20.4:1 Metal Gearmotor 25Dx65L mm HP 24V with 48 CPR Encoder

Overview

These cylindrical brushed DC gearmotors have the same 25 mm diameter case and 4 mm diameter gearbox output shaft, so it is generally easy to swap one version for another if design requirements change, though the length of the gearbox tends to increase with the gear ratio. See the 25D metal gearmotor datasheet (5MB pdf) for more information, including detailed performance graphs for each gearmotor version.

High-Power (HP) 24V
Rated Voltage	Stall Current	No-Load Current	No-Load Speed (RPM)	Extrapolated Stall Torque		Max Power (W)	Approx Gear Ratio	Without Encoder	With Encoder
				(kg⋅cm)	(oz⋅in)
24 V	2.7 A	80 mA w/o encoder 100 mA with encoder	10,000	0.4	5.5	12	no gearbox	–	item #5720
			2300	2.0	28	12	4.4:1	item #5701	item #5721
			1000	4.1	57	11	9.7:1	item #5702	item #5722
			490	7.9	110	10	20.4:1	item #5703	item #5723
			300	12	160	9.3	34:1	item #5704	item #5724
			220	15	210	8.5	47:1	item #5705	item #5725
			140	23	320	–	75:1	item #5706	item #5726
			100	29	400	–	99:1	item #5707	item #5727
High-Power (HP) 12V
Rated Voltage	Stall Current	No-Load Current	No-Load Speed (RPM)	Extrapolated Stall Torque		Max Power (W)	Approx Gear Ratio	Without Encoder	With Encoder
				(kg⋅cm)	(oz⋅in)
12 V	5.0 A	250 mA w/o encoder 300 mA with encoder	10,000	0.4	5.5	10	no gearbox	–	item #4840
			2200	1.7	24	9.4	4.4:1	item #3201	item #4841
			1000	3.9	54	10	9.7:1	item #3202	item #4842
			500	7.4	100	9.4	20.4:1	item #3203	item #4843
			300	11	150	8.9	34:1	item #3204	item #4844
			220	15	210	8.4	47:1	item #3205	item #4845
			130	22	310	–	75:1	item #3206	item #4846
			100	29	400	–	99:1	item #3207	item #4847
Medium-Power (MP) 12V
Rated Voltage	Stall Current	No-Load Current	No-Load Speed (RPM)	Extrapolated Stall Torque		Max Power (W)	Approx Gear Ratio	Without Encoder	With Encoder
				(kg⋅cm)	(oz⋅in)
12 V	1.8 A	80 mA w/o encoder 100 mA with encoder	8200	0.17	2.4	3.5	no gearbox	–	item #4860
			1800	0.71	10	3.2	4.4:1	item #3225	item #4861
			800	1.7	24	3.4	9.7:1	item #3226	item #4862
			380	3.2	44	3.1	20.4:1	item #3227	item #4863
			230	4.7	65	2.8	34:1	item #3228	item #4864
			170	6.4	89	2.8	47:1	item #3229	item #4865
			100	8.5	120	2.3	75:1	item #3230	item #4866
			79	11	150	2.3	99:1	item #3231	item #4867
			46	18	250	2.1	172:1	item #3232	item #4868
			35	24	330	–	227:1	item #3233	item #4869
Low-Power (LP) 12V
Rated Voltage	Stall Current	No-Load Current	No-Load Speed (RPM)	Extrapolated Stall Torque		Max Power (W)	Approx Gear Ratio	Without Encoder	With Encoder
				(kg⋅cm)	(oz⋅in)
12 V	0.9 A	50 mA w/o encoder 60 mA with encoder	5600	0.14	1.9	1.8	no gearbox	–	item #4880
			1200	0.53	7.4	1.7	4.4:1	item #3249	item #4881
			580	1.3	18	1.8	9.7:1	item #3250	item #4882
			280	2.4	33	1.7	20.4:1	item #3251	item #4883
			170	3.7	51	1.6	34:1	item #3252	item #4884
			120	4.8	67	1.4	47:1	item #3253	item #4885
			75	7.1	99	1.4	75:1	item #3254	item #4886
			57	8.7	120	1.2	99:1	item #3255	item #4887
			33	13	180	1.1	172:1	item #3256	item #4888
			25	16	220	1.0	227:1	item #3257	item #4889
			15	23	320	378:1	–	item #3258	item #4890
High-Power (HP) 6V
Rated Voltage	Stall Current	No-Load Current	No-Load Speed (RPM)	Extrapolated Stall Torque		Max Power (W)	Approx Gear Ratio	Without Encoder	With Encoder
				(kg⋅cm)	(oz⋅in)
6 V	6.0 A	420 mA w/o encoder 500 mA with encoder	10,000	0.3	4	7	no gearbox	–	item #4800
			2200	1.2	17	6.7	4.4:1	item #1570	item #4801
			1000	2.3	32	5.9	9.7:1	item #1571	item #4802
			480	4.8	67	5.9	20.4:1	item #1572	item #4803
			290	6.8	94	5.1	34:1	item #1573	item #4804
			210	9.1	130	4.9	47:1	item #1574	item #4805
			130	14	190	4.5	75:1	item #1575	item #4806
			99	15	210	3.9	99:1	item #1576	item #4807
			57	27	380	–	172:1	item #1577	item #4808
Low-Power (LP) 6V
Rated Voltage	Stall Current	No-Load Current	No-Load Speed (RPM)	Extrapolated Stall Torque		Max Power (W)	Approx Gear Ratio	Without Encoder	With Encoder
				(kg⋅cm)	(oz⋅in)
6 V	2.0 A	100 mA w/o encoder 120 mA with encoder	6200	0.15	2.1	2.1	no gearbox	–	item #4820
			1300	0.63	8.7	2.1	4.4:1	item #1581	item #4821
			630	1.3	18	1.9	9.7:1	item #1582	item #4822
			290	2.5	35	1.9	20.4:1	item #1583	item #4823
			180	3.9	54	1.7	34:1	item #1584	item #4824
			130	4.8	67	1.5	47:1	item #1585	item #4825
			80	7.5	100	1.5	75:1	item #1586	item #4826
			61	9.1	130	1.4	99:1	item #1587	item #4827
			35	14	190	1.2	172:1	item #1588	item #4828
			27	17	240	1.1	227:1	item #1589	item #4829
			16	25	350	–	378:1	item #1590	item #4830
			12	31	430	–	499:1	item #1591	item #4831

