SPECIFICATIONSelf-levelling vehicle support arrangementThe present invention relates to a self-levellingvehicle support arrangement for use, for example,during the inspection and maintenance of a motorvehicle.
According to one aspect of the presentinvention, there is provided a vehicle supportarrangement comprising platform means arranged to pivot in a controlled manner from an inclinedramp position into an elevated horizontal positionunder the weight of a vehicle moved fully onto theplatform means. The platform means which, for example, is constituted by two spaced side-byside tracks, is kept in its horizontal position by the weight of the vehicle throughout inspection and maintenance of the vehicle. When work on the vehicle has been completed, it can simply be moved back along the platform means to enable the latter to be returned in a controlled manner to its normal inclined position. Preferably, control of the pivotal movement of the plafform means is effected by hydraulic dampers.
According to another aspect of the present invention, there is provided a self-elevating vehicle support arrangement comprising two tracks arranged side-by-side in spaced parallel relation and pivotally mounted intermediate their ends on respective stands for movement between an inclined ramp position in which a vehicle can be moved onto the tracks, and a horizontal position in which a vehicle on the tracks is in an elevated position, the tracks pivoting from their inclined to horizontal positions under the weight of a vehicle moved sufficiently far onto the tracks that its centre of gravity has been taken past the axis of pivoting of the tracks, each said track being provided with at least one telescopic damper which extends between the track and the ground and serves to damp pivotal movement of the track, and each said track when in its horizontal position being supported both by its stand and by support means which engage the track at a position spaced form the stand and disposed on the side thereof remote from the end of the track which is lowermost when the track is inclined.
Advantageously, the support means of each track is constituted by a said telescopic damper so arranged that when the track is inclined the damper is extended whereas when the track ishorizontal the damper is fully contracted.
Preferably each track is provided with a said telescopic damper extending between the groundand the track and connected to the latter at aposition spaced from the track stand on the side thereof remote from the support means, this damper being arranged to be in a contracted state when the track is inclined and in an extended state when the track is horizontal.
For safety reasons, it is desirable to provide one or more stabilising legs pivoted on each track adjacent its end which is lowermost when the track is inclined. These legs are arranged to swing downand lock the tracks in position when horizontal.
The vehicle support arrangement can be mounted on wheels to provide a trailer towable, for example, behind a breakdown vehicle.
A self-elevating vehicle support arrangement embodying the invention will now be particularly described by way of example, with reference to the accompanying diagrammatic drawings, in which:Figure 1 is a side elevation of the vehicle support arrangement shown as it starts to pivot from an inclined to a horizontal position under the weight of a vehicle, telescopic dampers of the vehicle support arrangement being shown in section;Figure 2 is a view similar to Figure 1 but showing the vehicle support arrangement in its horizontal position; andFigure 3 is a plan view of the vehicle support arrangement.
As shown in the drawings, the self-elevating vehicle support arrangement comprises platform means in the form of two tracks 1 which are pivotally mounted in parallel side-by-side relation on respective stands 2. Each track 1 comprises two spaced longitudinally-extending members 30 joined by a plurality of angle-iron cross-pieces 31.
Each stand 2 is of frame construction and rigidly carries a pivot pin 3 at its upper end. This pin 3 is pivotally engaged by a pivot tube rigidly connected to the corresponding track 1. The axes of pivoting A-A of the two tracks are coincident and lie substantially midway between the track ends. The right-hand end of each track 1 (as viewed in the drawings) is closed by a stop plate 17.
Associated with each track 1 are two verticallyorientated hydraulic dampers 5 and 6 of telescopic piston-cylinder construction, the damper 5 being arranged to the left of the stand 2 (as viewed in Figures 1 and 2) and the damper 6 to the right.
Although generally unnecessary, if desired the dampers 5 and 6 may be fixed relative to the stands 2 by means of flat strip tie bars (not shown) connected between the stands 2 and the bases 8 of the dampers 5 and 6; similarly transverse flat strip tie bars can be provided to connect each of the dampers 5 and 6 associated with one track 1 with the corresponding damper of the other track 1. The tracks 1 could, if desired, be likewise interconnected by tie rods (not shown). Where transverse connections are provided, they are preferably adjustable in length to enable different vehicle track widths to be accommodated.
The piston rod 10 of each hydraulic damper 5 is connected to the underside of the corresponding track 1 in such a manner as to allow for the slight change in distance which occurs between the pivot axis A-A and the point of intersection of the vertical piston rod 10 and the track 1 upon pivotal movement of the latter; thus, for example, the upper end of the piston rod 10 can be slidably connected to the track 1 for movement lengthwise of the track during pivoting of the latter. The piston rod 11 of each damper 6 is similarly connected to the underside of the corresponding track 1. In most practical applications of the vehicle support arrangement, mechanical provision for the above-mentioned distance change which occurs upon pivoting of the tracks, has proved unnecessary, slight tilting of the dampers 5 and 6 being acceptable.
The tracks 1 are arranged to pivot between an inclined, ramp position (see Figure 1) in which the left hand end of each track 1 touches the ground, and a horizontal inspection position (see Figure 2); as will be more fully described hereinfafter, this pivotal movement (see arrow B in Figure 1) is brought about by the weight of a vehicle 20 driven onto the tracks 1. In the absence of a vehicle upon the tracks 1 , the balance of these tracks 1 is arranged to be such that they reside in their inclined position.
