 36c on the crane device 36, if applicable, via a pair of hydraulic lines 66a and 66b. Preferably, the hydraulic system of base unit 16 includes crane device cylinder 36c while the hydraulic system of lead unit 18 includes the extension cylinder 32. As would be obvious to one skilled in the art, the hydraulic cylinder 36c is extendable and retractable by selectively pressurizing one of the hydraulic lines 66a and 66b, respectively, while the other line functions to return hydraulic fluid to reservoir 38 via solenoid valve 40d and return line 28b. SCREEDING DEVICE Referring now to FIGS. 6 - 10, another embodiment 10' of the present invention further comprises a screeding device 72 positioned at an outer end 14b of the extendable tube assembly 14. The tube assembly 14 is substantially similar to tube assembly 14 discussed above with respect to placing apparatus 10 and will not be discussed further in detail herein. The tube assembly 14 is pivotally mounted to swivel portions 18a and 16a of a lead vehicle 18 and a base vehicle 16 in the same manner as discussed above. Base unit 16 and lead unit 18 are also identical to the units discussed above with respect to placing apparatus 10 and thus will not be discussed again in detail. Optionally, the base unit 16 may include a crane device 36 for raising and lowering sections 20a of the supply pipe 20. Optionally, one or more movable units may support and transport a screeding device independent of any concrete supply conduit, such that the units are operable to smooth, level and/or grade concrete that has already been placed at the support surface. Preferably, the screeding device 72 is a laser controlled screed mounted at the outer end 14b of the tube assembly 14, and adjacent to the discharge nozzle 14c. The screeding device 72 is pivotally mounted at the outer end 14b so as to be pivotable from side to side in order to compact and smooth the concrete being placed by the placing and screeding apparatus. Preferably, screed 72 comprises a mounting beam 75, which is mounted on an arm 74, which is pivotally mounted at outer end 14b of tube assembly 14 and is pivotable about a pivot axis or swivel point 74a at the end of the tube. An hydraulic cylinder 76 is pivotally mounted at one end to a mounting bracket 78 on tube assembly 14 and pivotally mounted at an opposite end to a bell crank type arm or bracket 80, such that extension and retraction of the hydraulic cylinder 76 pivots the entire screed 72 and arm 74 about swivel 74a. The screeding device 72 is pivotable relative to tube assembly 14 in order to provide proper orientation of a plow 84 and/or other screeding components as the lead unit 18 and pipes 14 pivot arcuately relative to base unit 16. For example, as shown in FIG. 9, the screeding device 72 may be pivoted 45° in one direction as the tubes are rotated in a first direction, and then pivot 90° for an opposite orientation with respect to the tube assembly 14, to provide proper orientation for arcuate movement in the opposite direction. Screeding device 72 may be a conventional screeding device, or may be a laser controlled screed similar to the types disclosed in commonly assigned U.S. Pat. No. 4,655,633, issued to Somero et al., and/or U.S. Pat. No. 4,930,935, issued to Quenzi et al., the disclosures of which are incorporated herein by reference. Preferably, as shown in FIGS. 6 and 6 A, screed 72 is substantially similar to the screeding device disclosed in U.S. Pat. No. 4,930,935 and comprises a pair of generally vertical adjustable supports 82 which are adjustable via extension and retraction of a pair of hydraulic cylinders 83. As cylinders 83 are extended or retracted, an inner support rod 82a is movable along and within an outer cylindrical sleeve 82b, which is fixedly secured to mounting beam or cross member 75, such that a lower end 82c of supports 82 is vertically adjustable with respect to beam 75 and tube assembly 14. Because screed assembly 72 is preferably substantially similar, but to a smaller scale, to the screed assembly disclosed in U.S. Pat. No. 4,930,935, a detailed discussion of the screed assembly will not be repeated herein. Suffice it to say, as best seen in FIG. 6A, screed assembly 72 preferably includes an elongated plow 84, an auger 85 and a vibratory screed 86. Plow 84, auger 85 and screed 86 are all mounted to an end frame 87 at each end, each of which are connected to one another by a horizontal cross member 87a. Plow 84 is rigidly secured to frames 87 and is operable to establish a rough grade of the uncured concrete dispensed via dispensing nozzle 14c. Auger 85 is a spiral, continuous auger which is rotated via a shaft 85b rotatably driven by a motor 85a (FIG. 10) to further smooth the concrete and to carry excess concrete toward one end of screed assembly 72. Vibratory screed 86 comprises a screed strip or plate 86a and a rotatable shaft 86b which is driven via an hydraulic rotation motor 86c. A series of weights (not shown) are secured concentrically to the shaft 86b such that rotation of shaft 86b causes vibration of the screed strip 86a to smooth and compact the concrete. Vibration of the motor 86 and plow 84 is isolated from the remainder of the screed assembly 82 by a plurality of rubber mounts (not shown) which absorb the vibration and prevent vibration of the remainder of the plow, auger, screed assembly and the placing and screeding apparatus 10'. As discussed in U.S. Pat. No. 4,930,935, end frame 87 is preferably pivotally mounted at lower end 82c of supports 82 to allow pivoting of the frames 87 about a generally horizontal axis 87b. A pair of self-leveling cylinders 88 are mounted at an upwardly extending mounting plate 87c at each end frame 87, with their opposite or rod end 88a mounted to a bracket 82d positioned at lower end 82c of supports 82. Self-leveling cylinders 88 may then be extended or retracted to pivot end frames 87 about axis 87b, to maintain a level interface between plow 84, auger 85 and screed 86 and the uncured concrete, preferably in response to an electronic leveling sensor (not shown). By maintaining the proper angle and orientation of the plow and screed with respect to the concrete, the plow is substantially precluded from digging into the concrete surface as it moves therealong. The electronic level sensor detects when the plow pivots about horizontal axis 87b and provides a signal to the controls of the hydraulic cylinders 88 such that they extend or retract to counter the detected rotation of the plow, in the same manner as disclosed in U.S. Pat. No. 4,930,935 referenced above. Preferably, screed assembly 72 further includes a pair of laser receivers (not shown), preferably mounted at an upper end 82e of vertical supports 82. The hydraulic cylinders 83 are extendable and retractable to maintain the screed and plow assembly at the appropriate level with respect to a signal from a laser beacon projector, as disclosed in U.S. Pat. No. 4,655,633, referenced above. The laser receivers detect a reference plane generated by the projector, and the controls of screeding device 10' automatically adjust the hydraulic cylinders 83 accordingly. As shown in FIGS. 7 and 8, a simplified screed assembly 72' may be pivotally mounted at outer end 14b of pipe assembly 14 of placing and screeding apparatus 10'. Screed 72' is similar to screed 72 and preferably comprises a pair of vertical adjustable supports 82' and a vibratory plow 84', which is movably mounted at a lower end of each of the supports 82'. Similar to the vibratory screed 86, discussed above, the vibratory plow may vibrate horizontally along pins 84a' in response to actuation of a vibrating motor (not shown). Preferably, vertical supports 82' comprise laser beacon receivers 89, which are 360° omni-directional receivers which detect the position of a laser reference plane such as that provided by a long range rotating laser beacon projector (not shown). A control (not shown) receives and processes signals from the laser receivers and is operable to automatically adjust the level of the vibratory plow 84' via a pair of hydraulic cylinders 83' positioned along each vertical support 82'. As discussed above with respect to placing apparatus 10, placing and screeding apparatus 10' may be remotely controlled via a wire or radio signal, or may include an operating station 30 on the base or lead units 16 or 18 for an operator to drive and control the placing and screeding apparatus, as shown in FIG. 8. The operating station 30 may comprise a seat 30a, steering wheel 30b, and controls for actuating the various solenoids 40 in order to control all aspects of the placing and screeding apparatus. Referring now to FIG. 10, an hydraulic schematic for lead unit 18 of placing and screeding apparatus 10' is shown. The drive motors 44 and hydraulic cylinders 56a and 56b of steering system 52, and pipe extending cylinder 32 are operable via solenoid valves 40a, 40b and 40c and pump 28, in the same manner as discussed above with respect to FIG. 5. Operation of the screeding assembly 72 or 72' is preferably also provided via hydraulic pump 28 and associated hydraulic lines, cylinders, and motors, as discussed below. Pump 28, reservoir 38, and hydraulic solenoids 40 are preferably positioned in movable support 18, in order to minimize the length of the hydraulic lines necessary to reach from the solenoids 40 to the hydraulic cylinders on the outer tube or on the screeding device. In order to raise or lower screed 72, a pair of hydraulic solenoids 40e and 40f is provided which provides pressurized fluid to a right and/or left screed elevation hydraulic cylinder 83a and 83b via a corresponding pair of hydraulic fluid lines 92a and 92b and 93a and 93b, respectively. Preferably two solenoids are provided to separately raise and lower each side of the screed assembly in order to change the angle of the plow and screed assembly, if desired. The hydraulic cylinders 83a and 83b function in a known manner to raise or lower either or both sides of the vibratory plow relative to the ground. Furthermore, the screed self-leveling cylinders 88, which are operable to level the plow 84 and screed 86 in response to a signal from the level sensor, are extended and retracted via pressurized fluid lines 94a and 94b and another hydraulic solenoid 40g. The two hydraulic cylinders 88 are plumbed together such that each cylinder extends and retracts the same amount as the other, thereby providing even and uniform pivoting of the plow, auger, and screed assembly. This provides a more uniform surface of concrete and further reduces the possibility of digging one end of the plow or screed into the uncured concrete. Additionally, the vibratory motor 86c of screeding device 86 is preferably an hydraulically actuated motor and is actuated via a pair of hydraulic lines 96a and 96b and another hydraulic solenoid 40h. As hydraulic line 96a is pressurized, motor 86c causes rotation of shaft 86b which further causes vibration of screed 86, in order to compact and smooth the concrete after it has been placed by the dispensing nozzle 14b. Hydraulic motor 85a for rotating or driving auger 85 is similarly actuated via a pair of hydraulic lines 97a and 97b and an hydraulic solenoid 40i. In order to pivot the screeding device 72 relative to tube assembly 14, hydraulic cylinder 76 may be extended or retracted via a pair of hydraulic fluid lines 98a and 98b and another hydraulic solenoid 40j. Hydraulic cylinder 76 is also preferably a conventional cylinder and may be extended and retracted in a known manner, as discussed above. Because screed 72 is preferably positioned at outer end 14b of tube assembly 14, which is extendable and retractable relative to lead unit 18 via outer tube 15d, hydraulic lines 92a, 92b, 93a, 93b, 94a, 94b, 96a, 96b, 97a, 97b, 98a and 98b are preferably extendable and retractable with outer tube 15d. Preferably, the hydraulic lines are wound or coiled about a spring biased hydraulic hose reel (not shown), such that the hydraulic lines may extend and retract corresponding to extension or retraction of tube assembly 14. The hose reels are spring biased to recoil the hydraulic lines as the outer tube, and thus dispensing nozzle 14c', is retracted relative to movable support 18. The hydraulic lines may be joined and wound about a single hose reel or may be separately wound around separate hose reels, without affecting the scope of the present invention. Alternately, the hydraulic lines may be telescoping tubes or may otherwise extend and retract in any known manner between movable support 18 and screeding device 72. ROTATABLE SCREED HEAD Referring now to FIGS. 11 - 14, a placing and screeding apparatus 10" may comprise a rotatable screeding device 104 positioned at an outer dispensing nozzle 14c' of tube assembly 14. Preferably, base unit 16, movable support 18, and tube assembly 14 are substantially similar to those described above with respect to placing apparatus 10, such that no further discussion of their structural components and operation is required herein. At an outer end of the tube assembly 14, a dispensing nozzle 14c' is mounted which includes a 90° elbow for directing the concrete in a generally downwardly direction. An opening is provided in an upper portion of nozzle 14c' for a shaft 112 of screeding device 104 to pass therethrough, as discussed below. Rotatable screed 104 comprises a lift cylinder 106, a rotational motor 108, a vertical support 110 and a rotatable shaft 112 which extends through vertical support 110 and dispensing nozzle 14c' to connect to a rotatable screed head 114. Rotatable head 114 is a generally cylindrically shaped tube with an open top and bottom and a lower ring 114a, which is upwardly turned at an outer edge 114b thereof. A plurality of ribs 116 extend from a center portion 114c of rotating head 114 outwardly, where shaft 112 is secured, to an outer, cylindrical ring 114d which defines the cylindrical head 114. The lower ring 114a functions to compact the concrete as the head 114 is moved over the placed, but uncured concrete. Hydraulic motor 108 is mounted to a bearing block 118, which is secured between a pair of articulating support arms 120, such that bearing block 118 and motor 108 are substantially precluded from rotating, while the motor may cause rotation of the shaft 112 of screeding device 104. Hydraulic cylinder 106 is mounted at one end to an upper portion of dispensing nozzle 14c' and at another end to motor 108, such that extension and retraction of hydraulic cylinder 106 lifts and lowers motor 108 and thus shaft 112 and rotating head 114, while articulating arms 120 extend or fold in response to such vertical movement of motor 108. Preferably, lift cylinder 106 is operable to automatically raise or lower motor 108, shaft 112 and head 114, in response to a signal from a laser receiver 119, which is preferably mounted at an upper end of screeding device 104. Lift cylinder 106 is controlled in response to the laser signal in a similar manner to the lift cylinders 83 and 83' of screeding devices 72 and 72', discussed above. During operation, concrete is provided through dispensing nozzle 14c' and received within cylindrical portion 114d of rotating head 114. As the movable support 18 moves arcuately and/or the tubes 14 extend and/or retract, the screeding device 104 places concrete in the particular targeted areas and is operable to simultaneously spread and smooth the concrete as it moves therealong. Rotation of shaft 112 by motor 108 causes corresponding rotation of rotating head 114 to spread and smooth the concrete as the head is moved over the newly placed concrete. The lower ring 114a provides a generally smooth and flat surface which smoothes the uncured concrete as the head is rotated and moved radially and arcuately relative to the base unit 16. Because the lower screed head 114 is generally circular and curved upwardly around the entire circumference of head 114, screeding device 104 is operable to smooth and compact uncured concrete via movement in any direction, such that the screed device does not have to be pivoted 90° when lead unit 18 reverses its direction. Referring now to FIG. 14, an hydraulic schematic is shown for the movable support 18 of placing and screeding apparatus 10". Because the drive system motors 44, the cylinders 56a and 56b of the steering system 52, and tube extension cylinder 32 are identical to those discussed above with respect to placing apparatus 10, the details of these systems will not be repeated herein. Hydraulic cylinder 106 of screeding device 104 is extendable and retractable via a pair of hydraulic fluid lines 122a and 122b and an hydraulic solenoid 40k. Hydraulic solenoid 40k may be manually actuated, or preferably electronically actuated in response to a signal received from laser receiver 119 on screeding apparatus 104. Additionally, hydraulic motor 108 is operable to rotate the rotatable head 114 of screeding device 104 in response to pressurized fluid being supplied to one of its ports 108a and 108b via hydraulic fluid lines 126a