Abstract:
A straddle-lift carrier for transporting long heavy loads, having  adjusta width for accommodating various size loads and for compacting the carrier for storage. The adjustable width allows the carrier to negotiate relatively narrow passages. A high degree of maneuverabiltity is achieved by utilization of independently driven and steered traction wheels. Raising and lowering of loads is accomplished by hydraulically operated forklift mechanisms disposed on either side of the carrier. Operation of the carrier is controlled by a handheld remote control unit.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to carriers for transporting bulky loads in confined areas, and in particular to a multi-directional, self-propelled, straddle-lift carrier capable of negotiating relatively narrow passageways while transporting a long, heavy load. 
     Industrial trucks are often required to move about in narrow aisles in warehouses and factories. They must, therefore, be very maneuverable in order to handle loads in the manner required. Conventional forklift trucks are generally impractical for this type of operation because of their rather limited maneuverability. Furthermore, even forklift trucks which are more maneuverable, such as that disclosed in U.S. Pat. No. 3,031,024 to Ulinski, are still unsuitable because the load is ordinarily oriented perpendicular to the direction of travel. This problem becomes more acute with longer loads. 
     Similarly, naval combat vessels generally have relatively narrow interior passageways. One of the current techniques for transporting long weapons aboard such vessels is to utilize manually operated hand-lift trucks. Often two such hand-trucks are employed: one at each end of the weapon container. 
     Currently, the combined load capacity of a pair of these hand-trucks is about 5,000 pounds. However, the weight of weapons is escalating, and some weapons, such as the TOMAHAWK missile, may weigh up to 7,000 pounds. Manual effort to lift and move such loads is becoming unrealistic. 
     Powered versions of the end-lifting trucks in some cases have proven impractical because they increase the overall length of the transporter/load combination beyond tolerable limits. Furthermore, controlling coordination of two transporters in tandem could be a relatively complex and costly problem to overcome. 
     A straddle-lift carrier would seem to be an appropriate answer to the above described requirements. Most such carriers, however, are fairly large in size and thus are impractical for use and storage in areas having limited space. A straddle-lift carrier which could be expanded to carry relatively wide loads, but which could be collapsed for fairly compact storage would be desirable. 
     SUMMARY OF THE INVENTION 
     Accordingly, one object of this invention is to straddle and lift heavy, elongated loads. 
     Another object of this invention is to transport such loads. 
     A further object of this invention is to be capable of maneuvering in relatively narrow passageways while transporting long, heavy loads. 
     A still further object of this invention is to accomodate loads of various widths. 
     Yet another object of this invention is to be controlled by means of a single unit remote from the carrier. 
     Still another object of this invention is to require a minimum of self-storage space. 
     The above and other objects are realized in the subject invention by a rigid frame carrier having an inverted U-shaped cross section. The frame has integral telescoping apparatus for adjusting the frame width. A hydraulic pump actuates hydraulic cylinders which are linked to lifting beams having fork tines for engaging and lifting a load. 
     The carrier is moved by two drive wheels situated on either side of the frame. Traction is applied to these drive wheels by electric motors or some other propulsion source. The speed and direction of each wheel is independently controlled to provide for turning or rotation of the carrier. Additionally, servo-steering motors are provided for rotating the drive wheels so that oblique or lateral motion may be obtained. Caster wheels are mounted adjacent the drive wheels for balance and maneuverability. 
     Control of steering and driving is centered in a single, handheld, remote control unit by which the carrier can be driven or steered in any direction. A control panel is located on the carrier frame for housing the control circuits as well as switches and controls for the hydraulic lift system, batteries, etc. 
