Hydraulic Hoisting Apparatus For Use With A Road Vehicle

Abstract

A hydraulic hoisting apparatus for a gantry vehicle with hydraulic motor means for propelling the vehicle and with front and rear hoisting devices. Either the hoisting devices or the motor means are selectively driven by two flows of a fluid medium discharged from two outlets of a motor driven main pump, and flowing first through two control valves, and then through two hoist valves, respectively. The hoist valves control direction and speed of the hoisting devices, and the control valves direct the two flows either to the hydraulic propelling motor means of the vehicle or to the hoist valves.

Description

BACKGROUND OF THE INVENTION

The present invention is concerned gantry vehicles, and other movable cranes, for bulky and heavy loads, such as vans. During practical operation of gantry cranes of this type with vans and the like, it has been found that in many cases it is only necessary to lift the load off the vehicle to put the load down, to load or unload, and then place the load again on the vehicle. A self-propelled gantry vehicle is known in which two portal structures are connected by girders, and carry at each corner a cylinder and piston hoisting device mounted for universal movement at the corners of the gantry structure. Due to this construction, it is possible to move the hoisting means to any selected point of the load for attaching the hoisting means to the load, depending on the kind and shape of the load. On the legs of the portals, wheels are mounted on pivoted arms which during driving of the gantry vehicle roll on the road, while during loading and unloading operation, the structure rests on the ground. At least two wheels on two legs are driven by two hydraulic motors.

The hydraulic apparatus by which the hoisting means are controlled in accordance with the prior art are rather complicated, and it is one object of the invention to provide a hydraulic hoisting apparatus of simple construction which is mounted on a road vehicle, such as a gantry structure.

Another object of the invention is to provide a hydraulic apparatus of this type in which the power for propelling the wheels of the vehicle, and for hoisting loads, is supplied by a single prime mover motor driving a single pump.

Another object of the invention is to provide a hydraulic apparatus of the above described type, which permits a variation of the road speed of the gantry vehicle, without requiring a main pump having a variable and adjustable flow volume.

Another object of the invention, is to provide in the hydraulic apparatus control valve means for selectively directing the flow from the main pump either to the hoisting devices, or to the propelling motors of the vehicle.

SUMMARY OF THE INVENTION

With the above objects in view, an embodiment of the invention comprises motor driven pump means having a plurality of pump outlets, a pump inlet, and a reservoir to which the pump inlet is connected; a plurality of control valves having control valve inlets connected with the pump outlets, first control valve outlets connectable with hydraulic motor means for propelling the vehicle, and second control valve outlets; at least one hoist valve for controlling lifting and lowering movement of a hydraulic hoisting means mounted on the vehicle, and having a hoist valve inlet communicating with the second control valve outlet of one of the control valves, a first hoist valve outlet connected with the hoisting means, and a second hoist valve outlet for discharge into the reservoir; and means for actuating the control valves to connect the control valve inlets with the second control valve outlets, respectively, for operating the hoisting means, or to connect the first control valve outlets with the hydraulic motor means while actuating the hoist valve to connect the hoist valve inlets with the second hoist valve outlets, respectively, so that the hydraulic motor means is operated to propel the vehicle.

In the preferred embodiment of the invention two hoisting devices are mounted on the vehicle, and two hoist valves control the lifting and loading movements of the hoisting devices. The hoist valve inlets communicate with the second control valve outlets, respectively, and first hoist valve outlets are connected with the hoisting devices, respectively, while second hoist valve outlets are provided for dischrage into the reservoir. In this manner, two separate hoisting device, each of which may include two or more hoisting cylinder and piston means, are separately provided with two flows of the fluid medium discharged from the two outlets of the motor driven main pump means.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is the left half of a simplified diagram illustrating a hydraulic apparatus in accordance with the invention;

FIG. 2 is the right half of the diagram; and

FIG. 3 is a perspective view illustrating a gantry vehicle which is provided with the appratus of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a prime mover in the form of a Diesel motor D is provided which drives a pump 1, which may be, for example, a high pressure radial piston pump. Pump 1 has first and second pressure outlets 1a and 1b to which conduits 2 and 3 are connected. Equal volumes of a fluid medium are discharged by pump 1 at the two pump outlets 1a and 1b, independently of the pressures prevailing in conduits 2 and 3. The two flows of fluid medium through outlets 1a and 1b do not influence each other.

