GB2356221A

GB2356221A - Pivoted latch for a lifting platform

Info

Publication number: GB2356221A
Application number: GB0027462A
Authority: GB
Inventors: Iain Douglas Gardiner
Original assignee: Ross and Bonnyman Engineering Ltd
Current assignee: Ross and Bonnyman Engineering Ltd
Priority date: 1999-11-11
Filing date: 2000-11-10
Publication date: 2001-05-16
Also published as: GB0027462D0; GB9926620D0

Abstract

A latch assembly comprises a hooked latch-bolt 30, pivotally mounted to a frame 10, and a formation 21, e.g. pin or shoulder, mounted on a door 20. When the door 20 is moved relative to the frame, the pin 21 engages the hook 30 and causes it to rotate about its pivot pin 31. As the hook 30 rotates, the door 20 is drawn toward and held securely against the frame 10. The door 20 may be a lifting platform for a vehicle and may be hinged to runners 15 slidably mounted on vertical columns which form the frame 10.

Description

1 2356221 1 "Latch" 2 3 This invention relates to a latch suitable for a

door 4 on a vehicle, and particularly for latching a tail lift 5 mounted on a vehicle (e.g. at the rear) to enable the 6 transfer of heavy objects between the ground and the 7 vehicle. Although called a tail lift, such apparatus 8 can be located at the front or side of the vehicle 9 instead of the rear, but it is conventional for tail 10 lifts to be located at the rear of e.g. the truck bed. 11 12 Conventional designs of tail lifts generally 13 incorporate a pair of columns spaced apart a rear 14 opening of the truck loadspace and a platform that is 15 pivotally mounted e.g. via hinges at its base to the 16 truck bed. The platform can be pivoted about the 17 hinges to a vertical configuration in which it extends 18 across the opening, or can be placed in a horizontal 19 configuration to be raised and lowered relative to the 20 columns for operation as a tail lift. The platform is 21 typically attached to runners that are slidable on the 22 columns and can typically be powered by cables and/or 2 1 hydraulic rams in order to move the runners along a 2 rear face of the columns.

3 4 When the tail lift is in its vertical configuration, it is conventional for there to be a latching assembly in 6 order to keep the platform against the runners or 7 columns and so prevent it from falling back into the 8 horizontal configuration, since this is inconvenient 9 and dangerous, especially when the vehicle is moving.

Existing designs of latch include a pin and a recess on 11 the platform and column respectively that engage one 12 another when the platform is raised along with the 13 runners in relation to the columns. This is very 14 satisfactory in most situations, but it is desirable also for the platform to be held securely against the 16 runners or columns in order to prevent it rattling.

17 18 According to the present invention there is provided a 19 latch for a door for closing an opening in a frame, the latch comprising a hook on one of the frame and the 21 door and a co-operating formation on the other of the 22 frame and door, the hook and co-operating formation 23 being arranged to engage one another when the door is 24 moved relative to the frame, the hook being pivotally attached to the door or the frame so that upon engaging 26 the co-operating formation, the rotation of the hook 27 about its pivot point draws the door and frame 28 together.

29 The formation is typically constrained to move in an 31 arc.

32 3 1 According to the present invention there is also 2 provided lifting apparatus comprising a platform 3 assembly movable in relation to a frame, the platform 4 assembly having a platform that is pivotable between a generally horizontal configuration and a vertical 6 configuration, the apparatus having a latch comprising 7 a hook connected to one of the platform assembly and 8 the frame, and a co-operating formation on the other 9 that engage one another when the platform is moved in relation to the frame, the hook being pivotally 11 attached to the platform assembly or the frame so that 12 upon engagement of the formation and the hook, the 13 rotation of the hook about its pivot point draws the 14 platform and frame together.

16 The formation is typically constrained to move in an 17 arc.

18 19 The hook is preferably pivotally mounted on the or each frame side member such as a column. The formation is 21 typically a pin extending from one or each side member 22 of the platform, but can be an internal shoulder or pin 23 on the platform. The hook is typically arranged in a 24 downwardly pointing configuration so that the pin on the door engages it, lifts it from its resting 26 configuration and rotates it around its pivot point 27 until the door is held securely against the frame.

