GB2250267A

GB2250267A - Improvements in or relating to fork lift trucks

Info

Publication number: GB2250267A
Application number: GB9121529A
Authority: GB
Inventors: David Alan Read
Original assignee: FIELDEN ENGINEERS Ltd
Current assignee: FIELDEN ENGINEERS Ltd
Priority date: 1990-10-10
Filing date: 1991-10-10
Publication date: 1992-06-03
Also published as: GB9022002D0; GB9121529D0

Abstract

Stabilizers 12 are raised and lowered by operating a hydraulic cylinder 42 which is connected to a cross number 44 extending across the base of the main upright of masts 38 and 40. Movement of the piston 46 out of or into the cylinder 42 causes the cross member 48 to be raised or lowered. The stabilizer 12 is slidably mounted on a guide post 56 and the guide extends downwardly from the cross member 48 and is connected to the guide rod 50 by a shaft 58 carrying a sprocket 60. A chain 54 passes around the sprocket 60 and around a sprocket 62 mounted on the cross member 48 such that, as the cross member 48 is moved up and down by the piston 46 the sprocket 60 and 62 are caused to move up and down by the same amount but the stabilizer 12 which is fast with the chain 54 (which chain is also fast with the main mast 38) causes the stabilizer to move up and down at twice the rate of movement of the piston 46. Prof. each stabilizer has load engaging pads mounted pivotally or by springs on the stabilizer cam. Pref. a telescopic piston adjusts the spacing of the forks. Pref. the truck is used for picking up a number of drums at once. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO FORK LIFT TRUCKS.

The present invention relates to drive arrangements for load engaging means and to a method of operating such drive arrangements. The invention is particularly, although not exclusively applicable to load engaging means of fork lift trucks.

The present invention also relates to a load engaging arrangement and to a method of engaging a load which is particularly, although not exclusively applicable to the engaging of loads to be carried by a fork lift truck.

The present invention further relates to a doubleacting fluid operated, cylinder arrangement and a method of operating a double-acting fluid operated cylinder arrangement. The invention is particularly, although not exclusively, applicable to such cylinders for moving the tines of a fork lift truck.

According to one aspect of the present invention a drive arrangement is arranged to drive a load engaging means, the arrangement including a primary drive connected to the load engaging means by a secondary drive with movement of the primary drive being arranged to power the secondary drive.

The secondary drive may be connected to two spaced load engaging means, and a secondary drive may be associated with each load engaging means.

The primary drive may be arranged to cause movement of a first member and a secondary drive or drives may be arranged to move with the first member.

According to another aspect of the present invention a drive arrangement is arranged to drive two spaced load engaging means, the arrangement including a primary drive arranged to cause movement of a first member and secondary drives associated with each of the spaced load engaging means, the secondary drives being arranged to move with the first member.

operation of the primary drive may be arranged to power the secondary drives.

The secondary drives may be arranged to cause movement of the load engaging means relative to the first member.

The primary drive may comprise a cylinder and piston, and may comprise a single such cylinder and piston. The cylinder and piston may be hydraulically operated.

The primary drive may be located closer to one of the load engaging means than it is to the other load engaging means.

The secondary drive or drives may comprise a chain drive with the load engaging means being constrained to move with the chain. Movement of the primary drive may be arranged to cause movement of the chain.

The load engaging means may be arranged to move a greater distance than the primary drive, and may be arranged to move approximately twice the distance of the primary drive.

The load engaging means may be arranged to move downwardly to engage a load.

The present invention also includes a method of operating a drive arrangement as herein referred to.

According to a further aspect of the present invention a load engaging arrangement includes a plurality of load engaging members mounted on a support arm, the support arm being movable towards or away from a load, the inclination of each of the load engaging members being variable independently of each other.

Each load engaging member may be movable translationally, independently of each other and each load engaging member may be movable translationally about two transverse axes independently from each other.

Each load engaging member may be arranged to engage a different article at two spaced locations.

Each load engaging member may be arranged to move against a resilient force when the load engaging member engages a load.

Each load engaging member may be connected to the arm by resilient means and that connection provided by the resilient means to the arm may be provided at two spaced locations for each. load engaging member.