VEHICLE DRIVE

Conduit 2 is connected with the inlet 4a of a first control valve 4. As schematically indicated control valve 4 is shiftable between a neutral position of rest, and two control positions for connecting the inlet 4a to different outlets. Conduit 3 is connected with the inlet 5a of a second control valve 5 which is constructed and operated in the same manner as control valve 4. Control valves 4 and 5 are mechanically interconnected as schematically indicated at 5h and are held by a spring in the neutral positions. When manual means act on the actuating means 5h, first control valve 4 is moved out of its neutral position to one of the control positions, whereupon during further movement of the manually operated means, the second control valve 5 is also moved out of the neutral position to the corresponding control position.

If the manually operated means, shown in FIG. 3 to be manual levers 87a, are returned to a neutral position, the control valves 4 and 5 are returned by springs to the neutral position of rest. In this position, illustrated in FIG. 2, the inlet 4a is connected with an outlet 4b of control valve 4, and the inlet 5a is connected with an outlet 5b of control valve 5. Outlet 4b opens into a conduit 6, and outlet 5b opens into a conduit 7 which lead to inlets 8a and 9a of hoist valves 8 and 9, respectively, from which the two flows of fluid medium are returned through outlets 8b and 9b, conduits 10 and 11, and return conduit 12 to a low pressure area. In the return conduit 12, a pressure maintaining valve 13 is provided, so that the returned fluid medium passes at low pressure through a filter 23 into a container or reservoir 24, as shown in FIG. 2. The hydraulic medium is sucked from reservoir 24 through a manually operable valve 24a and a suction conduit 24b to the suction inlet 1c of the pump 1.

Control valve 4 has an outlet 4c which is connected by conduit 14 with the outlet 5c of control valve 5. A common conduit 15, which branches into conduits 16 and 17, connects outlet 5c with two hydraulic drive motors 18 and 19, as shown in FIGS. 2 and 3, which are mounted on a gantry structure 8, and more particularly on the front legs 81 of the structure. Motors 18 and 19 drive the wheels 90a and 90b, respectively, which are mounted on a steering linkage of which only two brackets 91 are shown. Since hydraulic motors 18 and 19 act on the front wheels, they must rotate at the same speed. Second inlets of hydraulic motors 18 and 19 are connected by a common conduit 22 with the outlet 5d of control valve 5, and by conduit 22a with the outlet 4d of control valve 4. A leakage conduit 22b connects the outlets of hydraulic motors 18 and 19 through filter 23 with the reservoir 24.

Control valves 4 and 5 are constructed as slide valves with variable flow cross section, and the two outer control positions are respectively associated with forward and reverse rotation of the hydraulic motors 18 and 19. By moving the control slides, not shown, of control valves 4 and 5, to the left or right, to one of the control positions out of the neutral position shown in FIG. 2, the inlet 4a is connected with the outlet 4c, or with the outlet 4d. Accordingly, at the control valve 5, the inlet 5a is either connected with the outlet 5c or with the outlet 5d, in the two control positions of valve 5. The outlet 4b is then connected with the respective other outlet of the outlets 4c and 4d, and the outlet 5b is connected with the respective other of the two outlets 4c and 5d. Conduit 2, which is connected with inlet 4a, is connected by an overpressure return valve 25 and a discharge conduit 26, with the return conduit 12.

The above described part of the hydraulic apparatus serves for controlling the drive motors 18 and 19, and includes two suction check valves 70a and 70b which connect conduits 15 or 22, respectively with the return conduit 12, and which are arranged so that the fluid medium can flow only in the direction from conduit 12 to the conduits 15 or 22. Pressure limiting valves 71 and 72 are connected between conduits 15 and 22, and permit flow in opposite directions.

