Abstract: A proportionally extendable multi section boom crane is provided with an automatically erectable mast pivotally carried by one of the boom sections. The mast, which has a secondary sheave on the outer end thereof, normally rests in a stowed position adjacent the boom section on which it is mounted. The load line of the crane extending from the winch at the base of the boom section is trained over the secondary sheave, as well as sheave structure on the outermost end of the outer boom section. Elongated rod structure carried by one of the extendable boom sections outwardly of the crane has coupling means thereon engageable with the mast to initiate erection thereof after the proportionally movable boom sections have been extended a predetermined extent, normally after about 50% extension thereof.

Abstract: A mobile vehicle is provided with a multiple purpose material handling and working apparatus including a boom, and a tool supporting boom extension supported on the free distal end of the boom for rotation about an axis parallel to the longitudinal axis of the boom. The boom extension includes a body, a linkage structure movable between unpivoted and pivoted positions relative to the body, a coupling, and a linkage drive assembly mounted on and movable with the body for driving the linkage structure between unpivoted and pivoted positions. A rotary drive motor is supported on the boom for rotating the boom extension relative to the boom.

Abstract: A playground unit having a rotatable horizontally disposed deck adapted to support at least one passenger is provided with a control means operatively connected to the deck to limit the rotational speed thereof. The control means is a hydraulic governor comprising a fluid reservoir, a pump, and a valve with interconnecting fluid lines and check valves providing appropriate directional flow of fluid between the reservoir, pump and valve. The valve automatically moves between an open and closed position depending upon the rotational speed of the unit. The force required to maintain the rotational speed of the playground unit is much greater when the valve is closed as compared to when the valve is open.

Abstract: A playground unit having a rotatable horizontally disposed deck adapted to support at least one passenger is provided with a control device operatively connected to the deck to limit the rotational speed thereof. The control device is a hydraulic governor comprising a fluid reservoir, a pump, and a valve with interconnecting fluid lines and check valves providing appropriate directional flow of fluid between the reservoir, pump and valve. The valve automatically moves between an open and closed position depending upon the rotational speed of the unit. The force required to maintain the rotational speed of the playground unit is much greater when the valve is closed as compared to when the valve is open.