In the inclined position of the tracks 1 , the dampers 5 are fully contracted whereas the dampers 6 are fully extended. Conversely, in the horizontal position of the channels, the dampers 5 are fully extended while the dampers 6 are fully contracted; indeed the horizontal positions of the tracks 1 is defined by arranging for the dampers 6 to have a height when fully contracted which is equal to the height of the stands 2. With such an arrangement, when the tracks 1 are horizontal, the weight of the tracks and the vehicle supported thereby is borne by the stands 2 and the fullycontracted dampers 6 acting as support means.
In an alternative construction (not shown) the horizontal positions of the tracks 1 are defined by rigid support means which engage the right-hand end of the tracks 1 (as viewed in Figure 1 ) as the latter move into their horizontal positions; the tracks 1 are thus supported when horizontal by the stands 2 and the rigid support means, the dampers 6 being unloaded. Since in their construction the dampers 6 do not act as support means, there is no need for these dampers to be fully contracted when the tracks 1 are horizontal.
Each damper 5, 6 may incorporate a one-way valve which opens to permit rapid extension of the damper but which closes to damp the contraction of the damper under the influence of the weight of a supported vehicle. With such an arrangement, the dampers 6 damp movement of the tracks into their horizontal positions whereas the dampers 5 damp movement of the tracks into their inclined positions.
A respective U-shaped stabilising leg 12 is pivoted to each track 1 to the left of the damper 5 (as viewed). This leg 12 is retained in a stowed position by a spring clip 1 3 when the track 1 is in its inclined position; upon the track 1 being moved into its horizontal position, the leg 12 is swung down (see arrow C in Figure 2) and taken slightly past the vertical into an operative position defined by a stop 14 carried by the track 1. The length of each leg 12 is such that with the tracks 1 horizontal, movement of the leg 1 2 through its vertical position raises the adjacent portion of the corresponding track 1 slightly above the level at which it would normally reside in its horizontal position; this raising movement is enabled by resilience in the track.As a result of this arrangement, the legs 1 2 are positively retained in their operative positions ensuring that the tracks 1 cannot accidently incline. To facilitate movement of the legs 12 through their vertical positions, handles 33 are provided on the legs 12.
Each stabilising leg 12 can be provided with an associated stop plate (not shown) rigid therewith, this plate being arranged to lie flat against the upper surface of the corresponding track 1 when the leg 12 is held in its retaining clip 13. Upon the leg 12 being swung down into its operative position, the stop plate sits up from the track 1 to prevent the vehicle 20 from moving leftwards (as viewed) off the tracks 1.
Use of the self-elevating vehicle support arrangement will now be described.
Initially, the tracks 1 will be in an inclined position with the legs 1 2 stowed and the dampers 6 fully extended. In this position, vehicle 20 can be driven (or pulled by suitable tackle) fully onto the tracks 1 such that the centre of gravity of the vehicle is to the right of the pivot axis A-A (as viewed in Figured 1). The weight of the vehicle 20 now acts to upset the balance of the tracks 1 and causes them to move in the direction of arrow B.
This movement is inhibited at least by the contracting dampers 6 (and possibly also by the expanding dampers 5) so that the vehicle 20 is gently moved into an elevated horizontal position.
When the tracks 1 have moved into their horizontal positions, the legs 1 2 are moved into their operative positions. The underside of the vehicle 20 can now be conveniently and safely inspected and, if necessary, worked upon.
To move the vehicle 20 off the tracks 1, simply requires the legs 1 2 to be stowed and the vehicle 20 to be shifted into a position in which its weight causes the tracks to return to their inclined positions.
The tracks 1 are preferably made dismountable from their stands 2 to facilitate stowage, the dampers 5 and 6 either being arranged to swing up parallel to the tracks during stowage or being disconnectable therefrom.
Various modifications can, of course, be made to the described vehicle support arrangement.
Thus, for example further safety means can be provided to mechanically lock the dampers 5 in their fully extended positions during inspection and maintenance of a vehicle 20 on the tracks 1.
Furthermore, the telescopic dampers 5 and 6 of each track could be hydraulically interconnected such that damping is effected by the passage of hydraulic fluid from the contracting to the expanding damper rather than by the passage of fluid past the piston in each damper; it would, of course, be possible to hydraulically interconnect all four dampers together rather than just in pairs.
Instead of the telescopic dampers 5 and 6, other damping means could be used. Thus, a circular motion damper could be arranged to directly damp pivotal movement of the track pivot tube relative to the pivot pin 3. With such an arrangement rigid support means would benecessary to define the horizontal position of thetracks in a manner already described.
In all the vehicle support arrangementsdescribed hereinbefore, the tracks 1 have beenarranged to pivot automatically from their inclinedto horizontal positions as a vehicle is moved fullyonto the tracks, this pivoting being controlled bydamping means. However, it is also possible toarrange for the pivoting movement of the tracks tobe controlled by manually operable loweringmeans operated subsequent to the vehicle beingmoved fully onto the tracks. Such manuallyoperable lowering means can comprise a controllable damper, friction brake, screw arrangement or any other suitable device.
Any of the hereinbefore described forms of vehicle support arrangement can be mounted on wheels to provide a trailer towable, for example, behind a breakdown vehicle. Thus with reference to the illustrated vehicle support arrangement, each stand 2 and each damper 6 could be provided with a pair of wheels, the dampers 5 either being dispensed with entirely or being suitably stowed during towing. The two track assemblies are preferably connected to a towing vehicle by a suitable towing frame connected to one end of each track in a manner enabling the spacing of the tracks to be set as desired.