HOISTING APPARATUS

The gantry vehicle illustrated in FIG. 3 includes two U-shaped portals 80 whose legs 81 support the front wheels 90a and 90b which are driven by hydraulic motors 18 and 19, while the rear wheels 93 are not driven. Girders including bars 83 and 85, and trusses 84 connect the two portals 80. The transverse top bars 82 of portals 80 carry universal joints 82a on which hoisting means 27, 28 in front, and hoisting means 29, 30 in the rear, are supported. Each of the hoisting means 27 to 30 includes a pivotally suspended cylinder, in which pistons 27a, 28a etc. are mounted, as best seen in FIG. 1. Pistons have piston rods 27b, 28b etc. having joints at the lower ends in which hooks 27c are mounted. The hydraulic cylinder and piston motors 27, 28 together constitute a front hoisting device, and the rear cylinder and piston means 29, 30 constitute a rear hoisting device. The front and rear hoisting devices are operated by the flows of fluid medium from the pump outlets 1a and 1b, respectively, and are associated with the hoist valves 8 and 9, and with the control valves 4 and 5, respectively. The arrangement will be particularly described with reference to the hoisting means 27 and 28 which simultaneously raise and lower the front end of a load, shown to be a van 100. The corresponding hydraulic arrangement for operating the hoisting means 29 and 30, is only partly shown in FIG. 2, and represented by the illustration of the hoist valve 9, which corresponds completely to hoist valve 8.

As noted above, the hoist valve 8 controls the operations of the cylinder and piston motors 27 and 28. Hoist valves 8 and 9 are constructed in the same manner as control valves 4 and 5. Hoist valve 8 has two outlets 8 c and 8d, and hoist valve 9 has two outlets 9c and 9d. Outlet 8d is connected by conduits 31 and 32, a check valve 33, and by a conduit 34 with the flow divider 35 which divides the flow of fluid medium in conduit 34 into two flows of equal flow volume, independently of the pressures prevailing in the two outlet conduits. One outlet of the flow divider 35 is connected by conduit 36 with the hoist cylinder 27, and the other outlet is connected by conduit 37 with the hoist cylinder 28. Since all hoist means 27 to 30 are identically constructed only hoisting means 27 will be explained in detail. Conduit 36, which contains a pressure responsive check valve 38, opens into the lower annular chamber 39 formed in the cylinder by a piston 27a which also forms a chamber 40. As noted above, the piston rod 27b carries the hook or attaching means 27c which is attached to a corner of the load van 100. The upper cylinder chamber 40 is connected by conduits 41 and 42 with the outlet 8c of the hoist valve 8.

Fluid medium can flow through the flow divider 35 in both directions. When the fluid medium flows from both conduits 36 and 37 to the flow divider 35, the two streams are combined in conduit 34. In this direction of flow, the check valve 33 remains closed. If the pressure in conduit 34 is sufficient, a preliminary pressure valve 43 opens and connects conduit 34 with outlet 8d of hoist valve 8. Check valves 38 permit a flow out of the annular chamber 39 into conduit 36 only if the control conduit 44 of the check valve 38 is under pressure. The conduit 44 is connected by a conduit 73 and another conduit 49 with the inlet 48a of a selector valve 48, whose purpose will be explained later on. Another outlet 48b of selector valve 48 is connected by pressure conduit 47 with the outlet of an auxiliary pump 45 which sucks through a suction conduit 46, a fluid medium out of the reservoir 24.

Each of the hoisting cylinder and piston means 27 to 30 is associated with a hoist setting valve, hoist setting valves 51 and 52 being shown connected with hoist cylinder and piston means 27 and 28. The hoist setting valves 51 to 54 are mounted on the legs of the portals 80, as shown for hoist setting valves 51 and 52 in FIG. 3. The hoist setting valves 51 to 54 are of identical construction which will be specifically described with reference to hoist settting valve 51 which has an inlet 51e connected by conduit 45 with selector valve 48 by conduit 49, as shown in FIGS. 1 and 2. The outlet 51b is connected by conduits 58, 59, and 60 with a return conduit 12, and a valve port 51c is connected by conduit 57 with conduit 41, while a valve port 51b is connected by conduit 56 with conduit 36. In the neutral position shown in FIG. 1, which is assumed by the slide of hoist setting valve 51 due to the action of springs, all valve ports 51a, 51b, 51c and 51d are separated from each other. By shifting the hoist valve 51 to one of the two control positions, different connections are obtained. In one control position, port 51a is connected with port 51c, and port 51b is connected with port 51d, while in the other control position port 51a is connected with port 51d, and port 51b is connected with port 51c.

STEERING APPARATUS

The steering of the gantry structure during the drive is accomplished by a hydraulic circuit. The steering linkage is not illustrated in FIG. 3, except for the brackets 91 which carry the front wheels 90a and 90b.

