GB1562342A

GB1562342A - Vehicle power take-off units

Info

Publication number: GB1562342A
Application number: GB761077A
Authority: GB
Original assignee: SHERRIFF P
Current assignee: SHERRIFF P
Priority date: 1978-02-08
Filing date: 1978-02-08
Publication date: 1980-03-12

Description

(54) IMPROVEMENTS IN OR RELATING TO VEHICLE POWER TAKB-OFF UNITS (71) 1, PEmt ALAN SHBRRIFF, a British subject, of Oakdene Mill Lane, Black Bourton, Oxon, England do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a vehicle power take-off unit for use with a mechanically propelled wheeled vehicle.

In order to drive various items of mechanical equipment such as generators, pumps and compressors, and a variety of handtools, a mechanical power source is required.

Usually, this power source is provided by an internal combustion engine coupled directly to the mechanical equipment. Although a motor vehicle is often available, it is not normally practicable to make use of its engine to provide motive power for such equipment owing to the difficulty in providing a power take-off from the engine.

In accordance with the present invention there is provided a portable power take-off unit for use with a wheeled vehicle, comprising a mobile endless wheel-engaging surface mounted in a frame adapted to locate beneath a driven wheel of the vehicle with the wheel tyre resting on the endless surface, means to maintain the vehicle wheel in contact with the endless surface, a poweroutput connection coupled to the mobile surface to provide a mechanical drive therefrom when the wheel is driven while resting on the endless surface, and an element operable to provide a stationary surface beneath the wheel when the vehicle is to be driven off the unit.

Preferably the wheel engaging surface is a friction roller, and the means for maintaining the vehicle drive wheel in contact with it is a second roller, spaced from and parallel to the friction roller, and arranged so that the vehicle drive wheel settles into the gap therebetween.

Preferably the friction roller is coupled to the power output connection by means of a chain or pulley. These are capable of providing a weak link in the power take-off so that should the load rise suddenly, the vehicle does not suddenly jolt. Also a slipping clutch may be used. In some cases a manually-operable clutch in the drive takeoff is desirable to facilitate disconnection of the drive without having to switch off the engine of the vehicle. Obviously this applies particularly when hand-tools are being driven directly off the power take-off, for example by the use of a flexible sleeve having a rotary core.

In the preferred arrangement, the rollers are in fixed positions relative to a frame, and a ramp is provided to enable the vehicle to be driven onto the rollers of the unit.

In an alternative arrangement the distance between the rollers is variable and the frame is arranged so that it may be placed around the drive wheel when it is initially in contact with the ground. The rollers are then drawn together so as to contact the wheel and lift it clear of the ground. For this purpose, one side of the frame may be open and a jack may be provided to draw the rollers together.

The invention will now be described in more detail, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a plan view of a power takeoff unit for use with a motor driven vehicle; Figure 2 is an end elevation of the unit shown in Fig. 1; and, Figure 3 is a plan view of the unit coupled to apparatus and with a drive wheel of the vehicle placed thereon.

In Figures 1 and 2, the power take-off unit comprises a pair of parallel spaced rollers 1, 2 fixed on respective shafts 3, 4 which are mounted in roller bearing 5, 6, 7, 8 set in a frame 9. The rollers are provided with friction surfaces for engaging a tyre 12 of a motor vehicle drive wheel A pulley 10 is mounted on a shaft extension of the shaft 7 of the roller 1 and drives a V-belt 16 providing a power output from the unit.

The pulley 10 is connected by means of the belt 16 to an idler pulley 14 mounted on a shaft 17 of an item of mechanical equipment such as a pump, generator, compressor, mechanical saw, or an arc welding set.

Fixture may be provided on the side of the unit for attaching the driven mechanical equipment to it.

In Figure 3, the unit is shown with a sliping access ramp 11 leading from ground level to the power take-off unit to enable the vehicle to be driven on and off the unit.

In operation, a vehicle is driven so that its drive wheel mounts the access ramp 11 and comes to rest on the two spaced rollers 1, 2. In Figure 3, one drive wheel 13 of a four-wheel, front-wheel drive car is shown resting on the rollers 1 and 2 of the power take-off unit. The other drive wheel (not shown) of the car rests on the ground and is normally chocked to prevent movement.

