Patent GB-903561-A (GB)
Title: Improvements in or relating to adjustable legs
IPC: F16B7/14
Filed: 1960-03-15
Abstract: 903,561. Clamp fastenings. MARTIN THOMAS Ltd., and NICHOLLS, J. W. Aug. 26, 1960 [March 15, 1960], No. 9094/60. Class 44. An adjustable leg comprises a leg member 3 formed on its exterior surface with ratchet means disposed along its length, a tubular member 1 surrounding the leg member, a sleeve 4, located around the leg member and within the tubular member, a split collet 5 on the sleeve member radially deformable so as to be engageable with the ratchet means, a clamping means 2 on the tubular member, the collet having an exterior surface engageable by an interior surface of the clamping means arranged so that the downward load on the clamping means urges the collet to grip the ratchet means, a first detent means 11 for holding the sleeve in an upper position in relation to the tubular member, in which position the collet is locked on the ratchet means, the first detent means being releasable to permit release of the collet from the clamping means, and a second detent means 8 for holding the sleeve member against withdrawal from the tubular member but releasable to permit such withdrawal. As shown, the clamping means 2 is welded to the lower end of the member 1 and is of internal frusto-conical shape. The leg member 3 has a screw-thread which forms the ratchet means and the collet is formed with an internal screw-thread for engaging the threads of the member 3. The outer surface of the collet is of frusto-conical shape to be engaged by the internal surface of the clamping-ring 2 to clamp the collet to the member 3. Welded to the sleeve 4 is a further sleeve 6 which is of sufficient diameter just to slide inside the member 1 and this sleeve is provided with an axially-extending open-ended slot 10. The sleeve 4 is formed with the detent means 11 which is pressed out to extend through the slot 10 in the sleeve 6. The member 1 is formed with an axially-extending slot 7, the lower end of which is provided with the detent means 8 which is bent outwardly. A collar 9 surrounds the member 1 between the detent means 8 and 11 and it has an inwardly-projecting stop-block 12 which projects through the slot 7 and the slot 10 so that it can be engaged by the end of the detent means 11. The detent means 8 normally engages a lip 15 formed on the collar 9. To adjust the position of the leg member 3 the detent means 8 is pressed in so that it is clear of the lip 15 and the member 3 and sleeve 4 can then be pulled downwardly until the detent means 8 is engaged by the lower surface of the block 12; this movement is sufficient to disengage the collet 5 from the clamping-ring 2 and the member 3 can then be moved relative to the collet. After adjustment the load on the leg causes the clamping-ring 2 to engage the collet 5 and press it into contact with the inner member 3. If it is desired to remove the member 3 and sleeve 4, from the member 1 the second detent means 8 is pressed in so that it clears the block 12. Attached to the clamping ring 2 is a socket 17 for attachment thereto of a crossbar 18 forming part of a staging. The cross-bar 18 carries a pin 19 for engaging holes in the inner and outer members to locate these members when the sleeve 4 is removed and the leg is to be non-adjustable. The pin 19 is slidably mounted in a housing 20 attached to the cross-bar 18 and is engaged and disengaged by means of a knob 21. In a modification instead of the member 3 and collet being threaded they are formed with rings or other ratchet means.