Abstract: A crane including a telescoping boom has a base boom member and an inner member slidably mounted in the base boom member with a first end projecting from the base boom member. The inner member includes first and second connector elements. A boom extension has a first end including first and second attachment elements. The boom extension also includes first and second spaced bracket assemblies and is shiftable between use and storage positions. A first support associated with the base boom member includes a holder for pivotably retaining the first bracket assembly and a second support has a rail projecting from the base section. A slider is slidably supported by the rail, and an actuator connected between the slider and the boom shifts the slider between a retracted position and an extended position relative to the base boom member. A method of deploying a boom extension is also disclosed.

Abstract: An electro-hydraulic operating system for an extensible boom includes one or more hydraulic cylinders for imparting relative motion between the boom sections to retract the boom according to an electronically stored program of sequences of movement and speeds. A source of pressurized hydraulic fluid is fed through appropriate control valves which include solenoid valves in fluid communication with a source of pressurized hydraulic fluid. The solenoid control valves are supplied with control currents proportional to the desired flow rates of fluid to the hydraulic cylinders in order to achieve speed and position control according to the stored program. A metering valve structure is provided for operation in conjunction with the solenoid control valves.

Abstract: The metering valve includes a housing assembly defining a metering cavity therein. At least one inlet port supplies fluid to be metered to the cavity, and at least one output port outputs metered fluid from the cavity. A valve seat in the cavity is disposed between the input and output ports, a pilot chamber and a pilot port to the pilot chamber. A control element in the pilot chamber is displaceable in proportion to the pressure of pilot fluid input to the pilot port. A valve spool is mounted for reciprocating movement in the metering cavity, and the spool is coupled to the control element and displaceable therewith. The spool has a metering flange for operative engagement with the valve seat in the cavity. The position of the metering flange with respect to the valve seat controls variable flow rates of fluid between the input port and output port of the valve housing assembly.

Abstract: An alignment device on a crane boom having telescopic boom sections and a side stowable boom extension swingable from a stowed position to a working position and connectable to a nose assembly on a boom section by upper and lower clevis connections on each side of the nose assembly. The alignment device includes an abutment assembly mounted on the nose assembly boom section, and another abutment assembly mounted on another boom section. The abutment assemblies engage each other during relative retracting movement of the boom sections and forcibly engage the end of the boom extension to align the apertures of the clevis connection and nose assembly to facilitate the insertion of the pin therein.