A first member may be pivotally connected to the arm with each load engaging member being pivotally connected to the first member. At least one of the load engaging members may be directly connected to the first member by a pivot. At least one, and preferably two load engaging members may be pivotally connected to a second member which second member is pivotally connected to the first member. The two load engaging members which are pivotally connected to the second member may be so connected at locations spaced from each other. The second member may be pivotally connected to the first member at a location spaced from the pivotal connection of the first member to the arm.

According to another aspect of the present invention a method of engaging a load with a plurality of load engaging members comprises moving a support arm carrying the members towards the load with each load engaging member engaging the load and being able to have their inclinations altered separately from each other, if necessary, in order that the load is engaged at two locations by each load engaging member.

The method may comprise each load engaging member engaging the load at two spaced locations.

The method may comprise each load engaging member engaging a different article.

The method may comprise each load engaging member being able to move translationally, if necessary, in order to engage a load, and each load engaging member may be able to be moved translationally about two transverse axes in order to engage a load.

The present invention also includes a method of engaging a load using a load engaging arrangement as herein referred to.

According to a further aspect of the present invention, a double-acting fluid operated cylinder arrangement is provided in which a working region is defined in part by a first portion facing a first direction, the first portion being constrained to move with a first piston, and the working region being defined in part by a second portion facing the first direction, the second portion being constrained to move with a second piston, the areas of the first portion and second portions being proportional to the relative degrees of movement of the first and second portions, the first piston being arranged to move at the same time as the second piston in a different direction.

The areas of the first and second portions may be substantially equal.

The first portion may be arranged to move adjacent to the second portion, and the first portion may be arranged to pass the second portion during part of the movement of the pistons. The first portion may surround the second portion.

An inlet valve or alternatively or additionally an outlet valve may be connected to the working region with those valves being respectively arranged to emit fluid into, or release fluid from the working region.

The first power chamber may be provided in which fluid may be pressurised in order to power the first piston in the first direction, and when fluid is pressurised in that power chamber, fluid may also be capable of being introduced into the working chamber.

The second power chamber may be provided in which fluid may be pressurised in order to power the second piston in a second direction, different from the first direction, and when fluid is pressurised in the second power chamber, fluid may also be capable of leaving the working chamber.

At least one of the power chambers may be provided at a region spaced from the working chamber and may be provided by a remote cylinder and piston. Said remote cylinder and piston may be constrained to move with said first and second pistons.

The cylinder may be arranged to be connected to an intermediate arm, and the first and second pistons may be arranged to be connected to first and second arms respectively which first and second arms are movable simultaneously towards or away from the intermediate arm.

The present invention also includes a method of operating a double-acting fluid operated cylinder as herein referred to.

The present invention includes any combination of the herein referred to features or limitations.

The present invention may be carried into practice in various ways, but several embodiments will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a side view of a fork lift truck attachment 10 with upper stabilisers 12 occupying their highest position; Figure 2 is a view similar to Figure 1 with the stabilisers 12 occupying their lowest position; Figure 3 is a front view of the attachment with the stabilisers 12 in the highest position; Figure 4 is a view similar to Figure 3 with the stabilisers 12 in the lowest position; Figure 5 is a side view of a first embodiment of one stabiliser 112; Figure 6 is a side view of the stabiliser 112 engaging the upwardly facing surface of three barrels 114; Figure 7 is a side view of a second embodiment of one stabiliser 212;; Figure 8 is a side view of the stabiliser 212 engaging the upwardly facing surface of three barrels 214, and Figure 9 is a sectional view of a hydraulic cylinder used to operate outer tines of the attachment.

As shown in Figures 1 and 2, the fork lift truck attachment 10 is arranged to be mounted on the front of a conventional fork lift truck by means of mounting brackets 14, and hydraulic power is connected from the truck to the attachment at unions 16, In use, the attachment approaches a stack of barrels with the stabiliser 12 being in the raised position shown in Figures 1 and 3 and the lower tines 18, 20 and 22 being at the lower level of a barrel at the bottom of the stack to be lifted with that lower level being on the ground, when the stack is on the ground, or that lower level being above the ground, for instance when the barrels are being taken off a stack of barrels or off the back of a lorry.

The central tine 20 is inserted along the row to be lifted and may extend between three pairs of barrels located side by side. The outer tines 18 and 22 are spaced slightly from the side of the barrels to be raised, during insertion of the tines, and are then brought inwardly to engage the side of three barrels in the row by moving in the direction from the position of the tines 18 and 22 shown in Figure 3 towards the position shown in Figure 4.