and 126b, respectively, and an hydraulic solenoid 40m. Because outer tube 15d of tube assembly 14 is extendable relative to movable support 18, hydraulic lines 122a, 122b, 126a and 126b preferably comprise roll-up hoses, which are wound or coiled about a spring biased hydraulic hose reel (not shown), similar to the hydraulic lines of placing and screeding apparatus 10', discussed above. AIR CUSHION UNITS Referring now to FIGS. 15 - 20, an alternate embodiment 200 of the present invention comprises an extendable tube assembly 214, a lead unit or movable support 218 and a base unit 216. Base unit 216 and lead unit 218 of concrete placing apparatus 200 are air cushion devices, which comprise one or more lift fans 217, which are operable to raise the units above the support surface via a cushion of air between the unit and the support surface. Because these units travel on a cushion of air and thus do not require wheels or the like travelling along the ground, these units may be used in areas where concrete has already been placed, in order to add more concrete or to screed the placed concrete, without damaging or displacing any of the already-placed concrete. Also, the cushion of air functions to spread out the weight of the units over a large area or foot print, which minimizes the pressure of the units on the support surface or ground. Due to the low ground pressure of these units, they are well suited to operation in areas with limited load holding capability, such as corrugated metal decks of elevated slabs. Similar to the movable wheeled units discussed above, the air cushion units are operable to support and move either a discharge conduit or pipe for placing uncured concrete or a screeding device for smoothing/grading already placed concrete, or both, without affecting the scope of the present invention. As shown in FIGS. 15 - 17 and 19, movable support or lead unit 218 may be generally disc shaped, with an upper disc portion 218a and a cylindrical side wall 218b extending downwardly therefrom. However, as shown in FIGS. 35-40 and 47, the air cushion units may be generally rectangular-shaped, or hexagonal-shaped, or may be any other shape, without affecting the scope of the present invention. Movable support 218 may comprise two or four fans 217, or any other number of fans which are capable of lifting the unit off the ground. A brush-skirt seal 219 extends around the lower circumference of each unit to at least partially restrict or contain the cushion of air beneath the movable support and to prevent excessive dust and the like from blowing outward when the fans are activated. Fans 217 comprise a motor 217a which is operable to rotate blades 217b. Fans 217 are preferably pivotally mounted about a horizontal axes or pin 221, such that as the fans pivot slightly, the change in direction of air flow causes movement of the unit 218 along the ground, while still pushing enough air to support the unit above the ground. Preferably, the pivot axes 221 are generally parallel to one another and parallel to tube assembly 214, such that pivoting of the fans causes a movement of the unit 218 generally normal to tubes 214. Fans 217 are preferably mounted to lead unit 218 with their shafts 217c (FIG. 18) extending generally vertically, such that the fan blades 217b are oriented generally horizontally with respect to the ground. Preferably, fans 217 are conventional fan and motor units, such as a Kohler 25 horsepower motor with a Crowley fan, or any other known and preferably commercially available fans and motors. Optionally, as shown in FIG. 19, a directional fan 223 may be provided atop lead unit 218. Directional fan 223 may be pivotally mounted to lead unit 218 such that a shaft 223 a extends generally horizontally and supports and drives generally vertically oriented fan blades (not shown). Directional fan 223 may then be pivotable about a vertical axis or pivot 223b to push lead unit 218 in a direction generally opposite to the direction in which the fan blades are directed. Movable support 218 further comprises a pair of upwardly extending brackets or trunnions 218c, which are fixedly mounted to disc portion 218a. Trunnions 218c further include a notch or groove 218d for receiving a support pin 214e on an outermost tube 215d of tube assembly 214. Trunnions 218c are oriented to receive the tube assembly 214 such that tubes 214 extend generally between the two or four fans and motors and preferably generally parallel to the pivot axes 221 of the motors 217. Base unit 216 is similar to lead unit 218 in that it comprises two or four fan/motor assemblies 217 for lifting and supporting base unit 216 on a cushion of air above the ground. Base unit 216 further comprises an upper, disc shaped, swivel portion 216a and a lower, cylindrical side walled, base portion 216b, wherein the upper swivel portion 216a is rotatably mounted at an upper end of base portion 216b. A brush skirt 219 extends around a lower circumferential edge of the base portion 216b to provide a generally uniform engagement of the unit to the ground and to prevent excessive dust from being blown into the air when the fans are activated. Similar to lead unit 218 discussed above, each of the fan/motor assemblies 217 are preferably pivotally mounted to swivel portion 216a of base unit 216 along a pivot pin or axis 225, such that a slight rotation of the fan motors relative to base unit 216 may cause the base unit 216 to move along the ground in a direction generally normal to the pivot axes 225. Additionally, as shown in FIG. 16 A, base unit 216, and/or movable support 218, may include a plurality of casters, rollers or wheels 299 mounted to the frame of the air cushion units to ease manual movement of the units when the engines are shut down. Base unit 216 further comprises an S-shaped pipe connector 235 which further comprises an upper elbow 235 a and a lower elbow 235b, which are pivotally connected together in a known manner via a pivotable connector 235c (FIG. 18). An opening is provided through the side wall of base portion 216b for a passageway for supply tube 220. A supply hose or pipe section 220 is then connectable to a lower and outer end 235d of lower elbow 235b, while extendable pipe assembly 214 is connectable to an outer and upper end 235e of upper elbow 235a. Upper elbow 235a further comprises a mounting bracket 237 which extends upwardly therefrom and includes a cylindrical pivot or mounting pin 237a extending outwardly from each side of bracket 237. Similar to lead unit 218, base unit 216 includes tube mounting trunnions 216c, which are mounted to an upper portion of swivel portion 216a and include a notch or groove 216d for receiving the pivot pin 237a of bracket 237 on upper elbow 235a, thereby pivotally securing upper elbow 235a to swivel portion 216a. Upper elbow 235a may then pivot about a generally horizontal axis, in order to accommodate changes in the level of tube assembly 214 when lead unit 218 may be positioned at a different height from base unit 216. Clearly, other means for pivotally mounting connector 235 to base unit may be implemented, without affecting the scope of the present invention. In order to secure swivel portion 216a of base unit 216 to base portion 216b, while allowing for relative rotation therebetween, a plurality of rollers are positioned around an outer, circumferential edge of base unit 216. More particularly, as shown in FIG. 18, base portion 216b comprises a plurality of lower, vertically oriented rollers 226, which are positioned between an upper portion of cylindrical base portion 216b and an outer edge of swivel portion 216a and which are rotatable about horizontal pivot pins 226a. Rollers 226 engage an upper edge 216e of base portion 216b and a lower surface 216f of swivel portion 216a in order to support swivel portion 216a on base portion 216b, while allowing relative rotation therebetween. Furthermore, a plurality of brackets 227 extend upwardly from the upper portion of base portion 216b and provide vertical mounting pins 229a for mounting horizontal rollers 229 in spaced locations around an outer, circumferential edge 216g of swivel portion 216a. Rollers 229 function to prevent lateral movement of swivel portion 216a relative to base portion 216b, while still allowing relative rotation therebetween. Additionally, a plurality of upper rollers 231 are rotatably mounted to horizontal pins 231a on brackets 227 to also prevent vertically upward movement of swivel portion 216a relative to base portion 216b, while again allowing relative rotation therebetween. Preferably, an hydraulic rotation motor 233 (FIG. 18) may be provided on base unit 216 to drive or rotate swivel portion 216a relative to base portion 216b, in order to cause arcuate movement of dispensing end 214b of tube assembly 214. Preferably, as shown in FIG. 18, motor 233 is mounted to swivel portion 216a and includes a toothed pinion 233a, which is rotatable via actuation of motor 233 and which engages a correspondingly toothed gear 233b extending around an inner circumferential edge 216h of base portion 216b. Actuation of motor 233 causes rotation of pinion 233a, which causes subsequent movement of gear 233b relative to motor 233, such that swivel portion 216a is thus rotated about base portion 216b while being supported and guided by rollers 226, 229 and 231. Motor 233 may be operable in either direction, such that dispensing end 214b may be arcuately driven back and forth with respect to base unit 216. Base portion 216b is substantially non-rotatable even when raised above the ground because the concrete supply pipes 220 are connected through the opening in base portion 216 and thus substantially preclude rotation of base portion 216b. Preferably, base unit 216 further comprises an hydraulic pump 228 and reservoir 238 (FIG. 20), which is operable as a power source for rotation motor 233 and a plurality of tube assembly extenders, as discussed below. Optionally, as shown in FIG. 16A, pipe assembly 214 may pivot via a pivotable trunnion 216c' which is pivotable about a generally vertical axis via a turntable mounting arrangement of trunnion 216c' to base unit 216. In the illustrated embodiment 200a, the upper pipe elbow 235a' is mounted to trunnion 216c' and is pivotally connected to a connector pipe section (not shown). The connector pipe section and a lower elbow (also not shown) are mounted to or supported at an upper portion or surface 216i of the air cushion unit, while a lower end 235d' of the lower elbow is connected to supply pipe 220, which is also at least partially supported along the upper portion or surface of the air cushion base unit. Extendable pipe assembly 214 is generally similar to extendable pipe assembly 14, discussed above with respect to placing apparatus 10, in that it preferably comprises a plurality of nested or telescoping pipes 215a, 215b, 215c and 215d. However, because lead unit 218 may not be operable to travel radially outwardly from base unit 216, pipes 215a - 215d are extendable and retractable relative to one another via a plurality of hydraulic extending devices 243, 245 and 247. As best shown in FIGS. 15 and 16, each hydraulic device 243, 245 and 247 comprises an hydraulic cylinder 243a, 245a, and 247a and a rod/piston 243b, 245b, and 247b, respectively. An inward end 243 c of hydraulic cylinder 243 a is fixedly mounted to a bracket or collar 249 at an inner end of second tube 215b, while hydraulic cylinder 243a is also slidably supported within another collar or bracket 251 mounted at an inner end of third tube 215c. An end 243d of rod 243b is also mounted to an inner end of first tube 215a via a bracket 253. Similarly, an inner end 245c of hydraulic cylinder 245a is fixedly mounted to bracket 251 , while the cylinder 245a is slidably supported^ within another bracket 255, which is fixedly mounted to an inner end of outer tube 215d. An end 245d of rod 245b is then mounted to bracket 249 on second tube 215b. Similarly, an inner end 247c of hydraulic cylinder 247a is secured to bracket 255 on outer tube 215d, while an inner end 247d of rod 247b is secured to bracket 251 on the third tube 215c. Accordingly, as best shown in FIG. 16, as rod 243b is extended from hydraulic cylinder 243a, second tube 215b is moved outwardly from innermost tube 215a. Similarly, as rod 245b is extended from cylinder 245a, third tube 215c is moved outwardly from second tube 215b, while collar or bracket 251 slides along cylinder 243a. Likewise, as rod 247b is extended from cylinder 247a, outer tube 215d and lead unit 218 are moved outwardly from tube 215c, while bracket 255 slides along cylinder 245a. Preferably, as discussed below with respect to FIG. 20, each of the hydraulic cylinders 243, 245, and 247 are plumbed in series such that each rod is moved relative to its respective cylinders in a similar amount as the other rods and cylinders. The rods of the hydraulic cylinders preferably provide a dual passageway for fluid to pass through the rod and into the appropriate receiving cavity within the cylinder, as shown in FIG. 20. Accordingly, an hydraulic line 24 Id need only be provided from an inner end of one cylinder to the rod end of the next outer cylinder, while a second hydraulic line 241c is provided from an outer end of each inwardly positioned hydraulic cylinder inwardly along the cylinder to connect to the rod end of the next outwardly positioned cylinder, such that the hydraulic lines 241c and 24 Id remain fixed relative to their respective hydraulic cylinders and/or rod ends and thus do not require spring biased hose reels and hoses or the like to extend or retract the lines with the tube assembly 214 (FIGS. 15 and 20). Although shown and described as being extendable and retractable via a plurality of hydraulic cylinders plumbed in series, the tube assembly may alternately be extendable and retractable via conventional hydraulic cylinders or any other known means, and may even be individually extendable and retractable relative to one another, without affecting the scope of the present invention. Referring now to FIG. 20, an hydraulic schematic is shown for base unit 216. Power source or pump 228 is operable to draw hydraulic fluid from reservoir 238 and to extend and retract the hydraulic cylinders 243, 245 and 247 via an hydraulic solenoid 240n and a pair of hydraulic fluid lines 241a and 241b. Preferably, pressurized fluid may be provided through hydraulic line 241a in order to extend the tubes, while pressurized fluid may be provided through hydraulic line 241b in order to retract the tubes. More particularly, hydraulic line 241a is preferably connected with a passageway 243e extending longitudinally through rod 243b, such that the pressurized fluid is received in an outer end portion or receiving cavity 243f of the hydraulic cylinder 243 a. Similarly, hydraulic line 241b is connected to a second, outer passageway 243g through rod 243b to provide fluid to an inner end receiving cavity 243h of hydraulic cylinder 243 a. Each of the cylinders 245 and 247 are similarly plumbed, with an hydraulic line 241c connecting the outer end cavity 243f, 245f of the inwardly positioned hydraulic cylinders 243, 245 to the central passageway 245e, 247e of the rod of the next outwardly positioned hydraulic cylinder 245, 247, while a second line 24 Id connects the inner cavity 243h, 245h of the inwardly positioned hydraulic cylinder 243, 245 to the outer passageway 245g, 247g of the rod of the next outwardly positioned hydraulic cylinder 245, 247. Accordingly, as pressurized fluid is provided through hydraulic line 241a or 241b, the rods 243b, 245b and 247b extend from or retract into their respective cylinders uniformly with the other rods and cylinders. Hydraulic pump 228 is also operable to actuate hydraulic rotational motor ' 233 to rotate swivel portion 216a relative to base portion 216b of base unit 216. Rotational motor 233 is preferably operable via a solenoid 240o and a pair of hydraulic fluid lines 257a and 257b, which are connected to ports 233c and 233d, respectively, of motor 233. The rotational direction of the motor 233 is determined by which line 257a or 257b is pressurized by pump 228 and solenoid 240o, as would be apparent to one skilled in the art. As one of the fluid lines 257a or 257b is pressurized, rotational motor 233 functions to rotate pinion 233a to cause rotation of swivel portion 216a relative to base portion 216b via gear 122b, thereby swinging movably support 218 and outer end 214b of tube assembly arcuately with respect to base portion 216. Referring now to FIGS. 21 and 22, an alternate embodiment 200' is shown which is substantially identical to placing apparatus 200, discussed above, except placing and screeding apparatus 200' further comprises a screeding device 272 positioned at an outer end 214b of pipe assembly 214. Screeding device 272 may be a conventional screeding apparatus, a plow, auger and vibratory screed assembly or a vibratory plow assembly, as discussed above with respect to placing and screeding apparatus 10', or may be a