GB2409402A

GB2409402A - Telescopic slide

Info

Publication number: GB2409402A
Application number: GB0428050A
Authority: GB
Inventors: Norman Bunce; Robert Witcutt; Ian Stanford; Jason Brookes
Original assignee: WIDNEY UK Ltd
Current assignee: WIDNEY UK Ltd
Priority date: 2003-12-22
Filing date: 2004-12-22
Publication date: 2005-06-29
Anticipated expiration: 2024-12-22
Also published as: GB2409402B; GB0428050D0; GB0329553D0

Abstract

A telescopic slide 120 has a fixed slide member 124 adapted to be mounted to a support and a plurality of movable slide members 121, 122, 123 mounted for movement telescopically relative to the fixed slide member and to one another such that the slide may be extended and retracted by the application of a force. An interlock means 142, 143 is operative between adjacent pairs of the movable slide members to determine the order in which said moveable members extend relative to the fixed slide member and to each other during extension of the slide. The interlock means may be configured such that the movable slide members are constrained to extend in sequence starting with an outermost movable slide member 123 adjacent the fixed slide member 124 and ending with innermost slide member 121 to which the load is mounted. Various different interlock mechanisms are disclosed.

Description

24 09402 e 1 se. ee.

TELESCOPIC SLIDE APPARATUS

The present application relates to a telescopic slide apparatus.

Telescopic slides have a number of industrial applications, one use being for carrying a load such as a particular item of equipment from a stored (racked) position to an extended (open) position. For such applications the equipment is mounted on one end of the slide and the other end of the slide is mounted on a wall or other suitable support. Normally the innermost slide member is the load carrying member and the outermost slide member is the fixed slide member. A typical slide comprises a plurality of elongate slide members mounted telescopically relative to one another on ball bearings. Such slides may have any desired number of slide members but typically have between two and five slide members. The slide members are moveable from a fully retracted position wherein all slide members lie within the outermost slide member to an extended position when only an end of each slide member is retained within an adjacent slide member. When a force is applied to the slide along the axis of the slide, the individual slide members slide on their bearings relative to one another. The slide can thus be extended or retracted according to the direction of the force. The load is mounted on the innermost slide member in the telescopic arrangement, as this slide member provides the greatest possible range of movement.

When a slide is extended, the first slide member to move is the slide member with the least friction acting upon it. This is usually the innermost slide member as it has a direct connection to the extending force. The innermost slide member reaches a desired maximum extension and is then prevented from extending further by a suitable travel stop. As the innermost member can move no further, if the extending :e e: e.. :. :e ce; force is still applied, this triggers the movement of the adjacent intermediate slide member which has the next most direct connection to the force. Each intermediate slide member is thus triggered to move in turn until the full extension is achieved.

When a large piece of equipment (load) is mounted on the end of the innermost slide member, the loads acting on the ball bearings that support the slide members as they move can be very large. This can result in a phenomenon known as 'ball creep' or ball skid'. In such cases the forces on the ball bearings are so great that the friction between the ball bearing and the bearing surface causes the ball bearing to skid rather than roll. This means that greater force is required to extend the slide and the maximum extension can be restricted. If a restricted extension occurs, the ball bearings will not return to their prime position upon retraction of the slide and following repeated operation the extension of the slide will reduce with each cycle.

The applicants have found that this is a particular problem when the innermost slide member moves first during extension. In this case the bearings of each subsequently extended slide member are subjected to greater forces due to increased bending moments as the load extends. Even if this force is not on average great enough to cause ball creep or ball skid, the force on each ball bearing of a slide member is not equal. The greatest forces occur on the innermost bearing adjacent to the upper edge of the slide member and the outermost bearing adjacent to the lower edge of the slide member. The forces on these bearings may be sufficient to cause ball creep or ball skid problems to occur with much lighter loads than may be otherwise predicted.

It is thus an object of the present invention to provide an improved telescopic slide.

:e c: :. :e.e According to a first aspect of the present invention there is provided a slide comprising a fixed slide member adapted to be mounted to a support and a plurality of movable slide members mounted for movement telescopically relative to the fixed slide member and to one another such that the slide may be extended and retracted by the application of a force, said slide further comprising interlock means operative between adjacent pairs of the movable members to determine the order in which said moveable slide members extend relative to the fixed slide member and to each other during extension of the slide.

In this manner the individual movable slide members in a telescopic slide can be adapted to move in a sequence that reduces the possibility of the occurrence of ball creep or ball skid. This in turn provides a slide design particularly well suited to heavy duty or high load applications.

The interlock means may be adjustable, either during manufacture or later, to select the order in which said movable members extend relative to the fixed slide member and to each other during extension of the slide.

The slide members may be mounted one inside another, with the fixed slide member being the outermost and an innermost movable slide member being adapted to support a load, at least one intermediate movable slide member may be provided between the fixed slide member and the innermost slide member.

The interlock means may be operative such that, in use, on application of a force to the innermost slide member, each movable slide member extends relative to an outer adjacent slide member in turn, starting with the outermost intermediate movable slide member and finishing with the innermost movable slide member.

:.;: :e ë..

The interlock means may be arranged such that, in use, on application of a force to the innermost movable slide member to extend the slide, the innermost movable slide member together with the, or all the, intermediate movable slide members move relative to the fixed slide member until the outermost intermediate movable slide member reaches a maximum limit of extension, thereafter the innermost movable slide member together with the, or all, of any further intermediate slide members moves relative to the outermost intermediate movable slide member, said process repeating until all the movable slide members have reached their maximum limit of extension or until the extending force is removed.

