GB2024774A - Guided elevators - Google Patents

Abstract

In lifting and lowering apparatus of the kind comprising a pair of parallel upright hollow guide members 20 and a platform hingedly attached to a pair of runners each running within a guide member, a web (23) of each runner extends through a slit (21) in the associated guide member (20) and has a front flange (24) carrying support flanges (25, 26), which hingedly supporting one end of the platform, a pair of upper pad members (30, 31) of anti-friction material and a similar lower pad member (33), the pad members providing bearing surfaces for the runner acting respectively forwardly and rearwardly against the guide member. The pad members are of reinforced elastomeric material, for example nylon with molybdenum disulphide. In an alternative embodiment (Figures 1-6, not shown) there is only a single pad (18) on each runner, at its upper end, and a pad (15) on the guide member engaging the rear face of the runner. The apparatus may be fitted on a vehicle. <IMAGE>

Description

SPECIFICATION Improvements in or relating to load lifting and lowering apparatus The invention relates to load lift and lowering apparatus of the kind comprising a pair of parallel, spaced apart upright rigid guide members along each of which travels a runner mounted on a load carrier, there being provided means connected to each runner to pull it upwardly along the guide member or lower it down the guide member so as to raise or lower the load carrier. Such apparatus will hereinafter be referred to as "load lifting and lowering apparatus of the kind described". More particularly but not exclusively, the invention relates to vehicle tail lifts for raising and lowering loads at the rear end of a vehicle.

Hitherto, in load lifting and lowering apparatus of the kind described each runner has normally comprised at least one roller to allow the runner to run freely up and down inside the associated guide member.

According to the invention there is provided load lifting and lowering apparatus of the kind described comprising at least one pad member arranged between each runner and associated guide member to provide a bearing surface between each runner and the associated guide member.

Each guide member may be hollow, at least a part of each runner being slidable within the associated guide member.

There may be at least one upper pad member and at least one lower pad member associated with each runner and associated guide member.

The or each upper pad member may be arranged to provide a bearing surface between a surface of the associated runner facing the load carrier and an inside surface of the associated guide member facing away from the load carrier and the or each lower pad member may be arranged to provide a bearing surface between a surface of the associated runner facing away from the load carrier and an inside surface of the associated guide member facing the load carrier.

The or each upper pad member may be secured to the associated runner and the or each lower pad member secured to the associated guide member.

Alternatively, both pad members may be secured to the associated runners, or both pad members may be secured to the associated guide members, or the or each upper pad member may be secured to the associated guide member and the or each lower pad member secured to the associated runner.

Each guide member may be of box section and each runner may comprise an elongate member movable telescopically within the guide member, one or more upper pad members being secured to each runner adjacent the top thereof and on the same side thereof as the load carrier, and one or more lower pad members being secured inside each guide member adjacent the bottom thereof and facing towards the load carrier.

Alternatively, each guide member may be hollow and have a longitudinal slit formed therein parallel to the longitudinal axis of the guide member, each runner being movable within an associated guide member and having support means extending through the slit for supporting the load carrier, one or more upper pad members being secured to each runner inside the associated guide member adjacent the top of the runner and on the same side of the runner as the load carrier, and one or more lower pad members being secured to each runner inside the associated guide member adjacent the bottom of the runner and on the side thereof away from the load carrier.

The support means may comprise a web and there may be two upper pad members arranged one each side of the web of each runner. Alternatively a single upper pad member may be secured to each runner.

The pad material may be anti-friction material, for example molybdenum disulphide in nylon or material sold under the name polypenco nylatron GS.

The invention further provides a vehicle comprising load lifting and lowering apparatus according to the invention.

By way of example, two embodiments of load lifting and lowering apparatus according to the invention will now be described with reference to the accompanying drawings in which: Figure lisa side view of a lower part of a column and runner assembly of a first embodiment of load lifting and lowering apparatus; Figure 2 is a view from the left of the assembly of Figure 1, Figure 3 is a sectional view on the line Ill-Ill of Figure 1; Figure 4 is a side view of the runner of Figure 1 with the centre of the runner cut away; Figure 5 is a view from the right of the runner of Figure 4; Figure 6 is a plan view of the runner of Figure 4; Figure 7 is a side view of a runner of a second embodiment of load lifting and lowering apparatus according to the invention; and Figure 8 is an underneath plan view of the runner of Figure 7 with a guide member shown in broken lines.

With reference to Figures 1 to 6 in which a first embodiment of the invention is described a guide member 10, is an elongate metal upright member of box section. The guide member is made, for example, of mild steel. A base portion of the guide member 10 is cut away to allow a metal runner 11 to slide inside the guide member. The runner 11 comprises a tubular portion 12 which is telescopically slidable inside the guide member 10 and flanges 13 to which a platform (not shown) is pivotally secured.

It will be appreciated that when the platform is in a horizontal load carrying position, the weight of the platform exerts a moment which urges the rear of the platform towards the guide member 10. Irrespective of the vertical position of the runner, the force exerted by the runner on the guide member will be directed at the lowest point of contact between the rear of the runner 11 and the rear wall 14 of the guide member that is at the base of the guide member 10.

To provide a bearing surface at this point, a rectangular pad 15 is secured by countersunk screws 16 to the inside of the guide member 10 adjacent its base. Thus as the runner moves up and down in the guide member, the runner bears against the pad 15.

While the moment exerted by the platform causes the runner to exert a force in a direction away from the platform at the base of the guide member, the moment exerted by the platform causes the top of the runner to exert a force on forward wall 17 of the guide member. This force on the forward wall will be exerted at or near the highest point of contact between the runner and the forward wall 17 of the guide member and accordingly a second rectangular pad 18 is secured adjacent the top of runner 11 by countersunk screws 16 to bear against the front wall 17 of the guide member. Thus as the runner 11 slides inside the guide member 10, the pad 18 bears against the front wall 17 of the guide member 10.