     Other objects, advantages, and novel features of the invention will become apparent from the detailed description of the invention which follows the accompanying drawings wherein: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a general view of a straddle-lift carrier according to the present invention; 
     FIG. 2 is a plan view of the carrier illustrated in FIG. 1; 
     FIG. 3 shows an end of the carrier as viewed along line 3--3 of FIG. 2; 
     FIG. 4 shows a width adjustment mechanism for the carrier frame as viewed along line 4--4 of FIG. 2; 
     FIG. 5 shows a side of the carrier as viewed along line 5--5 of FIG. 2; 
     FIG. 6 shows a hydraulic lift mechanism as viewed along line 6--6 of FIG. 5; 
     FIG. 7 shows a plane view of a control unit according to the invention; 
     FIG. 8 shows a side of the control unit as viewed along line 8--8 of FIG. 7; 
     FIGS. 9A to 9F show various operations of the carrier when operated in one of the two modes of operation; and 
     FIGS. 10A to 10D show various operations of the carrier when operated in the second mode of operation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings wherein like reference numerals designate identical or corresponding parts among the several views, and more particularly to FIG. 1, there is shown generally a straddle-lift carrier 10 according to the present invention. 
     The carrier 10 has a frame, generally designated 12. In the embodiment shown in FIG. 1, the frame 12 is constructed of steel members which form a unit having an inverted, U-shaped cross-section. The interrelation of these members is shown more clearly in FIGS. 2, 3, 4 and 5. 
     The sides of the frame have inner base channels 16a and 16b and outer base channels 18a,b as shown in FIG. 1. These channels support base plates 19a,b. Columns 20a-d are mounted vertically on the base plates 19a,b and support lateral beams 22a,b. 
     The connecting structure between the sides of the frame 12 includes a mechanism for adjusting the width of the carrier in order to accomodate different size loads and to make the carrier more compact for storage when not in use. As shown in FIG. 2 there are two first horizontal channel members 24a,b extending from the lateral beam 22a. Likewise, there are two second horizontal channel members 26a,b extending from lateral beam 22b. The members 26a,b are spaced to fit between members 24a,b. 
     In the embodiment shown in FIGS. 2 and 3 both sets of members 24a,b and 26a,b are U-channels which are oriented with their open sides facing inwardly. External rollers 28a-d are attached to channel members 26a,b such that they will roll along the outward surfaces of channel members 24a,b. In addition to the external rollers 28a-d, there are two internal horizontal rollers 30a,b and eight internal vertical rollers 32a-h. The horizontal rollers 30a,b are attached to channel members 26a,b such that they will roll along the inner surfaces of the outward walls of channel members 24a,b. 
     The vertical rollers 32a-h are attached to channel members 26a-b such that they will roll along the inner surfaces of the upper and lower walls of channel members 24a,b. In this manner members 24a,b and 26a,b are connected but may slide relative to each other. Since the members 24a,b and 26a,b are rigidly connected to respective sides of the carrier frame 12, any relative motion will result in either a widening or narrowing of the space between the sides of carrier frame 12. 
     As shown in FIGS. 2 and 4 a first cross-member 34 is mounted between the ends of members 26a,b in order to provide rigidity between those members. A second cross-member 36 is mounted between the ends of members 24a,b by means of spacer plates 38a,b to provide rigidity between those members. 
     Adjustment of the width of the carrier 10 is accomplished by means of threaded shafts 40a,b which are threaded through ball bearing nuts 42a,b. The nuts 42a,b are mounted on the cross channels 34 and 36 respectively by means of nut mounting plates 44a,b respectively which are attached as shown in FIG. 4. Plate 44b is given extra rigidity by means of gusset plates 45a,b extending between plate 44b and cross-channel 36. 
     The threaded shafts 40a,b extend through the lateral beams 22a,b respectively in which they are supported and retained by respective support bearings 46a,b. Ratchet handles 48a,b are attached to the ends of the shafts 40a,b respectively for turning these shafts. Pins 49a,b are inserted through the other ends of shafts 40a,b to prevent their backing out of ball-bearing nuts 42a,b. 
     As the threaded shafts 40a,b are turned they will exert either pulling or pushing forces on the members 24a,b and 26a,b causing the carrier frame 12 to either expand or contract in order to accommodate different load widths. The ratchet handles 48a,b provide leverage for turning shafts 40a,b respectively and would be equipped to be turned in both clockwise and counterclockwise directions as may be desired. 
