> **Source:** Core Electronics is an Australian maker-electronics retailer and manufacturer based in Newcastle, NSW, run by a team of makers and educators. We design and manufacture our own product lines (PiicoDev, CE originals) and are official retailers for iconic maker and industrial brands including Raspberry Pi, Arduino, Adafruit, SparkFun and DFRobot. Orders ship Australia-wide from our Newcastle warehouse. Prices are in AUD and include GST. Pricing, stock and dispatch on this page are generated from the store's live catalog. Full machine-readable index: https://core-electronics.com.au/llms.txt # 73:1 Metal Gearmotor 20Dx42L mm **Type:** Product page · **SKU:** POLOLU-1163 · **Brand:** [Pololu](https://core-electronics.com.au/brands/pololu-australia) **Page:** https://core-electronics.com.au/73-1-metal-gearmotor-20dx42l-mm.html ([markdown](https://core-electronics.com.au/73-1-metal-gearmotor-20dx42l-mm.html.md)) ## Retired product This product is retired and no longer available for purchase. Search the catalogue for an alternative. ## How to buy - **Search the catalogue:** `https://core-electronics.com.au/search/{query}.md` (URL-encode the query; pages 2-3 at `search/{query}/{page}.md`; `search.md?q=` also works) - **Payment methods, purchase orders, policies and contact details:** https://core-electronics.com.au/llms.txt ## Description **New versions available!** Pololu have replaced these older short-shaft versions of Pololu's 20D mm gearmotors with a much wider assortment of gear ratios that feature longer output shafts. You can find the full selection of these new versions [**here**](https://core-electronics.com.au/components/motors/metal-gearmotors.html). The older versions are now only available by large-volume special order. Please [contact us](https://core-electronics.com.au/contact) for more information. Note that the following product page is being left here for historical purposes; it has not been updated to reflect Pololu's current offering of 20D mm gearmotors. The 20D mm line of brushed DC gearmotors all have the same dimensions except for the length of the gearbox, and they are intended for use at 6 V. In general, these kinds of motors can run at voltages above and below this nominal voltage, so Pololu should comfortably operate in the 3 – 9 V range. Higher voltages could start negatively affecting the life of the motor, and lower voltages might not be practical. Four different gear ratios are available: | Gear Ratio | No-Load Speed@ 6 V | No-Load Current@ 6 V | Stall Torque@ 6 V | Stall Current@ 6 V | |---|---|---|---|---| | [**29:1**](https://core-electronics.com.au/29-1-metal-gearmotor-20dx41l-mm.html) | 450 RPM | 250 mA | 25 oz-in | 3.2 A | | [**56:1**](https://core-electronics.com.au/catalog/product/view/sku/POLOLU-1450) | 250 RPM | 250 mA | 45 oz-in | 3.2 A | | [**73:1**](https://core-electronics.com.au/73-1-metal-gearmotor-20dx42l-mm.html) | 180 RPM | 250 mA | 60 oz-in | 3.2 A | | [**154:1**](https://core-electronics.com.au/154-1-metal-gearmotor-20dx44l-mm.html) | 90 RPM | 250 mA | 120 oz-in | 3.2 A | **Note:** Stalling gearmotors can greatly decrease their lifetimes, occasionally resulting in immediate damage to the gearbox. This is especially true for the higher gear ratios, which can generate enough torque to damage themselves. Prolonged stalls (on the order of seconds) can result in thermal damage to the motor windings and brushes. The gearmotor face plate has two mounting holes threaded for M2.5 screws, and you can use Pololu's custom-designed [20D mm metal gearmotor bracket](https://core-electronics.com.au/pololu-20d-mm-metal-gearmotor-bracket-pair.html) (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. | \| [![](https://a.pololu-files.com/picture/0J1194.290.jpg?ed4f2f8e73f1d28ec05b8e9ac82b0a9a)](https://a.pololu-files.com/picture/0J1194.1200.jpg?ed4f2f8e73f1d28ec05b8e9ac82b0a9a) \| \|---\| \| Pololu 20D mm gearmotor with bracket and hub. \| | \| [![](https://a.pololu-files.com/picture/0J2596.250.jpg?5f864c4954fddd4e384b6f72b39afeba)](https://a.pololu-files.com/picture/0J2596.1200.jpg?5f864c4954fddd4e384b6f72b39afeba) \| \|---\|---\| \| White Pololu Wheel 60×8mm on a Pololu 20D mm Metal Gearmotor. \| | |---| This gearmotor has an output shaft with a diameter of 4 mm; the [Pololu universal aluminum mounting hubs for 4mm shafts](https://core-electronics.com.au/pololu-universal-aluminum-mounting-hub-for-4mm-shaft-4-40-holes-2-pack.html) can be used to mount Pololu's larger [Pololu wheels](https://core-electronics.com.au/hardware/wheels.html) (60mm-, 70mm-, 80mm-, and 90mm-diameter) or