GR-EP-45ENC 45mm 12V 20W Planetary Gearmotor with Encoder

This is a very useful size of motor for medium-scale automation, special effects and industrial processes. It is more powerful than most common 'hobby' gearmotors of 25mm or 36mm size, and yet not so powerful as to demand expensive high-current power & control circuitry. It is also able to handle much more torque than model gearmotors with smaller gears and/or non-planetary gearboxes.

One benefit of this model is that the relatively low motor speed (6000rpm no-load at 12V) generates lower noise levels than more-powerful motors of the same size which usually generate their power with very high rpms.

The wide range of gearbox sizes offer differing output characteristics to suit many different applications. Please see performance details listed under Technical Details below. If you intend to operate the motor with a continuous load do not exceed the continuous torque ratings described for the different gearbox options, running at a higher torque than these ratings for extended periods of time would be likely to cause the motor to overheat.

CAD models are available, please contact us for a copy.

Integrated Encoder

The motor has a hall-sensor based quadrature encoder mounted to its rear, inside the black plastic rear cover. The encoder is not required for operation (and won't affect operation if left disconected), but for many projects it provides very useful feedback of the speed, and relative position, of the motor. It is accessed via a female 4-pin connector on the rear of the motor, each motor is supplied with a compatible 4-pin connector with Red, Black, Yellow and White wires. Power for the encoder (<10mA) should be provided to the Red lead (+5V VCC), and Black lead (GND/ground), ensure that the correct polarity connection is made to these wires.

It has a dual-channel output (channel A Yellow lead, Channel B White lead), with 7 complete pulses per channel, per rotation of the motor (7 PPR). One of the channels is out of phase with the other, as such it is possible to tell both the speed (from pulse frequency) and direction (by reading the pulses of one channel and comparing it to the other) of the motor. The nature of the signals that are generated is illustrated below. Given the approximate no-load motor speed of 6000rpm for the 12V motor (when at 12V) the pulse frequency may be up to 700Hz per channel if counting complete pulses, or as much as 2800Hz if your controller is counting pulse edges across both channels together (4 x counting). 

The gearbox ratio multiplies the number of motor rotations for each rotation of the output shaft, for example for the 3.7:1 gearbox which has an exact ratio of 3 ¹²⁄₁₇ : 1 the encoder will read 7 x 3 ¹²⁄₁₇ = 25.94 (4 s.f.) pulses per encoder channel, per rotation of the output shaft. See precise ratios for the other gearbox sizes under Technical Details below.

User Advice

This motor operates like any other DC motor and so may be used at voltages other than the nominal 12V with changed operating characteristics (please be aware that the warranty does not cover operation above 12V which is likely to shorten the lifespan). Reducing the voltage reaching the motor will decrease the output speed and current for a given load, while increasing the voltage will increase the speed and the current. 

To change the direction of rotation swap the polarity of the power to the motor contacts (invert positive and negative). This is usually done via a control switch or controller, for example our rocker switch harness or GLA-CU-X3 control units.

You should fit circuit protection to protect both the motor from stalling/overheating and your power source from overload. At a minimum this would be a fuse in series with a motor, but you might want to fit a more sophisticated protection device such as the GR-SENS instead.

Make sure to read the performance tables for your selected gearbox option under 'Technical Details' below, so that you have an understanding of the torque, current and speed that you can expect from the motor. If you're unsure about selecting the appropriate motor for the task please send details of your application to us and we'll guide you through the options. 

Jump to section:    Motor Dimensions   —   Gearbox Build Detail  —  Operating Characteristics 3.7:1   —   Operating Characteristics 19.2:1  —   Operating Characteristics 50.9:1   —   Operating Characteristics 99.5:1   —   Operating Characteristics 369:1

Motor Dimensions

For the diagram below the dimension L is 33.6mm for the 3.7:1 gearbox, 44.9mm for the 19.2:1 gearbox, 56.2mm for the 50.9:1 and 99.5:1 gearboxes and 67.5mm for the 369:1 gearbox. Please allow for +/-1mm on overall length. CAD models are available, please contact us for a copy.

Gearbox Build Detail

Motor Performance Guide (figures are for the output at the shaft, and per gearbox ratio):

The breaking (absolute maximum) output torque for the 3.7:1 gearbox is 60kg-cm (5.88Nm), be wary of shock/impact loads that could exceed this.

*Highlighted values should not be reached. You should use mechanical and/or current-based protection to protect the motor from overload (using for example a clutch, fuse, or digital current limiting switch), since if is operated at too high a sustained load, or allowed to stall, the motor could quickly overheat.

