Abstract: An aerial lift comprising a frame, an articulated boom including a first and second boom portions, a workman support structure mounted on the upper end of the second boom portion for pivotal movement relative thereto about a generally horizontal axis, and a mechanism for leveling the workman support structure throughout the range of movement of the first and second boom portions, the leveling mechanism including first and second sections of elongate material extending through the boom portions, a hydraulic assembly connected to the second section and including a hydraulic cylinder, a piston dividing the cylinder into first and second chambers, and a piston rod having one end fixedly connected to the piston, and a hydraulic accumulator communicating with one of the chambers.

Abstract: An aerial lift including an improved structure for supporting the bucket or platform and compensating for changing forces on the bucket support structure as the bucket rotates from a side hung position to a forward position. The compensating structure provides for leveling of the bucket when the bucket rotates from the side hung position to the forward position and such that the bucket will be maintained level in both the side hung position and the forward position.

Abstract: An aerial lift having means for sensing a combination of the load placed on the upper end of the upper boom and the relative position of the upper boom with respect to horizontal and for generating a signal or interrupting supply of hydraulic fluid to the upper boom lift cylinder in the event the moment on the upper boom exceeds a selected moment.

Abstract: An aerial lift includes a bucket mounted at the outer end of an articulated boom assembly having upper and lower booms. A hydraulic cylinder is provided for extending the upper boom relative to the lower boom, and a rotary actuator is provided for varying the rotational position of the bucket relative to the upper boom. An auxiliary cylinder, actuated in response to actuation of the upper boom hydraulic cylinder, provides hydraulic fluid to the rotary actuator so as to maintain the bucket in a substantially level position as the articulated boom assembly is raised and lowered. The load train including a chain and sector-shaped sprocket automatically compensate upper boom angle for changes in the angle of the lower boom relative to horizontal so that the rotary actuator is actuated only in response to actual changes in the angular position of the upper boom relative to horizontal.

Abstract: A hydraulically operated aerial lift with an improved bucket position control device supported by the bucket. Control valves for controlling operation of the aerial lift hydraulics are mounted on the stationary frame of the lift and the bucket position control device supported by the bucket is operably connected to the control valves by an optic fiber.

Abstract: Apparatus for controlling operation of an aerial lift having a boom. A hydraulic fluid pump is connected to a hydraulic cylinder, and the control arrangement controls the supply of hydraulic fluid from the hydraulic fluid pump to the cylinder and controls the supply of hydraulic fluid pressure to a first pilot fluid port and to a second pilot fluid port of a pilot operated control valve to control operation of the pilot operated control valve. A first hydrulic fluid conduit operably connects the hydraulic fluid pump to a first pilot fluid port, and a second hydraulic fluid conduit operably connects the hydraulic fluid pump to a second pilot fluid port of said control valve. A control handle selectively vents hydraulic fluid from the first fluid conduit and the second fluid conduit to control fluid pressure at the pilot ports.

Abstract: Apparatus for use in supporting a plurality of override control handles of a control valve assembly, the control handles supported for movement in a first direction between engagement and disengagement with the control valve spools and supported for movement in a second direction to cause controlled movement of the valve spools. The apparatus includes a plate having slots housing the control handles and the plate being supported for slideable movement such that movement of one control handle between a valve spool engaging position and a disengaged position causes movement of the other control handles between an engaged position and a disengaged position.

Abstract: A hydraulic control valve including an override control lever and an improved construction for selectively connecting the control lever to the valve spool. The control lever is selectively connected to the valve spool such that, during normal operation of the control valve, the control handle is disconnected from the valve spool, and the valve spool is freely movable and without frictional resistance of the control handle. The control lever can be moved into engagement with the valve spool such that movement of the control lever causes a consequent movement of the valve spool.