Self loading and unloading pre-cast concrete hauling unit

A computer automated hydraulic hauling unit for transporting precast concrete bridge segments from a casting site to an erection site. The apparatus includes a transportable chassis having computer controlled hydraulic members with means to elevate precast bridge segments from casting forms. The operator sets the lifting and transport parameters in the computer controller from the control panel for elevation and lift control. Each segment is rolled into place on a trailer bed and through automated electronic circuits the hydraulic cylinders apply force to raise the segments onto a movable and uniform beam structure. After elevation to a preselected height each segment is anchored by means of pinning vertical interlocking beams made of high strength structural steel. This computerized hydraulic beam trailer can accommodate one or two segments per load. This apparatus provides construction companies with a safe, automated method to transport precast segments by a self-loading and unloading mechanism that eliminates expensive extra hauling operations.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention pertains to construction hauling equipment, and more 
particularly to an apparatus and method for transporting concrete cast 
bridge segments from the casting site to the bridge erection site. 
2. Description of the Prior Art 
Various equipment has been developed to transfer materials and articles 
between locations having different vertical and horizontal positions. For 
example, U.S. Pat. No. 3,103,291 shows a vehicle useful for loading and 
unloading airplanes, and U.S. Pat. No. 3,446,379 shows a scissors type 
high lift elevating mechanism. U.S. Pat. No. 4,162,873 discloses an 
extensible boom lift which includes a table mounted on a scissors-type 
lifting device and supporting a beam which is rotatable about a vertical 
axis. An extensible boom is supported by the rotatable beam. 
The handling of precast concrete bridge segments at bridge construction 
sites has always presented difficult problems. The common practice is to 
erect two stationary cranes at great expense; the first crane is used to 
load the concrete segments from the casting site onto transport vehicles 
and the second crane is used at the construction site to unload the 
vehicles and mount the segments in place. 
From the teachings of the existing art, there is no provision for 
transporting and erecting a precast concrete segmented bridge without the 
use of two cranes in addition to transport vehicles. 
Thus a need exists for a single vehicle which will replace the function of 
the expensive stationary cranes at both the casting site and the bridge 
construction site and which will additionally perform as the transport 
vehicle between the two sites. Such a vehicle would have the lifting and 
mounting characteristics of a crane type vehicle as well as the 
stabilizing load characteristics of the transport vehicle. This vehicle 
would also be computer automated for efficient, accurate, and inexpensive 
operation. 
In addition to the prior difficult problems of erecting precast bridge 
segments, there have also been difficulties in determining the weight of 
concrete segments during construction in order to prevent crane collapse 
or structure failure. 
From the teachings of the existing prior art, there is no provision for 
weighing or accurately measuring the mass of the concrete segment during 
erection. Thus a need exists for a single vehicle which will function both 
as a crane type vehicle as well as provide a computerized digital read out 
of the weight of each concrete segment so that the operator who knows the 
design capacity of the structure under construction will not exceed this 
capacity by adding a concrete segment whose weight will cause the entire 
structure to fail. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a computer automated 
vehicle for transporting loads, particularly precast concrete bridge 
segments, said vehicle is economical to manufacture and maintain and 
repair as well as simple in its construction, is reliable and safe in its 
operation and may be controlled by a single operator. 
These objects are achieved to a great extent by providing a vehicle, either 
a trailer or a self-propelled vehicle with two longitudinal lattice beams 
and tailgate which together provide the main strength of the vehicle as 
well as the support for the hydraulic lifting system and vertical locking 
system. The hydraulic lifting system is comprised of a series of four 
hydraulic cylinders embodied vertically in the lattice beams which when 
extended apply force to a separate beam that vertically lifts the load. 
Comparably the vertical locking system is adjacent to the hydraulic lifting 
system and is comprised of intersliding rectangular steel beams to provide 
telescopic action wherein the innermost beam is attached to the load 
lifting beam and can be held stationary at a desired height by inserting a 
steel pin that protrudes through the walls of the intersliding beams. 
