Abstract: A clamping device for the play-free fixing of a bar has clamping jaws radly slidably mounted in the housing of the device, into an outer release position and an inner clamping position. A double-acting servo-piston is disposed about the bar and has connected to it wedge elements which extend axially between the housing and the respective jaws and which have inclined faces engaging correspondingly inclined faces of the jaws, so that axial movement of the servo-piston causes the jaws to move inward towards or outward from the clamping position. A releasable locking device may additionally be provided for locking one or more of the wedge elements and the piston to the wall of the housing when the piston is in its position corresponding to the clamping position of the jaws.

Abstract: A clamping device includes three clamping jaws guided at an angle in a hong for engaging an axially displaceable load-bearing rod. Reliable clamping is obtained without alteration of the setting position reached. This is achieved by providing a servo-piston in the housing, which piston is displaceable in both directions by servo-force and is directly connected to the clamping jaws. The frictional force between the rod and the bearing faces of the clamping jaws as well as between the guide faces of the clamping jaws and their associated guide tracks in the housing, as well as the angle of inclination of the guide tracks are such that, in operation, self-locking occurs. The clamping action of the clamping jaws may be released only by moving the servo piston.

Abstract: A safety arrester for arresting a hydraulically operated lifting ram of a hydraulic elevator comprises an arrester body within which a plurality of brake shoes are located. The brake shoes are segments of a ring around a passage through the arrester body for receiving the ram, are spring biassed into frictional engagement with the ram, and are displaceable out of engagement with the ram by hydraulic actuator means.