The car is then put into gear and, owing to the effect of the differential and the fact that the other drive wheel is locked in position with chocks, the wheel 12 alone rotates on the rollers 1, 2. The roller 2 provides mechanical power through the pulley 10 which is connected to the mechanical equipment through the belt 16 and pulley 14. A mechanical manual clutch (not shown) may also be provided in the output drive from pulley 14.

Instead of the pulley and belt system, a train of gears may be used, a drive pinion, in this case, being mounted on the shaft 3. Alternatively, a flexible drive system formed by a sleeved rotary core may be coupled to the shaft 17 to provide the power output.

When the vehicle is to be removed from the unit it is, of course, necessary to provide a positive engagement of the tyre with the unit in order to allow the vehicle to be driven back down the ramp. This positive engagement may be achieved in many different ways. The simplest way is to lock the two rollers, or at least the one nearest the ramp, against rotation. This may be achieved by applying a brake pad to its friction surface, for example by a horizontal screw jack passing through the frame beneath the ramp 11 (see broken outline assembly 20 in Figure 2). A second way is to provide wedges in the frame which can be moved beneath the rollers to prevent their rotation. A third way is by means of an S-shaped brake band passing around the roller or rollers and having one end fixed to the frame and the other end to a free end of a hand lever movable between an inoperative position, by the tyre, to a position slackly around the roller, and an operative position at which the band grips the roller surface. This is illustrated in Figure 2 at 30 in pick-and-dot outline.

A second way of providing the positive engagement is to introduce a slide plate between the wheel tyre and the rollers and which may comprise a top section of the ramp surface. The slide plate is capable of limited horizontal movement sufficient for it to be driven, when released from its inoperative position, by the tyre to a position between the tyre and the rollers. It then stops and the vehicle drives forwards over the stationary slide plate to the ramp.

A third way is to have the rollers mounted in a sub-frame capable of being raised and lowered to bring the rollers into and out of engagement with the tyre, respectively.

The sub-frame may be jacked between its two working positions and transfers the weight of the tyre to fixed surfaces provided on the frame.

In another embodiment (not shown), one wall of the frame 9 may be open between the rollers 1, 2. The shafts 3, 4 are mounted in displaceable bearings such that the distance between the rollers is variable by adjustment of a screw jacking means (not shown). The rollers are first separated as far as possible and the frame is then positioned so that the rollers 1, 2 extend on either side of one of the vehicle drive wheels while it is resting on the ground, by making use of the open side of the frame 9.

The rollers are drawn towards one another by means of the jacking device or, alternatively, an hydraulic system, which lifts the drive wheel clear of the ground. The unit may then be operated in the manner previously described.

In one embodiment of the invention corresponding to that shown in the drawings, the motor vehicle was driven at a speed corresponding to 20 M.P.H. while sta tionary. The rollers were 5" diameter and spaced by 2z''. At an indicated engine speed in second gear of 20 M.P.H. an output drive of 1350 rpm was obtained from the unit. Over a prolonged period no overheating of the engine or differential was noticed.

It will be recognised that the invention enables a family of tools to be provided with power at sites where there are no electrical power connections, and with more power than can be provided by the sort of electric motor customarily used in tools such as electric drills. Moreover, by driving an electrical power source with a suitable level voltage-load characteristic, it is possible to power electrical tools at locations and garages where no other electrical supply is provided. If an air compressor is driven by the unit instead of a generator, a range of compressed air tools, such as percussion tools of the jack-hammer type can be powered.

An air compressor unit, with an adjustable pressure controller, also enables an article such as an inflatable dinghy, air bed or other low pressure pneumatic structure to be inflated quickly and safely to its working pressure.

WHAT I CLAIM IS: 1. A portable power take-off unit for use with a wheeled vehicle, comprising a mobile endless drive wheel-engaging surface mounted in a frame adapted to locate beneath a driven wheel of the vehicle with the wheel tyre resting on the endless surface, means to maintain the vehicle wheel in contact with the endless surface, a poweroutput connection coupled to the mobile surface to provide a mechanical drive therefrom when the wheel is driven while resting on the endless surface, and an element operable to provide a stationary surface beneath the wheel when the vehicle is to be driven off the unit.