The interlock means may comprise means adapted to couple adjacent pairs of the movable slide members when the slide is retracted so that they are constrained to move together in response to the application of a force to extend the slide.

The interlock means may comprise a resilient element mounted to one of the movable slide members and operative to couple said one of the movable slide members to an adjacent movable slide member when the slide is retracted, the arrangement being such that the resilient member can be deformed to release the coupling when a force acting to extend one of the coupled movable slide members relative to the other reaches or exceeds a pre-determined value. In this arrangement, a different predetermined force may be required to release the coupling between the various pairs of adjacent movable slide members. The relative values of the predetermined forces required to release the couplings between the various pairs of adjacent movable slide members may determine the order in which the movable slide members are extended.

:;:: em:- :e ee.

The interlock means may comprise a spring mounted to said one of the movable slide members.

In one embodiment, the spring is a leaf spring and is adapted to engage with a co- operating formation on the adjacent movable slide member to couple the slide S members together. The co-operating formation may be slot or indentation, or a projection, or a further leaf spring on the adjacent movable slide member.

In an alternative embodiment, the spring is adapted to bias a ball bearing into engagement with a surface of the adjacent movable slide member, the ball bearing co- operating with a formation on the surface when the slide is retracted to couple the movable slide members together. The formation may be a projection or an indentation or recess. The spring may biases two ball bearings into contact with respective surfaces on the adjacent movable slide member, each ball bearing co-operating with a formation on the respective surface of the adjacent movable slide member when the slide is retracted to couple the movable slide members together. The, or each, surface in the adjacent movable slide member may be a groove or slot.

The interlock means may be in the form of a catch member mounted to one of the movable slide members, the catch member having an arm with a catch formation adapted to engage with a corresponding catch formation on an adjacent movable slide member, the arm being resiliently biased so that the catch formations inter-engage when the slide is in a retracted condition to couple the adjacent movable slide members together. The arrangement may be such that, in use, the arm is moved against the resilient bias force to release the corresponding catch formation when the force acting to extend one of the coupled movable slide members relative to the other :e : ate:e :e.e reaches or exceeds a predetermined value. The catch member may be made of a plastics material such that the arm is inherently resilient.

The interlock means may comprise a latch member movably mounted to one of the movable slide members, the latch member having a latch formation adapted to engage with a corresponding formation on an adjacent movable slide member when the latch member is in a first, latching position to couple the adjacent movable slide members together when the slide is retracted, the latch member being movable from the latching position to a release position in which the corresponding formation is released from engagement with the latch formation to release the coupling. The arrangement may be such that, in use, the latch member is moved from the latching position to the released position when the movable slide member to which it is mounted reaches a desired maximum limit of extension relative to an outer adjacent slide member. The latch member may have a foot portion adapted to engage a surface of an outer adjacent slide member, said surface comprising a hole or recess into which the foot moves when the movable slide member to which the latch member is mounted reaches the desired maximum limit of extension relative to the outer adjacent slide member to cause the latch member to move from the latching position to the released position. Engagement of the foot in the hole or recess may act as a travel stop to limit extension of the movable slide member to which it is mounted relative to the outer adjacent slide member. The corresponding formation may be provided on an inner adjacent movable slide member. The corresponding formation on the adjacent movable slide member may be provided on a further latch member movable mounted to the adjacent movable slide member.

According to a second aspect of the present invention there is provided a slide :..: e.e:e :e ee.

comprising a plurality of slide members mounted telescopically relative to one another such that they may be extended and retracted, wherein the members are adapted so that when a suitable force is applied to extend the slide the members each moves in turn, starting with the outermost of the members intermediate between the outermost member and the innermost member and finishing with the innermost member.

According to a third aspect of the present invention there is provided a telescopic slide comprising a plurality of slide members mounted telescopically, said slide members being slidably moveable relative to one another such that the slide may be extended or retracted by the application of a force, and spring means, wherein said spring means are engageable with corresponding formations provided on the slide members in order that the individual slide members move relative to one another in a desired sequence when said force is applied.

In order that the invention be more clearly understood, specific embodiments are described further herein, by way of example only and with reference to the accompanying drawings in which: Figures la-c are a series of schematic diagrams showing the forces on a typical telescopic slide as it extends; Figures 2a-c are a series of schematic diagrams showing the forces on the telescopic slide of figure 1 as it extends in a desired sequence according to the present invention; Figure 3a shows a plan view of a telescopic slide according to the present :. ;:: cee. :e :. ee; invention; Figure 3b is a cross-section along line A-A in figure 3a; Figure 3c is a view in an enlarged scale of the cross- section of figure 3b; Figure 4a shows a plan view of an alternative telescopic slide according to the S present invention; Figure 4b is a cross-section along line A-A in figure 4a; Figure 4c is a view in an enlarged scale of the cross-section of figure 4b; Figure 5a shows a plan view of an alternative telescopic slide according to the present invention; Figure Sb shows a side view of the telescopic slide of figure Sa; Figure Sc shows in an enlarged scale part of the side view of the telescopic slide of figure Sb; Figure Sd is a perspective view of part of the telescopic slide of figures Sa-c; Figure Se is a cross-section of the telescopic slide of figures Sa-d; IS Figure Sf is an enlarged view of part of figure Se; Figure Sg is a plan view of a slide member of the slide according to figures Sa-f; Figure Sh is a side view of the slide member of figure Sg; Figure Si is a view of a spring means provided within the slide member of . e:: . A:::.

