Which device is mounted on the oil pump shaft for speed measurement?

Which device is mounted on the oil pump shaft for speed measurement?

• A. Tach generator
• B. EGT sensor
• C. Fuel flow meter
• D. Altimeter

Answer: (A)

The device that measures speed by converting rotational motion into an electrical signal is the tach generator. It’s mounted on the engine’s accessory drive, commonly on or driven by the oil pump shaft, so as the engine RPM changes, the generator produces pulses proportional to that speed. Those pulses feed the tachometer and often the engine control systems, giving a real-time RPM reading and enabling proper timing and control. Other options aren’t used for measuring engine speed: an exhaust gas temperature sensor tracks heat from the exhaust, not rotation; a fuel flow meter measures how much fuel is flowing, not how fast the engine is turning; and an altimeter measures altitude using air pressure.

The device that measures speed by converting rotational motion into an electrical signal is the tach generator. It’s mounted on the engine’s accessory drive, commonly on or driven by the oil pump shaft, so as the engine RPM changes, the generator produces pulses proportional to that speed. Those pulses feed the tachometer and often the engine control systems, giving a real-time RPM reading and enabling proper timing and control.

Other options aren’t used for measuring engine speed: an exhaust gas temperature sensor tracks heat from the exhaust, not rotation; a fuel flow meter measures how much fuel is flowing, not how fast the engine is turning; and an altimeter measures altitude using air pressure.