28 29 Upward movement of the door typically forces the door to which the hook is attached to move in an arc 31 governed by the rotation of the hook around its pivot 32 point.

33 4 1 Alternatively, the hook can be pivotally mounted on the 2 door, and the formation can be a pin extending from a 3 side member of the frame. In this embodiment, the hook 4 is arranged in an upwardly pointing configuration so that the pin on the frame engages it, pushing it 6 downwardly from its resting configuration and rotates 7 it around its pivot point until the door is held 8 securely against the frame. 9 10 The platform assembly typically comprises one or more 11 runners slidably engaged with a respective column, and 12 a platform hingedly attached to the runners. The hook 13 is preferably arranged in a downwardly pointing 14 configuration so that the pin on the platform engages 15 it, lifts it from its resting configuration and rotates 16 it around its pivot point until the platform is held 17 securely against the runner or the frame. 18 Alternatively, the hook can be mounted on the platform, 19 and the pin can be mounted on the column so that the 20 hook is arranged in an upwardly pointing configuration 21 and engages the stationary pin on the column, and 22 forces the platform to which it is attached to move in 23 an arc governed by the rotation of the hook around the 24 pin. 25 26 The hook can typically pivot in a plane perpendicular 27 to the plane of the door. 28 29 The hook is typically provided with a face that engages 30 the formation (e.g. a pin). The face is typically 31 provided with a seat so that the formation engages the 32 seat. As the door or platform is moved upwardly, the 33 formation engages the face of the hook and moves it in 1 an arc around its pivot point. Continued upward 2 movement of the door or platform forces the formation 3 to travel along the face of the hook, and also 4 continually pivots the hook around its pivot point.

The formation typically engages the seat and the upward 6 movement of the platform or door causes the hook to 7 continue to pivot. The arcuate movement of the hook 8 causes the platform or door to move in an arc governed 9 by the pivoting of the hook around its pivot point, and thus the platform or door is moved closer to the frame 11 as the arcuate movement of the hook and formation draws 12 them together.

13 14 An embodiment of the present invention shall now be described, by way of example only, with reference to 16 the accompanying drawings, in which:

17 Figs. la, b and c show top and side views of a 18 hook for incorporation in lifting apparatus; 19 Fig. 2 shows a side view of a further embodiment of lifting apparatus; 21 Fig. 3 shows the Fig. 2 apparatus with the 22 platform raised to engage the hook; 23 Fig. 4 shows the Fig. 2 and 3 apparatus with the 24 platform raised further so as to pivot the hook; Fig. 5 shows a stage similar to Fig. 4 from a 26 perspective view; 27 Fig. 6 shows an alternative view to Fig. 2 where 28 the platform is about to engage the hook; and 29 Fig. 7 shows a front view of the hook in the Fig.

4 and 5 position; 31 Fig. 8a is a side view of an alternative hook; 32 Fig. 8b is a schematic view of the hook of Fig. 8d 33 engaged with a pin provided on the platform in 6 2 3 Referring now to the drawings, lifting apparatus 4 comprises a frame in the form of columns 10 that can typically extend around an opening (or at least on 6 either side of an opening) on a vehicle (not shown), 7 although in the embodiment shown in the figures they 8 form part of a test bed, and the present invention is 9 not limited to use on vehicles. The columns 10 have runners 15 on their rear faces that can slide up and 11 down in relation to the columns 10. At the base of the 12 runners 15, a platform 20 is hingedly connected (not 13 shown) so as to be pivotable from a horizontal position 14 (not shown) to a vertical position as is shown in the figures. There is typically a catch (not shown) 16 provided at the hinge between the platform 20 and the 17 runners 15 to keep the platform 20 from falling from 18 its vertical configuration, and the apparatus also 19 includes a latch in the form of one or more hooks 30 each connected by a pivot pin 31 to a respective column 21 10. There is a stop 32 or a shoulder cut into the 22 lower surface of the hook 30 that abuts against a 23 shoulder on the column 10 so as to prevent the hook 30 24 from dropping below a horizontal attitude when pivoting around the pin 31.

26 27 A hook 30 is typically provided on each column 10 at 28 equivalent heights on the columns 10, although in 29 certain embodiments one hook will be sufficient.