custom wheels and mechanisms to the gearmotor’s output shaft (see the right picture above). Alternatively, you could use Pololu's [4mm scooter wheel adapter](https://core-electronics.com.au/pololu-aluminum-scooter-wheel-adapter-for-4mm-shaft.html) to mount many common scooter, skateboard, and inline skate wheels to the gearmotor’s output shaft, and you can use Pololu's [12mm hex wheel adapter](https://core-electronics.com.au/12mm-hex-wheel-adapter-for-4mm-shaft-2-pack.html) to use this motor with many common hobby RC wheels. The gearbox’s output shaft also works directly with the 120mm-diameter [Wild Thumper wheels](https://core-electronics.com.au/dagu-wild-thumper-wheel-120x60mm-pair-with-4mm-shaft-adapters-metallic-red.html), as shown below. | [![](https://a.pololu-files.com/picture/0J2608.250.jpg?35d6e548d9a175130d13c96b8915ed6f)](https://a.pololu-files.com/picture/0J2608.1200.jpg?35d6e548d9a175130d13c96b8915ed6f) | |---| | Dagu Wild Thumper wheel 120×60mm (metallic red) with Pololu 20D mm metal gearmotor. | **Dimension Diagram** 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** (172k pdf). | [![](https://a.pololu-files.com/picture/0J7030.601.jpg?962d2bdedafad034d1e926c6ed8cde0f)](https://a.pololu-files.com/picture/0J7030.1200.jpg?962d2bdedafad034d1e926c6ed8cde0f) | |---| | Dimensions of the original Pololu 20D mm metal gearmotors with shorter output shafts. Units are mm over \[inches\]. This diagram only applies to the listed gear ratios. | This diagram is also available as a downloadable PDF (172k pdf). **Selecting the Right Gearmotor** Pololu offer a wide selection of metal gearmotors that offer different combinations of speed and torque. Pololu's [metal gearmotor comparison table](https://core-electronics.com.au/search/compare/51) can help you find the motor that best meets your project’s requirements. | ![](https://a.pololu-files.com/picture/0J838.600.jpg?fc41071cc34361a828546fe0fcc0b14f) | |---| | Some of the Pololu metal gearmotors. | **People often buy this product together with:** | [![Pololu Universal Aluminum Mounting Hub for 4mm Shaft, #4-40 Holes (2-Pack)](https://a.pololu-files.com/picture/0J1106.100.jpg?46a23ff3e5be0d235783ab6d78a37749)](https://core-electronics.com.au/pololu-universal-aluminum-mounting-hub-for-4mm-shaft-4-40-holes-2-pack.html) | [Pololu Universal Aluminum Mounting Hub for 4mm Shaft, #4-40 Holes (2-Pack)](https://core-electronics.com.au/pololu-universal-aluminum-mounting-hub-for-4mm-shaft-4-40-holes-2-pack.html) | |---|---| | [![Pololu 20D mm Metal Gearmotor Bracket Pair](https://a.pololu-files.com/picture/0J4654.100.jpg?c5beaa94cc078fcb4c7c4f0cd0998e6b)](https://core-electronics.com.au/pololu-20d-mm-metal-gearmotor-bracket-pair.html) | [Pololu 20D mm Metal Gearmotor Bracket Pair](https://core-electronics.com.au/pololu-20d-mm-metal-gearmotor-bracket-pair.html) | |---|---| **Dimensions** | Size: | 20D x 44L mm | |---|---| | Weight: | 43 g | | Shaft diameter: | 4 mm | **General specifications** | Gear ratio: | 73:1 | |---|---| | No-load speed @ 6V: | 180 rpm | | No-load current @ 6V: | 250 mA | | Stall current @ 6V: | 3200 mA | | Stall torque @ 6V: | 60 oz·in | **File downloads** - **Dimension diagram for the Pololu 20D mm metal gearmotors (172k pdf)** **Note:** This dimension diagram only applies to Pololu's older versions with shorter output shafts (gear ratios 29:1, 56:1, 73:1, and 154:1 only). - **3D models of 20D mm gearmotors (1MB zip)** This file contains 3D models (in the step file format) of the 20D mm gearmotors. **Note:** these models only accurately represent to Pololu's older versions with shorter output shafts (i.e. gear ratios [29:1](https://core-electronics.com.au/29-1-metal-gearmotor-20dx41l-mm.html), [56:1](https://core-electronics.com.au/catalog/product/view/sku/POLOLU-1450), [73:1](https://core-electronics.com.au/73-1-metal-gearmotor-20dx42l-mm.html), and [154:1](https://core-electronics.com.au/154-1-metal-gearmotor-20dx44l-mm.html)). **Recommended links** - **[MATLAB script to plot motor performance curves for Pololu brushed DC gearmotors](https://www.mathworks.com/matlabcentral/fileexchange/54695-polulu-motor-plot-generator)** This MATLAB script, written by Ali Asgher Mansoor Habiby, plots speed, power, current draw, and efficiency as they vary with torque when you input the gearmotor specifications. It also prints the resistance of the motor, and the current draw and torque at which maximum efficiency and maximum power occur. ## Images - [Product image 1](https://core-electronics.com.au/media/catalog/product/7/3/73_1_metal_gearmotor_20dx42l_mm__pololu_1163__00.jpg)