However, it will be understood that the steering motor 67 shown in FIG. 2 can be connected with the steering linkage to obtain angular displacement of brackets 51. The hydraulic steering motor 67 includes a steering cylinder 68 in which a piston 68a is movable, and provided with oppositely projecting piston rods 68b, so that two annular chambers 66a and 66b are formed in cylinder 68. Chambers 66a and 66b are respectively connected by conduits 64 and 65 with a steering valve 62 which is connected by a conduit 61 with the selector valve 48, and by a conduit 63 with the filter 23 and the low pressure reservoir 24. The piston rods 68b are connected in the usual manner with the steering linkage of which only the pivotally mounted bearing brackets 91 are shown in FIG. 3. Pressure indicating gauges 74 are respectively connected with conduits 2, 47 and 26, a pressure limiting valve 75 being provided in conduit 26.

A station 87 is provided for the driver, and contains a driver's seat, levers 87a for operating the controls valves 4 and 5, levers 87c for operating hoist valve 8 and hoist valve 9, a steering wheel 87b, and a manual means for shifting selector valve 48 between a position activating the steering motor 67 and another position activating a hoist setting valve 51 and 52. The bottom plate 88 is suspended by U-shaped carriers 88a on the transverse bar 85.

The selector valve 48 serves the purpose of shifting the flow from the auxiliary pump 45 either to the hydraulic circuit of the steering motor 67 with the steering valve 62, or with the hydraulic circuit of the hoist cylinders 27 to 30, with the respective hoist setting valves of which only hoist setting valves 51 and 52 are shown. In the position of selector valve 48 illustrated in FIG. 2, the inlet 48b is connected with conduit 61 which is connected with the inlet of steering valve 62 and the inlet 48a connects conduit 49 by a conduit 63a with the conduit 63 to the reservoir 24. When selector valve 48 is placed in the second possible position, the pressure conduit 47 is connected with conduit 49 to the hoist setting valves 51, 52, while conduit 61 is connected with conduit 63a. A pressure limiting valve 69 connects pressure conduit 47 at the outlet of auxiliary pump 45 with the return conduit 63 which opens in the reservoir 24.

OPERATION

In order to propel the gantry structure 80 by drive motor 18, 19, the first control valve 4 is shifted to the left so that the supply conduits 16, 17 of hydraulic drive motors 18 and 19 receive pressure fluid from pump 1 through conduits 2, 14 and 15.

Depending on how far the first control valve 4 is shifted, the volume of the fluid medium supplied to hydraulic motor 18 and 19 is varied so that the equal rotary speed of motors 18, 19 is also varied. The fluid medium returned by the hydraulic motors 18 and 19 through the respective outlets flows through conduits 20 or 21, 22, 22a, 6, through hoist valve 8, return conduit 10, the pressure maintaining valve 13, and filter 23 into reservoir 24.

The stream of fluid medium discharged from outelt 1b of the main pump 1 through conduit 3 flows through the ports 5a and 5b of control valve 5, conduit 7, ports 9a and 9b of hoist valve 9, and return conduit 12, and pressure maintaining valve 13 through the filter 23 into reservoir 24 without any action on the hydraulic drive motors 18 and 19. If more fluid medium is discharged from pump outlet 1a into conduit 2, it can flow through control valve 4 to the hydraulic drive motors 18, 19, and a part of the flow is discharged through the overpressure valve 25 into reservoir 24.

When control valve 4 is fully opened, the two hydraulic drive motors 18 and 19 operate at half the maximum speed. If the control valve 5 is also gradually moved to the left, the connection of the ports 5a and 5b is interrupted, and the fluid medium under pressure can flow from conduit 3 through inlet 5a to outlet 5c and to the hydraulic drive motors 18 and 19. The return flow flows through conduit 22, the connected ports 5d and 5b, conduit 7, ports 9a and 9b of hoist valve 9, and through conduit 11 into the return conduit 12 which is connected with the reservoir 24.

Due to the successive actuation of the two flow varying control valves 4 and 5, which receive pressure medium from two separate outlets 1a and 1b of pump 1, it is possible to obtain a continuous variation of the number of revolutions of hydraulic motors 18 and 19, by the use of two streams of fluid of constant volume, which can otherwise be obtained only by a regulatable pump whose output flow can be varied by adjustment.

