Abstract: A hydraulic lifting apparatus includes a main hydraulic cylinder and main hydraulic circuit operatively connected to the main hydraulic cylinder. First and second spaced apart follower hydraulic cylinders are also provided. A hydraulic lifting system includes first and second lift towers. Each lift tower includes a main hydraulic cylinder, a main hydraulic circuit, and at least one follower hydraulic cylinder. A follower hydraulic circuit is operatively connected to the at least one follower hydraulic cylinder. A lifting beam spans between the first and second lift towers. The main hydraulic cylinder of each tower is positioned along the beam axis.

Abstract: A hydraulic lifting apparatus includes a main hydraulic cylinder and main hydraulic circuit operatively connected to the main hydraulic cylinder. First and second spaced apart follower hydraulic cylinders are also provided. A hydraulic lifting system includes first and second lift towers. Each lift tower includes a main hydraulic cylinder, a main hydraulic circuit, and at least one follower hydraulic cylinder. A follower hydraulic circuit is operatively connected to the at least one follower hydraulic cylinder. A lifting beam spans between the first and second lift towers. The main hydraulic cylinder of each tower is positioned along the beam axis.

Abstract: A hydraulically operated wedge lock system provides a releasable mechanical lock between telescoping boom segments. Each wedge lock mechanism includes a stationary backing wedge block that defines an angled smooth surface. A stationary shaft and piston is supported generally parallel to the backing wedge block. A slidable wedge block biased by a spring to a locked position is supported for reciprocal movement on the shaft along the angled smooth surface. Hydraulic fluid urges the slidable wedge block against the bias of the spring to an unlocked position.

Abstract: A hydraulically operated wedge lock system is disclosed to provide a releasable mechanical lock between relatively movable telescoping boom segments. Each wedge lock mechanism includes a backing wedge block connected to a relatively stationary boom segment It defines an angled smooth surface. A stationary shaft is supported generally parallel to the angled surface of the backing wedge block with a stationary piston secured to the shaft at an end. A slidable wedge block is supported for reciprocal movement on the angled surface. It includes a bore having a closed end defining a receptacle between the end and the stationary piston; and, a compression spring is disposed in the receptacle biased to urge the closed end of the bore away from the stationary piston. The end of the bore is closed with a gland to define a chamber with the piston. A port is provided to supply hydraulic fluid to urge the slidable wedge block against the bias of the spring.