PTO (Power Take-Off)

The power take-off is a gearbox-type device that connects to the truck's transmission or engine and provides a rotating shaft output to drive auxiliary equipment. On a hydrovac truck, the PTO drives one or more hydraulic pumps that in turn power the vacuum blower, water pump, boom hydraulics, and other truck-mounted systems. The PTO allows all equipment to be powered by the truck's existing engine rather than requiring a separate power source.

PTO-driven systems are the most common configuration for hydrovac trucks because they eliminate the weight, cost, and maintenance burden of an auxiliary engine. However, PTO systems require the truck engine to run at elevated RPM while the equipment is operating, which affects fuel consumption and engine longevity. Some manufacturers offer split-shaft PTO arrangements that allow the equipment to operate while the truck is driving to minimize setup time.

An alternative to PTO-driven equipment is a separate auxiliary engine dedicated to powering the hydrovac systems. This configuration allows the truck engine to be shut off while excavating, reducing fuel consumption and emissions. However, auxiliary engines add weight, cost, and another engine to maintain. The choice between PTO and auxiliary engine depends on the operator's priorities and local emission regulations.