When control valves 4 and 5 are moved to the right, as viewed in the drawing, the inlets 20 and 21 of the hydraulic motors 18 and 19 are supplied with high pressure fluid medium, while the return flow takes place through conduits 17 and 16. Consequently, the direction of rotation of hydraulic drive motors 18 and 19 is simultaneously reversed. The left control positions of control valves 4 and 5 are associated with the forward drive and the right control positions are associated with the reverse drive of the gantry vehicle 80.

If control valves 4 and 5 are quickly returned to the neutral position of rest, the hydraulic drive motors 18 and 19 cannot momentarily be brought to a standstill, since they are driven from the wheels 90a and 90b due to inertia movement of the gantry structure along the road, so that the hydraulic devices 18 and 19 begin to operate as pumps which requires that on the suction side of the hydraulic motors 18 and 19, the fluid medium is sucked through the suction check valve 70a and 70b out of the return conduit 12. In order to prevent underpressure, the pressure maintaining valve 13 throttles the flow of the fluid medium into the return conduit 12. The hydraulic devices 18 and 19, operating as pumps, press the fluid medium, depending on the direction of rotation, either into conduit 15 or into conduit 22, which are both connected with the control valves 4 and 5. Consequently, the fluid medium must be displaced by the pressure limiting valves 71 and 72, respectively, into the respective suction conduits.

During movement of the gantry vehicle on the road, the selector valve 48 is placed in the position shown in FIG. 2, so that the auxiliary pump 45 supplies the steering valve 62 through conduit 61 with fluid medium under pressure. When the steering valve 62 is turned by a manually operated member, pressure fluid flows through conduit 64 or 65 into the annular chamber 66 or 67, depending on the direction of rotation while the fluid flows out of the respective other chamber. Piston 68a is displaced, and operates by its piston rod 68b and by the steering linkage, not shown, the bearing brackets 91 of the steered pair of wheels 90a and 90b.

Since in this position of the selector valve 48, conduit 49 is connected with the low pressure reservoir 24, but not with the auxiliary pump 49, the pressure controlled check valve 38, connecting conduit 44 with the annular pressure chamber 39 of hoist means 27, is not under pressure and consequently does not open so that no fluid can flow out of the annular pressure chamber 39, whereby the pistons 27a, 28a rigidly support the front end of the load 100 on the hooks or touching means 27c, 28c.

HOISTING OPERATIONS

If the load, such as a van 100 is to be raised or lowered, control valves 4 and 5 are maintained in the illustrated neutral position of rest so that the flow of fluid medium to and from the hydraulic drive motors 18 and 19 is interrupted. Selector valve 48 is moved to the left so that the supply of pressure fluid to the steering valve 62 is interrupted, and the auxiliary pump 45 supplies pressure fluid through ports 48b, 48a of selector valve 48 and through conduits 49, 73 to the pressure controlled check valve 38.

The pistons of the hoisting means 27, 28, 29, 30 are controlled by hoist valves of which only hoist valves 8 and 9 respectively associated with the front hoist means 27, 28, and with the rear hoist means 29, 30, are shown.

The respective hoist valves 8 or 9 are moved to the right in order to lift the load. Pressure fluid in conduit 6 flows from port 8a to port 8d, through check valve 33, conduit 34, flow divider 35, conduits 36 or 37, and the opened pressure controlled check valves 38 into the lower annular pressure chambers 39 of the front hoisting means 27 and 28 carried by the transverse top beams of the gantry structure. The amounts of volumes of the fluid medium in conduits 36 and 37 are equal after passage through the flow divider 35, irrespective of the pressure in the hoist means 27 and 28, so that the pistons 27a and 28a are simultaneously raised. The front hoisting means 27 and 28 together form a front hoisting device, while the corresponding rear hoisting device is operated by hoist valve 9. The fluid medium displaced out of the upper chambers 40, flows through the hoist valve 8 and the return conduit 12 to the reservoir 24.

Before lowering the load 100, the hoist valves 8 and 9 are shifted to the left. The pressure fluid in conduit 6 flows now into the chambers 40 and presses the pistons 27a, 28a downward, while the fluid medium is displaced out of the annular chambers 29 and flows through the respective pressure responsive speed limiting valve 43 into the return conduit 12. The valves 43 have the effect that all pistons 27a, 28a etc. move downward at exactly the same speed, even if subjected to different loads.