With reference to Figures 7 and 8 in which a second embodiment of the invention is described, a guide member 20 is an elongate, metal upright member of box section having a longitudinal slit 21 formed therein. A runner comprises a rear flange 22, a web 23 and a front flange 24 to which is welded support flanges 25,26 to which one end of a load carrier (not shown) is hingedly mounted in an assembled load lifting and lowering apparatus. As shown in Figure 8, the rear flange 22 lies adjacent rear wall 27 of the guide member, the web 23 passes through the slit 21 formed in the guide member and the front flange 24 is spaced from the guide member 20.

Upper pad supporting flanges 28, 29 extend from the web 23 and support respective rectangular pads 30,31 which are secured to the flanges 28,29 by countersunk screws 32. The pads 30, 31 have chamfered longitudinal edges. In an alternative arrangement (not shown), a top portion of the web 23 and front flange are cut away and a single pad supporting flange is secured to the remaining portion of the web parallel to the rear flange 22. This allows a single upper pad to be used.

A lower rectangular pad 33 is secured to the side of the rear flange 22 away from the load carrier by further countersunk screws 32. The pad 33 has chamfered longitudinal edges.

Angle members 34 and 35 are secured to the web 23 to ensure that the runner remains aligned within the guide member 20. Plates 36, 37 are secured to the web 23 at the top of the runner and have holes therein for engagement by rope, cable or the like for lifting or lowering the runner. A buffer 38 is bolted to the front flange 24 to provide a stop for the platform when it is in the vertical stowed position.

It will be appreciated that when the platform is in a horizontal load carrying position, the weight of the platform exerts a moment which urges the rear of platform towards the guide member 20 and the top of the runner forwardly towards the slitted wall of the guide member. Thus the pads 30,31,33 are positioned on the runner in places where reactions between each runner and the associated guide member occur.

The pads are of anti-friction material, and are made of, for example, molybdenum disulphide in nylon or material sold under the name polypenco nylatron GS.

The advantages of these embodiments of the invention are that rollers are dispensed with from the runner assemblies thus rendering the runners simpler to assemble than has hitherto been possible.

The pads are simple to replace when worn.

It will be appreciated that although in one embodiment the upper pad is secured to the runner and the lower pad is secured to the guide member and in the other embodiment both upper and lower pad members are secured to the runner, the upper and lower pad members may both be secured to the guide members. Also, the upper pad member could be on the column and the lower pad member on the runner. Furthermore, rollers may be used instead of some of the pad members in each embodiment to provide a bearing surface or surfaces between the runners and the associated guide members.

Claims (16)

1. Load lifting and lowering apparatus of the kind described comprising at least one pad member arranged between each runner and associated guide member two provide a bearing surface between each runner and the associated guide member.

2. Load lifting and lowering apparatus as claimed in claim 1 in which each guide member is hollow, at least a part of each runner being slidable within the associated guide member.

3. Load lifting and lowering apparatus as claimed in claim 1 or claim 2 in which there is at least one upper pad member and at least one lower pad member associated with each runner and associated guide member.

4. Load lifting and lowering apparatus as claimed in claim 3 in which the or each upper pad member is arranged to provide a bearing surface between a surface of the associated runner facing the load carrier and an inside surface of the associated guide member facing away from the load carrier and the or each lower pad member is arranged to provide a bearing surface between a surface of the associated runner facing away from the load carrier and an inside surface of the associated guide member facing the load carrier.

5. Load lifting and lowering apparatus as claimed in claim 4 in which the or each upper pad member is secured to the associated runner and the or each lower pad member is secured to the associated guide member.

6. Load lifting and lowering apparatus as claimed in claim 4 in which both upper and lower pad members are secured to the associated runner.

7. Load lifting and lowering apparatus as claimed in claim 4 in which both upper and lower pad members are secured to the associated guide member.

8. Load lifting and lowering apparatus as claimed in claim 4 in which the or each upper pad member is secured to the associated guide member and the or each lower pad member is secured to the associated runner.

9. Load lifting and lowering apparatus as claimed in any of claims 1 to 5 in which each guide member is of box section and each runner comprises an elongate member movable telescopically within the guide member, one or more upper pad members being secured to each runner adjacent the top thereof and on the same side thereof as the load carrier, and one or more lower pad members being secured inside each guide member adjacent the bottom thereof and facing towards the load carrier.

10. Load lifting and lowering apparatus as claimed in any of claims 1,2,3,4 and 6 in which each guide member is hollow and has a longitudinal slit formed therein parallel to the longitudinal axis of the guide member, each runner being movable within an associated guide member and having support means extending through the slit for supporting the load carrier, one or more upper pad members being secured to each runner inside the associated guide member adjacent the top of the runner and on the same side of the runner as the load carrier, and one or more lower pad members being secured to each runner inside the guide member adjacent the bottom of the runner and on the side thereof away from the load carrier.

11. Load lifting and lowering apparatus as claimed in claim 10 in which the support means comprises a web and in which there are two upper pad members arranged one each side of the web of each runner.

12. Load lifting and lowering apparatus as claimed in claim 10 comprising a single upper pad member secured to each runner.

13. Load lifting and lowering apparatus as claimed in any preceding claim in which the or each pad member is made of anti-friction material.

14. Load lifting and lowering apparatus as claimed in claim 13 in which the pad material is nylon with molybdenum disulphide.

15. Load lifting and lowering apparatus as claimed in claim 1 or claim 2 comprising at least one roller to provide a bearing surface between a runner and an associated guide member.

16. Avehiclecomprising load lifting and iower- ing apparatus as claimed in any preceding claim.