Note: The listed stall torques and currents are theoretical extrapolations; units will typically stall well before these points as the motors heat up. Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. The recommended upper limit for continuously applied loads is 4 kg⋅cm (55 oz⋅in), and the recommended upper limit for intermittently permissible torque is 8 kg⋅cm (110 oz⋅in). Stalls can also result in rapid, potentially on the order of seconds, thermal damage to the motor windings and brushes; a general recommendation for brushed DC motor operation is 25% or less of the stall current.

In general, these kinds of motors can run at voltages above and below their nominal voltages and can begin rotating at voltages as low as 1 V. Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.

These gearmotors are functionally identical to the previous versions Pololu carried without end caps; they use the same motor, encoder, and gearboxes. The black plastic end cap is easily removable to access the encoder or slightly reduce the overall gearmotor size, but a little base plastic will remain, as shown below:

25D mm metal gearmotor with 48 CPR encoder (with end cap removed).

Details for this version

Exact gear ratio: (22×22×22×23) / (12×10×10×10) ≈ 20.4:1

Dimensions

The diagram below shows the dimensions of the 25D mm line of gearmotors, with units in mm over [inches]. This diagram is also available as a downloadable PDF (171k pdf).

Dimensions of the Pololu 25D mm metal gearmotors with encoders. Units are mm over [inches].

Warning: Do not screw too far into the mounting holes, as the screws can hit the gears. Pololu recommends screwing no further than 6 mm (0.24″) into the screw hole.

25D mm metal gearmotor with 48 CPR encoder (with end cap removed).

The 25D and 37D mm metal gearmotors with encoders have cables that are terminated with a 6-pin, 0.1″-pitch female connector.