rotating head screed, similar to screeding device 104, discussed above with respect to placing and screeding apparatus 10", and as shown in FIG. 21, or may be any other known means for compacting and smoothing the uncured concrete as it is placed by the dispensing nozzle of tube assembly 214. Because each of the screeding devices were already discussed above, a detailed description of their components and functions will not be repeated herein. As shown in FIG. 22, the hydraulic schematic for placing and screeding apparatus 200' is substantially similar to the schematic for apparatus 200, discussed above and shown in FIG. 20. However, hydraulic pump 228 of placing and screeding apparatus 200' may be further operable to raise and lower a rotating screed head device 272 via an hydraulic cylinder 206. Hydraulic cylinder 206 may be extended or retracted by pressurized fluid being provided thereto via lines 222a and 222b, respectively. Hydraulic lines 222a and 222b are pressurized via an hydraulic motor 228 and hydraulic solenoid 240k, which may be actuated in response to a signal received from a laser receiver 207, or may be manually actuated via a control panel or the like which may be mounted to base unit 216 or may be remotely located from the placing and screeding apparatus 200'. Similar to screeding device 104 of placing and screeding apparatus 10", rotation of rotatable screed head 212 (FIG. 21) is accomplished via a rotational motor 208, which is actuatable via of an hydraulic solenoid 240m and hydraulic fluid lines 211a and 211 b, in a similar manner as discussed above with respect to FIG. 14. Alternately, however, the hydraulic system of placing and screeding apparatus 200' may control other elevation cylinders, pivot cylinders, leveling cylinders, and/or vibratory motors, depending on the specific screeding device implemented, without affecting the scope of the present invention. Because the screeding device is extendable and retractable relative to the hydraulic pump located on base unit 216, the hydraulic lines required to raise, lower and/or rotate or pivot the screed head preferably comprise a plurality of hydraulic hoses coiled on at least one spring-biased hose reel (not shown) mounted at the base unit. Alternately, the hydraulic system could be mounted on the lead vehicle to eliminate the need for hose reels or the like. However, other means for providing actuation and control of the screeding device may be implemented, without affecting the scope of the present invention. Although depicted and described above as being connected to an air cushion base unit 216, air cushion lead unit 218 may otherwise be implemented with a wheeled base unit 216', as shown in placing and screeding apparatus 200" in FIG. 23, which is substantially similar to base unit 16 discussed above. Base unit 216' is preferably a four-wheeled drive and four-wheel steered unit and includes an hydraulic pump which is operable to drive and steer the wheels and which is further operable to extend and retract the pipe assembly 214 in a similar manner as discussed above with respect to base unit 216 of placing apparatus 200. As shown in FIG. 23, air cushion lead unit 218 may be extended out over a region where concrete has already been placed to add more concrete to a particular region, or to further smooth and compact the uncured concrete, if a screeding device is implemented on apparatus 200", while avoiding contact and disturbance of the already placed concrete. SWING TRACTOR Referring now to FIGS. 24 - 28, an alternate embodiment 300 of the present invention comprises a wheeled base unit 316, a telescopic extendable tube assembly 314 and a movable support or lead unit 318. Base unit 316 and tube assembly 314 are substantially similar to the base units and tube assemblies discussed above with respect to placing apparatus 10 and placing apparatus 200, respectively, such that a detailed description of these components need not be repeated herein. Lead unit 318 comprises a swing tractor, which is operable to support an outer end 314b of tube assembly 314 by freely rolling on wheels 320 as the tubes are extended outwardly from base unit 316. Arcuate movement or rotation of tube assembly 314 relative to base unit 316 is accomplished by axial movement of the wheels 320 of lead unit 318 via a rotational motor 322 (FIGS. 27 and 28). As best shown in FIGS. 24 and 25, lead unit 318 comprises a plurality of wheel trolleys 324 positioned about a circumferential edge 326a of an end frame or plate 326 of lead unit 318. Each wheel trolley 324 comprises a wheel 320, which is rotatably mounted on an axle 320a. The wheel trolleys 324 are defined by a pair of opposite side frame members 324a and a pair of opposite end frame members 324b, which generally surround their respective wheel 320. Each axle 320a of wheels 320 is mounted at each end to trolley side frame members 324a, such that the wheels 320 are freely rotatable within their frames 324a and 324b. Each end plate 324b of trolleys 324 further comprise a pair of rollers 327 rotatably mounted thereto on axles 327a extending outwardly from end plates 324b. Each end frame 326 of lead unit 318 has a generally U-shaped track or channel around its circumference, in order to provide a continuous, generally circular or oval-shaped track 326b extending around its circumference. Trolleys 324 are positioned between end frames 326, such that rollers 327 of wheel trolleys 324 rotatably engage channel 326b at each end of wheel trolleys 324. The wheel trolleys may thus travel around track or channel 326b in a direction which is generally axial relative to wheels 320. Each of the wheel trolleys 324 is connected to a next, adjacent wheel trolley via a drive chain or linkage 329, which is secured to each trolley 324 at each roller axle 327a. Preferably, each of a pair of chains 329 may be secured to rollers 327 on wheel trolleys 324 at an opposite end of wheel trolleys 324, to provide uniform driving of the wheel trolleys at each end thereof, thereby substantially precluding binding of the wheel trolleys as they are moved along channel or track 326b of end frames 326. End frames 326 of lead unit 318 further comprise a pair of upwardly extending arms 326d. Each arm 326d is connected to a corresponding arm 326d on the opposite end frame 326 via a generally cylindrical bar or rod 336. An outer tube 315d of tube assembly 314 preferably further includes a pair of laterally outwardly extending mounting arms or extensions 338 which extend from tube 315d and engage rods 336 on lead unit 318 for mounting the tube assembly 314 to lead unit 318. Mounting arms may be clamped, welded or otherwise secured to tube 315d. Arms 338 preferably further comprise downward-extending mounting portions 338a, which are correspondingly formed to uniformly engage the generally cylindrical rods 336, thereby substantially uniformly supporting tube assembly 314 on lead unit 318. Preferably, lead unit 318 is generally oval shaped and comprises a pair of gears or sprocket wheels 330 and 331 positioned substantially adjacent to each of the end plates 326 of lead unit 318. Sprocket wheels 330 and 331 are each rotatably mounted on an axle 330a and 331a, respectively, each of which is secured at opposite ends to axle mounting brackets 326c of end frames 326. Each of the sprocket wheels 330 and 331 comprises a plurality of gear teeth 330b and 331b, respectively, along their outer circumferential edges. Teeth 330b and 331b engage gaps 329a in chains 329, as the chains, and thus the wheel trolleys, are routed and driven around sprockets 330 and 331. Preferably, at least one of the sprocket wheels 330 and 331 or axles 330a and 331a is rotatably driven by a rotational motor 322 (FIGS. 27, 28 and 30), which is positioned at one of the ends of at least one of the axles 330a and 331a. As shown in FIG. 27, motor 322 may be mounted on axle 331, while axle 330a and thus sprocket wheels 330 are freely rotatable relative to frame 326. Accordingly, rotation of axle 331a by motor 322 causes rotation of sprocket wheels 331, thereby causing movement of drive chains 329 about the respective sprocket wheels 331, which further drives the rotation of the other sprocket wheels 330. The movement of chains 329 further drives the wheel trolleys 324 around channel 326b of end frames 326. As the wheel trolleys 324 are driven in a generally axial direction relative to axis 320a, wheels 320 function to sequentially engage the ground and pull the unit 318 laterally or sidewardly relative to tube assembly 314, thereby moving tube assembly 314 arcuately with respect to base unit 316. Preferably, rotational motor 322 is an hydraulic rotational motor and is interconnected to an hydraulic pump 328 on base unit 316 via a pair of hydraulic fluid lines 334a and 334b (FIG. 30). Because wheels 320 are not rotatably driven on lead unit 318, extension and retraction of the tube assembly 314 is preferably provided via a plurality of hydraulic cylinders 343, 345, and 347, similar to hydraulic cylinders 243, 245, and 247, discussed above with respect to placing apparatus 200. Preferably, the hydraulic cylinders 343, 345, and 347 are likewise plumbed in series, as discussed above with respect to hydraulic cylinders 243, 245, and 247. However, other means for extending and retracting the tubes 315a, 315b, 315c and 315d relative to base unit 316 may be implemented without affecting the scope of the present invention. As shown in FIGS. 24 and 26, lead unit 318 may be implemented with a wheeled base unit 316, which comprises four wheels 316d which are drivable and steerable via hydraulic pump 328, motors 344 and hydraulic cylinders 356a and 356b, in a similar manner as placing apparatus 10, discussed above. Likewise, a supply end 314a of pipe assembly 314 is preferably mounted to a trunnion 316c on a swivel portion 316a, which is rotatably mounted to a base portion or frame 316b of base unit 316. As discussed above, swivel portion 316a may further include a crane device (not shown) for lifting and positioning the supply pipes and hoses (also not shown) for connection to or detachment from supply end 314a of pipe assembly 314. As shown in FIG. 28, lead unit 318 may otherwise be implemented with an air cushion base unit 316', which is substantially identical to the base units of placing apparatus 200 and placing and screeding apparatus 200', discussed above. Similar to those units, base unit 316' may comprise two or more fans and motors 317, to provide proper lift for the air cushion device. An hydraulic motor (not shown) and a plurality of rollers 316c' (and other rollers not shown) are preferably included on base unit 316', to facilitate rotation of an upper portion 316a' relative to a lower portion 316b', in a similar manner as discussed above with respect to placing apparatus 200. Additionally, lead unit 318 may be implemented with a screeding device 372 for smoothing and compacting the concrete as it is dispensed from dispensing end 314b of tube assembly 314, as shown in FIG. 29. Screeding device 372 may be a conventional screeding device, a plow, auger and screeding device similar to the device disclosed in U.S. Pat. No. 4,930,935, referenced above and discussed with respect to screeding device 72, the simplified screeding device 72' with a vibratory plow, or a screeding device with a rotational head 314, as shown in FIG. 29, and as discussed above with respect to screeding device 104 of placing and screeding apparatus 10". However, other devices or means for smoothing and compacting uncured concrete as it is dispensed from the dispensing end 314b of the tube assembly 314 may be implemented, without affecting the scope of the present invention. It is further envisioned that a swing tractor unit may support only a screeding device for smoothing/grading uncured concrete that has already been placed at a targeted area of the support surface. The screeding device may be supported at the swing tractor, or may be supported by an extended or extendable support member extending from the swing tractor. Referring now to FIG. 30, an hydraulic schematic of the power source and motors and cylinders for a placing and screeding apparatus 300", as shown in FIG. 29 and discussed above. The drive system and motors 344 for the wheeled vehicle 316 are controlled via an hydraulic pump 328, an hydraulic solenoid 340a and hydraulic fluid lines 339a and 339b, which are identical to the drive system and motors 44 discussed above with respect to placing device 10 and FIG. 5. The steering cylinders 356a and 356b of base unit 316 are also operable via an hydraulic solenoid 340b and fluid lines 354a and 354b, in an identical manner as discussed above with respect to placing device 10 and FIG. 5. Because wheeled unit 316 is implemented with a movable support which is not operable to extend and retract the tube assembly 314, hydraulic motor 328 is further operable to actuate a solenoid 340n to pressurize hydraulic fluid lines 341a or 341b in order to extend and retract hydraulic cylinders 343, 345, and 347, in the same manner as discussed above with respect to placing apparatus 200 and FIG. 20. Furthermore, because wheeled base unit 316 is implemented with the swing tractor lead unit 318, hydraulic pump 328 is also operable to actuate an hydraulic solenoid 340p to provide pressurized fluid to one of hydraulic fluid lines 334a and 334b, in order to rotatably drive hydraulic motor 322 on lead unit 318, thereby driving wheels 320 axially around sprockets 330 and 331. Hydraulic fluid line 334a is connected to port 322a of motor 322 and may be pressurized to cause rotation of a motor shaft in one direction to drive the wheel trolleys 324 to pivot tube assembly 314 about base unit 316 in a first direction, while hydraulic fluid line 334b is connected to an opposite port 322b of motor 322 and may be pressurized to cause opposite rotation of wheel trolleys 324 and rotation of motor 322 and thus an opposite direction of movement of lead unit 318 and tube assembly 314. As shown in FIG. 29, placing and screeding device 300" may comprise a screeding device 372 with a rotating head 313, which is driven by a motor 308 and raised and lowered by an elevation cylinder 306. Accordingly, hydraulic motor 328 of base unit 316 is further operable to actuate an hydraulic solenoid 340k, which pressurizes an hydraulic line 304a or 304b to raise or lower the rotating head 313 via cylinder 306. Preferably, raising and lowering of the rotatable head 313 is performed automatically in response to a signal received from a laser receiver 312 positioned at an upper end of screeding device 372. However, the raising and lowering of the rotatable screeding head 313 may be performed manually, or in response from a signal from another type of leveling sensor or system, without affecting the scope of the present invention. Additionally, hydraulic motor 328 is operable to actuate a solenoid 340m for pressurizing hydraulic fluid lines 310a and 310b for rotatably driving hydraulic motor 308 and thus the rotatable screeding head 313 on screeding device 372. Because tube assembly 314 is extendable and retractable relative to base unit 316 while motors 322 and 308, along with hydraulic cylinder 306, are positioned toward a remote end of the tube assembly, hydraulic fluid lines 304a, 304b, 310a, 310b, 334a and 334b are preferably hydraulic fluid hoses which may be wound on multiple spring-biased hydraulic hose reels (not shown) to allow the hoses to unwind and thus extend outwardly with the tube assembly, and to wind back up or retract as the tube assembly is retracted. METHOD FOR PLACING CONCRETE Referring now to FIGS. 31 - 34, the process of placing concrete in a targeted area is shown with placing apparatus 10. The base unit 16 is positioned such that dispensing nozzle 14c at outer end or dispensing end 14b of telescopic tube assembly 14 may reach the farthest corner of the targeted area. The lead vehicle is driven to a point where the tubes 14 are fully extended, and then turned and oriented in a direction generally normal to the longitudinal direction of the tube assembly 14. The lead vehicle 18 is then driven arcuately back and forth along path 11a with respect to base vehicle 16 to place concrete within an area proximate to the dispensing end 14b of tube 14 while outer tube 15d is fully extended from lead unit 18, as shown in FIG. 31. Outer tube 15d may then be partially or fully retracted relative to lead unit 18, while lead unit 18 again travels arcuately along substantially the same path 1 la, to further place concrete in the region immediately adjacent to and radially inward from the first area, as shown in FIG. 32. As lead unit 18 is driven back and forth, along generally the same arcuate path, outer tube 15d may be retracted approximately 2 Vi feet with each pass, such that the preferred 7 feet of extension is fully retracted after three passes of lead unit 18. Upon completion of the first region, the lead unit 18 is driven back toward base unit 16, while still travelling along a generally arcuate path