GB2381279A

GB2381279A - Telescopic prop

Info

Publication number: GB2381279A
Application number: GB0220446A
Authority: GB
Inventors: M Ebrahim
Original assignee: EAZYPROP Ltd
Current assignee: EAZYPROP Ltd
Priority date: 2001-09-03
Filing date: 2002-09-03
Publication date: 2003-04-30
Anticipated expiration: 2022-09-03
Also published as: GB0121328D0; GB0220446D0; GB2381279B

Abstract

A telescopic prop includes two sliding members where one of the members has a series of grooves on its outer surface which interact with circular pins (4) carried on the inner surface of a locking collar (5). In use, to extend or retract the prop, face plate (7) is pushed down which displaces laterally the circular pins (4) thereby disengaging the two members (fig 5). When pressure on the top plate (7) is released, springs (16) force the top plate (7) upwards and consequently the circular pins (4) engage the grooves on the inner member, the action being facilitated by a sloping inner profile (9) on the collar (5). A level indicator (13) may be present on the collar (5) and the pins (4) may incorporate load cells to display the load being applied to the prop.

Description

Telescopic Assembly The present invention relates to a telescopic assembly and particularly, although not exclusively, to a support prop for use in the construction industry.

A variety of existing telescopic support props are known. Such props are typically used to provide temporary support for a structure during construction or repair thereof.

It is an object of the present invention to provide an alternative telescopic assembly, which may be used in a support prop, and which improves over existing designs.

According to the present invention there is provided a telescopic assembly comprising an inner member movably telescopically received into an outer member, the inner member having a surface with a plurality of spaced apart grooves formed therein and the outer member including a releasable locking means operative to lock the inner member relative to the outer member, the locking means comprising at least one elongate shear pin and operative to engage a lateral edge of the shear pin with a groove formed in the inner member thereby to lock the inner member relative to the outer member, and to permit the shear pin to be displaced from the inner member thereby to unlock the inner member relative to the outer member.

The locking means provides for quick and easy locking and release of the inner and outer members and hence adjustment of the telescopic assembly.

The plurality of grooves preferably each extend around the perimeter of the inner member in a direction perpendicular to that of relative movement between inner and outer members. The grooves preferably extend continuously around the inner

member. The inner member may be circular, square, rectangular or any other convenient shape in cross section.

The locking means preferably comprises a first set of grooves into which the or each shear pin is received when it is engaged with a groove formed in the inner member, thus locking the locking means and inner member together. The locking means preferably further comprises a second set of grooves into which the or each shear pin is received when displaced from the inner member. At least one surface of each of the second set of grooves is preferably arranged so that when the assembly is oriented in an upright configuration, with the inner member extending above the outer member, the or each shear pin is urged towards the inner member by the influence of gravity. As such, in normal use, the locking means will automatically adopt the locked position.

The locking means preferably comprises means for urging the or each shear pin out of engagement with the inner member, thereby to unlock the inner member relative to the outer member. Such means is preferably movable between an operative and nonoperative position and is preferably resiliently biased towards the non-operative position by suitable resilient means, such as a spring.

The locking means is preferably supported on the outer member by means of a screw thread, enabling the position of the locking means relative to the outer member to be adjusted by rotating the locking member relative to the outer member. Thus, when the or each pin of the locking means has engaged with a chosen groove in the inner member fine adjustment of the relative position of the inner and outer members may be achieved using the screw thread.

The locking means may include a skirt arranged to reduce ingress of debris, construction elements and the like, between the locking means and outer member which might otherwise foul the screw thread.

The telescopic assembly is preferably comprised in a support prop.

In order that the invention may be more clearly understood embodiments thereof will now be described by way of example with reference to the accompanying drawings of which: Figure 1 shows a telescopic prop according to the invention supported on a surface; Figure 2 shows a similar view to Figure 1 with the inner telescopic member shown extended further than in Figure 1; Figure 3 shows an enlarged view, partially in cross section and showing hidden detail, of the locking arrangement of the prop of Figure 1; Figure 4 shows a cross-sectional view of the arrangement shown in Figure 3 taken along the line IV-IV of Figure 3; and Figure 5 shows a view similar to Figure 3, but with the locking arrangement in a released state.

Referring to the drawings a prop comprises an inner elongate tubular or solid member 1 telescopically received into an outer elongate tubular member 2. Each member 1,2 is substantially circular in cross-section, although other cross-sectional shapes are possible such as square or rectangular. The inner member 1 has a number of generally evenly spaced apart circumferential grooves 3 along its length. The grooves are substantially semicircular in profile. At the free end of each member 1,2 there is mounted a foot la, 2a.

The inside surface of the opposite end of the outer member 2 is threaded and a releasable locking member 5 comprising an outer turnbuckle collar 6 and an externally threaded inner collar 6a is screwed into the threaded end of the outer member 2. The screw thread allows the position of the locking member 5 relative to the lower member to be altered. A cylindrical skirt 12 depends from the collar 6. The free end of the skirt 20 is directed inwardly and/or may include a seal to reduce ingress of debris between the skirt 12 and lower member 20.

The locking member 5 is operative to releasably lock the inner member 1 relative to the outer member 2 in order to prevent relative movement thereof. The base of the locking member is formed by the threaded turnbuckle collar 6. Extending from the upper surface of the collar 6 are two pairs of integral formations 19. Each formation defines a radially extending generally parallel sided slot. Each pair of formations 19 supports a shear pin 4, opposite ends of which extend into the slots defined by the respective formations 19. The pins 4 are arranged substantially parallel to each other and may move in the slots in which they are supported radially relative to the collar 6.