2. A unit as claimed in Claim 1, in which the endless surface is provided by spaced, axially paralled rollers and the power output connection is provided by a shaft extension of one of the rollers.

3. A unit as claimed in Claim 2, in which the shaft extension carries a pulley at its free end.

4. A unit as claimed in Claim 3 in which a belt on the pulley passes over a second, idler pulley attached to the frame and having a coupling for a power take-off connection.

5. A unit as claimed in any one of the preceding claims, provided with an attachment for temporary fixing to one side of the unit a support for apparatus which it to be driven by the unit.

6. A unit as claimed in Claim 2 or any one of claims 3 to 5 when dependent thereon, in which two rollers are provided and are spaced sufficiently for the lowermost arc of the tyre periphery to locate positively between them.

7. A unit as claimed in any one of the preceding claims, in which the endless surface is provided with braking means constituting said element.

8. A unit as claimed in Claim 7, in which the braking means comprises a flexible curved brake band having one end fixed to the unit and the other end attached to a member movable between two positions at one of which the brake band is slack and at the other of which the brake band tightly engages the endless surface.

9. A unit as claimed in Claim 7, in which the braking means comprises a brake pad provided with a positional controller operable to move the pad between positions at which it respectively engages with and disengages from the endless surface.

10. A unit as claimed in Claim 9 in which the brake pad position is controlled by a screw passing through the frame and having a handle outside the frame.

11. A unit as claimed in any of the preceding claims, including a mechanical wedge constituting said element and movable manually between a first position at which it locks said endless surface against movement in one direction, and a second position at which the endless surface is freed for rotation by the wheel.

12. A unit as claimed in any one of claims 1 to 6, in which the element is provided by a slide plate positionable between the endless surface and a vehicle wheel resting thereon, and a holding fixture is provided for temporarily fixing the slide plate to the unit when in this position so that the vehicle can be driven off the unit despite the mobile endless surface.

13. A unit as claimed in any one of claims l to 6, in which the frame carrying the endless surface is provided with a mechanism for lowering it from a first position at which a vehicle wheel rests on the endless surface, to a second position at which the weight of the wheel is transferred to fixed surfaces of the unit so that the vehicle can be driven off the unit.

14. A unit as claimed in any one of claims 1 to 6, in which the element comprises a latching device movable between two positions at one of which the endless surface is free and at the other of which the endless surface is mechanically locked to the frame.

15. A unit as claimed in any one of the preceding claims, in which the power output connection includes a manually operable clutch.

16. A unit as claimed in any one of the preceding claims, in combination with a compressor attached to the unit and driven by the power output connection.

17. A unit as claimed in any one of Claims 1 to 15, in combination with a portable electrical generator attached to the unit and driven by the power output connection.

18. A unit as claimed in any one of Claims 1 to 15, in combination with a flexible power output sleeve containing a rotary core driven by the power output connection.

19. A unit as claimed in any one of Claims 2 to 4, in which the frame is operable to enable it to be located around a wheel of the vehicle in contact with the ground and is closable to bring the two

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. and garages where no other electrical supply is provided. If an air compressor is driven by the unit instead of a generator, a range of compressed air tools, such as percussion tools of the jack-hammer type can be powered. An air compressor unit, with an adjustable pressure controller, also enables an article such as an inflatable dinghy, air bed or other low pressure pneumatic structure to be inflated quickly and safely to its working pressure. WHAT I CLAIM IS:

1. A portable power take-off unit for use with a wheeled vehicle, comprising a mobile endless drive wheel-engaging surface mounted in a frame adapted to locate beneath a driven wheel of the vehicle with the wheel tyre resting on the endless surface, means to maintain the vehicle wheel in contact with the endless surface, a poweroutput connection coupled to the mobile surface to provide a mechanical drive therefrom when the wheel is driven while resting on the endless surface, and an element operable to provide a stationary surface beneath the wheel when the vehicle is to be driven off the unit.

rollers against the tyre in front of, and behind its contact with the ground, jacking means on the frame being then operable to bring the two rollers closer together so that the vehicle wheel is lifted off the ground between them.

20. A unit as claimed in any one of the preceding claims, in which a ramp is provided for transferring the vehicle drive wheel between ground level and the enless surface.

21. A unit as claimed in Claim 1. arranged and adapted to operate substantially as described with reference to the accompanying drawings.