GB2083634A - Vehicle wheel turntable - Google Patents

Abstract

A turntable 1 for vehicle wheels comprises members 2, 3 separated by an element 4. The member 3 is rotatable relative to element 4 and member 3 and element 4 are slidable as a unit relative to member 2 whereby relative rotation between member 3 and element 4 is unaffected by forces tending to move the turntable laterally during turning of the vehicle wheel to check a particular characteristic thereof. Relative rotation between member 3 and element 4 may be facilitated by ball bearings 10 in groove 9 on the underside of member 3, or by the use of a lubricant between member 3 and element 4, or by making at least one of the confronting surfaces thereof from low friction material. The underside of element 4 may have a pin 13 which engages in a slot 12 in member 2 to allow sliding movement therebetween. The rim of element 4 may be provided with a scale 15 and member 3 with a pointer 16. <IMAGE>

Description

SPECIFICATION Improvements in or relating to vehicle turntables This invention concerns improvements in or relating to turntables for vehicle wheels and in particular, to turntables used for measuring various characteristics of the steered wheels, usually the front wheels.

According to the present invention a turntable for a vehicle wheel comprises a pair of members separated by an intermediate element, one of said members which in use is uppermost being rotatable relative to said element and, said one member and said element being slidable as a unit relative to said other member.

In use of the turntable a vehicle wheel is placed on the upper member and angular measurements for determining the various characteristics, e.g. toe in and toe out, on turns are determined by the relative rotation between the upper member and the intermediate element, the latter conveniently being provided with a scale measured in degrees and the upper member having a reference pointer, at least one of which is preferably adjustable. Any forces generated during such measurements tending to displace the turntable from under the vehicle wheel are accommodated by the sliding movement of the upper member and intermediate element relative to the base member. Because the upper member and intermediate element move as a unit relative to the base member such movement does not affect the relative rotation therebetween and consequently the angular measurements are not affected.

Preferably means is provided to facilitate relative rotation between the upper member and intermediate element. For example the components may be mounted on an axle pin profiled to allow relative rotation and prevent axial separation with one of the confronting surfaces of the upper member and intermediate element being provided with a continuous circumferential groove containing a plurality of ball bearings. Alternatively one of the confronting surfaces may consist of a low friction material or a friction reducing substance such as grease may be provided between the surfaces.

Preferably the intermediate element has a downward projection located in a radially extending slot in the base member, the projection being movable along the length of the slot and rotatable therein to allow omnidirectional sliding movement of the intermediate element and the upper member associated therewith relative to the base member.

Conveniently the slot and projection are profiled to prevent axial separation of the base member and intermediate element with the radially outer end of the slot being closed by a removable closure member to allow assembly of the components and subsequently limit movement of the projection along the length of the slot. Preferably the intermediate element is provided with a second downward projection, e.g. the lower end of the axle pin connecting the element and the upper member, located in an enlarged central aperture in the base member to limit rotation of the first projection in the slot.

Preferably means is provided to lock the upper member and the base member in a reference position in which all the components are axially aligned. Conveniently such means comprises a removable retaining peg which is located in aligned apertures in the base member and upper member, for example while a vehicle wheel is being positioned on the turntable, such means being releasable subsequently to allow the appropriate measurements to be made. Preferably the apertures are provided in a pair of opposed lugs extending radially outwards from the upper and base members respectively. In one preferred construction, two such locking means are provided at cirumferentially spaced positions.

Means may also be provided to lock the upper member and intermediate element against relative rotation, for example a removable locking stud located in aligned apertures in the upper member and intermediate element. Alternatively a removable retaining peg may be provided which is located in aligned apertures in all the components so as to lock the turntable in a reference zero position.

In one preferred construction the components are disc-shaped, the intermediate element being considerably thinner than the upper and lower members with the overall depth of the turntable being approximately 25 mm.

The invention will now be described in more detail by way of example only with reference to the accompanying drawings wherein: Figure 1 is a plan view of a turntable according to the present invention; Figure 2 is a section on the line A-A of Figure 1; Figure 3 is a section on the line B-B of Figure 1, and Figure 4 is a perspective view, to a reduced scale of the turntable shown in Figures 1 to 3.

The turntable 1 shown in the accompanying drawings comprises a pair of annular disc-like members 2, 3 separated by a relatively thinner intermediate disc-like element 4. The member 2 and element 4 are of similar diameter which exceeds that of the member 3 and the overall depth of the turntable is 25 mm.

The member 3 which in use is uppermost has a central, stepped bore 3a aligned with an opening 4a in the intermediate element 4 through which an axle pin 5 extends. The axle pin has an enlarged head 5a located in the stepped bore 3a and an externally threaded stem to which a lock nut 6 is secured to prevent axial separation of the upper member 3 and element 4. The stem portion of the pin 5 received in the opening 4a is formed with a groove 7 in which a plurality of ball bearings 8 are received to allow relative rotation between the upper member 3 and element 4. In addition the under surface of the member 3 is provided with a circumferential continuous groove 9 of channel section adjacent to the peripheral edge thereof in which a plurality of ball bearings 10 are located to facilitate such relative rotation.

The base member 2 provided with a carrying handle 2a has a central circular opening 11 in which the projecting end of the axle pin 5 and lock nut 6 are located. In addition the member 2 is provided with a slot 12 extending radially inwards from the circumferential edge thereof, the slot having a length approximately equal to one third the radius of the member 2. A guide pin 13 secured to the underside of the intermediate element 4 is received in the slot 12 and is both movable along the length of the slot, and rotatable in the slot to allow omnidirectional sliding movement of the intermediate element 4 and upper member 3 relative to the base member 2 to any one of several positions as shown in phantom lines in Figure 1.The slot 12 and guide pin 13 are profiled to prevent axial separation of the element 4 and the base member 2 and the radially outer end of the slot 12 is closed by a detachable closure plate 14 which allows assembly of the components and subsequently provides an end stop to limit outward sliding movement of the pin 13 in the slot 12.