     The means for engaging and elevating a load are shown more clearly in FIGS. 5 and 6. In the embodiment shown there are two identical lift mechanisms, one on either side of the carrier. In operation these two lift mechanisms would be operated in unison. However, for ease of understanding only one mechanism will be described. 
     Guide/support channels 50a,b are attached to the carrier 10 base by means of bottom support channels 14a,b and bottom cross channels 51a,b respectively. A cross-plate 52 is attached between the channels 50a,b at some elevation from the channels 14a,b and 51a,b for adding rigidity to channels 50a,b. 
     A two-way hydraulic cylinder 54 is mounted on cross-plate 52 by means of mounting bracket 56. Hydraulic cylinder 54 has a piston 58 to which is attached a tee member 60. The tee 60 consists of two plates 61a,b between which are mounted two sprockets 62a,b. 
     Lifting chains 64a,b are attached to cylinder bracket 56 on either side of cylinder 54. They are looped around the sprockets 62a,b and attached to sliding channels 66a,b respectively. Rollers 68a,b are attached to channel 66a, and rollers 68c,d are attached to channel 66b. The rollers 68a-d are disposed for engaging with channels 50a,b respectively. Thus it can be seen that as piston 58 is extended or retracted the sliding channels 66a,b will move in either an upward or downward direction. 
     Attached to channels 66a,b is a lifting beam 70 which spans almost the entire length of the carrier 10. Lifting tines 72a,b hang from either end of beam 70 for engaging the load. Detents, such as 73, are located along the upper edge of beam 70 so that the lifting tines 72a,b, which have matching internal teeth, may be adjusted to the proper length for a given load. 
     The cylinder 54 is actuated by hydraulic pump 108 mounted on the base plate 19b as shown in FIGS. 1, 2 and 3. Lifting is accomplished by pumping hydraulic fluid into the bottom of cylinder 54 which causes piston 58 to extend. Likewise, lowering is accomplished by pumping hydraulic fluid into the top of cylinder 54 which causes piston 58 to retract. 
     The carrier 10 is maneuvered and driven by means of steering and traction units 74a,b located on either side of the carrier 10. In the embodiment shown in FIG. 5 unit 74b consists of a motor control unit 76b, an electric motor 78b, a transmission 80b, and a drive wheel 82b. Unit 74a is identically equipped. 
     In order to maneuver in certain directions the drive wheels 82a,b must be turned. This is accomplished by means of servomotors 83a,b. In the embodiment shown in FIG. 5 servomotor 83b, which is identical to 83a, includes an electric motor 84b which drives a gear reducer 86b. A sprocket gear 88b is mounted in the reducer 86b. Chain 94b is looped between sprocket 88b and a second sprocket 92b mounted about drive wheel housing 90b. Thus, any rotation of sprockets 88a,b will result in rotation of the drive wheels 82a,b. 
     Caster wheels 114a-d are mounted at the corners of the carrier frame. These wheels provide additional mobile support and balance making the carrier 10 easy to maneuver about. 
     Power for the electric pump and motors may be supplied from two 36 volt batteries 106a,b. However, other voltages could be used depending on motor availability and load requirements. A control panel 100 is mounted on one side of the carrier frame 12. Panel 100 contains devices for monitoring various functions, such as battery level, and switches for operating various devices, such as the hydraulic lift system. The control circuits for the steering and drive systems are mounted inside panel 100. 
     The carrier 10 is operated by means of a remote control unit 120. The control unit 120 is shown in greater detail in FIGS. 7 and 8. The unit 120 has a body 122 in which are housed the electrical and electronic components for controlling the carrier 10. These components would consist of potentiometers and other devices connected to generate control signals for operating the carrier 10. 