In addition to the hydraulic lifting system and the vertical locking 
system, the vehicle has a tailgate comprised of two structural steel doors 
each hinged on the two longitudinal lattice beams which abut each other 
when closed at the center of the vehicle. The gate closure locking 
mechanism is hydraulic which when engaged joins the doors of the tailgate 
providing internal strength to the longitudinal lattice beam chassis. 
Hydraulic power is supplied to the longitudinal lattice beam by a motor 
and pump unit mounted on the vehicle with multiple controls located 
conveniently adjacent to each hydraulic member. 
The vehicle systems, namely the hydraulic lifting system, the vertical 
locking system and the tailgate assembly, are automated through computer 
control. The operator inputs set points at the control panel to control 
the hydraulic lifting system to raise the precast bridge segment off its 
pallet and then to lower the concrete bridge segment. The operator then 
inputs set points at the control panel to control the vertical locking 
system to stabilize and immobilize the concrete bridge segment for 
transport. Finally the operator inputs set points to automatically control 
the hydraulics and locking mechanism of the tailgate assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Although the disclosure hereof is detailed and exact to enable those 
skilled in the art to practice the invention, the physical embodiments 
herein disclosed merely exemplify the invention which may be embodied in 
other specific structure. The scope of the invention is defined in the 
claims appended hereto. 
The features of the present invention may be used with a self-propelled 
vehicle, that is a vehicle having a driver's cab, engine, transmission, 
drive train and steerable wheels, or it may be used in a trailer. For the 
purpose of illustration, a preferred embodiment is illustrated in the 
drawings as a trailer shown in FIG. 1. 
The prestressed concrete bridge segment hauling unit 10 comprises a chassis 
20 which is adapted for over the road travel by the use of conventional 
wheel and axle assemblies 30. The chassis 20 is attachable to and 
transportable by a tractor 70 through a standard hitch mechanism. 
Built onto the chassis 20 is a motor and a pump unit 90 which generates 
power for cylinders or RAMS 40(a), 40(b), 40(c) and 40(d) to raise and 
lower the concrete bridge segment. It will be noted that reference 
hereinafter to elements (c) and (d) not shown in the drawings are 
considered to be similar to elements (a) and (b) as shown in the drawings. 
Also built onto the chassis 20 are stabilizing cylinders 80 and tailgate 
locking cylinders 100 (see FIG. 3). The hydraulic controls for operating 
this system, as well be hereinafter described are preferably located 
within a station 110, 120 (FIG. 1) and 130 (FIG. 3) common to the member 
that they will control, which provides safe efficient as well as balanced 
operation. 
CHASSIS 
FIG. 1 shows chassis 20 built of structural steel beams forming the two 
longitudinal lattice beams of a size and configuration sufficient to lift 
the designed load. Embodied in this chassis are four hydraulic cylinders 
or Rams 40(a), 40(b), 40(c) and 40(d) shown in FIG. 1 which can be clearly 
seen in FIG. 5 to be supported by a lower chassis member or lower chord 
20(a) and laterally supported by chassis member or upper chord 20(b). When 
the cylinders are actuated by their control 140 in FIG. 1, hydraulic RAMs 
40(a), 40(b), 40(c), and 40(d) are forced vertically up or down depending 
on the control position. The RAMs in conjunction with the control apply 
the force necessary to move the lifting beams 50 (See FIGS. 1 and 3) which 
supports the load. To provide a margin of safety while in transport, the 
vertical force of the load caused by gravity will be restricted by four 
vertical locking devices 60(a), 60(b), 60(c), and 60 (d) shown in FIG. 1. 
Embodied in the longitudinal lattice beams of the chassis 20(a), 20(b), 
20(c), and 20(d) as shown in FIGS. 1 and 2, are rotational braces 150. 