The peripheral edge portion of the element 4 projecting radially outwards of the upper member 3 carries an adjustable scale 15 marked in degrees from 0 to 60 to either side of centre zero, and the upper member 3 has an adjustable reference pointer 16 aligned with the scale 15 for measuring relative rotation between the upper member 3 and element 4.

The base member 2 is provided with two circumferentially spaced radially extending apertured lugs 17,18 and the upper member3 is likewise provided with two corresponding circumferentially spaced radially extending apertured lugs 19, 20. Locking means consisting of two similar removable retaining pegs 21 each of which is located in axially aligned apertures in the lugs 17, 19 and 18, 20 respectively prevents sliding movement between the base member 2 and the upper member 3 and associated element 4 and locks the components in the reference position shown in full lines in Figure 1 in which the components are axially aligned.

The above described turntable facilitates the measurement of differential angles of vehicle wheels as follows; each front wheel for example of a vehicle is centrally positioned on a respective turntable, upper member 3 being locked relative to the base member 2 in the reference position shown in full lines in Figure 1 by the retaining pegs 21. The reference pointer 16 on the upper member and the scale 15 on each turntable are zeroed and the retaining pegs 21 removed. The conventional steering checking procedure is then carried out by steering the wheels to the right or left and noting the new position of the reference pointer 16 relative to the scale 15 on each turntable from which the angles turned through for each wheel can be determined.In this way toe in/toe out, wheel lock angle and full lock measurements can be made and further description is not given here as such procedures are well known to those skilled in the art.

Any tendency for eitherturntableto be displaced from underthewheels during the taking of the above measurements, e.g. if either wheel is not located centrally on the upper member 3 of the associated turntable, which would affect the readings made is accommodated for by sliding movement of upper member 3 and the element 4 relative to the base member 2. Such sliding movement may occur in any direction within the limits defined by the aperture 11 or slot 12 and does not affect the relative rotation between the upper member 3 and the element 4.

The turntable may be made from any suitable metal such as steel or alloy for example aluminium alloy or even plastics material so that the turntable can be made relatively light in weight and is easily handled.

It will be appreciated that the above described turntable may be modified in a number of ways, for example the ball bearing assembly allowing relative rotation between the upper member and intermediate element may be replaced by a low friction substance, e.g. grease, provided between the confronting surfaces or one of the confronting surfaces at least may be constituted by a low friction material.

Means may be provided to lock the upper member and intermediate element against relative rotation.

Such means may comprise a removable locking stud located in axially aligned apertures in the upper member and intermediate element.

The scale may be provided on the upper member and the reference pointer on the intermediate element. Furthermore only one of the scale and reference pointer may be adjustable.

The upper surface of the upper member may be constructed, e.g. serrated, so as to have a high coefficient of friction relative to the tyre of a vehicle wheel.

Claims (21)

1. Aturntable for a vehicle wheel comprises a pair of members separated by an intermediate element, one of said elements which in use is uppermost being rotatable relative to said element and, said one member and said element being slidable as a unit relative to said other member.

2. Aturntable according to Claim 1 wherein a scale is provided on one of said one member and said element and a reference pointer is provided on the other of said one member and said element for determining relative rotation therebetween.

3. A turntable according to Claim 2 wherein at least one of the scale and reference pointer is adjustable.

4. A turntable according to any one of the preceding Claims including means to prevent axial separation of said one member and said element.

5. Aturntable according to Claim 4wherein said means comprises an axle pin on which said one member and said element are mounted.

6. Aturntable according to Claim 5 wherein a stem portion of said axle pin is formed with an annular groove in which ball bearings are received.

7. A turntable according to any one of the preceding Claims wherein one of the confronting surfaces of said one member and said element is formed with a circumferentially extending groove in which ball bearings are received.

8. Aturntable according to any one of Claims 1 to 6wherein one of the confronting surfaces of said one member and said element is formed from low friction material.

9. A turntable according to any one of Claims 1 to 6 wherein a friction reducing substance is provided between the confronting surfaces of said one member and said element.

10. Aturntable according to any one of the preceding Claims wherein said element has a projection located in an elongate slot in said other member, the projection being movable along the length of the slot and rotatable therein.

11. A turntable according to Claim 10 wherein the slot and projection are profiled to prevent axial separation of said other member and said element.

12. Aturntable according to Claim 10 or Claim 11 wherein said slot is closed at one end by a removable closure member.

13. A turntable according to any one of Claims 10 to 12 wherein said element has a second projection located in an enlarged aperture in said other member to limit rotation of said element relative to said other member.

14. A turntable according to any one of the preceding Claims including means to lock said members against relative rotation.

15. Aturntable according to Claim 14 wherein said means comprises a pair of removable retaining pegs, each peg being engageable in respective aligned apertures in said members.

16. A turntable according to any one of the preceding Claims including means to lock said one member and said element against relative rotation.

17. A turntable according to any one of the preceding Claims wherein said members and said element are disc-shaped.

18. Aturntable according to Claim 17 wherein the diameters of said other member and said element are similar and exceed the diameter of said one member.

19. Aturntable according to Claim 17 or Claim 18 wherein said element is thinner than said members.

20. A turntable according to any one of the preceding Claims wherein the surface of said one member on which a vehicle wheel is located in use is constructed to have a high coefficient of friction relative to the tyre of a vehicle wheel positioned thereon.

21. A turntable for a vehicle wheel substantially as herein before described with reference to the accompanying drawings.