Lifts

Abstract

A lift system for mounting on a vehicle comprises: two turrets 14; a base plate 10 for mounting on the vehicle and supporting the turrets; two pairs of lifting arms (20, 22, figure 2), each pair conne

Description

Field of the invention The present invention relates to lifts for wheelchair users, and in particular to lifts for mounting on vehicles. Background to the invention Wheelchair lifts which can be mounted on vehicles are well known. One type of lift is mounted in the rear, or side, of a vehicle and comprises two support turrets mounted on the floor of the vehicle, with a pair of lifting arms connected to each of the support turrets, a support arm extending generally downwards form the outboard ends of each pair of lifting arms, and the lift platform supported at the lower ends of the two support arms. Typically such lifts are formed of metal components some of which are w elded together to form the lift structure. The welding process can lead to slight deformation of the components which can make assembly difficult and affect the operation and durability of the lift as the welding process is not completely consistent. Summary of invention The present invention provides a lift system for mounting on a vehicle. The lift system may comprise two turrets, a base plate arrange for mounting on the vehicle and arranged to support the turrets, two pairs of lifting arms, each of the pairs of lifting arms being connected to a respective one of the turrets, two actuators, each of the actuators acting between the two lifting arms in a respective one of the pairs of lifting arms, and a lift platform connected to the lifting arms and arranged to be raised and lowered by operation of the actuators. Each of the turrets may comprise a back plate and two side plates each connected to the back plate for example by releasable threaded fixings. Each of the lifting arms may be rotatably connected to said respective one of the turrets by a pin. The pin may be supported by the tw o side plates of said respective one of the turrets. Each of the side plates may have a flange at its lower end. The flange may have fixing apertures therethrough to receive fixings for fixing the side plates to the base plate. The back plate may have a flange at its lower end. The flange may have fixing apertures therethrough to receive fixings for fixing the back plate to the base plate. Each of the turrets may further comprise a brace arranged to extend between the side plates at an outboard end thereof. Tire brace may have fixing apertures therethrough for receiving fixings for fixing the brace to the side plates. The brace may further comprise a base having a fixing aperture therethrough for fixing the turret to the base plate. The base plate may have an aperture therethrough which is aligned with the aperture in the base of the brace, arranged to receive a fixing for fixing the turret and the base plate to the vehicle, for example to the floor or other structural component of the vehicle. The base plate may have, towards one end of the base plate, a plurality of sets of fixing apertures therethrough. Each set of fixing apertures may be arranged for fixing one of the turrets to the base plate in a respective position. The distance between the turrets may therefore be adjustable. The connection between the platform and the lifting arms can take any form and for example may vary depending on whether the platform is a split vertical folding platform, or a horizontal folding platform, or indeed any other design. The lift assembly may further include any one or more features of the embodiments of the present invention as will now be described by way of example only with reference to the accompanying drawings. Brief description of the drawings Figure 1 is a perspective view of a lift assembly according to an embodiment of the invention; Figure 2 is an enlargement of part of Figure 1; Figure 3 is a perspective view of the base plate and turrets of the assembly of Figure 1; Figure 4 shows detail of one of the turrets of Figure 1; Figure 5 is a perspective view of a brace forming part of the turret of Figure 4; Figure 6 is a perspective view of the brace of Figure 5 in place in the turret; Figure 7 is a plan view of the base plate of the assembly of Figure 1; Figure 8 is a perspective view of a side plate of one of turrets of the assembly of Figure 1; Figure 9 is a perspective view of a back plate of one of turrets of the assembly of Figure 1; and Figure 10 shows the assembly and fixings of the turret of Figure 4. Description of the Preferred Embodiments Referring to Figure 1, a lift system for a vehicle comprises a base plate 10 which is mounted on the floor of the vehicle, two turrets 12, 14 each mounted at a respective end of the base plate 10, two pairs of lifting arms 16, 18, 20, 22, each pair pivotably mounted on one of the turrets 12, 14, and a lift platform 24 connected to the outboard ends of the lifting arms 16, 18, 20, 22, by two support arms 26, 28. Each pair of lifting arms 16, 18, 20, 22 comprises an upper lifting arm 16, 20, and a lower lifting arm 18, 22, and is controlled by a hydraulic actuator 30, 32 acting between the inboard end of the lower lifting arm 18, 22 and the outboard end of the upper lifting arm 16, 20. In Figure 1 the lift is shown in a raised position, with a budge plate 34, also referred to as an inner barrier, which is mounted on the inboard end of the platform 24, lowered to bridge the gap between the platform 24 and the floor of the vehicle. From this raised position, the lift can be lowered to ground level, or raised into a stowed position in which the lifting arms 16, 18, 20, 22 are substantially vertical, and the platform 24 is pivoted upwards to a vertical stowed position. Referring to Figures 2 to 8, the two turrets 12, 14 are identical, so the details of one of them 14 will be described. The turret 14 is formed of a back plate 40, and two side plates 42, 44. The back plate 40 is generally rectangular, and arranged in an upright position, with each of its longer, vertical edges bent through 90° to form a connecting flange 46, 48. with the main area of the back plate 40 between the connecting flanges 46, 48 forming the back wall 50 of the turret 14. The back plate 40 therefore has a shallow U-shaped cross section. At the bottom end of the back wall 50 a further connecting flange 52 projects downwards, and slightly outwards to the rear. Each of the side plates 42, 44, one of which 42 is shown in Figure 6, is very generally L-shaped, with an upright section 54 at the rear and a foot 56 projecting forwards from the base of the upright section 54. The upright section 54 is bent inwards through 90° along its vertical rear edge to form a connecting flange 58, which extends along substantially the full height of the side plate 42. The upright section 54 has a wide region 60 towards its base and tapers in towards the top to fonn a tapered upper region 62. An upper pin aperture 64 is formed near the top of the side plate 42 and a lower pin aperture 66 is formed at the bottom of the tapered upper region 62, further from the rear edge of the back plate 42 than the upper pin aperture 64. The bottom edge of the side plate 42 over the width of the upright section 54 and the rear part of the foot 56 is horizontal and bent through 90° to form a rear mounting flange 68. The front end of the foot 56 extends down below the rear mounting flange 66, and is bent inwards through 90° to form a smaller front mounting flange 70 