This document is a technical manual for the Cummins PT FUEL SYSTEM. It describes the operating principles of the fuel system, fuel pump, pressure regulator, throttle, governor, injectors, supply lines, shut-down valve, inlet connections, drain lines, etc.
The document is a technical manual issued by the Departments of the Army and Air Force detailing the operation and maintenance of the Cummins PT Fuel System. It explains that the system operates on hydraulic principles where changing fuel pressure changes the amount of liquid delivered to injectors, utilizing components such as gear pumps, pressure regulators, governors, and shut-down valves.
The identifying letters, "PT," are an abbreviation for "pressure-time."
It is based on changing the pressure of a liquid flowing through a pipe to change the amount of liquid coming out of the open end.
The pressure regulator acts as a by-pass valve to limit the fuel pressure supplied to the injectors, with bypassed fuel flowing back to the suction side.