The engine will maintain an RPM appropriate for the throttle signal being sent. The governor will maintain the last output signal attained with these switches. Engine speed is controlled by the INCrease and DECrease switches and the display will indicate â€œINCREASEâ€ or â€œDECREASEâ€ as appropriate when these switches are depressed. RPM MODE - When the unit is in RPM mode, the display will read â€œTHROTTLEâ€ and the green RPM LED will be illuminated. If the pump is engaged and the OK to Pump LED is illuminated, PRESSURE will be the first mode selected otherwise Throttle will be the first mode. POWER ON - When the unit is first powered up, the display will show and the engine will remain at idle until the mode switch is pressed to select the desired operating mode, PRESSURE or RPM. Your explanation is almost word for word to what we were told and shown. We just had our delivery class last Saturday on our new engine. I believe Class 1's website (Hale IDEX) has a video clip showing how their electronic governor works. When drafting, you need to start in PSI mode until water is established, because if you start in PSI mode, the safety feature in the governor will sense no water pressure and return the engine to idle. You should always operate in PSI mode on a fireground with handlines deployed. This allows the pump pressure to remain at the set pressure when lines are opened/shut during operations. PSI mode uses a pressure transducer on the discharge side of the pump to tell the electronics how much RPM is needed to maintain a set pump pressure, using the cruise control segment of the engine's ECU. Not what you want selected for safety reasons when pumping handlines. If you are in pump, it will increase/decrease your discharge pressure, but will not compensate for lines being opened/closed. In a nutshell: RPM mode is an electronic throttle only, which regulates the engine speed.

Pierce fire commander