with a recess 71 in its free end. The base plate 10 is formed of a pressed sheet and is of constant cross section along its length. It lias a trough 80 in the centre with a generally flat base 82, and a front ridge 84 to the front of the trough 80, the front ridge 84 having a flat top 86, a rear wall 88 which forms the front wall of the trough 80. and an inclined front wall 90. A front mounting flange 92 extends forwards from the bottom of the inclined front wall 90, and has fixing holes 93 through it for fixing the base plate 10 to the vehicle floor. A rear ridge 94 is to the rear of the trough 80, the rear ridge 94 having a flat top 96, a front wall 98 which forms the rear wall of the trough 80, and an inclined rear wall 100. A rear mounting flange 102 extends rearwards from the bottom of the inclined rear wall 100, also having fixing holes 103 through it. The base plate may be symmetrical in profile about the centre of the central trough 80. It may even be completely symmetrical, including in the location of the various apertures through it, as in the example shown in Figure 7, so that the front and back are the same and the base plate can be fitted either way round. As can best be seen in Figures 4, 5 and 6, a brace 104 comprises a steel strip 105 with both ends 106 bent over at 90° and having a fixing hole through it. A base 107 extends inwards from the bottom edge of the strip 105, with its free end bent upwards to fonn a fixing flange 108, which has a row of fixing holes 109 extending through it. The feet 56 of the side plates 42, 44 have cooperating fixing holes through them. The brace 104 is arranged to fit around the front ends of the feet 56 of the side plates 42, 44 to hold them together, and is secured to the feet 56 by threaded fixings 110. A further aperture 111 in the base 107 is aligned with the recesses 71 in the mounting flanges 70 and a one of the fixing apertures 103 in the base plate 10 so that a fastening can be placed to extend through the brace 104, the turret 14 and the base plate 10 and also through the floor of the vehicle to secure the entire structure in position in the vehicle. Referring to Figure 10, the turret 14 is assembled by locating the vertical rear edge of each of the side plates 42, 44 inside the connecting flange 46, 48 of the back plate 40 and fixing the connecting flange 46, 48 on the back plate to the upright section 54 of the side plate, and fixing the connecting flange 58 on the side plate to the back wall 50 of the back plate 40. Aligned fixing holes 104 are provided for this purpose in the vertical rear edge of each of the side plates 42, 44 and the connecting flange 46, 48 of the back plate 40, and in the connecting flange 46, 48 on the back plate and the upright section 54 of the side plate. The fixings are threaded fixings, for example nuts and bolts. They may conveniently be m the form of rivet nuts 108 and bolts 110. The rivet nuts 108 may be shaped, for example square or hexagonal, with the holes for them being of a corresponding shape, which prevents rotation of the rivet nuts 108 in the holes during tightening of the bolts 110 into them. Once the turret is assembled, the lower pin apertures 64 in the two side plates 42, 44 are aligned with each other and arranged to receive a pin 112 for pivotably mounting the lower lifting arm 22 to the turret. Similarly the upper pin apertures 66 in the two side plates 42, 44 are aligned with each other and arranged to receive a pin 114 for pivotably mounting the upper lifting arm 20 to the turret. Referring back to Figure 4, the assembled turrets 12, 14 can then be mounted on the base plate 10, again by threaded fixings. For example the rear mounting flanges 68 can be fixed to the tops 86, 96 of the two ridges 84, 94, the front mounting flanges can be fixed to the front mounting flange 92 of the base plate 10, and the connecting flange 52 on the back wall of the back plate 40 can be fixed to the rear wall 100 of the rear ridge 94 of the base plate 10. In a modification to the arrangement shown, the side plates 42, 44 of the turrets may be fitted to the outside of the back plate 40, rather than the inside as shown. For a back plate 40 of the same size, this would of course alter the overall dimensions of the turret, and the required locations of the fixing holes in the base plate 10. However this can be used as a further adjustment of the assembly as the same turret components could be used for slightly different overall lift dimensions. As can be seen in Figures 4 and 7, the base plate 10 may have, at each end, two or more sets of fixing holes through it so that the turrets 12, 14 can be fixed to the base plate 10 in each of a plurality of different positions. For example, as shown in Figure 4, a first set of holes in the base plate 10 are used for fixing the turret 14 to the base plate 10. The connecting flange 52 on the rear wall of the back plate 40 is fixed to the base plate 10 using three out of the five holes 120 in the rear wall 100 of the rear ridge 94 of the base plate, and the rear mounting flange 68 of the side plate 42 is fixed using a pair of holes 122a in the top of each of the front and rear ridges 84, 94. However there are two further pairs of holes 122b in the top of each of the front and rear ridges 84, 94, nearer the end of the base plate 10, and a further hole in the rear wall 100 of the rear ridge 94 of the base plate which form part of a second set of holes in the base plate. Referring to Figure 5, it can be seen that there are two complete sets 122a, 122b of four holes in the top of each of the front and rear ridges 84, 94. It will also be noted that as the holes 120 in the rear wall 100 of the rear ridge are in a row extending along the base plate 10, the two sets of holes are not completely separate, and some of the holes 120 form part of both sets, being used in either position of the turret 14. Also referring to Figure 7, since there are two fill sets of fixing holes at each end of the base plate 10, the turrets 12, 14 can be mounted at three different distances from each other, one using the two innermost sets of holes, one using the two outermost sets of holes, and one using one inner and one outer set of holes. Since the base plate and turret structures described above have no welding, and are simply bolted together, there is no welding distortion and the overall structure can be more accurately assembled than a welded structure. It is also possible for the different components to be of different materials, for example different alloys, or composite materials such as carbon fibre. Also the structure allows for easy substitution of different parts. For example the back plates 40 of the turrets are typically used to bolt on additional products such as stop-safe barriers or vehicle door-opener mechanisms. The bolt on back plates of turrets mean that replacement back plates, for example with different holes compatible with different additional components, can be supplied with the lift, or even fitted to the lift after installation in the vehicle. While the embodiment shown in the drawings has a centrally splitting platform, the same lifting mechanism can be used with tradition one-piece platforms and also on horizontal folding platforms. In the case of horizontal folding platforms the folding mechanism may require additional side clearance compared to other platform designs. The adjustable turret spacing described above allows for more options to minimise overall outside width to accommodate this.

