GR-WM4 24V DC High Torque 35rpm Worm Gear Motor

The GR-WM4 is a robust 24V DC-nominal motor and gearbox combination providing a low speed high-torque output. The single stage all-metal worm-and-wheel transmission is self locking, able to hold position after power has been removed, while also producing little noise when in motion. 

The no-load output speed at 24V DC is 35rpm, reducing to 28rpm at the rated load of 85kg-cm (8.4Nm, 1189oz-in). The maximum output duty is 40%, up to 3 minutes in a continuous stretch. Peak starting torque (<1s) can exceed 200kg-cm (up to a maximum gearbox rating of 222kg-cm). 

Please see further operating details and dimensions under 'technical details' below.

£58.00 £69.60 inc VAT
In Stock

The GR-WM4 is a compact and low-noise solution for high-torque intermittent load applications. Potential applications include electric door openers, winches, turntables, special effects (theatre, TV), and home automation.

When used at 24V and up to the sustained load rating of 85-kg-cm the motor has a 40% duty rating. For example, this means that if it is run under load for 60 seconds then it should then have break of 60 x 6/4 = 90 seconds before operating again, to protect the motor and gearbox against overheating. The maximum continuous operating time is 3 minutes when under load. Greater duty cycle operation is possible if used at lower voltages and lower loads.

The gearbox body has three M6 threaded holes for mounting to, in a triangular pattern (at 50.8mm radius) around the output shaft. 

When mounting loads on to the output shaft bear in mind that larger-sized radial loads (those acting perpendicular to the shaft) should be supported by additional bearing/bushings, to avoid putting too much stress on the gearbox and shaft (which is rated up to an 8Nm radial load). For example a wheel with a centreline at the end of the shaft ought to be supported by a bearing on the opposite side too, if the load on the wheel is expected to be greater than 20kg. 

We stock a 10mm bore mounting hub ideal for use with this motor. Customised mounting solutions are possible too, please contact us if interested. 

Leads options

By default the motor is supplied with two 240mm long red and black leads (18AWG) with bare tinned ends to your controller. Options are provided to change these to 500mm or 1000mm long 1mm2 silicone rubber (high temperature) insulated cables, with bare tinned lead-ends. If you require any custom cable and connector combinations then please get in touch

User advice

The motor operates like any other brushed DC motor and so may be used at voltages other than the nominal 24V with changed operating characteristics (please be aware that the warranty does not cover operation exceeding 24V or above the duty cycle rating, either of which would increase the chances of premature failure). 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. The motor is neutrally timed and so will travel at approximately the same speed in both directions.

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 controller, we for example have rocker switches and remote receivers than can provide this function. 

Current protection, such as a fuse or automatic overcurrent switch should be used to ensure that the motor and gearbox are not damaged due to overloading.

It is recommended, though not strictly necessary, to 'break-in' a new motor and gearbox before use, this is done by running for a couple of minutes continuously in both directions (polarity one way then the other) under no load. This ensures that the gears are running freely and the motor brushes are well seated on the commutator before being subjected to a load. 

Dimensioned Drawing
Gearbox Build Detail
Size:Overall maximums 200 x 114 x 111mm
Mounting:Three M6 x 15mm threaded holes on a 50.8mm radius about the
output shaft (120deg equal radial seperation)
Body material:Steel
Gearbox:Single-stage all-metal worm-and-wheel, 60:1 ratio
Shaft details:10mm diameter by 35mm long, with 26mm long by 4mm
wide slot. Machined steel
Shaft support:Dual deep-groove 16100Z (10mm ID) ball bearings
Radial load rating:Up-to 82kg-cm (8Nm)
Equivalent to approximately 23kg across the end of the shaft
Gearbox load torque:
Up-to 222kg-cm (21.8Nm). Be aware that at higher voltages
the motor itself is easily able to generate greater torque than
this (see table below), so please ensure that there is current 
protection in place to prevent it exceeding this mechanical rating,
if there is a danger that your application may go beyond it
Operating temperature:
0°C ~ +45°C
Enclosure rating:
IP50, designed for indoor or covered use only
1890g (excluding optional lead additions)

Operating Characteristics (values at the output from the gearbox)

at 6V DC:
at 12V DC:
at 24V DC (nominal voltage):
No-load speed after gearbox:8.75rpm17.5rpm35rpm
No-load current:0.3A0.35A0.55A
Rated sustained torque, speed: 21kg-cm at 7rpm
42kg-cm at 14rpm85kg-cm (8.4Nm) at 28rpm
Rated load current:
Maximum duty cycle at rated load:100%100%40% (maximum 3 minutes continuous)
Maximum power torque, speed:53.2kg-cm at 4.37rpm106kg-cm at 8.75rpm213kg-cm at 17.5rpm
Maximum power current:1.9A3.8A7.5A
Maximum output power:
Stall torque:
106kg-cm (10.4Nm)*213kg-cm (20.9Nm)*426kg-cm (41.8Nm)*
Stall current:

*Warning: Avoid exceeding the maximum gearbox rating of 222kg-cm (21.8Nm), or stalling the motor, by adding circuit or load protection. Protection can take the form of a fuse, circuit breaker or digital current protection switch.

Please be aware that some of the values above are extrapolated from other measurements and there will be a small degree of 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 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, and also that the mounting hardware is capable of transferring the potentially very large torque generated by the motor safely and without damaging itself. 

Please contact us if you have any technical or commercial questions about this item.

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