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156:1 6V 20Dx44L - Metal Gearmotor View larger

156:1 6V 20Dx44L - Metal Gearmotor

Motor with 20 mm diameter and 44 mm length, 156:1 metal gear, 6 V operating voltage, 0.15 A to 2.9 A power consumption, 91 RPM speed and 7.9 kg*cm maximum torque. Pololu 3456

More details

ID: 570904

16,95€ gross (23% VAT)
13,78€ net

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Data sheet

DC motor powerOther
Gear materialMetal
Gear ratio156:1
Rotation speed93RPM
Shaft diameter4 mm
Shaft shapeD
Obustronny wał silnikaNie
Power supply voltage6V

More info


These small brushed DC gearmotors can deliver a lot of power for their size. This version has a 6 V brushed DC motor with precious metal brushes combined with a 156.25:1 metal spur gearbox. The gearmotor is cylindrical with a diameter of 20 mm, and the D-shaped output shaft is 4 mm in diameter and extends 18 mm from the face plate of the gearbox.


  • Gear ratio: 156.25:1
  • Supply voltage: 6 V
  • Speed: 91 RPM
  • Maximum torque: 7.9 kg*cm
  • Minimum power consumption: 0.15 A
  • Maximum power consumption: 2.9 A
  • precious metal brushes
  • Diameter: 20 mm
  • Length: 44 mm
  • Weight: 45 g
Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. In order to avoid damaging the gearbox, we recommend keeping continuously applied loads under 5 kg-cm (75 oz-in) for the versions with carbon brushes (12V CB and 6V CB) and under 3.5 kg-cm (50 oz-in) for the versions with precious metal brushes. Stalls can also result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes, especially for motors like this that can deliver a lot of power for their size; a general recommendation for brushed DC motors is to limit continuous current to approximately 25% of the stall current.

Supply voltage

Pololu 20D engines are available in two versions with the recommended voltage of 6 V and 12 V. These engines do not differ in power, but only with the current drawn, which for 12 V motors is half as low as for 6 V motors, which can be considerable easier when choosing drivers. It is possible to supply the motor with a lower or higher voltage, but this is associated with lower power or decrease their lifetimes, respectively.

Dimensions and weight

All motors have equal dimensions. Depending on the gear ratio, gearboxes differ in length, which can be seen in the following dimensions diagram. The metal gear housing has two threaded holes for M2.5 screws. Gear motors weigh 43 g, 44 g, 45 g or 46 g depending on the size of the gearbox.

Dimensions of the Pololu 20D mm metal gearmotors. Units are mm over [inches]. This diagram only applies to the listed gear ratios.
Do not screw too far into the mounting holes as the screws can hit the gears. We recommend screwing no more than 3.5 mm (0.14″) into the M2.5 mounting holes.

Double motor shaft

These gearmotors are optionally available with an additional 2 mm-diameter output shaft that protrudes 6 mm from the rear of the motor (see the middle picture below). This rear shaft rotates at the same speed as the input to the gearbox and offers a way to add an encoder, such as our magnetic encoder for 20D mm metal gearmotors as shown in the right picture below, to provide motor speed or position feedback.

Our offer includes magnetic encoders suitable for all types of Pololu 20D motors.

20D mm metal gearmotor CB with long-life carbon brushes.20D mm metal gearmotor CB with long-life carbon brushes and an extended motor shaft.Magnetic Encoder Kit for 20D mm Metal Gearmotors assembled on a 20D mm metal gearmotor with extended motor shaft.

Carbon Brushes

These small gearmotors are availble with precious metal brushes or long-life carbon brushes. All motors offer similar performances at their respective nominal voltages, just with the 12 V motor drawing approximately half the current of the 6 V motor and with the carbon brush versions having longer lifetimes than the one with precious metal brushes.

The CB versions (shown on the right), can be differentiated from versions with percious metal brushes (shown on the left) by their copper-colored terminals.Comparison of metal brushes (left) and carbon brushes (right)


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

Black Pololu 80x10mm wheelsWhite Pololu 80x10mm wheelsBlack Pololu 80x10mm wheel with motor mounted

Wild Thumper wheels ChromeWild Thumper wheels red matalicWild Thumper wheel with engine mounted

Black scooter/skate wheels with 200 mm, 144 mm, 100 mm, 84 mm, and 70 mm diameters.Aluminum Scooter Wheel Adapters


The gearmotor face plate has two mounting holes threaded for M2.5 screws, and you can use our custom-designed 20D mm metal gearmotor bracket (shown in the left picture below) to mount the gearmotor to your project via these mounting holes and the screws that come with the bracket.

Brackets for 20D engines20D engine with attached bracket and adapter20D engine mounted on a platform with a Scooter wheel

Motor controllers

We have a number of motor controllers and motor drivers that work with these 20D mm metal gearmotors. In particular, we recommend MC33296-based motor drivers, for which we have basic single and dual carriers and a dual-channel shield for Arduino.

Dual DC motor controller with MC33926Shield Arduino with a double DC motor driver with VNH5019 systemJrk G2 21v3 DC motor controller with USB communication

Current sensors

We have an assortment of Hall effect-based current sensors to choose from for those who need to monitor motor current:

0-5A current sensor module with ACS712-05Current sensor module ± 5A with ACS714Current sensor module ± 15.5A with ACS711EX system

Types and parameters of 20D Pololu engines:

In our offer you can find motors with gear ratios from 25: 1 to 488: 1, with a rated voltage of 6 V and 12 V and in versions MB with metal brushes and CB with carbon brushes. In addition, all engine variants are also available with single-sided or double-sided motor shaft.