relative to the base unit, such that the tube assembly 14 is partially retracted, as shown in FIG. 33. Preferably, the lead unit 18 is moved radially back toward base unit 16 approximately 7 feet, such that after lead unit 18 is moved radially inwardly toward base unit 16, outer tube 15d may again be extended from tube 15c and lead unit 18 to position dispensing nozzle 14c proximate to the already placed concrete. Lead unit 18 may then be driven back and forth along a second path l ib, while outer tube 15d is partially retracted after each pass. The processes described with respect to FIGS. 31 and 32 may then be repeated for the next sections or regions of the targeted area, without any gaps or insufficient concrete being placed in or between any of the regions. This process is repeated until all of the tubes are completely retracted and concrete has been dispensed over the entire targeted area, as shown in FIG. 34. The supply end 14a of tube assembly 14 may then be disconnected from the supply hose or tubes 20, several sections of the supply pipe may be removed, and the base unit 16 may be repositiohcd and reconnected to the supply line. Upon reconnection, the telescoping tubes may be extended such that the lead unit is again ready to begin placing concrete at the next targeted area. Because the extension and retraction of the tube assembly may be continuously adjusted while the tubes are traveling arcuately back and forth relative to the base unit, the dispensing end of the tube assembly may provide concrete to every location in the targeted area, thereby uniformly distributing the concrete and substantially precluding the possibility of an insufficient amount of concrete being dispensed in any given area. Although described with pipes of a preferred length and movement of the lead unit a preferred distance, clearly the scope of the present invention includes other placing and/or screeding apparatus' which have different length pipes and/or are moved a different distance when in use. Also, although FIGS. 31-34 show the process for placing concrete with wheeled vehicles, the process is substantially similar if the lead unit is an air cushion device or a swing tractor and/or if the base unit is an air cushion device. The telescopic tubes are then operable to radially extend and retract the tubes and air cushion or swing tractor support unit while the movable support unit and/or the base unit, whether it is an air cushion device or wheeled vehicle, are operable to move or to rotate or swivel to arcuately move the support unit and tube relative to the base unit. ARTICULATED PIPE ASSEMBLY Referring now to FIGS. 35-48, an alternate placing apparatus 400 comprises an articulated pipe or tube assembly 414, a generally fixed or non-movable base unit 416, and a plurality of movable air cushion supports or units 418. As used herein, the term "articulated" describes a jointed or bendable tube or pipe assembly which folds or bends between a retracted position, where the joints are substantially angled or bent, and an extended position, where the tube assembly is substantially straight or linear. A supply end 414a of articulating tube assembly 414 is connected to a concrete supply tube 20 at base 416. Tube assembly 414 comprises a plurality of pivotable pipe sections 415b, 415c and 415d, which are pivotable relative to a generally fixed supply end 414a, an inner or supply pipe section 415a and base 416, such that movable supports 418 and a discharge end 414b of tube assembly 414 are movable relative to base 416 to place uncured concrete at substantially all locations within a targeted area in the vicinity of base 416. Each pipe section 415a, 415b, 415c and 415d is connected to an adjacent section or sections via corresponding flexible hoses or tubes 415e, which bend or flex to allow pivotal movement between the pipe sections to define joints 431 a, 43 lb and 431 c. Additionally, a screeding device (not shown), such as the screeding devices discussed above with respect to placing and screeding apparatus 10', may be mounted at discharge end 414b of tube assembly 414 to grade and smooth the uncured concrete as it is placed at the support surface by discharge end 414b. Movable supports 418 are generally similar to the movable air cushion units described above with respect to placing apparatus 200, such that a detailed description will not be repeated herein. Suffice it to say that movable supports 418 comprise a pair of lift fans 418a and a body 418b which is movably supported by a cushion of air generated by the lift fans 418a between body 418b and the support surface. Each movable support 418 further includes a mounting trunnion 429 positioned at an upper surface 418c of the body 418b of movable supports 418. Trunnions 429 include a pair of notches or grooves 429a (FIG. 39) for pivotally receiving a pair of pins 425d of a mounting bracket 425 at each pipe section 415b, 415c and 415d, as discussed below. Movable supports 418 function to support each pipe section 415b, 415c and 415d remotely from the base unit 416 and allow the pipe sections to be movable relative to one another to move the discharge end 414b about a targeted area of the support surface, as discussed in detail below. Movable support 418 further includes a lower seal 451 (FIGS. 40 and 41), which extends around the lower circumference of each unit to at least partially restrict or contain the cushion of air beneath the movable support when the lift fans are activated. Lower skirt 451 may comprise a brush skirt seal, such as the brush skirt seal 219 of movable support 218, discussed above, or may comprise an inflatable seal 451. Inflatable seal 451 comprises a flexible bladder, wall or seal 452, which comprises a rubber-like material, such as Polyurethane coated nylon fabric or the like. Flexible wall 452 extends around a lower circumference 418d of movable support 418 and defines an inflatable cavity 453 therebeneath (FIG. 41). Preferably, flexible wall 452 is secured at an outer edge 452a to lower circumferential region 418d of body 418b of movable support 418, while an inner edge 452b is secured along an inner ring 418e at a lower surface of body 418b. Flexible wall 452 may be secured at its respective locations via a plurality of fasteners 454, such as bolts or screws, such as self tapping screws or the like. Flexible wall 452 is positioned circumferentially around the entire circumference of the lower portion of body 418b, such that inner edge 452b extends radially inwardly of at least a portion of the fans 418a of movable support 418. Accordingly, when fans 418a are activated, air is blown through a passageway 455 of body 418b and into cavity 453, such that a portion of the air from the fans functions to inflate seal 451, while the remainder of the air from the fans raises and supports movable support 418 above the ground or support surface. Inflatable seal 451 at least partially contains the air beneath the movable support and thus assists in supporting movable support 418 as the support unit is moved over the corrugated decking or concrete at the support surface. Similar to the air cushion units of placing apparatus 200, casters, wheels or rollers (not shown in FIGS. 35-42) may be mounted on the frame of the air cushion units to ease manual movement of the units when the engines are shut down. Because the seal 451 is flexible and rounded, as shown in FIG. 41, seal 451 functions to glide over placed concrete, and substantially reduces or precludes pushing or plowing of any already placed uncured concrete and accumulating the concrete around the outer edge of the movable support as it is moved along the placed concrete of the support surface. When operable, fans 418a are capable of raising and supporting movable support 418, such that there is a gap of approximately one and one-half to two inches between a lower surface 452c of inflatable seal 452 and the corrugated decking of the support surface or other support surface. Preferably, movable support 418 is operable to be raised and supported at least approximately one-half inch above any concrete which may be placed at the support surface. If rebar or other additional materials are placed above the corrugated decking, the air cushion support preferably also provides clearance over such materials. The movable support unit is, thus, capable of floating above the support surface and above any previously positioned rebar, or any already placed concrete, without damaging the preplaced concrete surface. Therefore, movable supports 418 may move over the support surface while placing and/or screeding the concrete at the targeted area of the support surface, without disrupting the concrete that has already been placed and/or screeded at that area. Referring to FIG. 39, each pipe section 415b, 415c, 415d of tube assembly 414 is pivotally mounted to trunnion 429 at upper surface 418c of each movable support 418. A pivotable trunnion mount or bracket 425 is clamped to each pipe section 415b, 415c and 415d generally near a midpoint thereof via a pair of clamps 425a. Clamps 425a are pivotally secured to the trunnion mount 425, which defines an opening 425c therethrough generally adjacent to clamps 425a. Openings 425c are formed to be larger diameter than the diameter of the pipe sections 415b, 415c and 415d, such that the pipe sections are insertable through openings 425c and are pivotable therein. Because the pipe sections are secured to clamps 425a, which are pivotably secured to mount 425, the pipe sections are pivotable with respect to mount 425, and thus movable support 418, about an axis 427a extending longitudinally along the respective pipe section. Trunnion mount 425 further includes a pair of oppositely extending generally cylindrical pins, axles or tubes 425d, which extend laterally outwardly from each side of trunnion mount 425. Cylindrical pins 425d are insertable within a pair of grooves or channels 429a of trunnion 429 and are pivotable about an axis 427b defined by pins 425d of mount 425. Accordingly, pipe sections 415b, 415c and 415d are pivotably mounted to each movable support 418, such that the pipe sections are pivotable about a pair of axes 427a and 427b, which are generally perpendicular to one another. This allows the pipe sections to pivot relative to movable supports 418 to accommodate for changes in the height or orientation of the movable supports as they may encounter uneven areas at the support surface or ground. Each pipe section 415a, 415b, 415c and 415d is connected at one or both ends to a hose section 415e (FIGS. 35, 36 and 38), such that a hose section is connected to the opposed ends of each adjacent set of pipe sections. Each hose section 415e is secured to the respective end of the pipe sections via a clamp 415f or any other known clamping means. Hose sections 415e are flexible and allow the adjacent pipe sections 415a, 415b, 415c and 415d to pivot with respect to one another, as shown in FIGS. 35 and 36, and define respective joints 431a, 431b and 431c. As best shown in FIG. 38, pipe sections 415b, 415c and 415d are pivotable relative to each other about a generally vertical axis 431 at each joint 43 la, 43 lb and 43 lc via flexing or bending tube sections 415e, which are vertically supported by a pair of pivotable linkages or members 421 and 422. Pivotable members 421 and 422 extend along each hose 415e and above and below each hose section 415e and are connected to the corresponding opposed ends of the adjacent pipe sections, such as 415b and 415c. Each joint 43 la, 43 lb, and 431c is thus defined by a pair of upper pivotable members and a pair of lower members which are preferably substantially similar, such that only one set will be described in detail, with the other set being similarly mounted to placing apparatus 400. The pivotable linkages 421 and 422 are secured to the opposed ends of the adjacent pipe sections by a mounting member 419 clamped to each pipe section 415a, 415b, 415c and/or 415d. Each mounting member 419 comprises a mounting bracket structure 419a for mounting a powered actuating or extending device, such as a pair of hydraulic cylinders 443, 444, which are cooperatively operable to cause pivotable movement of the pipe sections, as discussed below. As shown in FIG. 38, the mounting bracket 419a may be positioned at an upper or lower end of each mounting member 419. The mounting members 419 may then be reversibly mounted at the opposed ends of the adjacent pipe sections to allow one set of hydraulic cylinders to be mounted above the hose 415e and a second set of hydraulic cylinders to be mounted below the hose 415e. As is best seen in FIG. 38, each pivotable linkage 421, 422 comprises a substantially rigid beam or member, and is pivotally interconnected with the other linkage to define the vertical axis 431 positioned generally in the vicinity of a midpoint of each flexible tube 415e. Opposite ends 421c, 422c of members 421, 422 are fixedly secured to mounting members 419, while connecting ends 421a, 422a are pivotally secured together. Preferably, connecting end 421a of pivotable linkage 421 may be inserted within a forked connecting end 422a of linkage 422 and pivotably secured thereto. Preferably, one or both of the upper and lower pivotable members 421 further include a gear member 424a, which is fixedly secured at end 421a of pivotable member 421. Gear member 424a may be fixedly mounted to member 421 via insertion of the gear 424a within a slot or gap 42 lb of member 421 , and insertion of pins 424c through a plurality of openings 42 Id in gear 424a, in order to pin or otherwise secure gear 424a within slot 421b. However, gear 424a may be mounted to member 421 via any other known means, without affecting the scope of the present invention. Gear member 424a, and thus member 421, is rotatable relative to member 422 via the pair of hydraulic cylinders 443 and 444. Each hydraulic cylinder 443, 444 comprises a cylinder 443a, 444a and a rod end 443b, 444b, which is extendable and retractable relative to the respective cylinder via pressurized fluid, as discussed above with respect to hydraulic cylinder 32. A flexible belt 424b or chain linkage or the like is routed around gear member 424a and connected at each end to rod end 443b, 444b of hydraulic cylinders 443 and 444. Hydraulic cylinders 443 a and 444a may be secured to mounting bracket 419a via engagement of a generally cylindrical mounting member 445 at an end of cylinders 443a, 444a with corresponding notches or recesses 419d formed in brackets 419a (FIG. 38). Hydraulic cylinders 443 and 444 cooperatively extend and retract, such that as rod end 444b of cylinder 444 extends, rod end 443b of hydraulic cylinder 443 correspondingly retracts, and vice-versa. Because gear member 424a is fixedly secured to structural member 421, while being pivotable relative to structural member 422, pulling on belt or chain 424b by either hydraulic cylinder 443 or 444 results in pivotal movement of gear 424a relative to member 422, which further results in pivoting of structural member 421 relative to member 422, and thus pivoting of the adjacent pipe sections and movable supports relative to one another. As shown at joint 431a in FIG. 35, both the upper and lower pair of pivotable linkages 421, 422 may include a gear member 424a and hydraulic cylinders 443 and 444, which cooperatively extend and retract to pivot pipe section 415b relative to pipe section 415a. The additional pair of hydraulic cylinders may be beneficial or necessary to generate enough pulling force at the belts or chains 424b to pivot all three movable air cushion supports 418 relative to fixed pipe section 415a and base unit 416 about the corresponding vertical axis 431 of joint 43 la. As shown in FIG. 35, two pair of hydraulic cylinders may be positioned between the base unit and first movable support at joint 43 la, while only one set may be required to pivot or move the other movable supports relative to one another at the outer joints 43 lb and 43 lc. Base unit 416 of placing apparatus 400 is preferably substantially fixed relative to the support surface and supply tube 20. Base 416 preferably has two or more legs 416a which extend generally downwardly to support base 416 and supply end 414a of pipe section 415a of tube assembly 414 above the support surface. Preferably, legs 416a are adjustable, such as via a hand crank 416b or the like, such that the angle between the legs may be adjusted to correspondingly adjust the height at which base unit 416 supports the supply end 414a of tube assembly 414. The hand crank 416b may be threaded and one of the legs 416a may be correspondingly threaded, such that rotation of crank 416b pulls the legs toward each other or pushes them away in order to adjust the height of the base unit 416. Preferably, base 416 (FIGS. 35-37) is fixedly positioned at the support surface, such that supply end 414a and supply pipe section 415a of tube assembly 414 are substantially immobilized by base unit 416. Preferably, base unit 416 is secured via at least one restraining device 