The engine running time measurement is commonly referred to as the

• A. Hour meter
• B. Engine running time meter
• C. Tachometer
• D. Fuel gauge

Answer: (B)

Measuring how long an engine has been running is about tracking elapsed operating time to plan maintenance. The device that does this is called an hour meter, which records total hours of engine operation (often with tenths of an hour). Some references may use the term engine running time meter, but in practice the standard label you’ll see is hour meter. This is because maintenance schedules are based on how long the engine has run, not on how fast it’s turning or how much fuel remains. A tachometer measures engine speed in RPM, not running time, and a fuel gauge shows how much fuel is left. So the concept being tested is the hour meter, the tool used to track elapsed engine running time for maintenance purposes.