A chuck is composed of a collet sleeve, a sliding member, at least one linkage member, a collet, and a driving member. The collet sleeve includes an axial hole running therethrough and at least one opening in communication with the axial hole. The sliding member is slidably received in the axial hole of the collet sleeve. The linkage member is inserted through the opening of the collet sleeve and connected to the sliding member. The collet is inserted into the axial hole of the collet sleeve and connected to the sliding member. The driving member drives the linkage member and the sliding member to move for drawing in and pushing out the collet with respect to the collet sleeve.

Locking mechanism for the adjusting mechanism of a 4-jaw work holding rotary chuck of the kind having oppositely disposed pairs of jaws normally adjusted in position with equal and opposite movement but having provision for differential adjustment of one of each pair of oppositely disposed jaws relative to the other, the locking mechanism being constituted by a spring loaded driving member drivably connected to the adjusting mechanism and by a fixed element which the spring loaded driving member is capable of engaging non-rotatably, a turning moment applied to said spring loaded driving member in either direction being effective first to displace the latter from engagement with said fixed element and then to rotate the adjusting mechanism.

A router includes a tool holder which has a spindle with a bore to receive a router tool bit. A sleeve surrounds the spindle. A locking mechanism retains the router bit in the bore. The locking mechanism includes at least one rolling member in contact with the sleeve and which extends into the bore. The rolling member locks the router bit in the tool holder. A biasing member retains the sleeve in a locked position. The locking mechanism includes an activation member remotely positioned from the sleeve for moving the sleeve between the locked and unlocked position.

An annular collet (10) is externally fitted to a support rod (4) inserted into a housing (2), and an annular transmission member (14) is arranged around the collet (10) with an annular tapered clearance (C) interposed therebetween. A large number of balls (B) inserted into the annular tapered clearance (C) are pushed up by a pushing spring (17). When pressurized oil is supplied to a hydraulic actuation chamber (25), a clamping piston 24 moves the transmission member (14) downward, so that a tapered internal peripheral surface (15) of the transmission member (14) gets engaged with a tapered external peripheral surface (11) of the collet (10) while rolling the balls (B). Thereby, the collet (10) is diametrically contracted.

An electric motor device for powering a tool clamp, for example a resistance welding clamp, of the type comprising a casing of an electric motor 4 the shaft of which is connected to the clamp, to control the electrodes for opening, closing and clamping them onto a metal sheet, by a system of the through-the-motor type which converts the rotary motion of the shaft into translational motion of a mechanism 5 operating the clamp, this motor being linked to a control variator and a slaving device 10 coupled to the rotor of the motor. The device 10 being arranged at the end of the motor shaft, the shaft is fitted with a gear wheel 14 which can be operated from the outside, for rotating it manually, through at least one opening 15 in the casing offset with respect to the motor shaft.