31 The platform 20 has pins 21 jutting out from respective 32 side members directly below the hook 30 on each side of 33 the platform 20. When the platform 20 is in its 7 1 horizontal position shown in Fig. 2, the hydraulic rams 2 or pulleys etc can be operated to move the platform 3 assembly of the platform 20 and the runners 15 upwards 4 in relation to the column 10. Since the hook 30 is attached to the column 10 and does not move with the 6 runners 15, the upward movement of the platform 20 7 advances the pin 21 towards the lower surface 33 of the 8 hook 30. As the platform assembly 20, 15 travels 9 upwards, the pin 21 engages with the lower surface 33 of the hook 30, and starts to lift the hook 31 from the 11 position shown in Fig. 3 where the hook lower surface 12 33 is generally horizontal, to the position shown in 13 Fig. 4 where the surface 33 is at an angle as the hook 14 30 pivots around the pin 31. During this process, the pin 21 travels along the surface 33 to the end of the 16 hook 30 until it engages the seat 34 at the end. At 17 this point, the upward movement of the platform 20 and 18 the pin 21 is restrained to an arcuate movement by the 19 hook 30 that forces any further upward movement of the platform 20 into an arcuate line defined by its 21 rotation around the pivot pin 31. This is generally 22 shown by the dotted line R in Fig. 4. Movement of the 23 pin 21 along the line R as constrained by the pivotal 24 movement of the hook 30 around the pivot pin 31 draws the platform 20 nearer to the column 10. A rubber pad 26 on the platform 20 or the runner 15 can be provided in 27 order to buffer the two, and the platform 20 can simply 28 be driven upwards in the arcuate line R by the 29 hydraulic force of the conventional mechanism until sufficient force is applied on the rubber pad (not 31 shown) to keep the platform 20 firmly abutted against 32 the runner 15 and so avoid it rattling during transit.

33.

8 1 Modifications and improvements can be incorporated 2 without departing from the scope of the invention.

3 4 In one modified embodiment the seat for the hook 30 against which the pin 21 engages at the end of the 6 surface 33 as the platform assembly 20, 15 rises can be 7 shaped to have straight sides in the form of a square 8 or rectangle, the sides of which can be parallel to the 9 platform 20 or perpendicular thereto at their resting position with the platform 20 held against the runners 11 15.

12 13 Referring to Figs 8a and 8b there is shown an 14 alternative hook 40 that is similar to hook 30 but has an extended nose portion 42. The extended nose portion 16 42 is adapted to engage the pin 21 provided on the 17 platform 20 so that the pin 21 is less likely to become 18 disengaged from the hook 40 in use. The pin 21 on the 19 platform 20 moves upward with the platform 20 as described above, and the pin 21 engages a lower face 44 21 of the hook 30. As the pin 21 engages lower face 44, 22 hook 40 is lifted from the horizontal position shown in 23 Fig. 8a and moves in an arc as it is constrained to 24 pivot around pivot pin 41. As hook 40 pivots, pin 21 travels up face 44 to seat 46 (Fig. 8a) and the pivotal 26 movement of the hook 40 pulls the platform (not shown) 27 further towards the runners (not shown). Thus, the 28 platform 20 is held more securely against the runner 15 29 when the platform 20 is in its vertical position and the pin 21 is less likely to be disengaged in use as it 31 is retained in seat 46 by the nose portion 42.

9

Claims

1 CLAIMS

2 1. A latch for a door for closing an opening in a 3 frame, the latch comprising a hook on one of the frame 4 and the door and a co-operating formation on the other of the frame and door, the hook and co-operating 6 formation being arranged to engage one another when the 7 door is moved relative to the frame, the hook being 8 pivotally attached to the door or the frame so that 9 upon engaging the co-operating formation, the rotation of the hook about its pivot point draws the door and 11 frame together.

12 13

2. A latch according to claim 1, wherein the 14 formation is constrained to move in an arc.

is 16

3. A latch according to either preceding claim, 17 wherein the hook is pivotally mounted on the or each 18 frame side member.

19

4. A latch according to any preceding claim, wherein 21 the formation is a pin extending from a side member of 22 the door.