:. ::: figures Sa-g; Figure 6a is an exploded perspective view of a further embodiment of a slide in accordance with the invention, with insets showing certain details in an enlarged scale; S Figure 6b is a plan view of an end part of the slide of Figure 6a shown in an assembled condition; Figure 7, is a view similar to that of Figure 4c showing a further embodiment of a slide in accordance with the invention; Figure 8 is a view similar to that of Figure 3c showing a further embodiment of a slide in accordance with the invention; Figure 9 is a view similar to that of Figure 3c showing a further embodiment of a slide in accordance with the invention; Figure 10a is a plan view of a slide in accordance with a further embodiment of the invention; IS Figure lob is a cross sectional view taken on line X-X of Figure 8a; and Figures 10c and 10d are simplified schematic views similar to figure 8b illustrating operating of an interlock means of the slide of Figure 8a; Referring now to figure 1, a load 10 is mounted on the innermost movable slide member 21 of a telescopic slide 20. The telescopic slide also has a fixed outer slide member 24 and two intermediate movable slide members 22, 23 between the :e e: '.e:e :e.e innermost slide member and the fixed outer slide member. The inner slide member 21 and the intermediate slide members 22, 23 are mounted on ball bearings 31-36 (only two of which are shown in each figure for clarity). When an extending force is applied along the axis of the telescopic slide in the direction of arrow A, the slide member with the least friction upon it, in this case the inner member 21 slides on its bearings relative to the other members.

When the inner member slides, the greatest loads act on ball bearings 31 and 32.

These forces maintain the inner slide member in a level attitude. Once the inner movable slide member reaches its limit of extension, continued application of the extending force will cause the first intermediate slide member 22 to slide relative to the second intermediate slide member 23 as shown in figure 1(b). Similarly, once the first intermediate slide member 22 reaches its limit of extension relative to the second intermediate slide member 23, the second intermediate slide member is caused to slide relative to the outer fixed slide member 24 as shown in figure 1(c). It can be clearly seen from the figure 1 that the forces acting on the most loaded ball bearings 33, 34 and 35, 36 increases as each member slides due to the increased distance between the load and the respective bearings as the slide extends. This increase in the force on the ball bearings supporting the moving slide members increases the probability that ball skid or ball creep (as described above) will occur. If ball skid or creep occurs, the maximum extension of the slide 20 can be restricted and a greater force is required to fully extend the slide 20.

Figure 2 shows the telescopic slide 20 shown in figure 1 extending in a different sequence. In this case when an extending force is applied to the slide the second, outermost, intermediate slide member 23 is caused to extend relative to the fixed slide ' c:: A:::e :e;:: member whilst the first intermediate slide member 22 and the inner slide member 21 are constrained to move with the second intermediate slide member 23. Once the second intermediate slide member reaches its limit of extension, the first intermediate slide member 22 then extends relative to the second intermediate slide member and finally, the innermost movable slide member 21 extends relative to the first intermediate movable slide member 21. It can be seen that the forces on the ball bearings supporting the respective slide members as they are moving are lower than the corresponding forces shown in figure 1. It is thus less likely that ball skid or creep will occur when the movable slide members are extended in this sequence. The operation of the slide will thus be more reliable, extension will require less force and will not be restricted. Alternative, a slide extended in this sequence will be able to support a heavier load than an equivalent slide extended in the sequence shown in figure 1.

Referring now to figure 3, a telescopic slide 120 in which the sequence of movement or extension of the movable slide members may be preset is shown. The slide 120 has an inner movable slide member 121, two intermediate movable slide members 122, 123 and an outer slide member 124 which is adapted to be fixed to a support and which will be referred to as a fixed slide member. In figure 3 the slide is shown in a fully retracted position but may be extended in the manner shown in figure 2.

In this and all the embodiments described herein, the movable slide members are mounted on ball bearings to facilitate their relative movement in a manner well known in the art. However, any suitable means of mounting the movable slide members can be used.

' ::: t:. A:: i;. ..

The slide 120 has an interlock mechanism operative between adjacent pairs of the movable slide members that determines the sequence with which the slide members are extended relative to the fixed slide member and to each other. The interlock mechanism in this embodiment comprises leaf springs 142, 143 that are mounted to the first and second intermediate movable slide members 122, 123 respectively. Leaf spring 142 is mounted across a slot 132 in the first intermediate movable spring member and has a bend 142a that engages with a slot or recess 131 in the innermost movable slide member 121 when the slide is retracted, so as to couple the first intermediate slide member and the inner slide member together. The second leaf spring 143 is mounted across a slot 133 in the second intermediate movable slide member and has a bend formation 143a that engages in the slot 132 of the first intermediate slide member behind a further bend 142b in the first leaf spring 142.

This arrangement couples the first and second intermediate movable slide members together when the slide is retracted. In order that the movable slide elements extend in the sequence shown in figure 2, the interlock mechanisms are arranged such that a grater force is required to separate the inner movable slide member 121 from the first intermediate slide member 122 than is required to separate the first intermediate movable slide member 122 from the second intermediate movable slide member 123.

This can be achieved by using springs 142, 143 of different strengths, such that the spring 143 is weaker than the spring 142, and/or by varying the degree of interference between the springs 142, 143, their recess 131, 132 and each other.

When a force is applied to the inner most movable slide member 121 to extend the slide 120, the extension force is transmitted by means of the leaf spring 142, the first intermediate movable slide member 122, and the leaf spring 143 to the second t' t' e: ::: t:e::e intermediate movable slide member 123. Because the spring force of the leaf springs 142, 143 is greater than the friction between the second intermediate slide member 123 and the fixed outer slide member 124, the second intermediate movable slide member 123 is caused to move relative to the fixed slide member 124 to extend the slide. This movement continues until the second intermediate movable slide member 123 abuts a suitable travel stop (not shown) which defines a maximum permitted extension of the second intermediate movable slide member.

