The 90-volt DC motor provides far more utility than that of the 1/2HP AC/DC motor Sherline used to offer prior to 1994. A DC motor offers its maximum torque at low RPM where you need it most, so the full speed horsepower rating of an AC/DC motor can be a little deceiving as far as offering practical, useable power. The DC motor also offers smoother and quieter operation. The motor now features externally replaceable brushes, making replacement of worn brushes a simple task taking just a few minutes.
To power and control the motor a more sophisticated speed control unit is required. The control we have developed accepts any incoming AC current from 100 VAC to 240 VAC, 50 or 60 Hz and automatically outputs 90 VDC to the motor, so this unit can be used anywhere in the world without a transformer. All you need is the correct wall plug or converter.
In addition, a load compensating circuit has been designed into the controller. As load is applied, the speed control will add power to attempt to hold a constant speed. Once the on/off switch is switched to the "ON" position, a speed control knob is used to vary the speed over the entire range. With the two-position pulley in the "normal" position on a Sherline headstock, the speed range is about 70 to 2800 RPM. In the "high torque" position the maximum speed is cut in half but torque at any given speed is much greater. If you are using the motor in non-Sherline applications, the maximum no-load speed of the motor shaft itself is 6000 RPM.
ELECTRIC MOTOR SPECIFICATIONS FROM MANUFACTURER