Abstract: An automatic lubricant dispenser has a lower housing part formed with an outlet, a piston displaceable along an axis in the lower part and forming therein a compartment, a spindle extending along the axis, threaded into the piston, having an upper end above the piston provided with a lower coupling half, and a body of fluent lubricant filling the compartment. An upper housing part removably securable to the lower part holds an electrical motor unit having an output shaft projecting downward at the axis and provided with an upper coupling half axially engageable with the lower coupling half. The coupling halves are axially engageable to rotationally couple the motor output shaft to the spindle so that electrical energization of the motor when the coupling halves are engaged displaces the piston and expresses lubricant from the outlet. A sensor connected to the shaft generates an output after a predetermined angular displacement of the shaft.