Abstract: A locking mechanism for releasably locking a rotatable arm 3 to a generally cylindrical axle or wheel 6. The mechanism comprises a slot 7 extending around a region of the axle 6, the slot having first and second abutment surfaces spaced apart in the direction of said movement. A heel member 17, rigidly fixed to the arm 3, projects from the arm into the slot and provides third and fourth spaced apart abutment surfaces 19,27, said third abutment surface 19 being arranged to engage said first abutment surface 18 to prevent rotation of the axle 6 in a first direction. A locking wedge 21 is provided which is moveable between a first release position in which the wedge lies outside the slot 7 and a second locking position in which the wedge projects into the slot to engage said second abutment surface 10 of the slot and said fourth abutment surface 27 of the heel member 17 to prevent rotation of the axle 6 in a second direction opposite to said first direction.

Abstract: The invention relates to a lens mounting suitable for use in a high performance optical instrument. The mounting (10) comprises a body or housing, a linear guide (16; 18; 36; 46; 64) mounted on the body, a lens carriage (14; 34; 44; 62) moveable along the linear guide, and a linear drive, which may be in the form of a ball-screw drive and comprising a ball-screw (20; 80) extending substantially parallel to the linear guide and a ball-screw follower (22; 68) linked to the lens carriage such that rotation of the ball-screw moves the carriage axially along the guide. One or more elements of the ball-screw drive are mounted relative to the linear guide to permit a degree of relative movement therebetween to accomodate misalignment between the linear guide and ball-screw.

Abstract: A locking arrangement suitable for use in precision optical instruments comprising first and second mountings (56, 58) defining respective opposing first and second concave surfaces (60, 62) and a member (64) for location between the mountings and defining oppositely directed convex surfaces (66, 68) for engaging a respective concave surfaces. A clamping arrangement (72, 74) is provided and has an adjustment configuration in which the member (64) is rotatable about an axis passing through the engaging surfaces and a locking configuration in which, with the first mounting (56) fixed in position and the second mounting (58) fixed against movement along the axis, the surfaces are held in locking engagement.

Abstract: The invention is concerned with a weapon aiming system for use in a fire control system such as those used in a military tank. The aiming system includes a linkage which connects a mirror with an angularly movable weapon (a gun). Upon angular movement of the gun its movement is transferred through the linkage to the mirror. The ratio of angular movement imparted between the weapon and the mirror is 2:1. Two exemplary embodiments are described and in each the linkage includes two parallelogram linkage sets each set comprising a connecting link joining two parallel arms. The system also includes a slider crank positioned in the system to form a first side of a variable triangle of links in the system. The second side of the variable triangle is formed by one parallel arm of one of the parallelogram linkage sets and the third side is formed by at least part of the connecting link.

Abstract: A zoom lens cam mechanism has two cam follower bearings mounted on a common shaft and arranged so that they engage against and roll on opposite sides of a cam groove or slot so as to reduce backlash.