A gearmotor consists of an electric motor (DC or AC) combined with a geared speed reducer.
Spur, helical, or worm gears may be used in single or multiple stages. The configuration
may be either parallel shaft (emerging from the front of the motor) or right-angle shaft.
Gearmotors are often rated in input horsepower; however, output torque (commonly measured
in inch-pounds) and output speed are the critical values.
DC motors can be operated from rectified alternating current or from low-voltage battery
or generator sources. This low-voltage design includes external connection lugs for input
power. With the rear endshield removed, the brush assemblies and commutator that form a
DC motor's electrical heart are clearly visible.
Both designs feature linear speed/torque characteristics over the entire speed range.
SCR rated motors – designed for use with common solid-state speed controls – provide
high starting torque for heavy load applications and reversing capabilities, with
complementary active material to compensate for additional heating caused by rectified
AC input. Designs are also available for use with generated low-voltage DC power or
remote applications requiring battery power.