FIG. 2 shows three structural steel members that compose this stationary 
bracing system. The purpose of the rotational brace is to negate the 
rotational force on the lower cord 20A (FIGS. 1 and 2) imposed by the 
wheel and axle assemblies that are affixed directly to the lower chords 
20A. 
TAILGATE AND HITCH SYSTEM 
The hitch is a structural extension of the main chassis consisting of a 
ball and metal hinge for pivoting members. The hitch is a common well 
known connection between a tractor and trailer. FIG. 3 shows a general 
elevation view of the tailgate assembly which includes two doors left 
(15A) and right (15B), and these doors are attached to hinges 17 on which 
these doors swing. Additionally attached to the doors is the hydraulic 
cylinder 100 that firmly closes the doors. The pressure in the hydraulic 
cylinder is set by the computer panel generally indicated by numeral 81 at 
the control panel and then adjusted through an analog circuit with a feed 
back loop to a microprocessor to insure that the pressure has been 
properly achieved Alternatively under manual control, the hydraulic 
control or lever (120) is actuated to cause the hydraulic cylinder (100) 
to pull together the tailgate doors left (15A) and right (15B) thus 
causing any pressure on mechanical locks 16 located on the upper and lower 
portions of the tailgate doors to be released. The operator then rotates 
the locks out of their respective eyes 16A. Then the operator actuates the 
hydraulic control lever (120) to cause the hydraulic cylinder 100 to 
release the binding force pin 10A such that pin 10A may be pulled out of 
the assembly to separate the tailgate into two freely swinging doors on 
four massive hinges 17. At this time the doors 15A and 15B are then swung 
shut and the hydraulic control lever is actuated either manually or 
through computer control to cause cylinder 100 to move such that pin 10A 
may be replaced. Then mechanical locks 16 are rotated into eyes 16(a) and 
if they don't engage then lever 120 is actuated so that hydraulic cylinder 
100 forcibly pulls the doors 15A and 15B together which will cause locks 
16 to engage the eyes 16(a) thus locking the tailgate under load. A safety 
bar 250 extends across the tailgate assembly connected to the beams 50. 
Bar 250 is attached for safety reasons and could be any other type of 
device to serve this purpose, such as a chain. 
HYDRAULIC LIFTING SYSTEM 
The hydraulic cylinders used to apply the forces necessary for lifting and 
lowering the concrete segments are embodied within the longitudinal 
lattice beam framework (20 of FIG. 1) of the segment hauling unit. Each of 
the hydraulic Rams has its cylinder bearing surface mounted parallel to 
reduce side thrust (See 40(a), 40(b), 40(c), and 40(d) in FIGS. 1 and 5). 
The base of the cylinders are mounted in a pocket that is affixed to the 
lower chord 20(a) in FIG. 5 and the top of the cylinder is cradled in a 
pocket fabricated into upper chord 20(b) in FIG. 5. The bearing end of the 
Ram is attached to the lifting beam 50 in FIG. 5 by a bolt. 
Each of the cylinders 40(a), 40(b), 40(c), and 40(d) are equipped with 
raising and lowering ports (see FIG. 5) which are plumbed to the motor and 
pump unit 90 in FIG. 1 through a singular control 140 in FIG. 1. The 
hydraulic jacking control system employs equal force to move each of the 
hydraulic Rams. That is the system maintains equal pressure and thus equal 
force on each jack. This system ensures that no twisting force is 
transmitted to the concrete load or bridge segment being hauled 
FIG. 4 shows the hydraulic plumbing schematic which depicts the flow of oil 
from the reservoir tank where it is pressurized by the high pressure 
hydraulic pump to the divider valve 141 in FIG. 1 which splits the system 
into two main parts: part 1 being raising or lowering the load and part 2 
being stabilizing the trailer and locking the tailgate. Operations of part 
1 are separate from those of part 2 and the divider valve provides a 
margin of safety against part 1 operations accidentally being employed 
while part 2 operations are active and vice versa. Activating the 
directional valve to energize part 1 circuit pressurizes the lift and 
lower valve which is electrically controlled by a solenoid and is capable 
of being controlled manually if necessary. The relative position of this 
valve directs the flow of hydraulic fluid to ports on the hydraulic 
cylinders that cause lift in the direction of the valve position. In line 
at each of the lifting and lowering cylinders is an electrically 
controlled solenoid valve that is controlled by the control panel via 
sensors and can regulate the flow to that cylinder thus creating a lifting 
system controlled by parameters programmed into the control panel and 
monitored by electronic sensors. When the directional valve energizes part 
2 of the system, the flow pressurizes the 3 stabilizing cylinders 80 and 
the tailgate locking cylinder 100. 
