Abstract: An aerial work platform apparatus includes a shiftable counterweight which shifts in response to movement of the boom in order to maintain optimum balance of the apparatus during movement of the boom and platform. The counterweight shifts towards and away from the front of the apparatus, and also in a vertical direction. Several constructions for shifting the counterweight are disclosed.

Abstract: A pump enable system includes a variable-displacement piston pump having a displacement control device. The displacement control device controls displacement of pistons in the pump based on a position thereof, and a position control system in the pump controls a position of the displacement control device based on a load on the pump. An over-ride system selectively over-rides the position control system such that the displacement control device assumes a position which reduces displacement of the pistons in the pump.

Abstract: The aerial work platform includes a support frame, wheels rotatably attached to the support frame, and an electric motor rotatably driving at least one of the wheels. A boom having a first end is pivotably mounted to the support frame, and a fluid motor raises and lowers the boom with respect to the support frame. A work platform is supported by a second end of the boom. A battery pack supplies power to the electric motor. A first support structure, for supporting an auxiliary power plant that supplements power supplied by said battery pack, removably attaches to the support frame.

Abstract: A tie rod extendable and retractable telescopic axle assembly wherein a pair of axle beams are slidably mounted in a box beam integral with a vehicle chassis. Steering linkage and associated wheel assemblies are mounted on the outer ends of the axle beams, and the inner ends of the axle beam within the box beam are telescopically mounted relative to each other which provides an increased wheel base when the axle beam are moved outwardly of the box beam. A hydraulic cylinder and piston rod assembly is mounted between the box beam and wheel assemblies so that the hydraulic cylinder and rod assembly function not only as an actuator for extending and retracting the axle beams but also as a tie rod for the wheel assemblies.

Abstract: An articulated riser system for aerial access equipment wherein a parallelogram linkage is provided by a support frame, a riser frame assembly, and a pair of substantially parallel arms pivotally connected at each end to the support frame and riser frame assembly. The parallel arms are positioned one above the other and the lower arm is provided with a multicell cross-sectional configuration larger than the tubular cross-sectional configuration of the upper arm so that heavier loads can be supported by aerial access equipment than if both parallel arms had the same cross-sectional configuration. A trough is provided in the upper surface of the lower arm so that the upper arm is nested therein when the parallelogram linkage is in its fully lowered and fully raised positions.

Abstract: A vehicular self-propelled aerial work platform wherein a lower telescopic boom assembly is connected to a riser frame assembly having an upper telescopic boom assembly also connected thereto. A work platform is connected to the outer end of the upper telescopic boom assembly. Both the lower telescopic boom assembly and the upper telescopic boom assembly can be elevated and extended to increase the reach of the aerial work platform. The lower telescopic boom assembly comprises tubular telescoping boom sections connected at opposite ends between a support on a turntable and the riser frame assembly, with a telescopic cylinder extending interior of the boom sections and connected at opposite ends between the same members providing a telescoping parallelogram boom mechanism, with hydraulic controls with interlocks for operating the boom in a predetermined sequence.

Abstract: An electrical deactivation circuit and a two piece overhead guard assembly including two separately movable bar members which extends upward and over the head of an operator located on the upper work platform of an aerial work platform. The guard bar members are connected to the frame of the upper work platform by a pair of movable support assemblies, the movement of which actuates impact detection induction type proximity switch means to interrupt electrical power applied to the electrical control circuits and stop the engine powering the aerial work platform. Each movable support assembly includes a pair of spring loaded mechanical subassemblies including a pair of clamp members between which is located an elongated coil spring whose stiffness is varied in accordance with the distance separation of the clamps. An inductive type proximity switch is located in the lower end portion of each spring to sense movement of the inner end of a respective guard bar member.

Abstract: A carrier track assembly for extensible and retractable boom machines wherein the carrier track assembly is positioned within the telescopic boom sections and has one end connected to the extension and retraction fluid cylinder in the base boom section and the opposite end connected to the inner end of the next adjacent extensible and retractable boom section, the carrier track assembly being supported by the extension and retraction fluid cylinder when the boom sections are fully extended. An elevated support member is secured to the fluid cylinder at a position between the inner end of the base boom section and the end connection of the carrier track assembly on the fluid cylinder, the carrier track assembly being reversely bent upon itself and supported by the elevated support member when the boom sections are fully retracted.

Abstract: A vehicular low profile self propelled aerial work platform assembly having a turntable positioned in a horizontal plane in close proximity to the axles of the vehicle. A parallelogram linkage is provided between a superstructure support frame carried by the turntable and a riser frame assembly to which one end of a telescopic boom assembly is pivotally connected, the aerial work platform being mounted on the outermost end of the telescopic boom assembly. A counterweight is detachably connected to the support frame and is formed with a trough aligned with a similar trough provided in the support frame, the parallelogram linkage includes a pair of tubular arms which extend through the troughs when the work platform is in the lowermost position.