Movement of the tines 18 and 22 is controlled by a hydraulic cylinder 24 fixed relative to the central tine 20 and being connected to the tine 18 by an internal telescopic piston 26 and being connected to the other tine 22 by an external telescopic piston 28. The pistons 26 and 28 and the cylinder 24 are located at the level of tines 18, 20 and 22 in order that the visibility of the operator in front of the truck is not impaired even when the tines 18, 20 and 22 are raised off the ground.

Movement of the tines 18 and 22 is guided by a pair of rods 30 and 32 which extend into respective tubes 34 and 36 which are fixed to, and extend across the main upright masts 38 and 40 at an elevation above the tines 18, 20 and 22. The attachment is then raised slightly by raising the mounting on the truck until the tines take the weight of the barrels in the stack to be lifted. Once the tines 18, 20 and 22 are in position relative to the two rows of three barrels the stabilisers 12 are moved downwardly from the position shown in Figures 1 and 3 towards the position shown in Figures 2 and 4. The stabilisers are moved downwardly until they grip the upwardly facing rims of the uppermost barrels in the stack, as shown in Figures 6 and 8. The stabilisers 12 are thus positioned to either side of the central tine 20, when viewed from the front.The barrels whose rims are engaged by the stabilisers may be the same barrels which the lower tines are arranged alongside, or may comprise the rims of a stack of barrels located on top of those barrels or may comprise the rims of barrels spaced from the lower barrels engaged by the tines by an intermediate layer of barrels. Thus if the lower layer of barrels includes six barrels, the attachment may co-operate with six, twelve or eighteen barrels in dependence upon whether there are one, two or three layers of barrels.

The stack of barrels is then raised by lifting the attachment on the truck, and tilting the attachment back slightly in an anti-clockwise direction when viewed in Figures 1 and 2, and the truck can then relocate the stack to the required position.

A stack can be deposited from the attachment by reversing the sequence of operation described above when engaging and lifting a stack.

The stabilisers 12 are raised and lowered by operating a hydraulic cylinder 42 which is connected to a cross member 44 extending across' the base of the main upright masts 38 and 40. A piston 46 extends from the cylinder and carries a cross member 48 at its upper end.

Guide rods 50 and 52 are fixed to each end of the cross member and extend telescopically downwardly into guide recesses in the respective upright masts 38 and 40. Thus movement of the piston 46 out of or into the cylinder 42 causes the cross member 48 to be raised or lowered.

Although there are' two stabilisers at either side (when viewed from the front) the movement of the stabiliser 12 at the left hand side of Figures 3 and 4 will now be described but it will be appreciated that the other stabiliser operates in the same way.

The stabiliser 12 is secured to adjacent ends of a chain 54. The stabiliser 12 is slidably mounted on a guide post 56 and the guide post extends downwardly from the cross member 48 and is connected to the guide rod 50 by a shaft 58. The shaft 58 carries a sprocket 60 about which the lower end of the chain 54 passes, and the upper end of the chain 54 extends around a sprocket 62 (shown at the right hand side in Figure 3) mounted on the cross member 48.

As the cross member 48 is moved up and down by the piston 46 so the sprockets 60 and 62 are caused to move up and down by the same amount. However, the stabiliser 12 is fast with the chain 54 and the chain is fast with the main mast 38. Accordingly the stabiliser moves up and down at twice the rate of the piston 46 between the position shown in Figures 1 and 3 and the position shown in Figures 2 and 4. Thus a single cylinder and piston can be used to effect movement of the stabiliser corresponding to approximately twice the stroke of the piston, and the height of the attachment (defined by the cross member 48) can be reduced to enable the attachment to pass beneath relatively low obstructions such as door ways.

Furthermore, the use of the single offset cylinder and piston affords the operator a greater field of view and the provision of a separate chain and sprocket drive for each stabiliser allows that piston and cylinder to be offset from the centre of the tine 20 with each stabiliser still being powered at an equal rate and with an equal force.

Barrels are particularly prone to damage due to the rough treatment which they receive. Accordingly, as shown in Figures 6 and 8, the upwardly facing rims of the top barrels 64, 66 and 68 may not necessarily present a planar gripping surface.

