Our engine dyno's and Power Take Off (PTO) dyno's are essentially computer-controlled AC motors coupled to the shaft of the engine or PTO. In the case of PTO dyno's, there may be a belt between a pulley on the motor shaft and a pulley on the PTO shaft, depending on the final speed and torque required by the system.
These machines vary widely in the kinds of computerized features included, depending on the needs of the customer.
Speed and power also vary widely. For example, the smallest (5 hp) such dynamometer Real Time has made so far was for R&D testing of chainsaw engines. The largest (450 hp) was for testing car engines. Test speeds vary from 540 rpm in many of the PTO dyno's to more than 12,000 rpm in some of the engine dyno's.
As an example, the following specifications apply to a 25 hp engine dyno supplied to a customer in New York:
The PTO dynamometers may be optimized to operate at a single speed (e.g., 540, 2,000 or 2,200 rpm), or dual speeds. In the latter case, the two shaft ends of the AC motor are belted differently to serve as power absorbers for the desired PTO speeds.