Because the second intermediate slide member 123 is constrained by the travel stop from further extension, continued application of the force to extend the slide 120 causes the weaker spring 143 to deform, enabling the first intermediate movable slide member to ride over the bend 143a, uncoupling the first intermediate movable slide member 122 form the second intermediate movable slide member 123. Thus the first intermediate movable slide member 122 can now extend relative to the second intermediate slide member 123.

Extension of the first intermediate movable slide member 122 continues until it contacts a travel stop (not shown) to define a maximum desired extension. Further application of the force to extend the slide 120 now results in the bend 142a of spring 142 being deformed so that the inner movable slide member 121 can ride over the bend 142a, uncoupling the inner movable slide member 121 from the first intermediate slide member 122. The inner slide member 121 is now free to extend relative to the first intermediate movable slide member 122 until it contacts a travel stop (not shown) which defines a maximum permitted extension. The slide 120 is now fully extended.

.e e.e e . . . . . . cee The slide 120 thus reaches full extension with minimum load on the ball bearings supporting the moving slide members as described in relation to figure 2.

It will be appreciated that by suitable modification of the interlock mechanism, the order in which the movable slide members extend relative to the fixed slide member and each other can be changed.

When the slide 120 is retracted, the springs 142, 143 will become reengaged in the slots 131, 132 to re-couple the moveable slide members 121, 122, 123 ready for the next extension An alternative embodiment is shown in figure 4. The slide 220 has an inner movable slide member 221, two intermediate movable slide members 222, 223 and an outer fixed slide member 224. In figure 4 the slide 220 is shown in a fully retracted position but may be extended in the manner shown in figure 2.

In this embodiment, the interlock mechanism uses only a single leaf spring 242 which is mounted across a slot 232 in the first intermediate movable slide member 222. The leaf spring has a first bend 242a which projects downwardly (as shown) through the slot 232 to engage behind a raised lip or projection 233 formed in the second intermediate movable slide member 223 to couple the first and second intermediate movable slide members together when the slide is retracted. A second bend 242b projects upwardly (as shown) and is arranged to engage in a slot 231 in the inner movable slide member 221 when the slide 120 is retracted to couple the first intermediate movable slide member and the inner movable side member together.

In order that the movable slide members extend relative to the fixed slide c c . c c eccee c c C C C C C C e cec c c C C C C a c cc 1J in member and each other in the order described above with reference to figure 2, it is arranged that a lower force is required to disengage the first bend 242a from behind the raised lip 233 on the second intermediate slide member than is required to disengage the second bend 242b from the slot 231 in the inner movable slide member.

As in relation to figure 3, when a threshold extension force is applied to the inner movable member 221 this force is transferred via the leaf spring 242 to the first and second intermediate movable slide members. Since the force required to decouple the movable slide members is greater than the friction force between the second intermediate movable slide member and the outer fixed slide member, the second intermediate slide member 233 is moved to extend relative to the outer fixed slide member 224. The movement of member 223 is halted at a maximum desired extension by a travel stop (not shown). If however the extension force is still applied, bend 242a of spring 242 deforms and is able to slide past raised lip 233 and thus member 222 is then free to slide relative to member 223. At this stage, the bend 242b is still engaged with the slot 231 in the inner movable slide member so that the inner slide member and the first intermediate movable slide member remain coupled together. As with slide member 223, the movement of slide member 222 is halted at a maximum extension by a travel stop (not shown). If the extension force continues to be applied, the bend 242b in spring 242 will deform and disengage from the slot 231 to allow the inner movable slide member 221 to extend relative to the first intermediate slide member until it is halted at a maximum extension by a further travel stop (not shown). The slide 220 can thus be extended in the desired sequence.

Referring to figure 5, a further alternative telescopic slide 320 is shown. The slide of figure 5 has an outer fixed slide member 323 an inner movable slide member cat ëa as.. ä..

ae.c a . äe ea. 321 and an intermediate movable slide member 322.

In this embodiment, the interlock mechanism includes a helical spring 341 mounted in a bore 331 provided in through the inner movable slide member 321. The spring 341 is maintained under compression and ball bearings 351 are provided at each end of the spring. The ball bearings 351 run in grooves 352 provided in the intermediate movable slide member 322. Two crosspins 361 extend through the inner movable slide member 321, one on either side of the spring 341. The pins 361 project into the grooves 352 and help to retain the ball bearings in position. The intermediate movable slide member 322 has a pair of raised lips 332 and the arrangement is such that the ball bearings engage behind the lips 332 when the slide is retracted to couple the intermediate slide member 322 to the inner movable slide member 321.

A threshold extension force applied to the inner movable slide member 321 will be transmitted via the ball bearings 351 and the raised lips 332 to the intermediate movable slide member 322. Because the force required to compress the spring 341 is greater than the friction force between the intermediate movable slide member and the outer fixed slide member, the extension force will cause the intermediate slide member to extend relative to the outer fixed slide member 323 up to a maximum extension determined by a travel stop (not shown). If a further extension force is applied to the inner movable slide member 321, the spring 341 will be compressed allowing the ball bearings 351 to slip past the lips 332 and the inner movable slide member 321 is then free to extend relative to the intermediate movable slide member 322.

It will be appreciated that instead of having raised lips 332, the intermediate ee e. c ec e . . . . . . . . . . ea. e movable slide member 322 may be provided with recess or holes into which the ball bearings 351 locate when the slide is retracted.

