GB2528987A

GB2528987A - A Motorised Skate for a Vehicle

Info

Publication number: GB2528987A
Application number: GB1414137.8A
Authority: GB
Inventors: John Reynolds
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-08-08
Filing date: 2014-08-08
Publication date: 2016-02-10
Anticipated expiration: 2034-08-08
Also published as: GB2528987B; GB201414137D0

Abstract

The present invention provides a motorised skate 1 for a vehicle, the skate 1 comprising a support for a wheel 2 of a vehicle and at least one powered wheel or track 7 by which the skate 1 can be propelled. A skate in accordance with the present invention enables an inoperative vehicle to be manoeuvred by a single person in a workshop type environment, or by recovery person where the vehicle is required to be repositioned prior to it being recovered or to be propelled on to a recovery vehicle or trailer.

Description

A Motorised Skate for a Vehicle The present invention relates to a motorised skate for a vehicle and is particularly, but not exclusively, applicable to a skate suitable for use for manoeuvring inoperative vehicles in a workshop environment or for roadside recovery of vehicles.

When a vehicle, such as a car, is not working it is commonly desirable to be able to move the vehicle short distances, for example to move the vehicle around a workshop, to recover the vehicle from an inconvenient location to a position where it can be winched onto a recovery vehicle, or to move the vehicle onto a recovery vehicle or trailer.

Normally in the above circumstances the vehicle is pushed by one or more individuals. However, this can be difficult if the ground is uneven or the vehicle has to be pushed up an inclined ramp. Furthermore, even on level surfaces it is difficult for a single person to push a vehicle and correctly manoeuvre a vehicle, normally requiring the vehicle to be steered through the open driver's door or window at the same time as the vehicle is pushed, making it difficult to steer the vehicle and to brake the vehicle, should this be necessary.

It is an object of the present invention to provide a motorised skate for a vehicle which overcomes some of the above mentioned problems.

According to the present invention there is provided a motorised skate for a vehicle, the skate comprising a support for a wheel of a vehicle and at least one powered wheel or track by which the skate can be propelled. (For the purposes of this specification vehicle wheel is to be interpreted to include both a vehicle wheel and any tyre fitted to the vehicle wheel).

The provision of a motorised skate in accordance with the present invention may permit a person to propel the vehicle by means of the skate, thus avoiding the need for the person to push the vehicle. This may not only make it possible for the person to propel a vehicle up inclines or across rough ground, which they may not have been able to push the vehicle over, but it may also allow the person to concentrate on looking where the vehicle is going and on steering the vehicle.

Advantageously, the skate comprises a main body portion, arranged in use to lie adjacent to an outer face of a vehicle wheel, and two arms each connected at their respective proximal ends to the main body portion, so that the arms may extend under the vehicle wheel, one to the front of the vehicle wheel and one to the rear of the vehicle wheel. This arrangement may permit the skate, which may be U-shaped, to be slid under the vehicle wheel so that the arms protrude in front and behind the vehicle wheel, with the main body portion of the skate abutting the vehicle wheel, permitting the skate to be positioned about a vehicle wheel without requiring the vehicle wheel to first be raised off the ground.

Preferably, a wheel or castor is provided at, or towards, the distal end of each arm for supporting the arm relative to the ground. Thus, if distal ends of the arms come into contact with the ground, for example when some of the weight of the vehicle is carried by the skate, the wheels or castors will permit the ends of the arms to roll along the ground with the main body portion of the skate.

Advantageously, the skate further comprises a clamping mechanism engaging with outer and inner faces of the vehicle wheel to clamp the vehicle wheel to the skate. Such a clamping mechanism enables the skate to engage with the vehicle wheel, to retain the vehicle wheel in place, so that the skate may be used to propel the vehicle while the vehicle wheel is retained securely in place on the skate. Preferably the clamping mechanism clamps the vehicle wheel to the skate so that the skate is maintained in a fixed upright position relative to the vehicle wheel. This is particularly advantageous if the powered wheel or track is located outwardly of the front face of a vehicle wheel when the skate is clamped to the vehicle wheel, for this will act to maintain the skate in an upright position, even if castors or wheels at the distal ends of the arms of the skate should fail to be supported, for example when on soft ground.