The stabiliser 112 shown in Figures 5 and 6 is provided with three gripping sections 70, 72 and 74 each of which has a downwardly facing resilient surface which may be movable upwardly relative to the sections against a resilient bias (as may the corresponding sections in Figures 7 and 8). The section 74 is pivotally connected to a first carrier 76 which is in turn pivotally connected to the free end of an arm 78 constrained to move up and down with the chain 54. The sections 70 and 72 are each pivotally connected to a second carrier 80 which is in turn pivotally connected to the first carrier 76 at a location spaced laterally from the pivotal axis of the first member 76 to the arm 78. The assembly supported from the arm 78 may balance itself in the position shown in Figure 5 or may be retained in that position by resilient means (not shown).

When the stabiliser 112 is brought down to engage barrels, as shown in Figure 6, each section 70, 72 and 74 is able to move in a vertical direction relative to the other sections such that the sections can occupy different elevations, and each section is able to pivot separately from the other about an axis transverse to the extent of the arm 78 to ensure that the rim at either side of each barrel can be engaged firmly by the associated section.

In Figures 7 and 8, each section 70, 72 and 74 is suspended from the arm 78 by spaced loops 82 which extend around mountings 84 extending transversely across the arm.

A spring 86 affords resistance to upwards movement of each end of the section with respect to the arm. The mounting of the sections on the arm is such that each section can move separately from each other upwardly relative to the arm, laterally to a limited extent in the direction of the arm, and pivotally about an axis extending transversely to and across the arm to ensure that the rim of each barrel is securely gripped, as shown in Figure 8.

In an alternative embodiment (not shown) a single carrier is pivotally suspended from the arm 78 shown in Figure 5. That single carrier has three sections connected to it in the same manner as the sections 70, 72 and 74 are suspended from the arm 78 shown in Figure 7.

When the attachment is lifting a stack of barrels which are taken from a larger block of barrels it is important that the two side tines 18 and 22 are both equally spaced from the central tine as otherwise the side tines may push against and upset the barrels to be lifted or the adjacent barrels in the stack. The double acting piston shown in Figure 3 comprising the hydraulic cylinder 24 and the internal piston 26 and the external piston 28 ensures that each side tine is equidistant from the central tine. This double-acting piston is shown in more detail in Figure 9.

In normal use, the space indicated at 88 and defined between the outer surface of the cylinder 24 and the inner surface of the external piston 28, together with the space 90 defined within the cylinder 24 beyond the inner end of the internal piston 26 define a sealed area with the spaces 88 and 90 being interconnected by a port 92.

In the illustrated position of the pistons, the tines 18 and 22 carried by the pistons 26 and 28 respectively are at their innermost position. In order to move the pistons towards their outermost position hydraulic pressure is applied via a conduit 91 into a space 94. The pressure acting on the end wall 96 of the piston 28 causes that piston to move to the right, when viewed in the drawing, taking with it the end wall 98 which defines the left hand face of the space 88. Thus fluid is forced from the space 88 through the port 92 into the space 90 to cause the piston 26 to move to the left as the fluid pressure in the space 90 acts on the wall 100 which (together with the nut 102) defines the left hand face of the space 90.

As the area of the wall 98 opening out the space 80 and the area of the wall 100 and the nut 102 facing the same direction are the same, the pistons 26 and 28 move away from the cylinder to the left and right respectively by exactly equal amounts.

In order to retract the pistons towards the position shown in Figure 9, fluid under pressure is applied to an inlet 104 to exert a pressure in a space 106 within the cylinder 24. The fluid in the space 106 acts on the left hand face of the wall 100 to push the wall 100 and the piston 26 to the right. That movement also causes the wall 100 to push fluid out of the space 90, through the port 92 into the space 88 to cause the wall 98 and the piston 28 to move to the left by an amount equal to the inwards movement of the piston 26.

Whilst it is envisaged that the spaces 88. and 90 will generally operate as a sealed area, an inlet valve 108 between the space 94 and the space 88 and an outlet valve 110 from the space 88 to a drain are provided. The valve 108 may admit fluid to the spaces 90 and 88 upon start up when pressure is applied to the conduit, or when there is a lack of fluid in the sealed area.

The outlet valve 110 will operate should there be too much fluid in the system to allow fluid out, for instance when fluid is applied to the inlet 104 and the nut 102 will not abut the right hand wall of the space 90 until excess fluid has been pushed past the valve 110.