Figures 6a and 6b illustrate a modification to the previous embodiment adapted for use with a slide having four or more slide members. The slide 420 in this embodiment has an outer fixed slide member 424, an inner movable slide member 421 and first and second intermediate slide members422, 423 respectively.

An interlock mechanism operative between the inner movable slide member 421 and the first intermediate movable slide member 422 is identical to that described above with reference to the previous embodiment. Thus the interlock mechanism comprises a compression spring 441 located in a through bore in the inner movable member and which biases ball bearings 451 into contact with grooves 452 on the intermediate movable slide member. The ball bearings 451 are arranged to engage behind raised lips 432 on the intermediate movable slide member to couple the intermediate movable slide member 422 and the inner movable slide member 421 together when the slide is retracted.

A similar interlock mechanism is operative between the first intermediate slide member 422 and the second intermediate movable slide member 423. This interlock mechanism is essentially the same as that between the inner movable slide member and the first intermediate movable slide member except that the compression spring 441a is located in a housing component 462 mounted to the first intermediate movable slide member 422.

The housing 462, which may be manufactured from a plastics material, is mounted to the first intermediate component 422 by means of a crosspin 463. An . he ce C ... . . . . . . . inverted U shaped recess or bore 464 extends through a main body portion 465 of the housing and is open along one side which faces a base portion 466 of the second intermediate movable slide member 423 when the slide is assembled. The spring 441a is located in the recess or bore 464 and a ball bearing 45 la is provided at either end of the spring. No crosspins are required to retain the ball bearings 451a, as a significant portion of the ball bearings remains within the recess 464 of the housing. The ball bearings 451a run in grooves 452a in the second intermediate movable slide member and are arranged to engage behind raised lips 432a on the second intermediate slide member 423 when the slide 420 is retracted.

The interlock mechanism between the first and second intermediate movable slide members 422, 423 operates in the same way as the interlock mechanism between the first intermediate movable slide member 422 and the inner movable slide member 421. To ensure that the slide extends in the sequence discussed above in relation to figure 2, the force required to separate the inner movable slide member 421 from the first intermediate slide member 422 is greater than that required to separate the first intermediate slide member 422 from the second intermediate slide member 423. This can be achieved by the use of different strength springs 441, 441a and/or by varying the relative interference between the ball bearings 451, 451a and the raised lips 432, 432a with which they engage. Thus, the spring 441a may be weaker than the spring 441 and/or the interference between the ball bearings 451a and the raised lips 432a on the second intermediate movable slide member may be less than that between the ball bearings 451 and the raised lips 432 on the first intermediate slide member.

Whilst in this embodiment the ball bearings 451, 451a are described as engaging behind raised lips 432, 432a on the adjacent movable slide member, it will be 8 e ..

e ee e. a e e e e ë e 8. e e e . 8 ace appreciated that other forms of protrusion may be used rather than raised lips. Indeed, the ball bearings may be arranged to engage with any suitable formation, such as a

recess for example.

The number of intermediate movable slide members can be increased as desired by using additional interlock mechanisms similar to those described between each adjacent pair of movable slide members.

It will be appreciated, that a housing similar to housing 462 could be used to provide the interlock mechanism between the inner movable slide member 421 and the first intermediate slide member 422. Similarly, it will be appreciated that the depending on the design of the first intermediate slide member 422, the interlock mechanism between the first intermediate movable slide member 422 and the second intermediate slide member 423 could be provided by locating the spring 451a in a through bore provided in the first intermediate movable slide member 422 rather than in a housing 462.

Figure 7 shows a further embodiment of a slide 520 which is similar to the slide 220 described above in relation to figure 4. The only difference between the slide 520 and the slide 220 lies in the way in which the single leaf spring 542 is mounted to the first intermediate movable slide member 522. As can be seen in figure 7, the spring 542 in slide 520 extends across two slots 532a, 532b formed in the base of the first intermediate slide member 522 and is riveted to a portion of the base between the two slot portions. The slide 520 is otherwise constructed and operates in manner essentially the same as for the slide 220 as described above. The advantage of the leaf spring 542 arrangement in the present embodiment is that it is easier to set the order in . . . ...

. e ee e e e he e. e e ce. .. e which the adjacent pairs of movable slide members 521, 522 and 522, 523 are decoupled from each other as the bends 542a, 542b in the leaf spring 542 are isolated from each other.

Figure 8 shows a further embodiment of a slide 620 in accordance with the invention. The slide 620 has an outer fixed slide member 624, an inner movable slide member 621, a first intermediate movable slide member 622 adjacent to the inner movable slide member and a second intermediate movable slide member 623 adjacent to the first intermediate movable slide member 622.

The slide 620 is shown in a retracted position in which the inner movable slide member and the first and second intermediate movable slide members 621, 622, 623 are coupled together by an interlock mechanism. The interlock mechanism in this embodiment comprises a catch member 666 fixedly mounted to the first intermediate movable slide member 622 by means of a pin 667. The catch member 666 has a first arm 668 which projects forwardly towards an end portion of the inner movable slide member 621. The first arm 668 has an expanded head portion 668a and defines a recess 668b between the head portion and a main body of the catch member. A corresponding catch formation 669 is mounted to the end portion of the inner movable slide member. The catch formation 669 is generally L shaped having a relatively thin upright portion 669a and a somewhat thicker horizontal (as shown) portion 669b. As shown in figure 8, when the slide 620 is retracted, the horizontal portion 669b of the catch formation is received in the recess 668b behind the head 668a of the first arm 668. This arrangement couples the first intermediate slide member 622 to the adjacent inner slide member 621.