COMPUTER CONTROL 
The concrete bridge segment hauling unit is automated through a computer 
controlled control panel 81 with set point control and digital read out 
for each of the critical variables needed to control the lifting and 
transport concrete bridge segments (See FIG. 8). The control panel 
consists of one digital read out display composed of conventional LEDs as 
well as a numeric keypad with letter designations for the particular 
critical transport variable which is to be read out and displayed. The 
transport variables measured are the height of the bridge segment from its 
center of gravity, the slope or longitudinal planar level, the cross slope 
or transverse planar level, the tailgate closure, and the lockpin 
insertion for secure transport of the 40 ton segment weight, and finally 
exact segment weight readout. Each height and planar level variable is 
measured through sensors (70A and B and 71A and B) which are placed on the 
trailer bed as shown in FIGS. 1 and 5. The tailgate closure variables are 
measured through additional magnetic micro switch sensor (18) as shown 
additionally in FIG. 3. 
The operator sequentially moves through the series of operation steps as 
described below and reads the digital display screen to see that each of 
the variables have been satisfactorily achieved the appropriate set point 
as previously set by the operator. A feed back loop with alarm limits 
prohibits the operator from moving the bridge segment until each of the 
transport variables has achieved the setting as preprogrammed in the 
computer. 
Each of the critical transport variables is controlled through the computer 
control panel (81) FIG. 1 after a set point is input by the computer 
activating a dc voltage output line whereby the magnitude of the voltage 
on that line is directly related to the magnitude of the setpoint input 
for the critical variable. The DC output voltage is input to the solenoid 
controls (82) which in turn controls the hydraulics on the various points 
on the trailer bed as shown in FIG. 1. There are four sets of hydraulics 
on the trailer bed a shown namely the bed raising hydraulics, the 
transverse control level hydraulics, the longitudinal control hydraulics, 
and the tailgate hydraulics. Each hydraulic when actuated by the solenoid 
control which pressurized and move the bridge segment bed in the 
controlled direction of the hydraulic's mounting. This movement will 
continue until the set point is reached. The computer determines that the 
set point has been reached by comparing the set point's voltage input to 
the solenoid with the detected output voltage of each sensor which is 
returned to the computer control panel from the appropriate sensors. When 
the two voltages reach an acceptable comparison range the computer stops 
outputing dc voltage to the hydraulics and the system is stabilized. 
The precast concrete bridge segment hauling unit will incorporate the use 
of well known digital electronic sensors and circuitry to provide an easy 
and accurate means by which the operator can control and monitor the 
mechanical functions of the trailer. This system will contain a main 
control panel with digital readouts and a programmable key pad, 
combination slope-cross slope sensors, laser optical sensors for vertical 
control, optical sensors to monitor mechanical functions such as spud 
pins, tailgate position, and to provide signals for comparator circuitry 
to effect switching functions. 
The control panel (81) of FIG. 1 and 8 is conveniently located for safe 
operation. Electrical power for the control panel is supplied by battery 
which is charged by a motorized hydraulic pump unit. Slope and cross slope 
sensors are mounted on the lifting beam both on the right and left . . . 
trailer 160 A and B of FIG. 1 and 5 and positioned at the center of the 
trailer 160A of FIG. 1. The function of these sensors is to constantly 
measure both longitudinal and transverse slope and signal the control 
panel (81) of FIG. 1. The incoming signals from these sensors are compared 
through a comparator circuit with the set point at the control panel. The 
differential in the comparison results in a corresponding differential in 
an outgoing voltage signal which triggers the flow of fluid to the load 
cylinders of FIG. 1. These load cylinders then raise or lower the bed via 
the hydraulics to maintain the preset slope parameters. 