The pressure responsive check valves 38 are safety valves and prevent a dropping of the load 100 if, for example, during operation, the conduit 36 breaks. The pistons 28a, 27a can only move downward, if conduits 44 are filled with fluid medium under pressure.

In accordance with the invention, each of the pistons of the hoisting means and the respective attaching hooks 20c is independently operable which facilitates the attachment of the hooks 27c to the van 100. For this purpose, hoist setting valves are provided for each piston, only hoist setting valves 51 and 52 for pistons 27a, 28a being shown in FIG. 1, and FIG. 3. It will be noted that each hoist setting valve 51 has actuating means located adjacent the respective attaching hook 27c, as shown in FIG. 3.

In the position of the hoist setting valves shown in FIG. 1 for hoist setting valves 51 and 52, all ports are disconnected. When the selector valve 48, see FIG. 2, is shifted to the left, pressure from auxiliary pump 45 in conduit 55 acts on inlet 51a of the hoist setting valve 51. If hoist setting valve 51 is shifted to the left, pressure fluid flows to port 51d and through conduits 56 and 36 and through the pressure responsive check valve 38 into the annular chamber 39 of hoisting means 27 so that piston 27a moves upward, and the fluid medium displaced out of the cylinder chamber 40 flows through conduits 41 and 57 to port 51c, and from there to port 51b and through conduits 58, 59, 60 and 12, back to the reservoir 24.

On the other hand movement of the hoist setting valve 51 to the right effects supply of pressure medium to the chamber 40 so that piston 27a, with the respective attaching hooks 27c moves downward. Since it is not necessary to lift the load 100 during the attachment of the attaching hooks 27c, it is sufficient to use the auxiliary pump 49 for supplying the fluid medium under pressure whereas for lifting the load 100, the main pump 1 is used, which also serves for driving hydraulic motors 18 and 19 for propelling the gantry vehicle.

For driving the gantry vehicle along the road, and for lifting and lowering the load 100, only a single pump, driven by a single prime mover combustion engine D, is required. In accordance with the invention pump 1 has first and second pump outlets 1a and 1b, through which two separate streams of fluid medium flow into control valves 4 and 5. If control valves 4 and 5 are in the neutral position of rest, one of the streams of fluids flows into the hoisting means 27 and 28 which together constitute a front hoisting device and the other stream flows into the hoisting means 29 and 30 which together constitute a rear hoisting device. Since control valves 4 and 5 are located upstream of the hoist valves 8 and 9, it is not possible to operate the front and rear hoisting devices during road movement of the gantry vehicle while the wheels 90a, 90b are driven by hydraulic motors 18 and 19. In this manner, it is prevented that the hoisting means are operated to raise and lower the load while the vehicle moves on a road.

From the above description of a preferred embodiment, it will be understood that the hydraulic apparatus of the invention requires only a prime mover and one constant output pump for propelling and road vehicle carrying the hoisting devices, and for lifting and lowering the load by means of the hoisting devices. The number of parts is small, and the general arrangement of the hydraulic system comparatively simple so that it is also possible to continuously vary the rotary speed of the hydraulic wheel motors 18 and 19, without using a pump with a variable and adjustable output.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of hydraulic hoisting apparatus for use with a road vehicle, differing from the types described above.

While the invention has been illustrated and described as embodied in a hydraulic hoisting apparatus with a single main pump having two outlets for fluid streams together driving the wheel motors of a vehicle, and separately driving front and rear hoisting devices for a load, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

Claims

I claim:

1. Hydraulic hoisting apparatus for use with a road vehicle, comprising, in combination, motor driven pump means having a plurality of pump outlets, a pump inlet, and a reservoir to which said pump inlet is connected; hydraulic motor means for propelling the vehicle; a plurality of control valves having control valve inlets connected with said pump outlets, respectively, first control valve outlets connectable with said hydraulic motor means, and second control valve outlets; a hydraulic hoisting means mounted on the vehicle, at least one hoist valve for controlling lifting and lowering movements of said hydraulic hoisting means, and having a hoist valve inlet communicating with said second control valve outlet of one said control valve, a first hoist valve outlet connected with said hoisting means, and a second hoist valve outlet for discharge into said reservoir; and means for actuating said control valve to connect said control valve inlets with said second control valve outlets, respectively, for operating said hoisting means, or to connect said first control valve outlets with said hydraulic motor means while actuating said hoist valve to connect said hoist valve inlet with said second hoist valve outlet so that said hydraulic motor is operated to propel the vehicle.