Claims

1. A lift system for mounting on a vehicle, the lift system comprising two turrets, a base plate arrange for mounting on the vehicle and arranged to support the turrets, two pairs of lifting amis, each of the pairs of lifting amis being connected to a respective one of the turrets, two actuators, each of the actuators acting between the two lifting arms in a respective one of the pairs of lifting amis, and a lift platform connected to the lifting amis and arranged to be raised and lowered by operation of the actuators, wherein each of the turrets comprises a back plate and two side plates each connected to the back plate by releasable threaded fixings.

2. A lift system according to claim 1 each of the lifting arms is rotatably connected to said respective one of the turrets by a pin, the pin being supported by the two side plates of said respective one of the turrets.

3. A lift system according to claim 1 or claim 2 wherein each of the side plates has a flange at its lower end, and the flange has fixing apertures therethrough to receive fixings for fixing the side plates to the base plate.

4. A lift system according to any preceding claim wherein the back plate has a flange at its lower end, and the flange has fixing apertures therethrough to receive fixings for fixing the back plate to the base plate.

5. A lift system according to any preceding claim wherein each of the turrets further comprises a brace arranged to extend between the side plates at an outboard end thereof, the brace having fixing apertures therethrough for receiving fixings for fixing the brace to the side plates.

6. A lift system according to claim 5 wherein the brace further comprises a base having a fixing aperture therethrough for fixing the turret to the base plate.

7. A lift system according to claim 6 wherein the base plate has an aperture therethrough which is aligned with the aperture in the base of the brace, arranged to receive a fixing for fixing the turret and the base plate to the vehicle.

8. A lift system according to any preceding claim wherein the base plate has, towards one end of the base plate, a plurality of sets of fixing apertures therethrough each set being arranged for fixing one of the turrets to tire base plate in a respective position, whereby the distance between the turrets can be adjusted.

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