Preferably, the clamping mechanism comprises a clamping member on each arm of the clamp. It may also be advantageous for the clamping mechanism to include an additional top clamping member to engage with the top of the vehicle wheel, for this will further assist in clamping the vehicle wheel to the skate and maintainingthe skate in an upright position relative to the vehicle wheel, which in turn is maintained in an upright position by of being attached to the vehicle.

Each arm of the skate may be arranged to be raised, to raise the vehicle wheel of the vehicle off the ground so that the vehicle wheel is supported by the skate.

Alternatively, the arms may be arranged to be moved together, so that they squeeze under the vehicle wheel and raise the vehicle wheel off the ground, so that the vehicle wheel is supported by the skate.

Advantageously, the skate comprises one or more actuators arranged to sequentially position the clamping members against the vehicle wheel, raise the vehicle wheel off the ground and then increase the force on the clamping members to clamp the skate to the vehicle wheel when the wheel is raised off the ground. This enables the clamping members to ensure that the skate is correctly positioned prior to raising the vehicle wheel, but permits the vehicle wheel to move relative to the clamping members as the vehicle wheel is raised, prior to the force on the clamping members being increased, to firmly clamp the raised vehicle wheel to the skate prior to the skate.

Preferably, the skate comprises one moveable clamping member towards a distal end of each arm, wherein each clamping member is resiliently biased towards the distal end of a respective arm and wherein the arms are resiliently biased apart. This resilient biasing may enable the vehicle wheel to be lowered and clamp released even if a power supply for the skate should fail. It also permits the clamping members and arms to be powered in one direction only, which may simplify design and construction of the skate.

The resilient biasing could be by means such as spring associated with each clamping member and the arms, or by biasing of a hydraulic fluid in a circuit for operating the clamping members and arms.

In one embodiment the skate may comprise a hydraulic circuit with a hydraulic pump arranged to first urge the clamping members into contact with the vehicle wheel, then to raise the vehicle wheel by moving the arms together and then to firmly clamp the skate to the vehicle wheel by firmly pressing the clamping members into contact with the vehicle wheel The hydraulic motor may be arranged to be switched off once the skate is clamped to the vehicle wheel, whereby the skate comprises one or more manually operable valves to enable the vehicle wheel to be subsequently lowered and released without use of electric power.

Advantageously, the skate may comprise a remote control unit, wired or wireless, arranged to be placed in a vehicle having a vehicle wheel supported by the skate, so that the remote control unit may be operated by a person sat in the vehicle in order to propel the skate and vehicle forwards and/or backwards. This permits a person to sit in a vehicle, where they are better able to steer the vehicle, (which may require considerable effort if the engine and the power steering is inoperative). It also enables the person to use the mirrors of the vehicle to assist in manoeuvring the vehicle and to be in a position where they can operate the handbrake orfootbrake, should this become necessary.

Preferably, the skate comprises a powered track on the main body, which track is arranged to propel the skate forwards and/or backwards. A track provides more traction than a single powered wheel and may provide for a more stable skate. It is also more able to cope with uneven ground and small obstacles than a wheel would be able to cope with, if the diameter of that wheel were equal to the height of the track. A tracked skate would be particularly advantageous in applications where a vehicle is to be recovered over an unpaved surface, such as grass or gravel.

Preferably, in use, the track of the skate is located adjacent an outer face of the vehicle wheel. This is particularly advantageous where the skate is maintained upright by being clamped to the vehicle wheel, for this will ensure the weight of the vehicle is transferred to the track, despite the track not being positioned directly below the vehicle wheel.

The skate may be battery powered, where the skate will only be required to move a vehicle over small distances. In a workshop or recovery application this would be advantageous, removing the need for any trailing lead. However, alternatively the skate could be wired to an exterior power supply, such as the mains or a vehicle supply, for example it could be connected to a recovery vehicle with which it is associated, or to the vehicle which it is to propel.

Where the skate is battery powered, the battery (which may be a standard 12 volt vehicle battery) is preferably readily detachable, with the skate arranged to receive the battery after the skate has been placed about a vehicle wheel to be raised by the skate.

The battery may significantly add to the weight of the skate and thus it will likely be easier for a person to position the skate without the battery.

