Hydraulic pumps circulate or transfer hydraulic fluids to tools and machinery, operating lifts, presses, cutters, pavers, and conveyors. Air-operated hydraulic pump units connect to an air compressor and require less operational effort than manual-operated pumps. Electric-operated pump units use DC batteries or connect to an outlet. Manual-operated pump units use hand or foot power, are lighter than other units, and can be used in hazardous locations or remote locations with limited access to other power sources. Hydraulic gear pumps produce constant, smooth flow rates at high pressures. Hydraulic vane pumps have a constant flow rate in various pressure conditions and create minimal pulsation during operation for a smooth flow rate. Hydraulic piston pumps handle high volumes of hydraulic fluid at high system pressures. Hydraulic PTO (power take-off) pumps couple to and are driven by a vehicle's motor.