Alternatively that excess fluid may be let out of the valve 110 when pressure is applied to the space 94 if either of the pistons do not come to rest against abutments at the outermost extent of their travel as a result of the great force applied to the large surface area defining the right hand surface of the space 94.

If desired, the valves 108 and 110 may be located remote from the cylinder.

In an alternative embodiment, the conduit 91 is vented to atmosphere. The movement of the pistons 26 and 28 outwardly is achieved by a parallel mounted hydraulic actuator 112. The cylinder 114 of the actuator 112 is secured to a member constrained to move with the piston 26 and the piston 116 of the actuator 112 is secured to a member constrained to move with the piston 28.

Accordingly when the piston 116 is urged outwardly from the cylinder 112 the pistons 26 and 28 are moved apart.

Claims

1. A drive arrangement arranged to drive a load engaging means, the arrangement including a primary drive connected to the load engaging means by a secondary drive with movement of the primary drive being arranged to power the secondary drive.

2. A drive arrangement as claimed in claim 1 in which the secondary drive is connected to two spaced load engaging means.

3. A drive arrangement as claimed in claim 2 in which a secondary drive is associated with each load engaging means.

4. A drive arrangement as claimed in a preceding claim in which the primary drive is arranged to cause movement of a first member with the secondary drive or drives being arranged to move with the first member.

5. A drive arrangement arranged to drive two spaced load engaging means, the arrangement including a primary drive arranged to cause movement of a first member and secondary drives associated with each of the spaced load engaging means, the secondary drives being arranged to move with the first member.

6. A drive arrangement as claimed in claim 5 in which the primary drive is arranged to power the secondary drives.

7. A drive arrangement as claimed in claim 5 or 6 in which the secondary drives are arranged to cause movement of the load engaging means relative to the first member.

8. A drive arrangement as claimed in any of claims 5 to 7 in which the primary drive comprises a cylinder and piston.

9. A drive arrangement as claimed in claim 8 in which the cylinder and piston are arranged to be operated hydraulically.

10. A drive arrangement as claimed in any of claims 5 to 9 in which the primary drive is located closer to one of the load engaging means than it is to the other load engaging means.

11. A drive arrangement as claimed in claim 2 or 3 or any of claims 5 to 10 in which the secondary drive or drives comprise a chain drive with the load engaging means being constrained to move with the chain.

12. A drive arrangement as claimed in claim 11 in which movement of the primary drive is arranged to cause movement of the chain.

13. A drive arrangement as claimed in any of claims 5 to 12 in which the load engaging means is arranged to move a greater distance than the primary drive.

14. A drive arrangement as claimed in claim 13 in which the load engaging means are arranged to move approximately twice the distance at the primary drive.

15. A drive arrangement as claimed in any of claims 5 to 14 in which the load engaging means are arranged to move downwardly to engage a load.

16. A drive arrangement substantially as herein described with reference to, and as shown in any of Figures 1, 2, 3 and 4 of the accompanying drawings.

17. A method of operating a drive arrangement as claimed in any of claims 1 to 16.

18. A method of operating a drive arrangement substantially as herein described, with reference to, and as shown in any of Figures 1, 2, 3 or 4 of the accompanying drawings.

19. A load engaging arrangement including a plurality of load engaging members mounted on a support arm, the support arm being moveable towards or away from a load, the inclination of each of the load engaging members being variable independently of each other.

20. An arrangement as claimed in claim 19 in which each load engaging member is moveable translationally, independently of each other.

21. An arrangement as claimed in claim 19 or 20 in which each load engaging member is moveable translationally about two transverse axes independently from each other.

22. An arrangement as claimed in any of claims 19 to 21 in which each load engaging member is arranged to engage a different article at two spaced locations.

23. An arrangement as claimed in any of claims 19 to 22 in which each load engaging member is arranged to move against a resilient force when the load engaging member engages a load.

24. As arrangement as claimed in any of claims 19 to 23 in which each load engaging member is connected to the arm by resilient means.

25. An arrangement as claimed in claim 24 in which the connection provided by the resilient means to the arm is provided at two spaced locations for each load engaging member.

26. An arrangement as claimed in any of claims 19 to 25 in which a first member is pivotally connected to the arm with each load engaging member being pivotally connected to the first member.