Preferably, the skate is less than 1 meter in length and has one or more handholds arranged to enable the skate to be picked up by a single person.

One example of a motorised skate in accordance with the present invention will now be described, by way of example only, with reference to the accompanying figures, in which like numerals are used throughout to indicate like parts and of which: Figure 1 is a perspective front view of a skate in accordance with the present invention; Figure 2 is a perspective rear view of the skate of Figure 1; Figure 3 is a perspective view of a remote control unit for the skate of Figures 1 and 2; Figure 4a is a schematic plan view of the main components of the skate in Figure 1 shown positioned about a wheel of a vehicle to be moved by the skate; Figure 4b is a schematic side elevation of the skate and vehicle wheel of Figure 4a; Figures 5a to Sb are views corresponding to Figure 4a and 4b, showing the skate at different stages of operation; and Figures 9 to 13 schematically illustrate the components of the hydraulic circuit of the skate of Figures ito Sb in the various stages of operation illustrated in Figures 4a to Sb.

Referring to Figures 1 and 2, these are respectively front and rear perspective views of a motorised skate, indicated generally as 1, in accordance with the present invention. In Figure 1, a wheel 2 of a vehicle to be manoeuvred by the skate 1 is additionally shown in broken line, to indicate how the skate 1 is to be positioned relative to the vehicle wheel 2.

The skate comprises a chassis plate 3, mounted on which are sprockets 4 and S and rollers 6 for attaching rubber track 7. Sprocket 5 is powered by a 12 volt DC electric motor 8 through gearbox 9 and drives the track 7 which propels the skate 1.

The chassis plate 3 also has mounted to it: hydraulic pump 10 driven by an electric motor 11; valve assembly 13; and a switch box 14 having a power on/off switch 15 for switching power to the skate on or off and a "lift" button 16 for actuating a clamping and lifting mechanism described below.

A battery bracket 17 is mounted to the back of chassis plate 3 and this supports a 12 volt battery 18. To the back of battery bracket 17 (see Figure 2) there is mounted an electronics control box 19, which includes a short range radio transmitter and receiver, an antenna 20 of which is mounted to the top of the control box 19. Also on the control box 19 is a power supply socket 21. This can either be connected by a short lead (not shown) to the terminals of battery 18, or by a longer lead to a 12 volt power take off on a vehicle or, via a 12 volt transformer, to the mains. Where the skate 1 is to be connected to the mains or to a vehicle power supply then there is no requirement for battery 18.

To the rear of the chassis plate 3 there is mounted a guide member 22 (see Figure 2) comprising a C -shaped steel channel, in which two wheel support members, indicated generally 23 and 24 are mounted. The wheel support members 23 and 24 are retained in the upright position shown by the guide member 22 and they may slide along the guide member 22 between stops 25 and 26.

Each wheel support member 23, 24 comprises a horizontal arm 27, 28 with a respective first clamping member 29, 30 extending vertically from a proximal end thereof, with each arm 27, 28 supported at a distal end by a respective wheel 31, 32.

Slidably mounted on each arm is a second clamping member 33, 34, the position of which is controlled by an associated hydraulic clamping ram 35, 36 (only clamping ram 36 is visible in Figure 2). The clamping member 29, 30 of respective wheel support members 23,24 are connected to respective ends of a hydraulic ram 37, hereinafter referred to as hydraulic lifting ram 37, for this ram may be operated to lift the vehicle wheel 2 by controlling the separation between the wheel support members 23, 24.

Although the lifting ram 37 controls the separation of the wheel supports members 23, 24, it does not control the position of members 23, 24 which can slide backwards and forwards between stops 25 and 26.

When the skate 1 is to be used on soft ground, a third wheel support member, indicated generally as 38 in Figure 1 (but for clarity omitted from Figure 2), may be bolted via holes 39 (shown in Figure 2) to chassis plate 3.

The third wheel support member 38 comprises an upright bar 40 on which at-shaped clamping member 41 is slidably mounted and on the arm 42 of which L-shaped clamping member 43 is slidably mounted.