417a and/or 417b (FIGS. 35, 36 and 42-48). Preferably a pair of restraining devices 417a and 417b are mounted at supply pipe section 415a at or near opposite ends thereof. A base restraining device 417a includes a pair of cables 433a (FIGS. 36 and 42) extending therefrom. The cables 433a may be extended and retracted via corresponding hand cranks 435a (FIG. 37), such that the tension in the cables may be adjusted to substantially limit lateral movement of supply end 414a and thus secure base unit 416 in the selected position. As shown in FIG. 42, cables 433 a may be secured to a fixed structure, such as steel columns 409 or the like, at the support surface. Preferably, a second restraining device 417b is mounted at an outer end of supply section 415a of tube assembly 414 and provides a second pair of cables 433b which extend outwardly from opposite sides of restraining device 417b. The cables 433b may be adjusted and tightened via rotation of corresponding hand cranks 435b at restraining device 417b (FIG. 37). By connecting cables 433a and 433c to fixed structures 409, and then tightening each cable by the associated hand cranks, the cables may be tightened to substantially preclude movement of base 416 relative to the support surface. As shown in FIG. 42, the cables may be secured to spaced apart structures, such that the pairs of cables extend in generally opposite longitudinal directions to further limit longitudinal movement of base 416 and supply pipe section 415a. As shown in FIG. 37, a base unit 416' may alternately comprise a single leg 416a', which is adjustable relative to base 416' and pipe section 415a via a hand crank 416b' or the like to adjust the height of supply end 414a of tube assembly 414. Similar to base 416, a rearward restraining device 417a of base 416' is positioned at supply end 414a of tube 414, while a second restraining device 417b is positioned at an opposite outer end of supply section 415a of tube assembly 414. Preferably, the hand cranks 435a and 435b are common parts such that they may be reversibly mounted to each side of their respective restraining devices 417a and 417b at pipe section 415a and base 416 or 416', as shown in FIG. 37. METHOD FOR PLACING CONCRETE Referring now to FIGS. 42-48, placing apparatus 400 may be implemented at an elevated surface 405 to place concrete at that surface. Because the movable air cushion supports 418 spread out the load of the units and pipe assembly, thereby reducing the pressure on the support surface, the air cushion supports may be implemented at a corrugated metal deck 407, such as the type typically used in construction of elevated slabs, without damaging the corrugated decking 407. The movable support units 418 move and support the tube assembly 414 over the deck as the placing apparatus dispenses and places concrete at a targeted area of the support surface 405. When placing apparatus 400 is set up at a targeted location, base unit 416 is first secured relative to the targeted support surface by tightly securing cables 433 a and 433b to fixed structures, such as vertical columns 409 of the building or structure, to substantially fix base unit 416 and prevent movement thereof as movable units 418 are pivoted relative to one another and base unit 416. As best shown in FIGS. 43-48, base unit 416, first restraining device 417a and second restraining device 417b are positioned relative to the columns 409 or other fixed structure such that cables 433a pull in one direction, while cables 433b pull in substantially the opposite direction, to prevent both lateral and longitudinal movement of pipe section 415a during placing of the concrete. The supply end 414a of fixed or supply pipe section 415a is connected to a supply pipe or hose 20, which provides a supply of uncured concrete to placing apparatus 400. Initially, each joint 431b and 431c between the movable supports 418 may be substantially straight (FIG. 43), to allow maximum extension of discharge end 414b from base unit 416 and joint 431 a. Concrete may then be placed along a generally arcuate path of a first targeted area 405a via pivotable movement about the first joint 43 la between fixed pipe section 415a and the first movable support 418. As shown in FIG. 44, after the concrete has been placed along the first arcuate path, one or both of the joints 431b and 431c may be angled to effectively shorten the extension of discharge end 414b from base unit 416 and joint 431 a. Joint 431 a is again pivoted to move discharge end 414b along a closer arcuate path to place concrete at a next inward region of the targeted support surface 405a. As shown in FIGS. 45 and 46, this process is repeated by further adjusting the angle between the respective movable units and pipe sections to further reduce the effective length of the tube assembly to shorten the distance of the discharge end 414b from base unit 416 and j oint 431 a. Joint 431 a is again pivoted back and forth to again move discharge end 414b generally arcuately with respect to joint 43 la to place concrete at a next inwardly position targeted area. As shown in FIG. 46, this process is repeated until joints 43 lb and 43 lc are pivoted to their maximum amount, whereby the first targeted area 405a of the support surface is substantially covered with the placed concrete. As shown in FIG. 47, the process may be continued at a next adjacent targeted area 405b by straightening out joints 431b and 431c to again extend discharge end 414b a maximum amount from inner joint 431a and base unit 416. Joint 431a may again be pivoted to place concrete at an outermost portion of the second targeted area 405b. The process described above with respect to FIGS. 44 through 46 is repeated for the second targeted area 405b until the entire area has been covered by the uncured concrete, as shown in FIG. 48. Cables 433a and 433b may then be loosened and then disconnected from the support structures. Supply end 414a of pipe assembly 414 may also be disconnected from supply line 20, such that base unit 416 may be repositioned to a next targeted area of the support surface. Although the process is described above as including the steps of pivoting the outer joints 431b and 431c to set an effective distance between the discharge end 414b and joint 431a, and then pivoting joint 431a to arcuately move discharge end 414b relative thereto, the angular adjustment of the three joints for 431a, 431b, and 431c may be continuously adjusted while the tubes are travelling arcuately back and forth relative to the base unit. The dispensing end of the tube assembly provides concrete to every location within the targeted area, thereby uniformly distributing the concrete and substantially precluding the possibility of an insufficient amount of concrete being dispensed in any part of the targeted area of the support surface. The hydraulic cylinders 443, 444 of the apparatus may be remotely controllable or may be controlled via a programmable control to automatically move the movable supports and discharge end of the tube through a programmed process, such as the process described above, without any manual intervention. The uncured concrete being placed by discharge end 414b may also be controlled by a valve (not shown) in pipe assembly 414, such that the entire placing process may provide a uniform distribution of concrete throughout the entire targeted area with little or no manual intervention once the placing apparatus has been set up. FLEXIBLE TUBE ASSEMBLY Referring now to FIG. 49, an alternate placing apparatus 500 comprises a plurality of movable air cushion supports 518, which movably support a pipe assembly 514. Preferably, pipe assembly 514 is connected to a base unit (not shown), such as a base unit of the types discussed above, and provides uncured concrete to a support surface via a discharge end 514b. The movable air cushion supports 518 are substantially similar to those of placing apparatus 400, discussed above, such that a detailed discussion will not be repeated herein. However, each air cushion support 518 includes a pair of winch systems 543a and 543b at at least one end of the support 518 and on generally laterally opposite sides of the air cushion support. The winch systems 543a, 543b include a spool or reel 545a, 545b and a cable 547a, 547b, respectively, and a powered winch or winding device (not shown), which is operable to extend and retract the respective cable, as discussed below. Air cushion supports 518 further include a spool or cleat 549a, 549b at an end opposite the winch systems 543a, 543b for securing an end of the cables 547a, 547b from the next adjacent support thereto. Tube assembly 514 comprises a flexible hose or tube 515 and is secured along an upper surface 518c of each movable support 518. The tube assembly 514 may comprise a single, long flexible tube or hose fixedly secured to upper surface 518c of each movable support 518 or may comprise multiple pipe sections 515b, 515c and 515d mounted to the upper surface 518c of a respective support 518 and interconnected with one another via a flexible tube or hose assembly 515e, similar to pipe assembly 414, discussed above. The tube assembly 514 further includes a flexible beam member 513 which extends along tube assembly 514, such as along an upper surface of the tubes 515e, as shown in FIG. 49. Flexible beam 513 is flexible in the generally horizontal direction, such that the movable supports may move laterally or pivot relative to one another, yet is substantially rigid and resistant to flexing in a vertical direction. Preferably, the flexible beam is a l A" x 12" beam comprising an ultra high molecular weight (UHMW) plastic, which provides flexibility in the horizontal plane, while providing substantial support or rigidity in the vertical plane. The tube assembly 514 thus vertically supports the tube or hose 515 and allows for pivotable movement of the movable supports 518 and discharge end 514b of tube assembly 514 relative to the other movable supports 518 and the base unit via generally horizontal flexing of the tube between each adjacent pair of movable supports. Pivotable movement of the adjacent movable supports relative to one another preferably is accomplished via cooperative extension and retraction of cables 547a and 547b by winch systems 543a and 543b, respectively. Cables 547a and 547b extend from spools 545a and 545b, respectively, and are connected at opposite ends to cleats 549a, 549b at corresponding sides of the next adjacent movable support. Preferably, the cables 547a, 547b are wound about their respective spools 545a, 545b, which are rotatable via the winches to extend and retract the cables, 547a and 547b. The winches are cooperatively operable to extend one cable 547a while correspondingly retracting the other cable 547b, such that the operation of the winches causes pivotal movement of one movable support relative to another, as shown in FIG. 49. Tube 515 flexes horizontally as one cable 547b pulls at a side of the movable support, while the other cable 547a is extended or unwound, thereby allowing the movable supports to pivot relative to one another. Placing apparatus 500 is operable in substantially the same manner as placing apparatus 400 discussed above. The movable supports are pivoted relative to one another via extension and retraction of the connecting cables, while the tube assembly 514 and movable supports 518 are also pivoted relative to a base unit to place concrete throughout a targeted area of the support surface. Because the tube assembly of placing apparatus 500 includes a flexible hose or tube and flexible beam, and does not include the multiple pipe sections, gear members and brackets of placing apparatus 400, placing apparatus 500 provides a lower cost and less complex means for placing concrete at the targeted area, while still providing the benefits of the air cushion supports. The flexible hose also provides a reduced mass of the placing apparatus. ARTICULATED WHEELED PLACING APPARATUS Referring now to FIGS. 50-52, a concrete placing apparatus 600 comprises a wheeled base unit 616, a wheeled movable support 618 and an extendable and retractable pipe assembly 614 supported thereon. Pipe assembly 614 is supported at or near a discharge end 614b by movable support 618 and at a supply end 614a by the wheeled base unit 616. Supply end 614a is connected to a connector pipe 613, which is pivotally mounted to base unit 616 at a rotatable trunnion 629 of base unit 616, as discussed below. The other end of the connector pipe 613 is connectable to a flexible supply hose or tube 620b, which is further connectable to the supply pipes and the pumping truck or concrete supply (not shown in FIGS. 50-52). Additionally, the discharge end 614b of pipe assembly 614 is connected to a discharge tube assembly 650 which is bendable or movable relative to discharge end 614b to place concrete in an arcuate path with respect to discharge end 614b of pipe assembly 614, as discussed below. In the illustrated embodiment, pipe assembly 614 is a telescoping conduit, similar to pipe assembly 214, discussed above, such that a detailed discussion will not be repeated herein. Briefly, pipe assembly 614 includes an inner pipe or tube 615a and an outer pipe or tube 615b, which slidably receives inner pipe 615a therewithin as outer pipe 615b is extended and retracted relative to inner pipe 615a. Extension and retraction of pipe assembly 514 is preferably accomplished by an hydraulic cylinder 643, similar to hydraulic cylinder 243, discussed above with respect to placing apparatus 200. Hydraulic cylinder 643 includes a cylinder portion 643a and an extendable and retractable piston rod portion 643b, which is extendable and retractable within and along cylinder 643 a via pressurized hydraulic fluid. Cylinder portion 643 a is mounted at an inner end 615c of outer pipe 615b via brackets 649, while an outer end of piston or rod 643b is secured at an inner end 615d of inner pipe 615a via brackets 651. Accordingly, extension and retraction of rod 643b relative to cylinder 643a causes a corresponding extension and retraction of outer pipe 615b relative to inner pipe 615a. Additionally, suitable seals (not shown) are assembled within tube assembly 614 to prevent concrete from leaking out of the tubing assembly as the sections 615a and 615b slide in and out relative to one another. Pipe assembly 614 also includes an anti -twist or anti-rotation device 670 which functions to limit or substantially preclude rotation or twisting of one of the pipe sections 615a, 615b relative to the other about their longitudinal axes. Anti -twist device 670 includes an elongated member 672, such as a hollow cylindrical pipe as shown in FIGS. 50 and 52, which extends alongside and generally parallel to pipe sections 615a, 615b, an inner pipe section mounting bracket or collar 672a and an outer pipe section slidable support or collar 672b. Elongated member 672 is fixedly secured to inner pipe section 615a at an inner end of member 672 by bracket 672a, while collar 672b is mounted or secured to the inner end of outer pipe section 615b and slidably mounted or connected to elongated member 672. Accordingly, as outer pipe section 615b is extended or retracted relative to inner pipe section 615a, collar 672b slides along member 672, while the inner end of the member 672 remains secured at inner pipe section 615a. Because elongated member 672 extends at least partially along pipe sections 615a, 615b and is offset from their longitudinal axes, member 672 and brackets or collars 672a, 672b substantially preclude twisting or rotating of pipe sections 615a, 615b relative to one another as the base unit 616 and/or the movable support 618 maneuver over uneven support surfaces and the like. Wheeled base unit 616 is an articulated wheeled vehicle which is movable along the support surface by wheels 624. The articulated vehicle 616 includes a rear portion 616a and a front portion 616b, which are pivotable relative to one another about a generally vertical pivot or axis 616c (FIG. 51). Each of the wheels 624 of the base unit 616 are hydraulically driven via independently operable hydraulic motors or the like (not shown), and the unit 616 is articulated for steering to minimized tire scrubbing on the deck surfaces while placing apparatus 600 travels over the support surface or deck. An actuator 617 (FIG. 51), such as an hydraulic cylinder or hydraulic motor, is preferably provided at one of the front and rear portions and is operable to pivot front portion 616b relative to rear portion 616a about pivot axis 616c, such that the articulated vehicle pivots or bends at its middle region to turn the vehicle as the vehicle is moved along the support surface. Actuator 617 may be an hydraulic cylinder connected to a lever arm of one of the front and rear portions, 616b and 616a, respectively, such that extension or retraction of the cylinder creates a moment arm at the lever and thus causes pivotal movement of one or both portions 616b, 616a about the axis 616c. Turning of the vehicle 