In brief
A geared motor is a drive unit consisting of an electric motor and an attached gearbox that reduces speed and increases torque at the output shaft.
Contents
What is Geared motor?
In a geared motor, the motor and gearbox are combined into a compact unit. The gearbox reduces the high motor speed to the speed required at the machine, increasing the torque accordingly. Geared motors drive conveyor belts, agitators, lifting equipment, dosing units and many other machines.
By type of gearbox, a distinction is made between, among others, helical geared motors with a coaxial output shaft, parallel shaft geared motors for shaft-mounted installation, bevel geared motors with right-angle output and good efficiency, and worm geared motors, which are compact and quiet-running but achieve lower efficiencies. Key parameters are the gear ratio, output speed, output torque, permissible overhung load and the service factor, which indicates how much reserve the gearbox has relative to the load in the particular application.
The parts subject to wear are mainly shaft seals, bearings and the gear oil. In the event of a failure, the question arises whether the motor or gearbox can be repaired individually or the entire unit must be replaced. Output dimensions, fixing and mounting position determine whether an alternative make fits without modification.
In practice: maintenance and procurement
An enquiry requires the nameplate data of the motor and gearbox, plus the mounting position, output shaft (solid shaft or hollow shaft with dimensions), flange or foot mounting and any brake. A photo of the installation situation helps when checking alternatives.
Synonyms and abbreviations: gear motor · gearmotor · geared drive · drive unit · gear reducer motor
Frequently asked questions
What is the difference between a helical and a bevel geared motor?
In a helical geared motor, the output shaft is in line with or parallel to the motor shaft. In a bevel geared motor, the rotary motion is deflected by 90 degrees, so that the motor lies at right angles to the driven shaft. The choice depends mainly on the installation space available and the layout of the machine; both designs achieve good efficiencies.
What does the service factor indicate for geared motors?
The service factor describes the ratio between the permissible torque of the gearbox and the torque actually required. It takes into account influences such as shock loads, switching frequency and daily operating time. A factor above the minimum value recommended for the application means reserve; values that are too low shorten the service life of the gearing and bearings.
What information is needed for a replacement geared motor?
Required are the motor's power, voltage and frequency, the output speed or ratio, output torque, gearbox type, mounting position and the type and dimensions of the output shaft. In addition, the mounting method, flange dimensions and additional equipment such as a brake or encoder are needed. If nameplate data are missing, dimensions and photos of the installation situation help.
Why is the mounting position important for a geared motor?
The oil quantity, the position of the breather, oil level and drain plugs, and the lubrication of the gearing all depend on the mounting position. If a gearbox is operated in a position other than the one intended, parts may be insufficiently lubricated or oil may leak. The mounting position therefore belongs in every spare parts enquiry.