When the vehicle wheel 2 has been raised by wheel supports 23, 24, as will be described later, the third wheel support member 28 may be used to clamp the top of the vehicle wheel 2 by locking the t-shaped clamping member and L-shaped clamping member in the positions shown, by inserting appropriate pins through the holes shown drilled through the t-shaped clamping member, L-shaped clamping member and upright bar 40.

This ensures that skate 1 remains upright, as shown, relative to the vehicle wheel 2 so that should the skate be used on soft ground where the wheels 31, 32 of the skate 1 find little support, then the weight of the vehicle on the vehicle wheel 2 will be carried by the track 7.

Referring now to Figure 3, here there is illustrated a remote control unit 44 which communicates via antenna 45 with the electronics control box 19. When the skate 1 has been positioned about a vehicle wheel 2, clamped to the vehicle wheel 2 and has raised the vehicle wheel 2, the remote control unit 44 may be placed on the floor of the driver footwell in the vehicle and the vehicle moved backwards and forwards by using foot operated buttons 46, 47.

Operation of the motorised skate of Figures land 2 will now be described with reference to Figures 4a to Sb, which for simplicity illustrate only the major components of the skate land its position relative to the vehicle wheel 2. Figures 4a, 5a, 6a, 7a and 8a show the skate from above whilst Figures 4b, Sb, 6b, 7b and 8b show the vehicle wheel 2 and skate las viewed when facing the inner face of the vehicle wheel 2. In Figures 4b, Sb, Gb, Jb and 8b the wheels 31 and 32 of skate 1 have also been omitted for clarity.

Referring to Figures 4a and 4b, with wheel support members 23, 24 fully extended against stops 25 and 26 (see Figure 2) on guide member 22, as represented by arrows 50, and with the second clamping members 33 and 34 fully extended to the position shown, as represented by arrows 51, the skate 1 is pushed by a operator in the direction of arrows 48. The wheel support members 23, 24 then pass under the vehicle wheel 2, until first clamping members 29 and 30 abut outerface 49 of the vehicle wheel 2.

With reference to Figures Sa and Sb, lifting ram 37 (see Figure 2) is then operated to move wheel support members 23 and 24 together in the direction of arrows 52, until arms 27, 28 of the wheel members 23, 24 abut the vehicle wheel 2, as shown in Figure 5b.

As the wheel support members 23, 24 and associated lifting ram 37 are move along guide member 22, the wheel support members 23, 24 will both abut the vehicle wheel 2 without displacing the main body of the skate 1 relative to the vehicle wheel 2. During this operation, the pressure of hydraulic fluids applied to lifting ram 37 is not sufficient to cause wheel support members 23,24 to raise the wheel of the vehicle 2.

With reference to Figures 6a and 6b, the clamping rams 35, 36 (see Figure 2) associated with each wheel support member 23, 24 are then operated to move respective second clamping members 33, 34 in the direction of arrows 53 of Figure 6a, until they abut the vehicle wheel 2. The pressure of hydraulic fluids applied to rams 35 and 36 is sufficient to ensure the vehicle wheel 2 is correctly positioned between pairs of first and second clamping members 29, 33 and 30, 34, as shown in Figure 6a, if necessary by pulling the skate 1 into position against the vehicle wheel 2. The pressure of hydraulic fluids applied to rams 35 and 36 is not sufficient to prevent the vehicle wheel 2 moving between pairs of clamping members 29, 33 and 30, 34.

With reference to Figures 7a and 7b, when the pressure applied to hydraulic lifting ram 37 of Figure 2 is increased, wheel support members 23, 24 will move in the direction of arrows 54 to raise the vehicle wheel 2 in the direction of arrow 55, until further lifting is prevented by the lifting ram 37 reaching its fully contracted state.

Although not shown, a number of rollers may be provided on the arms 27, 28 and second clamping members 33, 34to reduce the friction between the vehicle wheel 2 and the wheel support members 23, 24. Alternatively, freely rotating sleeves may be provided over the horizontal arms 27, 28 of the wheel support members 23, 24.

