Patent GB-1263120-A (GB)
Title: Shaft locking combination
IPC: F16B1/02
Filed: 1969-11-17
Abstract: 1,263,120. Clamps. LOURDES INDUSTRIES Inc. 17 Nov., 1969 [18 Nov., 1968; 12 May, 1969], No. 56151/69. Headings E2A and E2B. A shaft locking combination comprises a shaft 14 slidable through a housing to selected adjusted positions with respect to said housing and releasable locking means adapted to hold the shaft in each adjusted position against an applied axial load, comprising, a fixed abutment 24 within the housing, a plurality of collets 27, 27' bearing against the shaft, each collet having at least one bevelled outer surface, at least one compression ring 28, 28', having a bevelled inner surface complementary to and bearing against the bevelled outer surface of an adjacent collet, resilient drive means 21 biased to urge said collets and ring toward said abutment and into shaft-locking position, the collet nearest said drive means engaging tightly with the shaft and transmitting additional locking force from the shaft to an adjacent collet said locking force representing the sum of the forces developed and transmitted by the arrangement of the components of said locking means, and unlocking means 23 adapted to be actuated to counteract the bias of said drive means. In the construction shown of the collets has two bevelled surfaces and there are two compression rings, the compression ring 28' also has a second bevelled surface which is in engagement with the second bevelled surface of the first collet 27, the second bevelled surface of the second collet 27' is in engagement with a bevelled surface of the abutment 24, thus under the urge of the resilient drive means 21, the collet 27 is urged into clamping engagement with the shaft both by the compression ring 28 and the compression ring 28' and the collet 27' is urged into clamping engagement with the shaft both by the clamping ring 28' and the abutment 24. The unlocking means 23 is a piston which is moved to the left as shown, to counteract the bias of the means 21 by fluid which enters the housing through a port 37. The disposition of the collets, compression rings and resilient means 21 shown, act to prevent movement of the shaft to the right since any movement to the right of the shaft causes an increase in the clamping pressure. On the opposite side of the abutment 24 is a similar arrangement of collets, clamping rings resilient means and unlocking means acting in the opposite direction and released when fluid pressure is applied through the port 37. The shaft is connected to a piston and the piston is moved by fluid pressure applied either through a port 35 for movement to the right or through a port 34 for movement to the left. In a modification each collet only has a single bevelled surface and each compression ring similarly only has a single bevelled surface, each compression ring however bears on the side surface of the next collet and there is an additional collet which is engaged with the bevel of the abutment 24; this arrangement is repeated on the opposite side of the abutment. A construction is also described in which the shaft is clamped against movement in one direction only, the collets and compression rings being on one side only of the abutment; in this construction the compression rings and collets are divided into two groups each substantially contained in a cup shaped spacer one of the spacers also acting as the unlocking means; the arrangement is such that when a desired clamping pressure is being exerted by the collects on the shaft the end of the spacer adjacent the abutment engages the abutment to prevent further pressure and the second spacer engages the first; the abutment in this construction has a radial surface instead of a bevelled surface.