27. An arrangement as claimed in claim 25 in which at least one df the load engaging members is directly connected to the first member by a pivot.

28. An arrangement as claimed in claim 26 or 27 in which at least one load engaging member is pivotally connected to a second member which second member is pivotally connected to the first member.

29. An arrangement as claimed in claim 28 in which two load engaging members are pivotally connected to the second member which second member is pivotally connected to the first member.

30. An arrangement as claimed in claim 28 or 29 in which two load engaging members are pivotally connected to the second member at locations spaced from each other.

31. An arrangement as claimed in any of claims 28, 29 or 30 in which the second member is pivotally connected to the first member at a location spaced from the pivotal connection of the first member to the arm.

32. A load engaging arrangement substantially as herein described with reference to, and as shown in any of the accompanying drawings.

33. A method of engaging a load with a plurality of load engaging members comprising moving a support arm carrying the members towards the load with each load engaging member engaging load and being able to have their inclinations altered separately from each other, if necessary, in order that the load is engaged at two locations by each load engaging member.

34. A method as claimed in claim 33 comprising each load engaging member engaging the load at two spaced locations.

35. A method as claimed in claim 33 or 34 comprising each load engaging member engaging a different article.

36. A method as claimed in any of claims 33 to 35 comprising each load engaging member being able to move translationally, if necessary, in order to engage a load.

37. A method as claimed in claim 36 in which each load engaging member is able to move translationally about two transverse axes in order to engage a load.

38. A method of engaging a load with a plurality of load engaging members substantially as herein described with reference to, and as shown in the accompanying drawings.

39. A method of engaging a load as claimed in any of claims 33 to 38 when using a load engaging arrangement as claimed in any of claims 19 to 32.

40. A fluid operated cylinder including a working region defined in part by a first portion facing a first direction, the first portion being constrained to move with a first piston, and the working region being defined in part by a second portion facing the first direction, the second portion being constrained to move with a second piston, the areas of the first portion and the second portion being proportional to the relative degrees of movement of the first and second portions, the first piston being arranged to move at the same time as the second piston in a different direction.

41. A cylinder as claimed in claim 40 in which the areas of the first and second portions are substantially equal.

42. A cylinder as claimed in claim 40 or 41 in which the first portion is arranged to move adjacent to the second portion.

43. A cylinder as claimed in claim 42 in which the first portion is arranged to pass the second portion during part of the movement of the pistons.

44. A cylinder as claimed in claim 42 or 43 in which the first portion surrounds the second portion.

45. A cylinder as claimed in any of claims 40 to 44 including an inlet valve connected to the working region arranged to emit fluid into the working region.

46. A cylinder as claimed in any of claims 40 to 45 including an outlet valve connected to the working region arranged to release fluid from the working region.

47. A cylinder as claimed in any of claims 40 to 46 including a first power chamber in which fluid may be pressurised in order to power the first piston in the first direction.

48. A cylinder as claimed in claim 47 in which, when fluid is pressurised in the first power chamber, fluid is capable of being introduced into the working chamber.

49. A cylinder as claimed in any of claims 40 to 48 including a second power chamber in which fluid is arranged to be pressurised in order to power the second piston in a second direction, different from the first direction.

50. A cylinder as claimed in claim 49 in which, when fluid is pressurised in the second power chamber, fluid is capable of leaving the working chamber.

51. A cylinder as claimed in any of claims 47 to 50 in which at least one of the power chambers is provided at a region spaced from the working chamber.

52. A cylinder as claimed in claim 51 in which the or each power chamber is provided by a remote cylinder and piston.

53. A cylinder as claimed in claim 52 in which the remote cylinder and piston are constrained to move with the first and second pistons.

54. A cylinder arrangement as claimed in any of claims 40 to 53 in which the cylinder is arranged to be connected to an intermediate arm, and the first and second pistons are arranged to be connected to first and second arms respectively which first and second arms are moveable simultaneously towards or away from the intermediate arm.

55. A fluid operative cylinder arrangement substantially as herein described with reference to, and as shown in any of Figures 3, 4 and 9 of the accompanying drawings.

56. A double acting fluid operating cylinder as claimed in any of claims 40 to 55.

57. A method of operating a double acting fluid operated cylinder arrangement substantially as herein described with reference to, and as shown in any of Figures 3, 4 and 9 of the accompanying drawings.