Please be aware that many of the values above are extrapolated from other measurements and there will be some variance from motor to motor, allow for a safety factor of at least 15% above/below the given values when designing for your application. Output torque and power values are based upon an average 90% gearbox transfer efficiency for this gearbox, which more precisely has a 3.706:1 ratio. The continuous duty rating is based upon there being sufficient cooling for the motor and gearbox, the operating temperature should be kept below 45°C and free air flow should be ensured to prevent overheating. Be sure that any equipment that you use with the motor (power source and controller) is capable of handling the currents that the motor may demand.

The breaking (absolute maximum) output torque for the 19.2:1 gearbox is 180kg-cm (17.65Nm), be wary of shock/impact loads that could exceed this.

*Highlighted values should not be reached. You should use mechanical and/or current-based protection to protect the motor from overload (using for example a clutch, fuse, or digital current limiting switch), since if is operated at too high a sustained load, or allowed to stall, the motor could quickly overheat.

Please be aware that many of the values above are extrapolated from other measurements and there will be some variance from motor to motor, allow for a safety factor of at least 15% above/below the given values when designing for your application. Output torque and power values are based upon an average 81% gearbox transfer efficiency for this gearbox, which more precisely has a 19.203209:1 ratio. The continuous duty rating is based upon there being sufficient cooling for the motor and gearbox, the operating temperature should be kept below 45°C and free air flow should be ensured to prevent overheating. Be sure that any equipment that you use with the motor (power source and controller) is capable of handling the currents that the motor may demand.

The breaking (absolute maximum) output torque for the 50.9:1 gearbox is 360kg-cm (35.3Nm), be wary of shock/impact loads that could exceed this.

*Highlighted values should not be reached. You should use mechanical and/or current-based protection to protect the motor from overload (using for example a clutch, fuse, or digital current limiting switch), since if is operated at too high a sustained load, or allowed to stall, the motor could quickly overheat.

Please be aware that many of the values above are extrapolated from other measurements and there will be some variance from motor to motor, allow for a safety factor of at least 15% above/below the given values when designing for your application. Output torque and power values are based upon an average 73% gearbox transfer efficiency for this gearbox, which more precisely has a 50.89497252:1 ratio. The continuous duty rating is based upon there being sufficient cooling for the motor and gearbox, the operating temperature should be kept below 45°C and free air flow should be ensured to prevent overheating. Be sure that any equipment that you use with the motor (power source and controller) is capable of handling the currents that the motor may demand.

The breaking (absolute maximum) output torque for the 99.5:1 gearbox is is 360kg-cm (35.3Nm), try to prevent shock/impact loads that could exceed this. 

*Highlighted values should not be reached. You should use mechanical and/or current-based protection to protect the motor from overload (using for example a clutch, fuse, or digital current limiting switch), since if is operated at too high a sustained load, or allowed to stall, the motor could quickly overheat.

Please be aware that many of the values above are extrapolated from other measurements and there will be some variance from motor to motor, allow for a safety factor of at least 15% above/below the given values when designing for your application. Output torque and power values are based upon an average 81% gearbox transfer efficiency for this gearbox, which more precisely has a 13.734:1 ratio. The continuous duty rating is based upon there being sufficient cooling for the motor and gearbox, the operating temperature should be kept below 45°C and free air flow should be ensured to prevent overheating. Be sure that any equipment that you use with the motor (power source and controller) is capable of handling the currents that the motor may demand.

*Highlighted values should not be reached. The breaking (absolute maximum) output torque for the 369:1 ratio is 360kg-cm (35.3Nm), you should use mechanical and/or current-based protection to protect the motor from overload (using for example a clutch, fuse, or digital current limiting switch), since the motor is capable of generating a much greater torque than the output stage of the gearbox can handle. 

Please be aware that many of the values above are extrapolated from other measurements and there will be some variance from motor to motor, allow for a safety factor of at least 15% above/below the given values when designing for your application. Output torque and power values are based upon an average 73% gearbox transfer efficiency for this gearbox, which more precisely has a 50.895:1 ratio. The continuous duty rating is based upon there being sufficient cooling for the motor and gearbox, the operating temperature should be kept below 45°C and free air flow should be ensured to prevent overheating. Be sure that any equipment that you use with the motor (power source and controller) is capable of handling the currents that the motor may demand.

If you have any questions about this item, including for information on custom ratios, controllers, and bulk pricing, then please contact us.