. . ë e * . .. e , Be, The catch member 666 also has a second arm 670 similar to the first arm 668 but which projects backwardly towards an end portion of the second intermediate movable slide member 623. The second arm 670 has an expanded head portion 670a and defines a recess 670b between the head portion 670a and the main body of the catch member 666. A corresponding catch formation 671 is attached to the end portion of the second intermediate movable slide member 623 and which is received in the recess 670b when the slide is retracted, coupling the second intermediate slide member 623 to the adjacent first intermediate slide member 622. The catch formation 671 attached to the second intermediate movable slide member 623 is in the form of a lU round pin.

The first and second arms 668, 670 are resiliently biased to the positions shown in figure 8 but can be moved in a downward direction against the bias force to release their respective corresponding catch formations 669, 671 to decouple the movable slide members from each other. Recesses 632, 633 are provided in the first and second intermediate movable slide members respectively to accommodate the downward movement of the arms. In order that the movable slide members 621, 622, 623 extend in the order discussed in relation to figure 2 above, the force required to deflect the first arm 668 to decouple the inner movable slide member 621 from the first intermediate movable slide member 622 is greater than that required to deflect the second arm 670 to decouple the second intermediate slide member 623 from the first intermediate movable slide member 622. This can be achieved in a number of ways.

For example, the first arm 668 is thicker than the second arm 670 and so requires more force to be deflected downwardly. Furthermore, the catch formation 671 on the second intermediate movable slide member is round and so can pass over the head * * * * c 1 * * ce. e C * * * * 670a on the second arm more easily than the square sided formation 669b on the inner slide member can pass over the head 668a on the first arm.

The catch member 666 can be made of any suitable material but is preferable manufactured from a plastics material, the properties of the material providing the required resilience of the first and second arms 668, 670.

When an extension force is applied to the inner movable slide member 621, this force is transmitted via the interlock mechanism to the first and second intermediate movable slide members 622, 623. The force required to decouple the movable slide members is greater than the friction force between the second intermediate movable slide member 623 and the outer fixed slide member 623 and so the second intermediate slide member 623, together with the first intermediate slide member 622 and the inner movable slide member 621, extends relative to the outer fixed slide member 624 until its extension is halted by a travel stop (not shown). Continued application of the extension force will cause the second arm 670 of the catch member 666 to deflect downwardly so that the head 670a of the second arm passes under the catch formation 671 on the second intermediate movable slide member 623. This uncouples the first intermediate movable slide member 622 from the second intermediate movable slide member 623 so that the first intermediate movable slide member 621 can extend relative to the second intermediate slide member 623. At this stage, the first intermediate movable slide member 622 is still coupled to the inner movable slide member 621 by the first arm 668 of the catch member 666.

Extension of the first intermediate movable slide member 622 continues until it abuts a travel stop (not shown). Further application of the extension force to the inner : 't: e: . : r ce e movable slide member 621, will cause the first arm 668 to be deflected downwardly (as shown) so that the catch formation 669b on the inner movable slide member is able to slide over the head 668a of the first arm 668 to decouple the inner movable slide member 621 from the first intermediate movable slide member. The inner movable slide member is now free to extend relative to the first intermediate slide member 622.

When the slide 620 is retracted to the position shown in figure 8, the catch formations 669, 671 will reengage in the recesses 668b, 670b to once again couple the adjacent pairs of movable slide members. The heads 668a, 670a of the first and second arms have angled faces 668c, 670c to assist the catch formations 669, 671 in deflecting the first and second arms to make reengagement easier.

Figure 9 shows a further embodiment of a slide 720 in accordance with the invention, The slide 720 is similar to the previous slide 620 described above in relation to figure 8 and has a similar interlock mechanism. However, in this embodiment, rather than having a single catch member with two arms, separate catch members 766a, 766b are attached to each of the intermediate movable slide members 722, 723. Thus a first catch member 766a is attached to the first intermediate movable slide member 722 and has a single arm 768 projecting forwardly towards an end portion of the inner movable slide member 721. The arm 768 has a head 768a and defines a recess 768b between the head and the main body of the first catch member.

A catch formation 769 is mounted to the end portion of the inner movable slide member 721 and is received in the recess 768b to couple the first intermediate movable slide member 722 to the inner movable slide member 721.

. . . . . eve .. A second catch member 766b in mounted to the second intermediate movable slide member and also has a single arm 770 which extends forwardly towards an end portion of the first intermediate movable slide member 722. The arm 770 has a head portion 770a and defines a recess 770b between the head and the main body of the catch member 766b. A corresponding catch formation 771 is provided on the end portion of the first intermediate movable slide member 722 which is received in the recess 770b when the slide is retracted to couple the first and second intermediate movable slide members together. The corresponding catch formation 771 in this embodiment comprises a lug or projection provided on the first catch member 766a mounted to the first intermediate movable slide member 722.

The catch members 766a, 766b operate in a manner similar to the catch member 666 in the previously described embodiment, with the arms 768, 771 being deflected downwardly to decouple movable slide members during extension of the slide 720. So that the movable slide members extend in the sequence described above in relation to figure 2, the force required to decouple the first and second intermediate movable members 722, 723 is lower than that required to decouple the inner movable slide member 721 from the first intermediate movable member 722.

In all the previously described embodiments, the interlock mechanism for coupling adjacent pairs of the movable slide members has incorporated a resilient element which provides a bias force to maintain the coupling between the slide members. In these embodiments, the order in which the movable slide members extend is dependent at least partly on the relative bias force of the resilient elements coupling the various pairs of adjacent movable slide members. An alternative arrangement is shown in Figures lea to lOc which illustrate a slide 820 in which the c . a . a se . interlock mechanism is provided by means of latch members that are moved to couple and decouple adjacent pairs of the movable slide members.

