Patent GB-825926-A (GB)
Title: Improvements in or relating to interlock mechanism
Inventor: EASTHOPE GEOFFREY
IPC: E05B63/12
Filed: 1955-01-27
Abstract: 825,926. Door fastenings. BRITISH INSULATED CALLENDER'S CABLES Ltd. Jan. 27, 1956 [Jan. 27, 1955], No. 2543/55. Class 44 An interlock mechanism between a rotary member 1 and an axially movable member 2 in axial alignment therewith is adapted to prevent axial movement of the member 2 from a first position to a release position in which the axially movable member can be moved independently of the rotary member when the rotary member is in a first anugular position, to permit such axial movement when the member 1 is in a second angular position, to prevent movement of the member 1 from the second to the first angular position when the member 2 is in the release position and to permit such movement when the member 2 is in the first position. In the construction shown the member 2 is the bolt of a door of a cubicle or cage containing electrical apparatus and the member 1 is connected to a switch so that the door cannot be opened until the switch has been opened to cut off the supply of electricity to the apparatus and the switch cannot be closed whilst the door is open. The member 1 is connected to the switch by linkage (not shown) and when the switch is closed it is in the locking position shown in Fig. 1. Opening the switch rotates the member 1 through 45 degrees to an unlocking position. Fig. 1 also shows the member 2 in its locked position and this member is mounted on the door both for axial sliding movement and for rotation through 90 degrees. The interlocking mechanism 8 is fixed to the frame of the cubicle and consists of a cylindrical case 26 containing an inner sleeve 24 and an outer sleeve 25 mounted concentrically with the common axis of the members 1 and 2. The case 26 is fixed by a,U-shaped bracket to the frame of the cubicle. The inner sleeve 24 is mounted in the case so that while it can rotate it cannot move axially and the outer sleeve is capable of both axial and rotary movement. The member 1 is coupled to the sleeves by a pin 30 which passes diametrically through the member and which is a close fit in opposed holes 31 in the inner sleeve 24 so that the sleeve cannot move independently of the member 1. The extreme ends of the pin 30 are a close sliding fit in longitudinally extending slots 32 in the outer sleeve 25 so that the sleeve 25 is rotated when the member 1 is rotated but is free to move axially of it. A holding bolt 33 passes through the case 26 and through slots 34, 35 in both sleeves and since the slots 34 in the inner sleeve 24 only extend circumferentially this bolt prevents axial movement of the inner sleeve. The slots 35 in the outer sleeve also extend circumferentially but are each provided at one end with a longitudinally extending portion 36 which permits the sleeve to move axially when in one angular position. The member 2 is also provided with a diametrical pin 21 which engages slots in both of the sleeves. Each slot in the inner sleeve 24 has a portion 37 extending from the end face of the sleeve which is adjacent to an entry aperture 16 for the member 2, a circumferential portion 38 extending over an angle of 45 degrees and a short axially extending portion 39. Each slot in the outer sleeve has an axially extending portion 40 extending from the end of the sleeve and a circumferential portion 41 extending over an angle of 45 degrees. The interlocking mechanism operates in the following manner. When the switch is closed the member 1 is in the position shown in Fig. 1 and movement of the member 2 is prevented since the pin 21 is in the portions 39 of the slots in the inner sleeve which prevent its rotation and the holding bolt 33 is in the circumferentially extending portion of the slots 35 so that the outer sleeve cannot move axially, thus also preventing axial movement of the member 2. Opening the switch moves the member 1 through 45 degrees and through the pin 30 both sleeves rotate with the member 1 and also rotate the member 2 in view of the engagement of the pin 21 with the slot portions 39. The rotation of the outer sleeve 25 brings the slot portions 36 into alignment with the holding bolt 33 and the sleeve 25 and the member 2 can then be moved axially until the pin 21 becomes aligned with the circumferentially extending portions 38 of the slots in the inner sleeve 24. The member 2 can then be rotated through a further 45 degrees until the pin 21 becomes aligned with the axially extending slot portions 37 and 40 in the sleeves, which permit it to be withdrawn from the mechanism 8 to release the door. When the door is open the switch cannot be moved to its closed position since the holding bolt 33 is in the slot portions 36 and this prevents rotation of the sleeve 25.