The present invention provides a linear motion clamping unit capable of reliably holding the casing unit at an arbitrary position on the track rail with a small force. In this linear motion clamping unit, when the actuators are deenergized, the rollers arranged in the openings of the retainers are pushed by the spring force through the retainers to engage with the lock portions formed between the inclined surfaces of the wedge members and the side wall surfaces of the track rail. The resulting wedge action locks the casing unit on the track rail in one axial direction. When the actuators are energized, the rollers are released from the lock portions by the action of the retainers, thus unlocking the casing unit.

Apparatus for vertically regulating the dispensing height of stretchable wrapping material for stretch wrapping a load which comprises carriage means for varying the height of the carriage means between predetermined upper and lower positions, and safety means to prevent the fall of the carriage means to the lower position in the event of a failure of the height varying means. Also, a methods for preventing the accidental downward movement or falling of the carriage means in the event of a failure of the height regulating means which comprises providing safety means to grasp the frame means of a stretch wrapping apparatus when the height varying means breaks or fails.

A precise movement device of the type for guiding a movable member with hydrostatic pressure or a magnetic field and moving the movable member substantially without a friction. The device includes a mechanism for supporting the movable member by the use of hydrostatic pressure or a magnetic field and for guiding the movement of the movable member, and includes a mechanism for generating a resistance against the movement of the movable member when the movable member is to be stopped, such that the movable member can be stopped at a desired position accurately and in a reduced time.

A safety gear (1) comprising a frame provided with a braking surface, which, when the safety gear is braking, is pressed against a first guide surface of a guide rail. Mounted in the frame is a roller (3), which moves along a track in the safety gear. The track comprises at least a first gradient and a second gradient, the first gradient having a larger pitch angle than the second gradient. The roller is pressed against a second guide surface of the guide rail when the safety gear is braking. The roller (3) has a stronger grip on the track on the first gradient than on the second gradient.

A sliding safety gear designed to brake by gripping an elevator or counterweight guide rail includes a flexible frame surrounding the guide rail in the directions of the guiding surfaces of the guide rail. The frame is provided with a braking surface that meets a first guide surface of the guide rail when the sliding safety gear is braking. Attached to the frame is a force element that meets a second guide surface when the sliding safety gear is braking. The cross-section of the frame of the safety gear is substantially in the shape of the letter C. At least one of the ends of the jams of the C-shape is inside the C-shape.