Pumps for supplying liquid to hydraulic motors or other hydraulic devices and including constant displacement pumps, variable displacement pumps, and pumping units each unit comprising two or more pumps combined into a single unit; hydraulic motors including reciprocating motors, constant displacement rotary motors and variable displacement rotary motors; hydraulic transmissions each comprising one or more pumps and one or more hydraulic motors combined into a single unit; valves incorporated in pumps, pumping units, rotary motors and hydraulic transmissions for controlling flow of liquid therein; controls incorporated in variable displacement pumps, motors and hydraulic transmissions for varying the displacements thereof; hydraulic intensifiers