Slide 820 has an outer fixed slide member 824, and inner movable slide member 821, and first and second intermediate movable slide members 822, 823 between the inner and outer slide members.

A first latch member 872 is pivotably mounted to an end portion of the first intermediate movable slide member about a pivot pin 873. The latch member has an elongate body portion 874 which projects forwardly towards an end portion of the inner movable slide member 821. A recess 875 is formed in an upper surface of the elongate body portion and is adapted to receive a corresponding formation 876 mounted to, and projecting downwardly from, the end portion of the inner movable slide member. At the forward end of the elongate body portion, a foot 877 projects downwardly for sliding contact with a surface 878 on the second intermediate movable slide member 823. When the foot 877 is in contact with the surface 878 as shown in Figure lea, the latch member is held in a latching position in which the formation 876 mounted to the inner movable slide member 821 is retained in the recess 875 so that the inner movable slide member 821 and the first intermediate slide member 822 are coupled together for simultaneous movement.

A second latch member 879 identical to the first latch member 872 is pivotably mounted to an end portion of the second intermediate movable slide member 823 about a pivot pin 880. The second latch member also has an elongate body portion 881which projects forwardly towards an end portion of the first intermediate movable slide member 822. A recess 881a is formed in an upper surface of the elongate body . 4e 1 . . . portion and is adapted to receive a corresponding formation 882 mounted to and projecting downwardly from the end portion of the first intermediate movable slide member 822. In this case, the corresponding formation 882 is proved by a second foot projecting downwardly from a lower surface of the first latch member 872 at a rearward end thereof. The second latch member has a foot 883 which projects downwardly at the forward end of its elongate body portion for sliding contact with a surface 884 on the outer fixed slide member 824. When the foot 883 is in contact with the surface 884, as shown in Figure lea, the second latch member is held in a latching position in which the formation 882 on the first latch member 872 is retained in the recess 881so that the first and second intermediate movable slide members 822, 823 are coupled together for simultaneous movement.

With the slide 820 in a retracted condition as shown in figure lea, the two latch members are both in a latched position and all the movable slide members 821, 822, 823 are coupled together. If a threshold extension force is applied to the inner movable slide member 821, the second intermediate slide member 823 is caused to extend relative to the outer fixed slide member 824. As the second intermediate slide member 823 approaches its maximum permitted extension, the foot 883 on the second latch member 879, which has been sliding along the surface 884 on the outer fixed slide member 824, enters a hole or recess formed in the surface 884. This causes the second latch member 879 to pivot about the pin in the direction of arrow A in figure lOc, releasing the formation 882 on the first latch member 872 from the recess 881a and so decoupling the first intermediate movable slide member 822 from the second intermediate slide member 823. The first intermediate slide member 822 is now free to extend relative to the second intermediate slide member.

1 A. C e c bee eel

J

Continued application of the extending force extends the first intermediate movable slide member until it reaches its maximum permitted extension at which time the foot 877 on the first latch member 872 enters a hole or recess in the surface 878 of the second intermediate movable slide member 823 along which the foot has been sliding. This causes the first latch member 872 to pivot about the pin 873 in the direction of arrow C in figure led to release the formation 876 attached to the inner movable slide member 821 from the recess 875 in the first latch member and so decoupling the inner movable slide member 821 from the first intermediate slide member 822. The inner movable slide member 821 is now free to extend relative to the first intermediate movable slide member 822 in the direction of arrow B in figure led.

Additional travel stops may be provided to limit extension of the first and second intermediate movable slide member 822, 823 or the engagement of the feet 877, 883 on the latch members with the holes or recess in the surfaces on which they run may act as the travel stops.

The slide 820 is designed so that the latch member feet are automatically disengaged from their respective holes or recess when a force is applied to retract the slide 820. As shown in figure led, when the inner slide member 812 returns in the direction of arrow D, the formation 876 will come into contact with a face 885 on the latch member 872. The angle of the face 885 is such that when the latch member 872 is sitting in the recess, contact with the returning inner slide member 821 will flip the latch member 827 up out of the recess, thus leaving the first intermediate movable slide member 822 free to return to the closed position. The latch member 881a on the second intermediate movable slide member 823 will be similarly disengaged from its te. 8 488 1 8 eC 48 8 8 8 8 8 8 8 8 8 8 C e e e 08e C e recess by contact with the first intermediate slide member 822 as the slide is retracted.

It will be appreciated that other means of moving the latch members from a latched to a released position could be used. For example, a raised cam surface may be provided to move the feet to disengage the latch members rather than a hole or recess.

In each of the above embodiments more or less slide members may be provided if desired, provided suitable modification of the interlock arrangements is made.

Additionally, the interlock arrangements may be varied if it is desired to extend a slide in a different sequence. Furthermore the precise design of the interlock mechanism including the shape of the springs, slots and lips etc may be varied if desired to achieve a particular extension sequence or to accommodate more or less slide members.

The invention is particularly suited to heavy-duty applications in which the slide may be subjected to forces in excess of 500N It is of course to be understood that the invention is not to be restricted to the details of the above embodiments which are described by way of example only.

Claims

.e eee ë ce .. CLAIMS

1. A slide comprising a fixed slide member adapted to be mounted to a support and a plurality of movable slide members mounted for movement telescopically relative to the fixed slide member and to one another such that the slide may be extended and retracted by the application of a force, said slide further comprising interlock means operative between adjacent pairs of the movable slide members to determine the order in which said moveable members extend relative to the fixed slide member and to each other during extension of the slide.

