Mecanum wheels allow your robot to not only travel forward and backward, but also sideways! Nine rollers set on a 45° rotational axis parallel to the main rotational axis of the wheel enable a broad a range of movement. Rotating all four wheels in the same direction causes forward or backward movement, rotating the wheels on one side in an opposite direction to those on the other side causes the vehicle to rotate, and rotating the wheels on one diagonal in the opposite direction to those on the other diagonal causes side-to-side movement.
These mecanum wheels come in sets of 4 (2x left, 2x right). They are directly compatible with LEGO® shafts but also include adapters allowing them to mate with the shafts on many of our motors. They are about 65mm in overall diameter and weigh about 48.5g each.
Notes: For the best performance, there a few things you should know. The wheels might need a little lubrication to get the rollers moving well enough for lateral movement. Some basic grease works well. Since lateral motion relies on the motors moving against each other, you will get the smoothest lateral movement when the wheels are traveling at the same speed. The use of encoders (or some feedback loop) is recommended. Lastly, making sure your robot platform is balanced helps tremendously as well. Too much weight in the front or back can cause poor results.