These rugged wheels are designed to press-fit securely onto the 3mm D output shafts of Pololu's micro and 15.5D metal gearmotors. These gearmotors should be mounted onto the side of the hub with the protruding teeth, as shown on the right. The output shaft will slide into the socket easily at first but will achieve a snug fit when pressed through to the other edge of the hub.
The output shafts on Pololu's selection of Solarbotics metal gear motors will also fit these wheels, but because they are shorter they will have to be mounted onto the other side of the wheel where the fit is tighter (which means the Solarbotics metal gearmotors will not work with the quadrature encoder associated with this wheel). These wheels will also work in this orientation on the Pololu plastic gearmotors with 3mm D-shaft outputs.
Pololu's extended micro metal gearmotor bracket is specifically designed to work with this wheel. Please note that the non-extended version of Pololu's mounting bracket (product #989) will not work well with this wheel.
|Micro metal gearmotor with Pololu wheel 42×19mm and extended bracket.|
- Diameter: 1.65″ (42 mm)
- Width of tire: 0.75″ (19 mm)
- Weight: 0.66 oz (19 g)
- Shaft type: 3mm “D”
The hub has twelve teeth, each 3 mm wide and separated from its neighbors by 3 mm gaps. Pololu offer a quadrature encoder that uses these teeth to provide up to 48 counts per revolution (a linear resolution of just under 3 mm or 1/8″). The encoder is designed to work with Pololu's extended micro metal gearmotor bracket and Pololu's micro metal gearmotors as shown in the pictures below. The compact layout of the board fits all of the components within the envelope of the hub and tire, allowing the board to be mounted between the motor and a chassis. The encoder can be purchased as an individual unit or as a part of an encoder set that includes two encoders, a pair of extended brackets, and a pair of 42×19mm wheels.
The following oscilloscope capture shows the two encoder output channels while the 42×19mm wheel is spinning at close to 630 RPM. The two channels are approximately 90° out of phase, allowing you to determine both rotational speed and direction.
|Oscilloscope capture of encoder outputs with the wheel spinning at 630 RPM.|
Documentation and Resources:
We deliver Australia-wide with these options:
- $3 for Small Items (4-6 days, not tracked, only available on selected small items)
- $6.95 for Standard Post (2-4 days, tracked)
- $8.95 for Express Post (1-2 days, tracked)
- Pickup - Free! Only available to customers who live in the Newcastle region (only after we email you to notify your order is ready)
International Orders - the following rates are for New Zealand and will vary for other countries:
- $11.49 for Pack and Track (3+ days, tracked)
- $16.50 for Express International (2-5 days, tracked)
If you order lots of gear, the postage amount might increment based on the weight of your order.
Our physical address:
Unit 18, 132 Garden Grove Parade
Please checkout our customer service page if you have other frequently asked questions such as "do we do purchase orders" (yes!) or "are prices GST inclusive" (yes they are!). We're here to help - get in touch with us to talk shop.