99:1 Metal Gearmotor 25Dx54L mm LP 6V

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Pololu item #: 1587
Brand: Pololu
Status: Active and Preferred 
RoHS 3 compliant


This gearmotor consists of a low-power, 6 V brushed DC motor combined with a 98.78:1 metal spur gearbox. The gearmotor is cylindrical, with a diameter just under 25 mm, and the D-shaped output shaft is 4 mm in diameter and extends 12.5 mm from the face plate of the gearbox. This gearmotor is also available with an integrated encoder.

Key specifications:

voltage no-load performance stall extrapolation
6 V 61 RPM, 100 mA 9.1 kg⋅cm (130 oz⋅in), 2.0 A

Alternatives available with variations in these parameter(s): gear ratio motor type encoders? Select variant…

Compare all products in 6V Low-Power (LP) 25D mm Gearmotors.

Pictures

25D mm metal gearmotor.

Pololu 25D mm gearmotor with bracket.

Pololu 60×8mm wheel on a Pololu 25D mm metal gearmotor.

12mm Hex Wheel Adapter for 4mm Shaft on a 20D mm metal gearmotor.

Dagu Wild Thumper wheel 120×60mm (chrome) with Pololu 25D mm metal gearmotor.

Partially disassembled Dagu Wild Thumper 6WD chassis with one of the gearmotors visible.

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

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

Dimensions of the Pololu 25D mm metal gearmotors without encoders. Units are mm over [inches].

An assortment of Pololu metal gearmotors.




Overview

These cylindrical brushed DC gearmotors are available in a wide range of gear ratios and with five different motors (two power levels of 6 V motors and three power levels of 12 V motors). The gearmotors all 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 your design requirements change (though the length of the gearbox tends to increase with the gear ratio). Each version is also optionally available with an integrated 48 CPR quadrature encoder. See the 25D metal gearmotor datasheet (2MB pdf) for more information, including detailed performance graphs for each gearmotor version. You can also use our dynamically sortable 25D gearmotor comparison table to search for the version that offers the best combination of speed, torque, and current draw for your particular application. A more basic comparison table is available below.

Rated
Voltage		 Motor
Type		 Stall
Current		 No-Load
Current		 Gear Ratio No-Load Speed
(RPM)		 Extrapolated
Stall Torque		 Max Power
(W)

Without Encoder

With Encoder
(kg ⋅ cm) (oz ⋅ in)
12 V High-Power
(HP)		 5.0 A 250 mA
w/o
encoder


300 mA
with
encoder		 1:1 (no gearbox) 10,000 0.4 5.5 10 – item #4840
4.4:1 2200 1.7 24 9.4 item #3201 item #4841
9.7:1 1000 3.9 54 10 item #3202 item #4842
20.4:1 500 7.4 100 9.4 item #3203 item #4843
34:1 300 11 150 8.9 item #3204 item #4844
47:1 220 15 210 8.4 item #3205 item #4845
75:1 130 22 310 – item #3206 item #4846
99:1 100 29 400 – item #3207 item #4847
12 V Medium-Power
(MP)		 1.8 A 80 mA
w/o
encoder


100 mA
with
encoder		 1:1 (no gearbox) 8200 0.17 2.4 3.5 – item #4860
4.4:1 1800 0.71 10 3.2 item #3225 item #4861
9.7:1 800 1.7 24 3.4 item #3226 item #4862
20.4:1 380 3.2 44 3.1 item #3227 item #4863
34:1 230 4.7 65 2.8 item #3228 item #4864
47:1 170 6.4 89 2.8 item #3229 item #4865
75:1 100 8.5 120 2.3 item #3230 item #4866
99:1 79 11 150 2.3 item #3231 item #4867
172:1 46 18 250 2.1 item #3232 item #4868
227:1 35 24 330 – item #3233 item #4869
12 V Low-Power
(LP)		 0.9 A 50 mA
w/o
encoder


60 mA
with
encoder		 1:1 (no gearbox) 5600 0.14 1.9 1.8 – item #4880
4.4:1 1200 0.53 7.4 1.7 item #3249 item #4881
9.7:1 580 1.3 18 1.8 item #3250 item #4882
20.4:1 280 2.4 33 1.7 item #3251 item #4883
34:1 170 3.7 51 1.6 item #3252 item #4884
47:1 120 4.8 67 1.4 item #3253 item #4885
75:1 75 7.1 99 1.4 item #3254 item #4886
99:1 57 8.7 120 1.2 item #3255 item #4887
172:1 33 13 180 1.1 item #3256 item #4888
227:1 25 16 220 1.0 item #3257 item #4889
378:1 15 23 320 – item #3258 item #4890
6 V High-Power
(HP)		 6.0 A 420 mA
w/o
encoder