2. Apparatus as claimed in claim 1, wherein said motor driven pump means has two pump outlets; wherein two control valves each having one control valve inlet are provided, said control valve inlets being connected with said two pump outlets, respectively; wherein said second control valve outlets are connected with said hoist valve inlets of two hoist valves; comprising two hoist means; and wherein said first hoist valve inlets of said two hoist valves are connected with said two hoist means, respectively.

3. Apparatus as claimed in claim 1, wherein each of said control valves has a variable flow cross section so that actuation of any one control valve gradually increases or reduces the flow of fluid into said hydraulic motor means whereby the speed of said hydraulic motor means is increased or reduced.

4. Apparatus as claimed in claim 1, wherein said actuating means include a manually operated means for successively actuating said control valves.

5. Apparatus as claimed in claim 1, comprising conduit means connecting said first hoist valve outlet with said hoisting device; a hoist presetting valve shunting said conduit means; and auxiliary pump means supplying fluid to said hoist presetting valve so that said hoisting device can be set without operation of said hoist valve.

6. Apparatus as claimed in claim 1, wherein said hydraulic motor means has inlet means connected with said first control valve outlets; and further comprising conduit means connecting said inlet means with said reservoir; and suction check valve means in said conduit means.

7. Apparatus as claimed in claim 1 wherein said hydraulic motor means has inlet means and outlet means; further comprising pressure limiting valve means connecting said inlet means with said outlet means.

8. Apparatus as claimed in claim 1, wherein said hydraulic motor means are operable in opposite directions of rotation; wherein each of said control valves has a neutral position, and two control positions for rotation of said motor means in opposite directions; and wherein said actuating means include means for successively operating said control valves between said positions thereof.

9. Apparatus as claimed in claim 1, wherein said hoisting device includes a cylinder and a piston forming two chambers in said cylinder; and wherein said hoist valve has a neutral position, and two control positions for directing fluid into said two chambers, respectively, so that the movement of said piston is reversable for lifting and lowering a load.

10. Hydraulic hoisting apparatus for use with a road vehicle, comprising, in combination, motor driven pump means having a plurality of pump outlets, a pump inlet, and a reservoir to which said pump inlet is connected; hydraulic motor means for propelling the vehicle; a plurality of control valves having control valve inlets connected with said pump outlets, respectively, first control valve outlets connectable with said hydraulic motor means, and second control valve outlets; a plurality of hoisting devices mounted on the vehicle; a plurality of hoist valves for controlling lifting and lowering movements of said hoisting devices, respectively, and having hoist valve inlets communicating with said second control valve outlets of said control valves, respectively, a first hoist valve outlet connected with said hoist devices, respectively, and second hoist valve outlets for discharge into said reservoir; and actuating means for actuating said control valves to connect said control valve inlets with said hydraulic motor means while actuating said hoist valves to connect said hoist valve inlets with said second hoist valve outlets, respectively, so that said hydraulic motor means is operated to propel the vehicle.

11. Apparatus as claimed in claim 10, wherein said actuating means include means for successively operating said control valves between neutral positions in which said hydraulic motor means are not operated, and two control positions in which said hydraulic motor means rotate in opposite directions; wherein each of said control valves gruadually increases the flow cross section thereof when moving from said neutral position to one of said control positions so that the speed of said hydraulic motor means increases when said control valves are successively moved from said neutral positions to the respective control positions.

12. Apparatus as claimed in claim 10, wherein said road vehicle includes a gantry structure having wheels driven by said hydraulic motor means, and movably supporting one of said hoisting devices in front, and the second hoisting device in the rear; and wherein each of said front and rear hoisting devices includes two cylinder-and-piston hydraulic motors.

13. Apparatus as claimed in claim 12, comprising two conduit means connecting each hoist valve with said cylinders of one of said hoisting devices; two hoist presetting valves connected with said two conduits; and auxiliary pump means supplying fluid to said hoist presetting valves so that any one of said hoisting pistons can be raised and lowered for attaching a load without operation of said hoist valves and of said pump means.