GB1236530A - Locking device - Google Patents

Abstract

1,236,530. Locking rotary elements in any position; positive detents; fluid-pressure control. OFFICE NATIONAL D'ETUDES ET DE RECHERCHES AEROSPATIALES. 4 Sept., 1969 [11 Sept., 1968], No. 43812/69. Headings F2E and F2F. A device for locking in any position a rotatable or displaceable member having an irregular surface extending in the direction of movement of the member comprises an abutment means movable to and from the surface (transversely to the rotatable member's direction of movement), the abutment means being deformable in a direction parallel to its direction of movement to conform to the surface profile on engagement therewith, whilst being rigid in the direction of movement of the rotatable member. As shown, rectangular lamellae 59 are located in mutual contact in a through-opening 54 of rectangular cross-section in a sleeve 43 mounted in the annular skirt 37 of a piston 16. Each lamella has a longitudinally extending slot, and in the disengaged position of the device (not shown) the slots are mutually aligned and aligned with two corresponding slots 48, 49, in the wall of the sleeve 43. A pin 53, bridging the skirt 37, extends through all the slots. Between the inner end of the stack 71 of lamellµ 59 and the end 32 of piston 16 is located a rubber disc 39 which in the disengaged position of the device is parallel-sided (not as shown). The body (e.g. a model support in an aerodynamic wind tunnel) which is required to be locked in position is integral with a sector 11 having teeth 12, which may be the means used for orientating the body. In operation, compressed air is supplied to space 67 through port 68, forcing the lamellµ into contact with the teeth 12, or partly into the gaps between the teeth (see Fig. 8). The corresponding irregular shape of the inner end of the stack is accommodated by the rubber disc 39, Fig. 2. The irregular array of slots in the lamellµ is seen enclosing the pin 53, Fig. 2. The mutual support provided by the contact (over almost the whole face areas) of adjacent lamellµ, and the complete filling of the opening in sleeve 43 by lamellµ, together ensure that the stack is rigid in the direction of movement of sector 11, even if vibrations occur. Also the lamellµ, being relatively thin, can accommodate any position of the teeth 12. The piston skirt is prevented from rotating by a key 9, Fig. 3. When the pressure at port 68 is relieved, resilient washers 29 move the piston to the right again until ring 33 meets internal face 35. The compressed air may be dispensed with, in which case the washers 29 are located so as to apply the piston, and the piston is withdrawn by connecting port 68 to vacuum. The rubber disc 39 may be replaced by a sealed bladder filled with oil or grease, or by a plurality of springs cut out of the lamellµ or attached to them. In a modification (Fig. 9, not shown) the teeth 12 on sector 11 are replaced by rectilinear grooves or splines perpendicular to the plane of the sector.