The GR-WM5 is a compact DC motor and gearbox combination featuring a single-stage 56:1 reduction worm-wheel gearbox.
The output offers a no-load speed of 62rpm, and speed of 51rpm when under a 32kg-cm rated load, making it suitable for many automation projects.
A 12PPR quadrature encoder on the motor allows the output to be tracked accurately (672 pulses per revolution of the output shaft), enabling precise speed or position control and for multiple motors to be synchronised with an appropriate controller.
Please see further operating details under the 'technical details' below.
This motor model, new for 2021, is the fifth generation of worm gear motor solution that we have offered, with improvements being added year on year. The right-angle gearbox enables the motor to fit into positions that planetary and conventional spur gear motors wouldn't be able to, whilst also generating lower noise levels than most other gearbox types.
The steel and bronze single-stage gear reduction, with cast aluminium gearbox body, is far sturdier than many other compact motors available. The 10mm diameter 35mm long steel output shaft, with a 4mm groove, provides a convenient mounting profile which is compatible with many readily available couplers and bearings, including our 10mm mounting hubs. The motor is mounted via three M6 tapped holes, on a 50.8mm PCD about the output shaft (see drawing further down this page).
Inside, the motor uses both inductors and capacitors to minimise radiated electrical noise, as well as a ferrite ring on the motor wires, all intended to save future headaches when incorporating the motor into products that need to meet ever-tighter EMC standards (tested to EN61000-3-6-3).
CAD models are available, please contact us for a copy.
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 the thinner Red, White, Blue and Yellow wires. Positive power for the encoder (<10mA) should be provided to the White lead (+5V VCC), and counterintuitively the Red lead should be connected to ground/GND. Ensure that the correct polarity connection is made to these wires, red and black heat shrink is added at the ends of the wires to indicate the correct polarity.
It has a dual-channel output (channel A Blue lead, Channel B Yellow lead), with 6 complete pulses per channel, per rotation of the motor (12 PPR across both channels). 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 3400rpm for the 12V motor (when at 12V) the pulse frequency may be up to 3400 / 60 x 12 = 680Hz across both channels, if counting complete pulses, or as much as 1360Hz if your controller is counting pulse edges across both channels.
The gearbox ratio multiplies the number of motor rotations for each rotation of the output shaft, therefore with 12 complete pulses per motor rotation there are 12 x 56 = 672 complete pulses per output shaft rotation, across both encoder channels. In practice, as it is not a very high precision gearbox, the accuracy of the encoder is greater than the expected backlash of the output shaft.
As with any brushed DC motor it is possible to vary the output speed by regulating the supplied current with a DC motor speed controller, and to change the direction of rotation by swapping the polarity of the supplied current. We also stock power supplies, rocker switches, and remote switches that are ideal for controlling these motors. Current protection, such as a fuse or automatic overcurrent switch should be used to ensure that the motor is not damaged due to sustained overloading.
The motor, 49mm in diameter and ~108mm long (excluding gearbox), is fully enclosed but is not waterproof. The motor should be shielded from direct water exposure, and protected from condensation, if used outdoors. As the motor does not have active air cooling it should be used only up to 50% duty at the rated load, 5min maximum in any one continuous stretch (e.g. 5min on then 5min off), to avoid overheating.
Please see drawing below. CAD models are available, please contact us for a copy.
|Mounting:||3 x M6 tapped holes, each 15mm deep. PCD 50.8mm (around output shaft).|
|Overall size:||Approximately 164mm long, 92mm tall, 60mm deep (excluding output shaft).|
|Body material:||Cast aluminium gearbox housing with steel motor casing.|
|Gearbox type:||Single-stage worm transmission with 40Cr steel worm and bronze worm-wheel.|
|Operating temperature:||-5°C ~ +45°C. The motor is not suitable for unprotected outdoor use.|
|Shaft type:||10mm diameter (h7) by 35mm long.|
Features a 26mm long, 4mm wide and 2.5mm deep rectangular keyway.
|Shaft support:||Integrated steel sleeve bearing, 22mm long.|
|Weight:||870g, excluding lead/connector options.|
at 12V DC (nominal voltage):
at 6V DC:
|No-load speed after gearbox:||62rpm||31rpm|
|Rated (maximum 50% duty) |
|32kg-cm, 48rpm||16kg-cm, 24rpm|
|Rated load current:||3A||1.9A|
|Rated load output power:||15W||4.0W|
|Stall (peak) torque:||122kg-cm, 12Nm*||61kg-cm, 6Nm*|
*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 stalled for a sustained period the motor will burn out.
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. Be aware of the duty cycle limit, operating beyond this is likely to cause overheating. Free air flow should be allowed around the outside of the motor. 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.