Optical laser sensors 71A-71B are located close to the center of the 
trailer on the top chord (see FIG. 1 and 5) on both the left and right 
sides of the trailer. These sensors read a barcode linear scale on shafts 
70A and 70B which are mounted on the lifting beam and which vertically 
project through the laser sensors (71A and 71B) These sensors read the 
exact height of the lifting beam and send signals to control panel 81 of 
FIG. 1 which is preprogrammed to compare these signals with the 
preprogrammed set point signals and then to send out voltage level control 
signals through a solenoid to maintain the level parameter at the 
preestablished set point height. The signals engage air actuated solenoids 
located on bank 82 Which in turn actuate air cylinders 92 A,B,C, of FIGS. 
1 and 6 which engage and disengage the spud pins. Sets of micro switch 
roller cams 91 A,B,C,D of FIGS. 1,6, and 7 indicate the position of the 
pins and signal the control of the presence or absence of the locking spud 
pins thus prompting the operator to act accordingly. 
An additional feature of this segment hauling unit is the unique ability to 
calculate and measure accurately the weight of the transported load. This 
is accomplished by using a pizoelectric load cell to measure the pressure 
exerted on each hydraulic cylinder ram cross section and then by 
converting the resulting pressure to a voltage output signal. (See FIG. 5) 
The voltage output signal is then converted at the control panel to 
conventional weight units for digital read out. 
VERTICAL LOCKING SYSTEM 
FIG. 6 shows a cross sectional view of the vertical locking device 60 which 
is composed of a rectangular structural steel member called a spud 61 
which slides vertically within another rectangular structural steel member 
called a spud well 260. Four such spuds 61(a), 61(b), 61(c), and 61(d) 
provide the appropriate locking support for concrete load. The tolerances 
of outside dimensions of spuds and inside dimensions of the spud well 
should be as small as practical. The movement of sliding is aided by use 
of a lubricant such as grease which is injected between surfaces by a well 
known method of grease fittings. Four pins 6(a), 6(b), 6(c), and 6(d) may 
be inserted through predetermined aligned holes in the spud 61(a), 61(b), 
61(c), and 61(d)B and spud well 260(a), 260(b), 260(c), and 260(d). 
respectively, so that when pressure is released on hydraulic cylinders 40 
and the pins are inserted (See FIGS. 1 and 6), the force of the load 
resting on the lifting beam will be transmitted through spuds 61A,B,C,D 
(FIG. 6) to pins 6A,B,C,D then to spud wells 260(a), 260(b), 260(c), and 
260(d) which in turn transmits the pressure to the chassis 20A. Thus the 
supporting load is mechanically locked in place and does not rest on the 
pressurized fluid in the hydraulic cylinders during transport. 
FIG. 7 shows the mounting bracket for inserting a pin into one of the 
vertical locking beams to support the load during transit. Also shown are 
the electromagnetic microswitches which signal the computer controller 
that the spud pin 6 has been inserted into the beam of the vertical 
locking system 60. 
SEQUENCE OF OPERATION 
The essential operation of the concrete bridge segment transport unit is 
divided into two phases, namely (1) loading the concrete bridge segment 
from its manufacturing pallet and (2) unloading the concrete bridge 
segment at the construction site. Each of these phases may be either 
implemented automatically through computer control or manually through 
mechanical operator control. 