     A cover 124 having an arched ridge 125 is fastened over the body 122. Ridge 125 has an elongated slot 126 through which the control handle 127 protrudes. Handle 127 may be moved forward and back along the slot to initiate forward or reverse motion of the carrier 10. Handle 127 consists of a stem 128 to which is attached a head 129. In addition to moving along the slot 126 the handle 127 rotates about its Z-axis. Rotation of handle 127 controls steering of the carrier 10. 
     A mode switch 130 is mounted on cover 127. Switch 130 is a two-position toggle switch for selecting between the two modes of operation of the carrier 10. These modes of operation will be described shortly. The overall size of control unit 120 would be small enough to be handheld by an operator. The control unit 120 may be hardwired to the control panel 100 by means of an umbilical cable 140. Alternatively, the unit 120 may be equipped with a small radio transmitter and the control panel equipped with a comparable receiver for radio control. 
     Operating functions of the straddle-lift carrier 10 according to the subject invention are illustrated in FIGS. 9A-F and 10A-D. As indicated above there are two modes of operation for the carrier 10: a NORMAL mode and a LATERAL/OBLIQUE mode. FIGS. 9A-F illustrate operation of the carrier 10 in the NORMAL mode. In this mode the drive wheels 82a,b are maintained in a straight fore and aft orientation. The mode switch 130 is in the NORMAL position. 
     As shown in FIG. 9A when the handle 127 of control unit 120 is pushed forward the drive wheels 82a,b will operate to drive the carrier 10 forward. By moving handle 127 backward the carrier 10 will travel in reverse as shown in FIG. 9B. 
     Turning capability is illustrated in FIGS. 9C,D. Carrier 10 may be turned to the right by pushing handle 127 forward and rotating it clockwise. This will cause drive wheel 82b to operate at a higher speed than wheel 82a with the result that carrier 10 will move forward and to the right as shown in FIG. 9C. Counterclockwise rotation of handle 127 would result in a left turn as shown in FIG. 9D. The turning degree is determined by the amount of rotation of the handle 127. A small degree of rotation will result in a wide turn, whereas a larger degree of rotation will result in a sharper turn. 
     Carrier 10 can also be made to rotate about its own axis. As shown in FIGS. 9E and 9F, with handle 127 in a central or neutral position (i.e. no forward or reverse motion) rotation of the handle 127 will cause the drive wheels 82a,b to operate in opposite directions. Clockwise rotation will cause carrier 10 to yaw to the right, whereas counterclockwise rotation causes yaw to the left. 
     When the mode switch 13 is in the LATERAL/OBLIQUE mode position, the drive wheels 82a,b can be rotated for operation as shown in FIGS. 10A-D. In FIG. 10A control handle 127 is rotated a certain amount counterclockwise while in the neutral position. This will cause the drive wheels 82a,b to be turned to the left by an angle, θ. When the wheels 82a,b reach the desired angle, handle 127 can be pushed forward or back and carrier 10 will move at an oblique angle θ from straight forward or reverse. FIG. 10B shows similar operation but to the right. If the handle 127 is rotated 90° clockwise or counterclockwise then the carrier 10 can be driven laterally either to the right or to the left as shown in FIGS. 10C and 10D. 
     Some of the many advantages and new features of the subject invention should now be apparent in view of the foregoing description. For example, a straddle-lift carrier has been described which is capable of engaging and lifting elongated loads. The carrier is equipped with apparatus for adjusting its width in order to accommodate different size loads. This width adjustment feature also allows the carrier to be made compact for storage in minimal space. 
     The carrier according to the subject invention has steering and traction equipment which is controlled by a single, remote unit. The configuration of the steering and traction equipment provides numerous operations giving the carrier a high degree of maneuverability. 
     Numerous additional modifications and variations of the subject invention are possible in light of the above teachings. For example, a hydraulic system could be used in place of the threaded shafts for adjusting the frame width. Internal combustion engines or hydraulic motors could be used as prime movers in lieu of electric motors. Also, fluidic controls could be substituted for the electrical controls. Alternate drive wheel configurations could also be employed. Additionally, the carrier frame could be equipped to adjust its height in order to accommodate tall loads and to permit stacking. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.