The base of the locking member also supports two fixed guide pins 17, each protruding in opposite directions on opposite sides of the base.

The locking member further comprises a top portion 7 which is slidably mounted on the base portion. The top portion comprises an annular collar from which depend two opposed plates 8 the free ends of which are tapered, and two opposed grooved members 15. The grooved members 8 each include a groove 9 which is open towards the inside of the locking member, that is to say facing the inner member 1. The upper surface of each groove 9 extends substantially at right angles to the surface of the

member 15 in which it is formed and the lower surface 10 of each groove 9 extends away from the upper surface towards the open part of the groove.

A longitudinal elongate slot 18 is formed in each plate 8 and receives the end of one of the protruding pins 17 of the base of the locking member. The pin 17 and 8a slot arrangement captures the upper portion onto the base of the locking member and allows the upper portion to move longitudinally relative to the base.

Coil springs 16 are disposed between the upper and base portions of the locking member operative to resiliently urge the two apart.

A level indicator 13 is disposed on the top portion of the locking member. This facilitates alignment of the prop when in use.

A bearer plate 11 is fastened to the end of the inner member 1 which is received into the outer member 2. The bearer plate 11 fits closely into the outer member 2 restricting relative lateral movement of the inner 1 and outer 2 members and, because the diameter of the bearer plate exceeds that of the inner collar 6a of the locking member, preventing withdrawal of the inner member 1 from the outer member.

Figure 3 shows the inner member 1 locked relative to the outer member. The shear pins 4 are received into a groove 3 on the inner member and retained in this position by the surfaces of the two grooved members 15. The shear pins 4 are also received into the grooves defined by the formations 19 on the base of the locking member.

Thus relative movement of the inner 1 and outer 2 members is prevented.

To unlock the two members 1,2 the upper and lower portions of the locking member are urged together against the force of the coil springs 16. This has the effect of moving the plates 8 and grooved members 15 downward (in the illustrated configuration) relative to the shear pins 4. As the plates 8 are tapered they drive the

pips apart into the grooves 9, out of the groove 3 in the first member 1 and at least partially out of the grooves defined by the formations 19 on the base of the locking member, thus enabling the inner 1 and outer 2 members to be moved relative to each other.

When it is desired to lock the two members 1,2 relative to one another again the two portions of the locking member are released whereupon they are urged apart by the coil springs 16. When the prop is arranged in an upright manner as shown the shear pins 4 will now roll or slide along the base surface 10 of grooves 9 under the influence of gravity towards the inner member 1. If the inner member 1 is moved into the outer member 2 the shear pins 4 will then fall into a groove 3 in the inner member and be carried into the position shown in Figure 3, thus locking the inner 1 and outer 2 members together again.

Fine adjustment of the relative position of the inner 1 and outer 2 members can then be achieved by means of the screw thread by relative rotation of the locking member and outer member 2.

In the illustrated embodiment the shear pins 4 are straight. In an alternative embodiment a central portion of the shear pins is curved so that they better conform to the shape of the inner member.

As previously mentioned, however, the inner and outer members 1,2 may be of any convenient shape. It is preferable that the shear pins conform to this shape to maximise contact between the pins and the inner member 1 when in a locked state.

The prop is preferably constructed from metal, especially steel or aluminium.

The prop may include one or more load cells or other measuring devices in order to measure the load being borne by the prop. A load cell or other measuring device is preferably located in the shear pins 4.

The prop may be used on its own as a support or may be incorporated into other apparatus for example cantilever loading platforms, and mobile access and working platforms.

The above embodiments are described by way of example only. Many variations are possible without departing from the invention.

Claims

Claims 1. A telescopic assembly comprising an inner member movably telescopically received into an outer member, the inner member having a surface with a plurality of spaced apart grooves formed therein and the outer member including a releasable locking means operative to lock the inner member relative to the outer member, the locking means comprising at least one elongate shear pin and operative to engage a lateral edge of the shear pin with a groove formed in the inner member thereby to lock the inner member relative to the outer member, and to permit the shear pin to be displaced from the inner member thereby to unlock the inner member relative to the outer member.
2. A telescopic assembly as claimed in claim 1 wherein the plurality of grooves each extend around the perimeter of the inner member in a direction perpendicular to that of relative movement between the inner and outer members.
3. A telescopic assembly as claimed in any preceding claim wherein the locking means comprises a first set of grooves into which the or each shear pin is received when it is engaged with a groove formed in the inner member,
4. A telescopic assembly as claimed in claim 3 wherein the locking means comprises a second set of grooves into which the or each shear pin is received when displaced from the inner member.
5. A telescopic assembly as claimed in claim 4 wherein at least one surface of each of the second set of grooves is arranged so that when the assembly is oriented in an upright configuration the or each shear pin is urged towards the inner member by the influence of gravity.

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6. A telescopic assembly as claimed in any preceding claim wherein the locking means comprises means for urging the or each shear pin out of engagement with the inner member thereby to unlock the inner member relative to the outer member.
7. A telescopic assembly as claimed in any preceding claim wherein the locking means is supported on the outer member by means of a screw thread enabling the position of the locking means relative to the outer member to be adjusted by rotating the locking means relative to the outer member.
8. A telescopic assembly as claimed in claim 7 wherein the locking means comprises a skirt to reduce ingress of debris between the locking means and outer member.
9. A telescopic assembly as claimed in any preceding claim including means for measuring load supported by the assembly.
10. A support prop comprising a telescopic assembly as claimed in any preceding claim.
11. A support prop substantially as herein described with reference to the accompanying drawings.