500 mA
with
encoder		 1:1 (no gearbox) 10,000 0.3 4 7 – item #4800
4.4:1 2200 1.2 17 6.7 item #1570 item #4801
9.7:1 1000 2.3 32 5.9 item #1571 item #4802
20.4:1 480 4.8 67 5.9 item #1572 item #4803
34:1 290 6.8 94 5.1 item #1573 item #4804
47:1 210 9.1 130 4.9 item #1574 item #4805
75:1 130 14 190 4.5 item #1575 item #4806
99:1 99 15 210 3.9 item #1576 item #4807
172:1 57 27 380 – item #1577 item #4808
6 V Low-Power
(LP)		 2.0 A 100 mA
w/o
encoder


120 mA
with
encoder		 1:1 (no gearbox) 6200 0.15 2.1 2.1 – item #4820
4.4:1 1300 0.63 8.7 2.1 item #1581 item #4821
9.7:1 630 1.3 18 1.9 item #1582 item #4822
20.4:1 290 2.5 35 1.9 item #1583 item #4823
34:1 180 3.9 54 1.7 item #1584 item #4824
47:1 130 4.8 67 1.5 item #1585 item #4825
75:1 80 7.5 100 1.5 item #1586 item #4826
99:1 61 9.1 130 1.4 item #1587 item #4827
172:1 35 14 190 1.2 item #1588 item #4828
227:1 27 17 240 1.1 item #1589 item #4829
378:1 16 25 350 – item #1590 item #4830
499:1 12 31 430 – 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 (they 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.

Details for item #1587

Exact gear ratio: ``(22×22×22×22×22×23) / (12×10×10×10×10×10) ~~bb(98.78:1)``

Dimensions

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

Dimensions of the Pololu 25D mm metal gearmotors without encoders. Units are mm over [inches].

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

Gearmotor accessories

Pololu 25D mm metal gearmotor bracket pair.

Pololu 25D mm gearmotor with bracket.

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, you could use our 4mm scooter wheel adapter to 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, consider our 12mm hex wheel adapter, which lets you use this motor 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.

TB9051FTG Single Motor Driver Carrier.

Pololu dual VNH5019 motor driver shield for Arduino.

If you are looking for higher-level control interfaces, such as USB, RC, analog voltages, I²C, or TTL serial, consider our Motoron motor controllers, Jrk motor controllers, or RoboClaw motor controllers; these controllers are available in various power levels several of which can handle the 25D mm metal gearmotors (we generally recommend a motor controller that can handle continuous currents above the stall current of your motor).

Three Motoron M3H550 controllers being controlled by a Raspberry Pi.

Jrk G2 21v3 USB Motor Controller with Feedback.

RoboClaw 2×7A Motor Controller (V5B) in its included case.

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

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

Selecting the right gearmotor

We offer a wide selection of metal gearmotors that offer different combinations of speed and torque. Our metal gearmotor comparison table can help you find the motor that best meets your project’s requirements.

Dimensions

Size: 25D x 54L mm1
Weight: 91 g
Shaft diameter: 4 mm2

General specifications

Gear ratio: 98.78:1
No-load speed @ 6V: 61 rpm3
No-load current @ 6V: 0.10 A4
Stall current @ 6V: 2.0 A5
Stall torque @ 6V: 9.1 kg·cm5
Max output power @ 6V: 1.4 W
Motor type: 6V, 2.0A stall (LP 6V)

Performance at maximum efficiency

Max efficiency @ 6V: 34 %
Speed at max efficiency: 50 rpm
Torque at max efficiency: 1.4 kg·cm
Current at max efficiency: 0.36 A
Output power at max efficiency: 0.73 W

General specifications

Encoders?: N

Notes:

1
Length measurement is from gearbox face plate to back of motor (it does not include the output shaft or motor terminals). See dimension diagram for details.
2
D shaft.
3
Typical; ±20%.
4
Typical, ±50%; no-load current depends on internal friction, which is affected by many factors, including ambient temperature and duration of motor operation.
5
Stalling is likely to damage the gearmotor. Stall parameters come from a theoretical extrapolation of performance at loads far from stall. As the motor heats up, as happens as it approaches an actual stall, the stall torque and current decrease.

File downloads

Frequently-asked questions

Is it okay to stall this motor at its operating voltage?

No! Stalls can 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, which means keeping continuously applied loads around 25% or less of the stall torque.

Additionally, for many of our gearmotors with high gear ratios, the extrapolated stall torque is beyond what the gearboxes are designed to handle, and a stall could instantly damage the gears. Make sure to keep applied loads within the published limits for your gearmotor.

What do the dotted lines mean in the motor performance curves from the datasheet?
In our motor performance curves, the solid lines show the regions where we actually took measurements while the dotted lines show extrapolations beyond that. For many motors, we took measurements out to about 50% of the stall torque, since continued operation at loads past this point increasingly risk thermal damage to the windings. However, for higher gear ratios, going to 50% of the stall torque exceeds what is safe for the gearbox, so the measurements are further limited to not much past our recommendation for continuously applied loads.
What material is the gearbox output shaft made of, and can I get the shaft customized?
The shaft is composed of hardened stainless steel. Some customization is generally possible (e.g., different length or no D-shaft) for sufficiently high-volume orders. If this is something you are interested in, please email us.

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