Abstract: A hydraulic drive system utilizes four hydraulic motors arranged in mechanically coupled pairs with one motor from each pair always series hydraulically connected to one motor from the other pair. The other motors are selectively coupled parallel with each other or in series with the series connected motors. The combination of mechanical and hydraulic coupling provides an efficient drive system designed specifically for, but not limited to, the motor grader apparatus. The improved drive system herein disclosed provides both high speed-low power and low speed-high power operational modes and is capable of continuous operation in either mode. The improved drive system also provides superior control characteristics due to the hydraulic motor series lockup arrangement. The combination of mechanical and hydraulic coupling provides high power with good control or high speed with little heating of the hydraulic fluid.

Abstract: Disclosed herein is an improved pumping system for self-contained and, if desirable, portable machines adapted to efficiently spray or squeegee viscous sealing fluids on roadway pavement and parking lots, which fluids may contain suspended solid matter. For example, this fluid pumping assembly is especially suitable for spraying asphaltic or coal-tar-pitch emulsions containing sand onto asphalt road surfaces. Also disclosed is an improved hydraulic drive cylinder assembly and control means therefor employing an improved electrically controlled hydraulically operated drive network.