Abstract: A telescoping support has at its actuating head at which a roller engages a bar which emerges from the outer tube, a sleeve-like extension provided with a pawl which can engage the bar in a sleeve-locking manner under load to prevent spontaneous contraction of the support upon rupture of the roller.

Abstract: An elongatable support has a lever actuating a fork for displacing a roller out of wedging engagement between an inclined surface of a head on a tube from which a bar can telescopingly extend, and a surface of this bar. To prevent inadvertent actuation of the lever, an abutment is interposed between the lever and the tube and can be withdrawn manually against gravitational and/or spring force to allow actuation of the lever.

Abstract: An elongatable telescoping support, e.g. for use as a vehicle jack, comprises an outer prismatic tubular support and an inner prismatic tubular support telescopingly received in the outer support. A head is formed at the mouth of the outer support bar and has a guide surface inclined toward the outer support bar upon which a guide roller is shiftable. The guide roller is formed with a profiled portion adapted to grip a running surface of the inner support bar upon rotation of the guide roller to displace the inner bar out of the outer bar. According to the invention, rings at the end of the roller are received in the inclined windows which are formed in opposite walls of the prismatic head and a guide element is pivoted on this head and is urged, e.g. by a spring, in a direction tending to bias the roller inwardly and toward the outer support or bar.