The water brake is the circular aluminum object in the foreground. Bolted to the near side of the water brake is the torque arm. The end of the torque arm can be seen at the right side of the stand holding the brake. The brake is mounted on bearings and tries to turn with the engine during a test causing the torque arm to rise. There is a "torque cylinder" (a special oil filled hydraulic cylinder) on the right side that connects the torque arm to the water brake mount. The pushing up on the torque cylinder forces the oil into the big guage seen on the control console. Torque can be read off this guage. Also on the oil line from the torque cylinder is a pressure transducer which sends the pressure signal to the data acquisition computer. There is a pulse generator in the middle of the picture. It is driven off the water brake rotor and provides the RPM signal. The test engine is connected to the water brake with a driveshaft.