2. A slide as claimed in claim 1, in which the interlock means can be adjusted to select the order in which said movable members extend relative to the fixed slide member and to each other during extension of the slide.

3. A slide as claimed in claim 1 or claim 2, in which the slide members are mounted one inside another, with the fixed slide member being the outermost and an innermost movable slide member being adapted to support a load, at least one intermediate movable slide member being provided between the fixed slide member and the innermost slide member.

4. A slide as claimed in claim 3, in which the interlock means is operative such that, in use, on application of a force to the innermost slide member, each movable slide member extends relative to an outer adjacent slide member in turn, starting with the outermost intermediate movable slide member and finishing with the innermost movable slide member.

5. A slide as claimed in claim 3 or claim 4, in which the interlock means is arranged such that, in use, on application of a force to the innermost c . . . movable slide member to extend the slide, the innermost movable slide member together with the, or all the, intermediate movable slide members moves relative to the fixed slide member until the outermost intermediate movable slide member reaches a maximum limit of extension, thereafter the innermost movable slide member together with the, or all, of any further intermediate slide members move relative to the outermost intermediate movable slide member, said process repeating until all the movable slide members have reached their maximum limit of extension or until the extending force is removed.

6. A slide as claimed in any previous claim, in which the interlock means comprises means adapted to couple adjacent pairs of the movable slide members when the slide is retracted so that they are constrained to move together in response to the application of a force to extend the slide.

7. A slide as claimed in claim 6, in which the interlock means comprises a resilient element mounted to one of the movable slide members and operative to couple said one of the movable slide members to an adjacent movable slide member when the slide is retracted, the arrangement being such that the resilient member can be deformed to release the coupling when a force acting to extend one of the coupled movable slide members relative to the other reaches or exceeds a pre-determined value.

8. A slide as claimed in claim 7, in which a different predetermined force is required to release the coupling between the various pairs of adjacent movable slide members.

9. A slide as claimed in claim 8, in which the relative values of the predetermined forces required to release the couplings between the various e: e. . e: :: :e ... e t

pairs of adjacent movable slide members determines the order in which the movable slide members are extended.

10. A slide as claimed in any one of claims 7 to 9, in which the interlock means comprises a spring mounted to said one of the movable slide members.

A slide as claimed in claim 10, in which the spring is a leaf spring and is adapted to engage with a co-operating formation on the adjacent movable slide member to couple the slide members together.

12. A slide as claimed in claim 11, in which the co-operating formation comprises a slot or indentation provided in the adjacent movable slide member.

13. A slide as claimed in claim 11, in which the co-operating formation comprises a projection provided on the adjacent movable slide member.

14. A slide as claimed in claim 11, in which the co-operating formation comprises a further leaf spring mounted to the adjacent movable slide member.

15. A slide as claimed in claim 10, in which the spring is adapted to bias a ball bearing into engagement with a surface or groove of the adjacent movable slide member, the ball bearing co-operating with a formation on the surface or groove when the slide is retracted to couple the movable slide members together.

16. A slide as claimed in claim 15, in which the formation comprises a projection on the surface or groove adjacent movable slide member.

17. A slide as claimed in claim 15, in which the formation comprises an indentation or recess in the surface or groove.

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18. A slide as claimed in any one of claims 15 to 17, in which the spring biases two ball bearings into contact with respective surfaces or grooves on the adjacent movable slide member, each ball bearing co-operating with a formation on the respective surface of the adjacent movable slide member when the slide is retracted to couple the movable slide members together.

19. A slide as claimed in any one of claims 7 to 9, in which the interlock means comprises a catch member mounted to one of the movable slide members, the catch member having an arm with a catch formation adapted to engage with a corresponding catch formation on an adjacent movable slide member, the arm being resiliently biased so that the catch formations inter-engage when the slide is in a retracted condition to couple the adjacent movable slide members together.

20. A slide as claimed in claim 19, in which interlock means is arranged such that, in use, the arm is moved against the resilient bias force to release the corresponding catch formation when the force acting to extend one of the coupled movable slide members relative to the other reaches or exceeds a predetermined value.

21. A slide as claimed in claim 19 or claim 20, in which the catch member is made of a plastics material and the arm is inherently resilient.

22. A slide as claimed in claim 6, in which the interlock means comprises a latch member movably mounted to one of the movable slide members, the latch member having a latch formation adapted to engage with a corresponding formation on an adjacent movable slide member when the latch member is in a first, latching position to couple the adjacent movable äce see c ce ce e e ee e c ee cee e e e ec ee e e acee ee- e slide members together when the slide is retracted, the latch member being movable from the latching position to a release position in which the corresponding formation is released from engagement with the latch formation to release the coupling.

23. A slide as claimed in claim 21, adapted such that, in use, the latch member is moved from the latching position to the released position when the movable slide member to which it is mounted reaches a maximum desired extension relative to an outer adjacent slide member.

24. A slide member as claimed in claim 22 or claim 23, in which the latch member comprises a foot portion adapted to engage a surface of an outer adjacent slide member, said surface comprising a hole or recess into which the foot moves when the movable slide member to which the latch member is mounted reaches a maximum desired extension relative to the outer adjacent slide member to cause the latch member to move from the latching position to the released position.

25. A slide as claimed in claim 24, in which the corresponding formation is provided on an inner adjacent movable slide member.

26. A slide as claimed in any one of claims 22 to 25, in which the corresponding formation on the adjacent movable slide member is provided on a further latch member movable mounted to the adjacent movable slide member.

27. A slide as claimed in any previous claim adapted for heavy duty use.

28. A slide as hereinbefore described with reference to and as illustrated in the accompanying drawings.