616 may also or otherwise be accomplished via independent driving of one or more of the wheels 624 relative to the others via the hydraulic motors at each wheel, without affecting the scope of the present invention. Front portion 616b of articulated vehicle 616 includes a pipe assembly support 622, which includes a lower column 623 and trunnion 629 at the upper end of column 623. Trunnion 629 is pivotally mounted to support column 623 via a turntable bearing 629a (FIG. 51) or the like, such that connector pipe 613 and pipe assembly 614 are pivotable about the generally vertical axis 616c at the center region of articulated vehicle 616. A pair of mounting arms 626 support connector pipe 613 at a pair of mounting brackets or flanges 626a and are pivotally mounted to trunnion 629 via a pair of axles or pins 625, such that mounting arms 626 are pivotable about a generally horizontal axis defined by pins 625 with respect to trunnion 629 and articulated vehicle 616. Trunnion 629 extends upwardly a sufficient amount to provide clearance of mounting arms 626 and connecting pipe 613 over an upper portion of the articulated vehicle 616, in order to avoid interference between the vehicle 616 and pipe assembly 614 as the pipe assembly 614 is pivoted about pivot axis 616c at turntable 629a. The rear or base unit 616 is thus operable to support and carry or drag the flexible concrete supply line 620b as the placing apparatus 600 is moved throughout the targeted area. The trunnion 629 and turn table bearing 629a allow the wheeled vehicle or tractor to rotate nearly 360 degrees under the concrete delivery lines for maneuvering the base unit about the targeted area, and further allow the pipe assembly 614 to be pivoted about the generally vertical axis via movement of movable support 618, as discussed below. Movable support 618 includes a frame or cross member 632, which supports a pipe mounting frame 634 thereon, and a pair of wheels 625, one at each of the opposite sides of the cross member 632. Pipe support frame 634 extends upwardly from cross member 632 and supports the outer end 614b of pipe assembly 614 via one or more collars or brackets 635 secured or clamped at a desired location along outer pipe 615b. Movable support 618 further includes a pair of vertical wheel mounts 636, which are pivotally or rotatably mounted at the lateral ends of cross member 632 and extend downwardly therefrom. Wheels 625 are rotatably mounted to the lower ends of wheel mounts 636 and are steerable via rotation of wheel mounts 636 relative to cross member 632. Wheels 625 are preferably individually rotatably drivable via an hydraulic motor 636b (FIG. 50) at the lower end of each vertical wheel mount 636, such that the movable support 618 may be driven in the desired direction to move discharge end 614b of pipe assembly 614 in a generally arcuate path about articulated vehicle 616. Additionally, movable support 618 may be movable via extension and retraction of pipe assembly 614 without operating hydraulic motors 636b by allowing wheels 625 to freely rotate as the pipe assembly is extended or retracted. In the illustrated embodiment, rotation of vertical mounts 636 relative to cross member 632 is accomplished via a steering system 637, which includes a double-ended hydraulic cylinder 638, a chain or belt 639 and a pair of sprocket or gear members 636a, one mounted at the upper end of each of vertical wheel supports 636. Hydraulic cylinder 638 is mounted to pipe support frame 634 and extends laterally outwardly therefrom. Hydraulic cylinder 638 includes a pair of piston rods 638a extending from opposite ends of a cylinder portion 638b. An outer end of each piston rod 638a is connected to one of the ends of chain or belt 639, such that movement of the rod assembly 638a in either direction pulls the chain or belt 639 about the sprocket wheels 636a, thereby causing rotation of sprockets 636a with respect to cross member 632, and thus turning of wheels 625 in either direction with respect to cross member 632. Preferably, vertical wheel supports 636 extend downwardly from cross member 632 a sufficient amount to allow maximum turning of the wheels 625 with respect to cross member 632, without interference between wheels 625 and cross member 632. Accordingly, the degree of turning or pivoting of the wheel mounts 636 is dependent on the stroke of the hydraulic cylinder 638 and the size of the sprockets 636a, and is not limited by interference of the wheels 625 with the cross member 632 of movable support 618. Although shown as a double-ended hydraulic cylinder, clearly other means for imparting rotation or pivoting of wheels 625 about a generally vertical axis with respect to cross member 632 may be implemented without affecting the scope of the present invention. Concrete placing apparatus 600 further includes discharge tube assembly 650, which is connected to the discharge end 614b of tube assembly 614 and is operable to further direct the concrete being placed at the support surface to a particular targeted location. Discharge tube assembly 650 includes a flexible tube portion 652 which is connected to discharge end 614b of tube assembly 614, and an articulating support 654, which supports flexible tube 652 and is bendable in either direction to flex or bend tube 652 such that a discharge outlet 652a of tube 652 is swept through an arcuate path relative to discharge end 614b of pipe assembly 614 for discharging concrete along the path. Articulating support 654 is mounted at or secured to cross member 632 of movable support 618 and includes a mounting portion 656, a mounting arm 658 extending from mounting portion 656 in a forwardly direction, and a pivoting or articulating support 660 which is pivotally mounted at an end of arm 658. An actuator, such as hydraulic cylinder 662, is mounted between mounting portion 656 and a bracket 660a extending laterally from support 660. Bracket 660a provides a bell crank mounting arrangement for hydraulic cylinder 662, such that extension or retraction of hydraulic cylinder 662 causes pivotal movement in either direction of support 660 about a generally vertical pivot axis at the forward end of mounting arm 658 for support 660. An outer end 660b of support 660 includes a pair of vertical supports 664 extending upwardly therefrom. Vertical supports 664 include multiple mounting openings 664a therein or therethrough, which receive one or more mounting pins ,664b, for mounting pporting the outer end 652a of flexible tube 652, while the upper portions of the vertical supports 664 function to guide the tube 652 in either side to side direction as support 660 ' .-_.->via extension and retraction of hydraulic cylinder 662. The multiple openings 664a of vertical supports 664 allow for vertical adjustment of the outer end of discharge tube 652, via insertion of the mounting pin 664b in different openings along vertical supports 664, in order to vertically adjust the angle at which the concrete is discharged from the tube. This allows the discharge end 652a to be raised so that the operator may use the pressure and momentum of the pumped concrete to shoot or discharge the concrete as it emerges from the nozzle or discharge end 652a a short distance into areas that cannot otherwise be fully reached by the placing apparatus 600. Preferably, placing apparatus 600 is easily disassembled and reassembled to ease transport of the various components to a targeted support surface, which may be at an elevated deck of a building or the like. Concrete placing apparatus 600 thus provides a maneuverable placing apparatus which may be easily disassembled and assembled for cleaning and for transporting and moving the apparatus between and at targeted support surfaces or decks. Preferably, the machine is designed such that the components fit into standard sized man lift elevators commonly found at construction sites, whereby the components may be individually moved to an upper or lower deck level and assembled for use at that deck level. Once assembled, the placing apparatus 600 is connectable to the concrete supply pump via hoses or tubes and is then operable to place the concrete at the targeted areas. After assembly of placing apparatus 600 at a support surface, placing apparatus 600 is movable to a targeted location via driving and steering of articulated vehicle 616 and/or driving and steering of movable support 618. When positioned at the targeted location of the support surface, flexible supply tube 620b is connected to supply end 613b of connector pipe 613 and further connected to the supply tubes or pipes (not shown). Hydraulic cylinder 643a may then be extended to extend pipe assembly 614 outwardly via free rolling or corresponding driving movement of movable support 618 along the support surface. Alternately, movable support 618 may be driven away from base unit 616 to pull outer pipe 615b outwardly along inner pipe 615a to move the discharge end 614b of pipe assembly 614 to its extended position. As concrete is placed at the support surface, wheels 625 may be turned and driven in a desired direction, to move discharge end 614b of pipe assembly 614 in a generally arcuate path about pivot axis 616c of base unit 616. Discharge assembly 650 may also be actuated to sweep discharge end 652a of discharge tube 652 back and forth through a smaller, generally arcuate path about the discharge end 614b of pipe assembly 614. Similar to the above discussed placing processes, pipe assembly 614 may be partially retracted after each pass or sweep of the discharge end 614b of the pipe assembly 614, such that the next sweep of the pipe assembly 614 covers a different area of the support surface. After concrete has been placed at the entire targeted area, the supply pipes may be disconnected and the articulated vehicle and movable supports may be driven or otherwise moved to the next targeted location. The hydraulic cylinders and hydraulic motors of placing apparatus 600 are preferably controlled via an open loop, closed center hydraulic system which is operable to control the hydraulic fluid motors and fluid cylinders on both the movable units 616 and 618 and on the pipe assembly 614 and discharge assembly 650, similar to the hydraulic systems discussed above. Preferably, the hydraulic system and controls for placing apparatus 600 are remotely controllable, such that the apparatus can be driven and maneuvered from a remote location, or programmable to move the apparatus and dispense concrete in a programmed manner. Although shown as having a discharge end of the tube assembly for discharging uncured concrete onto a targeted area of the support surface, the placing apparatus embodiments of the present invention may also or otherwise include a screeding device at an outer end of the apparatus to grade and smooth the uncured concrete on the support surface following discharge from the discharge outlet of the pipe assembly. The screeding devices may be of the type discussed above with respect to placing and screeding apparatus 10' or placing and screeding apparatus 10", or other types of screeding devices, without affecting the scope of the present invention. The screeding device may be implemented with the discharge tube, such that the screeding device grades and smoothes the concrete following discharge from the discharge end of the tubes. Alternately, a screeding device alone may be positioned at an outer end of a support member, which does not place uncured concrete and is movable to move the screeding device relative to the support surface, such that the screeding device is operable to grade and smooth uncured concrete which was previously placed at the support surface. Each of the embodiments of the base units discussed above may be implemented with any of the embodiments of the lead units or movable supports. It is envisioned that in certain applications, a particular design or combination may be preferred. For example, it would be preferable to implement an air cushion lead vehicle and possibly even an air cushion base in areas where at least a portion of the concrete has already been placed, or where loading requirements dictate a low ground pressure unit, such as on decks for elevated slabs, while different units may be preferred when the concrete is to be placed over dirt or sand, since the air cushion units may kick up a substantial amount of dirt and dust over such terrain. It is further envisioned that the base and lead units of the present invention may be manually controlled, and may even include an operator station for an operator to sit at and drive the vehicles while controlling the extension and retraction of at least one of the tubes. However, and preferably, at least the lead unit of each embodiment is remotely controllable via radio or electronic wire and may even comprise a programmable control which is operable to automatically move the lead unit and the tube assembly through the steps described above with respect to FIGS. 31 - 34 or FIGS. 43-48 without any manual intervention required. The programmable control may also be operable to open and close a valve in the tube assembly to place concrete only in the appropriate areas to provide a generally uniform distribution of uncured concrete over the entire targeted area. The only manual intervention then is to position the base unit at the desired location and connect the supply end of the tube assembly to the supply hoses, tubes, and/or pipes, which are connected to a pumping device. Preferably, the base units of the present invention further include a radio receiver and control, which are operable to receive signals from a remote control transmitter used by an operator near the machine and to control the hydraulic drive motors, steering cylinders and other hydraulic cylinders and/or motors to maneuver the placing apparatus for placement of concrete at the support surface. Therefore, the present invention provides a placing and/or screeding apparatus which is easily maneuverable and which may easily be implemented in areas where a boom truck cannot reach, such as remote areas of buildings or areas with low overhead clearance, or raised or elevated areas where weight or ground pressure may be a concern. The apparatus may include a conduit or tube or pipe assembly which is operable to provide uncured concrete to a discharge end of the conduit. The conduit or tube may be extendable and retractable to move the discharge end throughout the targeted area of the support surface. It is envisioned that the tube or pipe assembly may be extendable via a telescoping assembly, an articulated assembly, a flexible, bending assembly, an accordion type or corrugated conduit assembly, or any other means for extending and retracting a discharge end of the apparatus relative to a base or support, without affecting the scope of the present invention. The present invention may further include a screeding device at a dispensing end of the tube assembly to grade and/or smooth and/or compact the concrete as it is placed, thereby eliminating the additional step of setting up a separate screeding apparatus and screeding the concrete after it has been placed. Alternately, various embodiments of the movable units may include only a screeding device for grading, smoothing and/or compacting previously placed uncured concrete. The screeding device may be implemented with one ore more of the wheeled units, air cushion support units and/or swing tractor units, without affecting the scope of the present invention. Additionally, the air cushion embodiments of the base and lead units facilitate movement of the apparatus over areas which are covered with uncured concrete, in order to place additional concrete and/or to smooth and compact the already placed concrete, without disturbing the uncured concrete which has already been placed and perhaps smoothed. The air cushion supports are especially useful in placing and/or screeding concrete in areas where a wheeled unit or other type of support may be too heavy or the support force too concentrated, such as on corrugated metal decking of elevated slabs. The air cushion supports spread the support force/weight of the supports and tube assembly and/or screeding device over a larger footprint to substantially reduce the ground pressure being applied at the support surface. One or more air cushion supports may be implemented with a concrete supply unit, such as a pipe or tube assembly, a hopper, or any other device which may provide/dispense concrete or other material at a targeted location, and/or a screeding device. The air cushion support(s) may be movable via movement of a tube assembly, such as extension/retraction and/or angular adjustment of the tube assembly, or may be movable via adjustment of an angle of one or more fan units, or pivotal movement of a base or other support, or any other means for moving the air cushion support generally horizontally over the support surface. Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the invention, which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law.