With a proportion of the weight of the vehicle, via vehicle wheel 2, now on the wheel support members 23, 24, the friction between the wheel support members 23, 24 and the guide member 22 is increased to an extent that would normally be sufficient to prevent them sliding along the guide members 22, even as the skate is propelled forwards and backwards. However, if necessary, any suitable locking means such as pins may be provided to lock one or both of the wheel support members 23, 24 in place. Alternatively, the wheel support members 23,24 may be allowed to initially travel a short distance along the guide 22 until a respective one of them meets as associated stop 25, 26 (see Figure 2).

With references to Figures 8a and 8b, the pressure to the hydraulic clamping rams 35, 36 (see Figure 2) is increased, urging the second clamping members into firmer contact with the vehicle wheel 2, as representative by arrows 56, clamping the vehicle wheel 2 tightly between respective pairs of first and second clamping members 29, 33 and 30, 34.

This acts to retain the skate 1 in an upright vertical position against the vehicle wheel 2, as the first clamping members 29,30 extend above the midpoint of the vehicle wheel 2 (see Figure 1) resisting the skate 1 tilting inwards towards the vehicle wheel 2. However, if additional support is required, particularly if the skate 1 is being used on soft ground, then the optional third wheel support member 38 may be fitted and, at this stage, manually clamped to the vehicle wheel 2, as shown in Figure 1.

With the skate 1 firmly clamped to the vehicle wheel 2, as shown in Figures 8a and Sb, the remote control unit 44 of Figure 3 can then be operated by the foot of a person sitting in the driving position of the vehicle to which the skate is fitted, in order to propel the vehicle forwards and backwards. The skate 1 would normally be fitted to a rear wheel of the vehicle and therefore the rear wheel, being a non-steering wheel, would keep the skate 1 aligned with the vehicle so that the skate would not unduly influence the direction of the vehicle, even though it would propel only the one wheel of the vehicle. This enables the person sitting in the vehicle to steer the vehicle in the normal manner, although if power steering is fitted and the engine is not running the steering may be heavier than normal. Sitting in the vehicle the person may also guide the vehicle with the assistance of the mirrors and may also control both the handbrake and footbrake.

Once the vehicle has been moved to a desired position, hydraulic lifting ram 37 and hydraulic clamping rams 35, 36 are all fully extended to their maximum extent, returning the wheel support members 23,24 and second clamping members 33, 34 to the positions shown in Figures 4a and 4b, permitting the skate ito then be slid out from under the vehicle wheel 2.

The skate is preferably less than 1 meter in length and preferably weights less than 25 kilograms, without the battery 18, so that it may be lifted and manoeuvred by a single person. The battery bracket 17, with the battery removed, is shaped to provide two handholds by which the skate may be lifted, the handholds extending to a position over the centre of mass of the skate, so that the skate may be lifted by the handholds and be maintained in an upright position.

With reference to Figure 1, the hydraulic pump 10, hydraulic accumulator 12. valve assembly 13 and the clamping rams 35,36 and 37 (see Figure 2) form a hydraulic circuit which enables the sequential operations of skate 1, described above with reference to Figures 4a to Sb, to be performed automatically once an operator has turned on the power button 15 and pushed "lift" button 16 seen in Figure 1. The hydraulic circuit also permits the vehicle wheel 2 to be subsequently lowered and released when the power button iSis switched off, or if the power supply (battery 18) should fail. This hydraulic circuit and the operation thereof is described below with reference to Figures 9 to 13, which show the circuit in different stages of operation, corresponding to the stages of operation illustrated in Figures 4a to 8b.

Referring first to Figure 9, this shows the pump 10, hydraulic accumulator 12, clamping rams 35, 36, lifting ram 37 and valve assembly 13 hydraulically interconnected.

Figure 9 also schematically shows a small reservoir 57, which is accommodated in the accumulator 12 and shows how the accumulator 12 is arranged, via piston 58 and spring 59, to urge hydraulic fluid generally anti-clockwise around the hydraulic circuit, as shown.

The valve assembly 13 comprises three pressure actuated valves 60, 61, 62, two non-return valves 63, 64, a pressure switch 65 and an electrically switched valve 66. The pressure switch 65 and switched valve 66 are electrically connected to the electronics control box 19 of Figure 2 and the switch valve 66 is arranged to be closed at all times when the skate is powered on by switch 15, but is arranged to open when the power is turned off, or when the power supply fails.

