The Model 1921 Tachometer Tester is used for the testing and calibration of electrical and mechanical tachometer generators and indicators. Two variable-speed brushless motors eliminate the need for gears while providing for a testing range of 10 to 50,000 RPM. Each motor/shaft is controlled by closed-loop system utilizing hall/encoder feedback and a digital motion control card. The result is a very reliable system with a speed accuracy of 0.005%. The control panel consists of an LCD back-lit display with RS-232 entry keypad, illuminated power switch, emergency stop button and a shaft rotating indicator.