Claims: The embodiments of the invention in which an exclusive property right or privilege is claimed are defined as follows: 1. A concrete placing device for placing uncured concrete on a support surface, said concrete placing device comprising: a base unit; a conduit comprising a supply end and a discharge end, said discharge end comprising a discharge outlet and being opposite said supply end, said supply end being mounted to said base unit and connectable to a supply of uncured concrete to be placed on the support surface, said conduit being operable to dispense the uncured concrete to be placed via said discharge outlet; and at least one movable support for movably supporting said discharge end of said conduit at a position remote from said base unit. 2. The concrete placing device of Claim 1 further comprising a screeding device at said discharge end of said conduit, said screeding device being operable to grade and smooth the uncured concrete at the support surface following discharge from said discharge outlet. 3. The concrete placing device of Claim 2, wherein said screeding device comprises a laser controlled leveling system. 4. The concrete placing device of Claim 2, wherein said screeding device comprises at least one of a plow, an auger, and a vibratory screed. 5. The concrete placing device of Claim 4, wherein said screeding device includes said plow, said auger and said vibratory screed, said plow, said auger and said vibratory screed being pivotally mounted to said screeding device, said screeding device further comprising at least one power source to pivotally adjust said plow and said vibratory screed with respect to the discharged uncured concrete. 6. The concrete placing device of Claim 2, wherein said screeding device comprises a vibratory screed. 7. The concrete placing device of Claim 6, wherein said screeding device further comprises at least one of a plow and an auger. 8. The concrete placing device of Claim 2, wherein said screeding device is operable via a power source positioned at one of said base unit and said movable support. 9. The concrete placing device of Claim 8, wherein said screeding device is operable via at least one hydraulic actuatable device, said at least one hydraulic actuatable device being connectable to said power source via at least one of a roll up hose and an extendable pipe. 10. The concrete placing device of Claim 9, wherein said hydraulic actuatable device comprises at least one of a pair of hydraulic leveling cylinders, a pivotable hydraulic cylinder, and an hydraulic motor. 11. The concrete placing device of Claim 2, wherein said screed comprises a rotating screed head, said discharge outlet being operable to discharge concrete within said rotating screed head. 12. The concrete placing device of Claim 11, wherein said rotating screed head has a cylindrical opening therethrough, said discharge opening and said rotating screed head being operable to discharge the concrete into said cylindrical opening and smooth the concrete via rotation of said rotating screed head. 13. The concrete placing device of Claim 1, wherein said movable support comprises a wheeled vehicle having at least two wheels. 14. The concrete placing device of claim 13, wherein said conduit is pivotally mounted to said movable support. 15. The concrete placing device of Claim 13, wherein said movable support further comprises a power source, at least one of said wheels being driven by said at least one power source. 16. The concrete placing device of Claim 13, wherein at least one of said wheels is steerable. 17. The concrete placing device of Claim 13, wherein said conduit comprises an extendable tube which is extendable and retractable relative to at least one of said base unit and said movable support. 18. The concrete placing device of Claim 17, wherein said extendable tube is telescopingly extendable. 19. The concrete placing device of Claim 17, wherein said movable support further comprises a programmable control, said control being programmable to move said movable support radially and arcuately relative to said base unit in a programmed pattern. 20. The concrete placing device of Claim 13, wherein said movable support comprises an operator control panel, said movable support being controllable by an operator at said movable support. 21. The concrete placing device of Claim 13, wherein said movable support is remotely controllable. 22. The concrete placing device of Claim 13 further comprising a screeding device positioned at said discharge end of said conduit. 23. The concrete placing device of Claim 13, wherein said base unit is movable. 24. The concrete placing device of Claim 23, wherein said base unit comprises a wheeled vehicle having at least two wheels. 25. The concrete placing device of Claim 24, wherein at least one of said wheels of said base unit is drivable, and at least one of said wheels of said base unit is steerable. 26. The concrete placing device of Claim 24, wherein said base unit comprises an articulated vehicle, a front portion of said articulated vehicle being movable relative to a rear portion of said articulated vehicle to at least one of steer said vehicle and pivot said conduit relative to said base unit. 27. The concrete placing device of Claim 1, wherein said movable support is an air cushion device having at least one lifting fan which is operable to raise and support said movable support relative to the support surface via a cushion of air between said movable support and the support surface. 28. The concrete placing device of Claim 27, wherein said conduit comprises an extendable tube which is extendable between an extended and retracted position relative to at least one of said base unit and said movable support. 29. The concrete placing device of Claim 28, wherein said extendable tube is telescopingly extendable and retractable. 30. The concrete placing device of Claim 29, wherein said telescoping tube is extendable and retractable in response to a powered extending device. 31. The concrete placing device of Claim 30, wherein said base unit comprises a base portion and a swivel portion rotatably supported by said base portion, said extendable tube being mounted to said swivel portion such that said movable support is arcuately movable relative to said base unit via rotation of said swivel portion and radially movable relative to said base unit via extension and retraction of said telescopic tube. 32. The concrete placing device of Claim 28, wherein said extendable tube is articulated about at least one joint and comprises at least two sections which are pivotable about said at least one joint relative to one another between the retracted position and the extended position. 33. The concrete placing device of Claim 32, wherein said extendable tube is articulated via at least one extending device positioned at said at least one joint. 34. The concrete placing device of Claim 33, wherein said at least one extending device comprises a pair of hydraulic cylinders and said at least one joint comprises a gear member which is fixed relative to one of said at least two sections, said hydraulic cylinders being cooperatively operable to move a belt member about said gear member to pivot said at least two sections relative to one another. 35. The concrete placing device of Claim 34, wherein said at least one movable support comprises at least two movable supports, each of said movable supports being connected via said extendable tube with a joint positioned between said movable supports to allow for pivotal movement of said each of said movable supports relative to one another. 36. The concrete placing device of Claim 32, wherein said base unit is held stationary via at least one cable such that movement of said movable support is relative to said stationery base unit. 37. The concrete placing device of Claim 28, wherein said extendable tube comprises a flexible hose and a flexible beam which is flexible in a horizontal direction while substantially limiting flexing in a vertical direction. 38. The concrete placing device of Claim 37, wherein said movable support is movable via at least two cables which are cooperatively extendable and retractable to pivot said movable support relative to said base unit. 39. The concrete placing device of Claim 38, wherein said at least one movable support comprises at least two movable supports interconnected via said at least two cables, said movable supports being movable relative to one another via extension of one of said cables and corresponding retraction of the other of said cables. 40. The concrete placing device of Claim 27, wherein said lifting fan is pivotable about an axis to move said movable support horizontally along the ground. 41. The concrete placing device of Claim 27, wherein said movable support further comprises a swing fan which is pivotable about a generally vertical axis at said movable support and is operable to move said movable support along the support surface relative to said base unit. 42. The concrete placing device of Claim 41, wherein said movable support is remotely controllable. 43. The concrete placing device of Claim 27, wherein said base unit is an air cushion device. 44. The concrete placing device of Claim 43, wherein said base unit comprises a base portion and a swivel portion rotatably supported by said base portion, said base unit further comprising a rotary motor which is operable to rotate said swivel portion relative to said base portion to move said conduit and said movable support arcuately relative to said base portion. 45. The concrete placing device of Claim 44, wherein said conduit comprises a telescopingly extendable tube which is extendable and retractable to move said discharge end of said extendable tube radially relative to said base unit. 46. The concrete placing device of Claim 27 further including a screeding device at said discharge end of said tube for grading and smoothing the uncured concrete that is placed on the support surface. 47. The concrete placing device of Claim 27, wherein said base unit is a wheeled vehicle. 48. The concrete placing device of Claim 1, wherein said movable support comprises a plurality of wheel trolleys which are connected to each other via a drive linkage, each of said wheel trolleys comprising a wheel which is rotatable on an axis, said wheel trolleys being rotatable about a closed path via a drive motor such that said trolleys are movable in a direction generally axially relative to said wheels. 49. The concrete placing device of Claim 48, wherein said movable support further comprises at least one sprocket wheel, said drive linkage engaging said sprocket wheel and said drive motor being operable to rotate said sprocket wheel such that said wheel trolleys are movable about a circumference of said sprocket wheel. 50. The concrete placing device of Claim 48, wherein said conduit comprises a telescopingly extendable tube and is connected to said movable support such that said extendable tube extends and retracts in a direction which is generally normal to said axes of said wheel trolleys. 51. The concrete placing device of Claim 50, wherein said drive motor is operable to rotate said wheel trolleys to move said discharge end of said extendable tube arcuately relative to said base unit. 52. The concrete placing device of Claim 51 , wherein said drive motor is operable via a power source positioned at said base unit. 53. The concrete placing device of Claim 52, wherein said drive motor is hydraulically actuatable, said hydraulic drive motor being connectable to said power source via at least one of a roll up hose and an extendable tube. 54. The concrete placing device of Claim 51, wherein said wheels are freely rotatable about their respective axes of said wheel trolleys, said wheels rotating as said extendable tube telescopingly extends radially outwardly from said base unit. 55. The concrete placing device of Claim 54, wherein said extendable tube comprises at least one extending device mounted therealong for moving said discharge end of said extendable tube radially relative to said base unit. 56. The concrete placing device of Claim 48, wherein said base unit comprises one of a wheeled vehicle and an air cushion device, said tube being pivotable about a generally vertical axis at said base unit, said discharge end of said conduit being arcuately movable relative to said base unit. 57. The concrete placing device of Claim 48 further comprising a screeding device positioned at said discharge end of said conduit, said screeding device being operable to grade and smooth the uncured concrete at the support surface following discharge from said discharge outlet. 58. The concrete placing device of Claim 1, wherein said conduit comprises a telescopingly extendable tube and at least one extending device for extending and retracting said telescoping tube relative to said base unit. 59. The concrete placing device of claim 58, wherein said telescoping tube comprises a first telescoping portion between said base unit and said movable support and a second telescoping portion between said movable support and said discharge outlet. 60. The concrete placing device of Claim 58, wherein said telescoping tube comprises at least three sections and said extending device comprises at least two hydraulic cylinders. 61. The concrete placing device of Claim 60, wherein said at least two hydraulic cylinders are interconnected via a plurality of hydraulic fluid lines such that said at least two hydraulic cylinders are operable via a single hydraulic supply at one of said hydraulic cylinders positioned adjacent to said base unit. 62. The concrete placing device of Claim 58, wherein said base unit is pivotable, said tube being movable arcuately with respect to said base unit. 63. The concrete placing device of Claim 1, wherein said conduit comprises an articulated tube having at least two sections pivotable relative to one another about at least one vertical axis at at least one joint of said articulated tube. 64. The concrete placing device of Claim 63, wherein said joint includes a flexible hose connected at each end to one of said at least two sections of said articulated tube, said flexible hose being flexible to allow for pivotal movement of said at least two sections relative to one another. 65. The concrete placing device of Claim 64, wherein said articulated tube includes an extending device positioned at said at least one joint, said extending device being operable to adjust an angle between said at least two sections in order to extend and retract said discharge end of said articulated tube relative to said supply end and said base unit. 66. The concrete placing device of Claim 65, wherein said at least one joint comprises first and second pivotable members and at least one gear member fixedly mounted at said first pivotable member, said gear member being rotatable relative to said second pivotable member to adjust the angle between said at least two sections. 67. The concrete placing device of Claim 66, wherein said extending device comprises at least one hydraulic cylinder mounted at said second pivotable member, said hydraulic cylinder being operable to rotate said gear member relative to said second pivotable member to adjust the angle between said sections. 68. The concrete placing device of Claim 1 , wherein said conduit comprises a flexible hose and a flexible beam which supports said flexible hose and is flexible in a horizontal direction and substantially limits flexing in a vertical direction, said conduit allowing for pivotal movement of said movable support relative to said base unit via horizontal flexing of said flexible hose and said flexible beam. 69. The concrete placing device of Claim 68, wherein said conduit further comprises an extending device which is operable to extend and retract said at least one movable support relative to said base unit via flexing of said conduit. 70. The concrete placing device of Claim 69, wherein said extending device comprises at least two cables interconnected between said base unit and said movable support, said cables being cooperatively extendable and retractable to flex said conduit to cause movement of said movable support relative to said base unit. 71. The concrete placing device of Claim 1, wherein at least one of said base unit, said conduit and said movable support is remotely controllable. 72. The concrete placing device of Claim 1 further comprising a programmable control, said at least one of said base unit, said conduit and said movable support being controlled via said programmable control to move said movable support in a programmed pattern relative to said base unit. 73. The concrete placing device of Claim 1, wherein said base unit further comprises a crane member for lifting and moving a supply tube when said base unit is to be connected or disconnected from the supply of uncured concrete of the supply tube. 74. A concrete placing and screeding apparatus for placing uncured concrete on a support surface and/or grading or leveling uncured concrete, said concrete placing and screeding apparatus comprising: a movable support; a conduit having a supply end and a discharge end, said supply end being opposite said discharge end, said supply end being connectable to a supply of uncured concrete to be placed, said conduit being supported by said movable support; and a screeding device at said discharge end of said conduit, said screeding device being operable to grade and smooth uncured concrete on the support surface following discharge from said discharge end of said conduit. 75. The concrete placing and screeding apparatus of Claim 74, wherein said screeding device comprises a rotatable screed head, said discharge end being positioned to discharge concrete within said rotating screed head. 76. The concrete placing and screeding apparatus of Claim 75, wherein said rotating screed head has a cylindrical opening therethrough, said discharge opening and said rotating screed head being operable to discharge the concrete into said cylindrical opening and smooth the concrete via rotation of said rotating screed head. 77. The concrete placing and screeding apparatus of Claim 74, wherein said screeding device comprises a vibratory screed. 78. The concrete placing and screeding apparatus of Claim 77, where said screeding device further comprises at least one of a plow and an auger. 79. The concrete placing and screeding apparatus of Claim 78, wherein said plow, said auger and said vibratory screed are pivotally mounted to said screeding device, said screeding device further comprising at least one power source to pivotally adjust said plow and said vibratory screed with respect to the uncured concrete. 80. The concrete placing and screeding apparatus of Claim 74, wherein said screeding device comprises a laser controlled leveling system. 81. The concrete placing and screeding apparatus of Claim 74, wherein said screeding device is operable via an hydraulic pump positioned remotely from said screeding device, said screeding device being connectable to said power source via at least one of a roll up hose and an extendable tube. 82. The concrete placing and screeding apparatus of Claim 74 further comprising a base unit, said conduit being supported at said supply end by said base unit. 83. The concrete placing and screeding apparatus of Claim 82, wherein said base unit is rotatable, said supply end of said conduit being mounted to said base unit whereby said discharge end is movable arcuately relative to said base unit in response to at least one of rotation of at least a portion of said base unit and movement of said movable support. 84. The concrete placing and screeding apparatus of Claim 83, wherein said conduit comprises an extendable tube. 85. The concrete placing and screeding apparatus of Claim 84, wherein said extendable tube comprises a telescoping tube, said discharge end of said conduit being movable radially relative to said base unit via extension or retraction of said telescoping tube. 86. The concrete placing and screeding apparatus of Claim 84, wherein said extendable tube comprises an articulated tube having at least two sections which are pivotable relative to one another. 