Mecanum Wheels, 8 inch

These wheels are sold in kits, unassembled.

We are introducing a new, smooth, convex roller profile for this 8" diameter wheel. This gray urethane rubber roller has a durometer rating of 65a. The roller has a polycarbonate core, and 2 high load bushings. The bushings ride on brass tubes, sandwiched between the plates with an M5 screw. This design has the same coefficient of friction as the former roller design, but with an improved smoother roll.

Here is a view of the new rubber roller.



12 rubber rollers are sandwiched between 2 aluminum plates, forming these 8" diameter Mecanum Wheels. These roller can be purchased individually, or in sets of 12.

Wheels can be purchased in a set of 4, or individually.

Wheels are sold without hubs, sprockets, or bearings. Many people in FIRST Robotics are using these wheels to play the 2010 FRC game. These wheels are being set up in two ways:

1. Sprocket-Driven

If driven by a sprocket, these parts are needed:

• Flanged ball bearings with 1.125" od: AndyMark offers a 3/8" id version (am-0573), and a 1/2" id version (am-0030)
• Two 250 sprocket spacers are needed to space the sprocket out away from the wheel, so the chain clears the edge of the wheel.
• A sprocket with a bolt hole circle of 1.875" diameter mounts to the wheels' interior screws.

2. Shaft-Driven

If the wheel is being driven directly by a rotating shaft (like one on the Toughbox), then use an AndyMark hub, like the 500 Key Hub to mount directly to the shaft. Also, some spacers and a 1/4-20 screw and a 1/4" washer to cap the end of the shaft will hold the hub (and wheel) onto the shaft.

Secification sheet for AndyMark Mecanum wheels

Coefficient of Friction

These are the coefficient of friction constants, as tested on tight pile carpet:

• 6" Mecanum Wheel: 0.6 static forward/reverse, 0.5 sideways
• 8" Mecanum Wheel: 0.7 static forward/reverse, 0.6 sideways
• 10" Mecanum Wheel: 0.54 static forward/reverse, 0.41 sideways

Downloads

Right Wheel .pdf layout print
Right Wheel CAD (.stp) right click, save as
Assembly Instructions, updated 2-2-10