The pump 10 is arranged to be operative once the "lift" button 16 (see Figure 1) is pressed and to continue to operate until pressure sensor 65 detects that the pressure in the circuit exceeds a predetermined value P4.

As a general overview, the pump 10 attempts to pump hydraulic fluid anti-clockwise around the circuit as shown, against the spring 59 within the accumulator 12, until the skate 1 is switched off, or the power supply fails, when the switched valve 66 opens, permitting the spring 59 in the accumulator 12 to force the fluid clockwise around the circuit, causing the clamping rams 35, 36 and lifting ram 37 to fully extend to the position shown in Figures 4a, 4b and 9.

Referring again to Figure 9, this shows the circuit when the skate 1 is positioned about a vehicle wheel 2, as shown in Figures 4a and 4b, when the skate 1 has been turned on at the switch 15 and the "lift" button 16 (see Figure 1) just pressed. The switched valve 65 closes on the power being turned on, (in Figures 9 tol3, an "X" next to a valve indicates the valve is closed) and the pump 10 has just started when the "lift" button 16 was pressed. At this stage the pressure in the hydraulic circuit is relatively low and pressure actuated valves 60 and 62 are closed, because the pressure is less than a threshold value, P1, below which valve 60 is closed and is thus also less than a higher threshold pressure, P2, below which valve 62 is closed.

As the fluid is pressurised by the pump 10, with vales 60, 62 closed, the fluid first urges the lifting ram 37 to contract, urging the wheel support members 23, 24 together, (see arrows 52 of Figures Sa and 5b), until the wheel support members 23, 24 come into contact with the vehicle wheel 2, as shown in Figures 5a and Sb. The vehicle wheel 2, with the weight of the vehicle on it, then prevents further movement of the wheel support members 23, 24 and thus prevents further contraction of the lifting ram 37. The pressure generated by the pump 10 then increases until pressure actuated valve 60 opens when the pressure exceeds a relatively low threshold pressure P1, allowing fluid to flow via pressure actuated valve 61, which is open at lower pressures, to clamping rams 35 and 36, as indicated in Figure 10. The pump 10 causes clamping rams 35, 36 to contract, urging second clamping members 33, 34 to move in the direction of arrows of 53 in Figure 6a, until they abut the vehicle wheel 2. This then prevents further movement of second clamping members 33, 34 and thus further contraction of associated clamping rams 35, 36.

As the wheel support members 23, 24 and clamping members 33, 34 are all abutting the vehicle wheel 2, resisting further movement of lifting ram 37 and clamping rams 35, 36 the pressure in the circuit builds until it exceeds threshold value P2, at which pressure P2 pressure actuated valve 61 closes preventing the pressure on the second clamping members 33, 34 increasing. The threshold pressure P2 is set so that the vehicle wheel 2 may still move between first and second clamping member pairs 29, 33 and 30, 34.

The fluid in the circuit then flows as illustrated in Figure 11, causing lifting ram 37 to contract further, raising the vehicle wheel 2 by urging the wheel support members 23, 24 further together, as shown in Figure 7b.

When the lifting ram 37 is fully contracted, as shown in Figure 11, the pressure generated by the pump 10 builds further until it exceeds a threshold value P3, significantly greater than P2. Pressure actuated valve 62 then opens, permitting fluid to flow as indicated in Figure 12, urging clamping rams 35, 36 to contract further, clamping the vehicle wheel 2 to the skate las shown in Figures 8a and 8b. As the vehicle wheel 2 resists further movement of clamping rams 35, 36 the pressure in the hydraulic circuit continues to build until it exceeds a threshold value P4, at which pressure switch 65 deactivates the pump 10. The vehicle wheel 2 is at this stage is both raised and firmly clamped to the skate 1. permitting the vehicle wheel 2 and thus the vehicle to be moved backwards and forwards by the skate 1.

When it is desired to lower the vehicle wheel 2 and release the skate land the skate 1 is turned off, or if the power should fail, switched valve 67 opens, as shown in Figure 13 permitting the spring 59 within the accumulator 12 to push piston 58 in the direction of arrow 67, permitting the hydraulic fluid to flow as shown in Figure 13, returning the skate to the state illustrated in Figures 4a and 4b. Alternatively switched valve 67 could be a manually operated valve, which would maintain the skate 1 clamped to the vehicle wheel 2 even if the skate 1 should be switched of or the power fail. The manual valve could then be opened at anytime it is desired to lower and release the vehicle wheel 2.