Using the encoder

A two-channel Hall effect encoder senses the rotation of a magnetic disk on a rear protrusion of the motor shaft. The quadrature encoder provides a resolution of 48 counts per revolution of the motor shaft when counting both edges of both channels. To compute the counts per revolution of the gearbox output, multiply the gear ratio by 48. The motor/encoder has six colour-coded, 8″ (20 cm) leads terminated by a 1×6 female header with a 0.1″ pitch, as shown in the main product picture. This header works with standard 0.1″ male headers, male jumper wires and precrimped wires. If this header is not convenient for the application, the crimped wires can be pulled out of the header or the header can be cut off. The following table describes the wire functions:

The Hall sensor requires an input voltage, Vcc, between 3.5 and 20 V and draws a maximum of 10 mA. The A and B outputs are square waves from 0 V to Vcc approximately 90° out of phase. The frequency of the transitions indicates the speed of the motor, and the order of the transitions indicates the direction. The following oscilloscope capture shows the A and B (yellow and white) encoder outputs using a motor voltage of 6 V and a Hall sensor Vcc of 5 V:

Encoder A and B outputs for 25D mm HP 6V metal gearmotor with 48 CPR encoder (motor running at 6 V).

Counting both the rising and falling edges of both the A and B outputs provides 48 counts per revolution of the motor shaft. Using just a single edge of one channel results in 12 counts per revolution of the motor shaft, so the frequency of the A output in the oscilloscope capture above is 12 times the motor rotation frequency.

Gearmotor accessories

• Mounting brackets: The face plate has two mounting holes threaded for M3 screws. The custom-designed 25D mm metal gearmotor bracket, shown below, can mount the gearmotor to a project via these mounting holes and the screws supplied with the bracket.

Pololu 25D mm metal gearmotor bracket pair.

Pololu 25D mm gearmotor with bracket.

• Wheels and hubs: The 4 mm diameter gearbox output shaft works with Pololu multi-hub wheels, as shown in the left picture below. The shaft also works with the Pololu universal aluminum mounting hub for 4mm shafts, which can mount larger Pololu wheels (60mm-, 70mm-, 80mm-, and 90mm-diameter) or custom wheels and mechanisms to the gearmotor’s output shaft, as shown in the right picture below.

Pololu 80×10mm multi-hub wheel on a Pololu 25D mm metal gearmotor with encoder.

Pololu 60×8mm wheel with 4mm hub adapter on Pololu 25D mm metal gearmotor with encoder.

Alternatively, the 4mm scooter wheel adapter can mount many common scooter, skateboard and inline skate wheels to the gearmotor’s output shaft, as shown in the left picture below. For a general-purpose hex adapter, the 12mm hex wheel adapter allows this motor to be used with many common hobby RC wheels, as shown in the right picture below.

A 25D mm gearmotor with encoder connected to a scooter wheel by the 4mm scooter wheel adapter.

12mm hex wheel adapter for 4mm shaft on a 25D mm metal gearmotor with encoder.

• Motor controllers and drivers: Motor drivers and motor controllers can be used with these 25D mm metal gearmotors. For the LP and MP versions, Pololu recommends its TB9051FTG-based drivers, including a basic single carrier, a dual-channel shield for Arduino and a dual-channel expansion board for Raspberry Pi. For the HP versions, Pololu recommends VNH5019-based motor drivers, available as single and dual carriers, though these can also be a good choice for the lower-power motors.

TB9051FTG Single Motor Driver Carrier.

Pololu dual VNH5019 motor driver shield for Arduino.

For higher-level control interfaces such as USB, RC, analogue voltages, I²C or TTL serial, Motoron motor controllers, Jrk motor controllers or RoboClaw motor controllers are available in various power levels, several of which can handle the 25D mm metal gearmotors. Pololu generally recommends a motor controller that can handle continuous currents above the stall current of the motor.

Three Motoron M3H550 controllers being controlled by a Raspberry Pi.

Jrk G2 21v3 USB Motor Controller with Feedback.

RoboClaw 2x7A Motor Controller (V5B) in its included case.

• Current sensors: Current sensors can be used to monitor motor current.

ACS711EX current sensor carrier -15.5A to +15.5A.

ACS724LLCTR-05AB Current Sensor Carrier -5A to +5A.