87. The concrete placing and screeding apparatus of Claim 83, wherein said base unit comprises one of a wheeled vehicle and an air cushion apparatus. 88. The concrete placing and screeding apparatus of Claim 87, wherein said base unit comprises a rotary motor which is operable to rotate a portion of said base unit whereby said discharge end of said conduit is movable arcuately relative to said base unit. 89. The concrete placing and screeding apparatus of Claim 82, wherein said base unit comprises an articulated wheeled vehicle. 90. The concrete placing and screeding apparatus of Claim 74, wherein said movable support is a wheeled vehicle. 91. The concrete placing and screeding apparatus of Claim 74, wherein said movable support is an air cushion device having at least one lift fan which is operable to support said air cushion device at the support surface via a cushion of air between said air cushion device and the support surface. 92. The concrete placing and screeding apparatus of Claim 74, wherein said movable support comprises a plurality of wheel trolleys which are connected to one another via a drive member, each of said wheel trolleys comprising a wheel which is rotatable on an axis, said wheel trolleys being rotatable about a closed path via a drive motor such that said trolleys are movable in a direction generally axially relative to said wheels, said conduit being mounted to said movable support such that said conduit extends longitudinally generally normal to said axes. 93. A concrete placing apparatus for placing uncured concrete on a support surface, said placing apparatus comprising: a swivel base comprising a swivel portion and a base portion for rotatably supporting said swivel portion at least one of above and on the support surface; an extendable conduit assembly comprising a supply end and a discharge end, said supply end being connectable at said swivel base to a supply of uncured concrete to be placed, said supply end being generally opposite to said discharge end, said discharge end being adapted to dispense the uncured concrete on the support surface; and a movable support for supporting said extendable conduit assembly on the support surface remote from said swivel base. 94. The concrete placing apparatus of Claim 93 further comprising a screeding device positioned at said discharge end of said extendable conduit assembly, said screeding device being operable to grade and smooth the uncured concrete on the support surface following discharge from said discharge end of said extendable conduit. 95. The concrete placing apparatus of Claim 94, wherein said screeding device comprises a vibratory screed. 96. The concrete placing apparatus of Claim 95, wherein said screeding device further comprises at least one of a plow and an auger. 97. The concrete placing apparatus of Claim 96, wherein said plow, said auger and said vibratory screed are pivotally mounted to said screeding device, said screeding device further comprising at least one power source to pivotally adjust said plow and said vibratory screed with respect to the uncured concrete. 98. The concrete placing apparatus of Claim 94, wherein said screeding apparatus comprises a rotatable screed head, said discharge end of said extendable conduit assembly being positioned to discharge concrete within said rotatable screed head. 99. The concrete placing apparatus of Claim 98, wherein said rotating screed head has a cylindrical opening therethrough, said discharge end and said rotating screed head being operable to discharge the concrete into said cylindrical opening and smooth the concrete via rotation of said rotating screed head. 100. The concrete placing apparatus of Claim 93, wherein one of said movable support and said swivel base is operable to move said discharge end of said extendable conduit assembly at least one of arcuately and radially relative to said swivel base. 101. The concrete placing apparatus of Claim 93, wherein said extendable conduit assembly further comprises at least one extending device positioned therealong which is operable to extend and retract said conduit assembly to move said discharge end radially relative to said swivel base. 102. The concrete placing apparatus of Claim 101, wherein one of said swivel base and said movable support is operable to move said discharge end arcuately relative to said swivel base. 103. The concrete placing apparatus of Claim 93, wherein said movable support comprises a wheeled vehicle. 104. The concrete placing apparatus of Claim 93, wherein said movable support comprises a plurality of wheel trolleys which are connected via a drive member, each of said wheel trolleys comprising a wheel which is rotatable on an axis, said wheel trolleys being rotatable about a closed path via a drive motor being operable to drive at least one sprocket wheel, said drive member engaging said sprocket wheel such that said trolleys are movable in a direction generally axially relative to said wheels. 105. The concrete placing apparatus of Claim 104, wherein said extendable conduit assembly is connected to said movable support such that said extendable conduit assembly extends generally normal to said axes of said wheel trolleys. 106. The concrete placing apparatus of Claim 105, wherein said drive motor and said sprocket wheel are operable to move said discharge end of said conduit assembly arcuately relative to said swivel base. 107. The concrete placing apparatus of Claim 93, wherein said movable support comprises an air cushion apparatus having at least one lift fan which is operable to support said movable support above the ground via a cushion of air between said movable support and the support surface. 108. The concrete placing apparatus of Claim 107, wherein said movable support further comprises a directional fan which is operable to move said discharge end of said extendable conduit assembly at least one of radially and arcuately relative to said swivel base. 109. The concrete placing apparatus of Claim 107, wherein said movable support is operable to move said movable support along the support surface whereby said discharge end is movable at least one of radially and arcuately relative to said swivel base. 110. The concrete placing apparatus of Claim 93, wherein said swivel base comprises one of a wheeled vehicle and an air cushion device. 111. The concrete placing apparatus of Claim 93, wherein at least one of said movable support, said swivel base, and said extendable conduit assembly is remotely controlled via a control. 112. The concrete placing apparatus of Claim 111, wherein said control is operable to control said at least one of said movable support, said swivel base, and said extendable conduit assembly via at least one of an electronic wiring and a wireless signal. 113. The concrete placing apparatus of Claim 93, wherein at least one of said movable support, said swivel base and said extendable conduit assembly is controllable via a programmable control, said at least one of said movable support, and said extendable conduit assembly being movable in a programmed pattern in response to said programmable control. 114. The concrete placing apparatus of claim 93, wherein said extendable conduit comprises a longitudinally telescopingly extendable and retractable tube assembly. 115. A concrete processing apparatus for placing and/or screeding uncured concrete at a support surface, said apparatus comprising: at least one of a concrete supply unit for providing uncured concrete to the support surface and a screeding device for grading and smoothing the uncured concrete on the support surface; and an air cushion support unit which is operable to support said at least one of said concrete supply unit and said screeding device. 116. The concrete processing apparatus of Claim 115, wherein said concrete supply unit comprises a conduit having a supply end for receiving uncured concrete and a discharge end for discharging the uncured concrete on the support surface. 117. The concrete processing apparatus of Claim 116 further comprising a base unit, said supply end of said conduit being supported at said base unit. 118. The concrete processing apparatus of Claim 117, wherein said base unit comprises one of a wheeled vehicle, an air cushion unit and a stationary support. 119. The concrete processing apparatus of Claim 117, wherein said conduit comprises an extendable tube which is extendable between an extended and retracted position relative to at least one of said base unit and said movable support. 120. The concrete processing apparatus of Claim 119, wherein said extendable tube is telescopingly extendable and retractable. 121. The concrete processing apparatus of Claim 120, wherein said base unit comprises a base portion and a swivel portion rotatably supported by said base portion, said extendable tube being movable arcuately relative to said base unit in response to one of rotation of said swivel portion and movement of said air cushion support. 122. The concrete processing apparatus of Claim 119, wherein said extendable tube and said support unit are at least one of arcuately movable and radially movable relative to said base unit. 123. The concrete processing apparatus of Claim 119, wherein said extendable tube is articulated about at least one joint and comprises at least two sections which are pivotable about said at least one joint relative to one another between the retracted position and the extended position. 124. The concrete processing apparatus of Claim 123, wherein said at least one air cushion support unit comprises at least two air cushion support units, each of said air cushion support units being connected via said extendable tube with a joint positioned between said movable air cushion support units to allow for pivotal movement of said each of said air cushion support units relative to one another. 125. The concrete processing apparatus of Claim 124, wherein said base unit and said supply end of said conduit are substantially fixed relative to the support surface. 126. The concrete processing apparatus of Claim 119, wherein said extendable tube comprises a flexible hose and a flexible beam which supports said flexible hose and is flexible in a horizontal direction while substantially limiting flexing in a vertical direction. 127. The concrete processing apparatus of claim 119, wherein said extendable tube is mounted to said air cushion support unit via a trunnion at said air cushion support unit which allows for pivotal movement of said extendable tube about a first axis which is transverse to said extendable tube and about a second axis extending longitudinally along said extendable tube. 128. The concrete processing apparatus of Claim 115, wherein said concrete processing apparatus includes said screeding device, said screeding device comprising a vibratory screed. 129. The concrete processing apparatus of Claim 128, wherein said screeding device further comprises at least one of a plow and an auger. 130. The concrete processing apparatus of Claim 115, wherein said screeding device comprises a rotating screed head. 131. The concrete processing apparatus of Claim 130, wherein said concrete processing apparatus comprises said concrete supply unit and said screeding device, said rotating screed head having a cylindrical opening therethrough, said concrete supply unit and said rotating screed head being operable to discharge the uncured concrete into said cylindrical opening and smooth the concrete via rotation of said rotating screed head. 132. The concrete processing apparatus of Claim 115, wherein said concrete processing apparatus comprises said concrete supply unit and said screeding device. 133. The concrete processing apparatus of Claim 132, wherein said supply unit comprises a conduit having a supply end and a discharge end, said supply end being connectable to a supply of uncured concrete, said screeding device being positioned at said discharge end to grade and smooth the uncured concrete being discharged therefrom. 134. A concrete placing apparatus for placing uncured concrete at a support surface, said concrete placing apparatus comprising: an extendable conduit having a supply end and a discharge end, said supply end being operable to receive a supply of uncured concrete, said discharge end being operable to discharge uncured concrete to the support surface, said extendable conduit having at least two sections pivotable about a generally vertical axis relative to one another; at least one air cushion support unit which is operable to support said extendable conduit; and a base unit which is operable to support said supply end of said extendable conduit. 135. The concrete placing apparatus of Claim 134, wherein said base unit is substantially fixed relative to the support surface. 136. The concrete placing apparatus of Claim 135, wherein said base unit is securable via at least one cable connecting said base unit to a stationary member. 137. The concrete placing apparatus of Claim 136, wherein said base is securable via at least two cables connecting said base unit to at least two stationary members, said cables being adjustable to tighten said cables to secure said base unit to the stationary members. 138. The concrete placing apparatus of Claim 134, wherein said extendable conduit is an articulated tube, said at least two sections being pivotable relative to one another about at least one joint. 139. The concrete placing apparatus of Claim 138, wherein said at least two sections are pivotable via at least one extending device which extends and retracts to pivot said sections relative to one another. 140. The concrete placing apparatus of Claim 139, wherein said at least one extending device comprises two extending devices along laterally opposite sides of said articulated tube, said extending devices being operable to cooperatively extend and retract to pivot one of said sections relative to the other. 141. The concrete placing apparatus of Claim 134, wherein said at least two sections comprise at least three sections and said at least one air cushion support comprises at least two air cushion supports, each of said air cushion supports supporting one of said at least two sections of said extendable conduit. 142. The concrete placing apparatus of Claim 134, wherein said at least one air cushion support includes a pair of cables connected between said air cushion support and one of said base unit and another air cushion support, said cables being cooperatively extendable and retractable to pivot said at least one air cushion support relative to said at least one of said base unit and said other air cushion support. 143. The concrete placing apparatus of Claim 134, wherein said extendable conduit comprises a flexible tube and a flexible beam which supports said flexible tube and is flexible in a generally horizontal direction, said flexible beam limiting flexing in a vertical direction. 144. The concrete placing apparatus of Claim 134, wherein said extendable conduit is mounted to said air cushion support unit via a trunnion at said air cushion support unit which allows for pivotal movement of said extendable conduit about a first axis which is transverse to said extendable conduit and about a second axis extending longitudinally along said extendable conduit. 145. The concrete placing apparatus of Claim 134 further comprising a screeding device positioned at said discharge end of said extendable conduit, said screeding device being operable to grade and smooth the uncured concrete on the support surface following discharge from said discharge end of said extendable conduit. 146. A concrete placing apparatus for placing uncured concrete at a support surface, said concrete placing apparatus comprising: an extendable conduit having a supply end and a discharge end, said supply end being operable to receive a supply of uncured concrete, said discharge end being operable to discharge uncured concrete to the support surface, said extendable conduit having at least two sections extendable and retractable relative to one another; a movable wheeled base unit which supports said supply end of said extendable conduit; and a movable support which is operable to movably support said discharge end of said extendable conduit. 147. The concrete placing apparatus of Claim 146, wherein said extendable conduit comprises a telescoping conduit, whereby one of said at least two sections is telescopingly extendable and retractable with respect to the other of said at least two sections. 148. The concrete placing apparatus of Claim 146, wherein said base unit comprises an articulated wheeled base unit having a front portion which is pivotable relative to a rear portion of said base unit. 149. The concrete placing apparatus of Claim 148, wherein said supply end of said extendable conduit is supported by said front end of said articulated base unit. 150. The concrete placing apparatus of Claim 149, wherein said movable support is operable to movably support said discharge end of said extendable conduit along an arcuate path, said base unit being articulatable to steer said base unit. 151. The concrete placing apparatus of Claim 150, wherein said movable support comprises a wheeled vehicle which is steerable to movably support said discharge end of said extendable conduit. 152. The concrete placing apparatus of Claim 151, wherein said movable support is independently movable via a drive motor to movably support said discharge end of said extendable conduit. 153. The concrete placing apparatus of Claim 152, wherein said movable support includes a support member and is steerable via a pair of wheels which are pivotably mounted to said support member, said wheels being correspondingly pivotable relative to said support member to steer said movable support. 154. The concrete placing apparatus of Claim 153, wherein said extendable conduit comprises a telescoping conduit, whereby one of said at least two sections is telescopingly extendable and retractable with respect to the other of said at least two sections, one of said sections being supported by said front end of said articulated base unit, the other of said sections being supported by said movable support. 155. The concrete placing apparatus of Claim 146, wherein said movable support comprises a wheeled vehicle which is steerable to movably support said discharge end of said extendable conduit. 156. The concrete placing apparatus of Claim 155, wherein said movable support is independently movable via a drive motor to movably support said discharge end of said extendable conduit. 157. The concrete placing apparatus of Claim 156, wherein said movable support includes a support member and is steerable via a pair of wheels which are pivotably mounted to said support member, said wheels being correspondingly pivotable relative to said support member about a generally vertical axis to steer said movable support. 158. The concrete placing apparatus of Claim 157, wherein said movable support is steerable in response to a double ended hydraulic cylinder, whereby one end of said hydraulic cylinder is extendable and retractable to pivot one of said wheels relative to said support and the other end of said hydraulic cylinder is correspondingly retractable and extendable to pivot the other one of said wheels relative to said support. 159. The concrete placing apparatus of Claim 146 further including a discharge tube assembly mounted at said discharge end of said extendable conduit, said discharge tube assembly including a flexible tube and being operable to move a discharge end of said flexible tube along an arcuate path relative to said discharge end of said conduit. 160. The concrete placing apparatus of Claim 159, wherein said discharge end of said flexible tube is vertically adjustable relative to said discharge end of said extendable conduit.

Inventors: HALLSTROM CHARLES A, KIERANEN CARL B, PIETILA MARK A, QUENZI PHILIP J, TORVINEN JEFFREY W, HALLSTROM, CHARLES, A., KIERANEN, CARL, B., PIETILA, MARK, A., QUENZI, PHILIP, J., TORVINEN, JEFFREY, W.
Applicants: CAPITAL FORMATION INC, HALLSTROM CHARLES A, KIERANEN CARL B, PIETILA MARK A, QUENZI PHILIP J, TORVINEN JEFFREY W, DELAWARE CAPITAL FORMATION, INC., HALLSTROM, CHARLES, A., KIERANEN, CARL, B., PIETILA, MARK, A., QUENZI, PHILIP, J., TORVINEN, JEFFREY, W.
Application year: 2000
Main classification: B28B13
IPC codes: E04F21