Abstract: A device for lifting and positioning building materials at different heights and angles. For example, positioning a sheet of drywall or plywood to be fastened to a ceiling or wall, or subsequently a container of materials such as drywall joint compound for finishing the fastened sheets. The lifting and positioning device comprises a platform assembly upon which to place material to be lifted and positioned. The platform assembly can be pivoted and fixed at any desired angle between horizontal and vertical (0 to 90 degrees) by an indexing arrangement. The platform assembly is pivotally connected to lift arm links. The lift arm links are pivotally connected to a lift arm assembly. The lift arm assembly is pivotally connected to a mast support assembly. The lift arm links, lift arm assembly and mast support assembly form a parallelogram. The platform assembly is raised and lowered by a floor jack placed upon a jack support platform.

Abstract: A pivot joint having an elastomeric sealing member between a pivot pin and a surrounding structure, including means for preventing the sealing member from extruding between the pivot pin and surrounding structure when lubricant is inserted into the joint under pressure.

Abstract: A combined brake and steering system for a vehicle having hydraulic braking and hydraulic steering. A single pump is utilized to supply both the brakes and steering. Two priority valves are arranged to assure that the brakes take precedence and receive an approximately constant flow of hydraulic fluid subject to a maximum pressure. The steering mechanism also normally receives a constant flow, subject to a maximum pressure which usually is different from the other maximum pressure.