I. Loading the Bridge Segment (FIG. 9A) 
The operator backs up the prestressed concrete bridge segment hauling unit 
to the pallet of a bridge segment that is to be transported to the 
construction site. (step 1) The operator then engages the stabilizing 
outriggers through the operator control panel to achieve a predetermined 
elevated level for the tractor bed (step 2). Then the operator 
mechanically removes the locking bar from the lifting beam (step 3). The 
operator then mechanically unlocks and opens the tailgate (step 4). The 
bridge segment is then rolled onto the center of the trailer (step 5). The 
operator then closes the tailgate and replaces the locking bar in order to 
give support and strength to the lifting beam assembly (steps 6 and 7). If 
the loading operation is computer controlled, then the operator may return 
to the computer control panel to program the loading operation and 
digitally input the desired height to which the bridge segment is to 
raised for transport (step 8). The operator then runs the computer program 
to compare and adjust the actual height and slope of the load with the 
setpoint or input height and slope. (step 9) The computer issues a series 
of dc voltages which are input to the solenoid control to control the 
hydraulics which will raise the trailer bed and then level it both 
longitudinally and transversely (step 10). The hydraulic flow of 
pressurized fluid which is raising the lifting beam is stopped once a 
sensor controlled feedback loop in the system detects that the appropriate 
height and planar level have been achieved. These sensors are located at 
each of the beams. The sensors indicate both the longitudinal level and 
transverse level as well as the height. The computer program through steps 
11 and 12 in FIG. 9A continually checks the beam height and beam level 
with feed back control over the hydraulics until the desired set point is 
achieved. When the proper height is detected by the sensor x and the 
transverse and longitudinal level have been achieved by null or neutral 
slope, the control panel computer prevents further movement in the 
hydraulic lifting or movement of the loaded beam. (step 13) The operator 
then can manually or automatically lock the lifting beam in this raised 
position through the heavy gauge pins which slide into holes shown in FIG. 
6 to lock the beam in place (step 14). The operator then raises the 
stabilizing cylinders so that the vehicle is mobile and able to transport 
the engaged bridge segment (step 15). 
II. Unloading the Bridge Segment (FIG. 9B) 
The operator transports the prestressed concrete bridge segment hauling 
unit (FIG. 1) with on board bridge segment that is to be delivered to the 
construction site (step 1). The motor of the hydraulic power unit (90) is 
then started by the operator. Now hydraulic levers 120, 130 are actuated 
to cause stabilizing cylinders 80, 80A to engage the ground and thus 
provide a more stable footing. (step 2) The operator removes the locking 
bar from the lifting beam and opens the tailgate using the hydraulic 
release (steps 3 and 4) The operator then unlocks the bridge segment for 
deposit by removing the sliding locking pins in the vertical support beams 
(step 5) If the unloading operation is computer controlled, then the 
operator may return to the control panel to program the unloading 
operation and digitally select the unloading parameters. (step 6) The 
operator then runs the computer program in order to compare and adjust the 
actual dismount slope of the segment with the setpoint slope. (step 7) The 
computer issues a series of dc voltages which are input to the solenoid 
control to control the hydraulic cylinders which lower the trailer bed as 
well as level it both transversely and horizontally (step 8). The 
hydraulic flow of pressurized fluid which is lowering the lifting beam is 
stopped once a sensor controlled feed back loop in the system detects that 
the appropriate height and planar level have been achieved. These sensors 
are located at each end of the beams. The sensors indicate both the 
longitudinal level and transverse level as well as height. (steps 9 and 
10) When the desired height and level are achieved the program 
automatically actuates a valve which holds the load in place while 
stationary support is provided to disengage the load on the construction 
site (step 11) Then the operator raises the stabilizing cylinders to 
disengage the now unloaded trailer. (step 12) The operator should then 
close the tailgate and replace the locking bar before driving the trailer 
away to pick up another load. (steps 13, 14, and 15) 
While a preferred embodiment of the invention has been illustrated in 
detail as the best mode for practicing the invention to illustrate the 
broader concepts of the present invention as well as the desirable 
specific details, further embodiments, variations, and modifications are 
contemplated all within the scope and spirit of the present invention as 
defined by the following claims.