The above describes one possible embodiment of the invention. It will however be realised that many alternatives are possible within the scope of the appended claims.

Particularly, it is envisaged that instead of using hydraulic rams mechanical actuators could be employed, possibly in the form of mechanical screws which could be sequentially controlled by an electrical circuit. This could possibly use optical sensors to determine the position of the wheel support members 23. 24 and/or clamping rams 35, 36, or alternatively could sense the current being drawn by the motors for each actuator or a combination thereof.

Claims

Claims 1. A motorised skate for a vehicle, the skate comprising a support for a wheel of a vehicle and at least one powered wheel or track by which the skate can be propelled.
2. A skate as claimed in Claim 1, comprising a main body portion arranged in use to lie adjacent to an outer lace of a wheel and two arms each connected at their respective proximal ends to the main body portion, so that the arms may extend under the wheel one to the front of the wheel and one to the rear of the wheel.
3. A skate as claimed in Claim 2, further comprising a wheel or castor at or towards the distal end of each arm for supporting the arm relative to the ground.
4. A skate as claimed in Claim 2 or 3, further comprising a clamping mechanism for engaging with the outer and inner faces of the wheel, to clamp the skate to the wheel.
5. A skate as claimed in Claim 4, wherein the clamping mechanism clamps the wheel to the skate so that the skate is maintained in a fixed upright position relative to the wheel.
6. A skate as claimed in Claim 4 or 5, wherein the clamping mechanism has a clamping member on each arm of the clamp.
7. A skate as claimed in any one of Claims 4 to 6, wherein the clamping mechanism further comprises a top clamping member to engage the top of the wheel.
8. A skate as claimed in any one of Claims 2 to 7, wherein each arm is arranged to be raised to raise the wheel off the ground so that it is supported by the skate.
9. A skated as claimed in any one of Claims 2 to 7, wherein the arms are arranged to be moved together to raise the wheel off the ground so that the wheel is supported by the skate.
10. A skate as claimed in any one of Claims 2 to 8, comprising one or more actuators arranged to sequentially position the clamping members against the vehicle wheel, raise the wheel off the ground and then increase the force on the clamping members to clamp the skate to the wheel after the wheel has been raised off the ground.
11. A skate as claimed in any one of Claims 2 to 10, wherein the skate comprises moveable clamping members, one towards a distal end of each arm, each clamping member being resiliently biased towards the distal end of a respective arm and wherein the arms are resiliently biased apart.
12. A skate as claimed in Claim 11, comprising a hydraulic circuit with a hydraulic pump arranged to first urge the clamping members into contact with the wheel, then to raise the wheel by moving the arms together and then to firmly clamp the skate to the wheel by firmly pressing the clamping members into contact with the wheel.
13. A skate as claimed in Claim 12, wherein the hydraulic motor is switched off once the skate is clamped to the wheel and whereby the skate comprises one or more manually operable valves to enable the wheel to be subsequently lowered and released without use of electric power.
14. A skate as claimed in any preceding claim, further comprising a remote control unit, wired or wireless, arranged to be placed in a vehicle having a wheel supported by the skate so that the remote control unit may be operated by a person sat in the vehicle in order to propel the skate and vehicle forwards and/or backwards.
15. A skate as claimed in any preceding claim, comprising a powered track on the main body arranged to propel the skate forwards and/or backwards.
16. A skated as claimed in Claim 15, wherein in use the track is located adjacent an outer face of the wheel.
17. A skate as claimed in any preceding claim, which is battery powered.
18. A skate as claimed in Claim 17, wherein the battery is detachable and arranged to be mounted on the skate after the skate has been placed about a wheel to be raised by the skate.
19. A skate as claimed in any preceding claim, which is less than lm in length.
20 A skate as claimed in any preceding claim, which has one or more handholds arranged to enable the skate to be picked up by a single person.
21. A skate substantially as hereinbefore described with reference to and/or as illustrated in bone or more of the accompanying figures.