23 24

5. A latch according to any one of claims 1 to 3, wherein the formation comprises an internal shoulder on 26 the door.

27 28

6. A latch according to any preceding claim, wherein 29 the hook is arranged in a downwardly pointing configuration so that the pin on the door engages it, 31 lifts it from its resting configuration and rotates it 32 around its pivot point until the door is held securely 33 against the frame.

1 2

7. A latch according to any preceding claim, wherein 3 upward movement of the door forces the door to which 4 the hook is attached to move in an arc governed by the rotation of the hook around its pivot point.

6 7

8. A latch according to any preceding claim, wherein 8 the hook can pivot in a plane perpendicular to the 9 plane of the door.

11

9. A latch according to claim 1 or claim 2, wherein 12 the hook is pivotally mounted on the door.

13 14

10. A latch according to claim 9, wherein the is formation is a pin extending from a side member of the 16 frame.

17 18

11. A latch according to claim 10, wherein the hook is 19 arranged in an upwardly pointing configuration so that the pin on the frame engages it, pushing it downwardly 21 from its resting configuration and rotates it around 22 its pivot point until the door is held securely against 23 the frame.

24

12. A latch according to any preceding claim, wherein 26 the hook is provided with a face that engages the 27 formation.

28 29

13. A latch according to claim 12, wherein the face is 30 provided with a seat so that the formation engages the 31 seat.

32 11 1

14. A latch according to claim 13, wherein as the door 2 or platform is moved upwardly, the formation engages 3 the face of the hook and moves it in an upward arc 4 around its pivot point. 5 6

15. Lifting apparatus comprising a platform assembly 7 movable in relation to a frame, the platform assembly 8 having a platform that is pivotable between a generally 9 horizontal configuration and a vertical configuration, 10 the apparatus having a latch comprising a hook 11 connected to one of the platform assembly and the 12 frame, and a co-operating formation on the other that 13 engage one another when the platform is moved in 14 relation to the frame, the hook being pivotally 15 attached to the platform assembly or the frame so that 16 upon engagement of the formation and the hook, the 17 formation is constrained to move in an arc governed by 18 the rotation of the hook about its pivot point so that 19 the platform and frame are drawn together. 20 21

16. Lifting apparatus according to claim 15, wherein 22 the formation is constrained to move in an arc. 23 24

17. Lifting apparatus according to either claim 15 or 25 claim 16, wherein the hook is pivotally mounted on the 26 or each frame side member. 27 28

18. Lifting apparatus according to any one of claims 29 15 to 17, wherein the formation is a pin extending from 30 one or each side member of the platform. 31 12 1

19. Lifting apparatus according to any one of claims 2 15 to 18, wherein the formation comprises an internal 3 shoulder or pin on the platform.

4

20. Lifting apparatus according to any one of claims 6 15 to 19, wherein the platform assembly typically 7 comprises one or more runners slidably engaged with a 8 respective column, and a platform hingedly attached to 9 the runners. 10 11

21. Lifting apparatus according to any one of claims 12 15 to 20, wherein the hook is arranged in a downwardly 13 pointing configuration so that the pin on the platform 14 engages it, lifts it from its resting configuration and rotates it around its pivot point until the platform is 16 held securely against the runner or the frame.

17 18

22. Lifting apparatus according to any one of claims 19 15 to 21, wherein the hook is mounted on the platform, 20 and the pin is mounted on the column or frame so that 21 the hook is arranged in an upwardly pointing 22 configuration and engages the stationary pin on the 23 column or frame, and forces the platform to which it is 24 attached to move in an arc governed by the rotation of the hook around its pivot point. 26 27

23. Lifting apparatus according to any one of claims 28 15 to 22, wherein the hook can pivot in a plane 29 perpendicular to the plane of the door. 30 31

24. Lifting apparatus according to any one of claims 32 15 to 23, wherein the hook is provided with a face that 33 engages the formation.

13 1 2

25. Lifting apparatus according to claim 24, wherein 3 the face is provided with a seat so that the formation 4 engages the seat.

6

26. Lifting apparatus according to claim 25, wherein 7 as the door or platform is moved upwardly, the 8 formation engages the face of the hook and moves it in 9 an upward arc around its pivot point.

11

27. A latch substantially as hereinbefore described 12 with reference to the drawings.

13 14

28. Lifting apparatus substantially as hereinbefore described with reference to the drawings.