These large ATR wheels are 6.75" in diameter. They come as pair since they have directional tread. This item also includes a custom machined hex shaft which locks into the wheel hub. These are similar to the TD-023-002, except the shaft is longer and two bearings per shaft are included. The end of the shaft is then drilled out to accept an encoder shaft. The shaft is bored to 1/4" and accepts the set screw from the shaft collar to lock the encoder shaft to the wheel shaft. Also included is a encoder mounting plate. The plate has a 3/8" hole and 4 bolt holes that match the holes in our ATR bases. This kit does not include the encoders. We suggest US Digital for great encoders.

The best way to put encoders on the robot is on non-driven wheels. That way during turns, bad traction, etc and the drive wheels spin, the encoders do not think the robot has moved. Our new 2nd generation ATR frames can be set up as 6WD. So just go with a 4WD and then add this wheel set. It will look like 6WD, but instead of driving the middle two wheels, let them be attached to encoders. The design of the 2nd generation ATR includes center wheel bearing holes that are lowered 1/16", so they will be making contact over most conditions. The tires are somewhat pliable, so all tires will be making contact, the center one will have the best contact, which is ideal for keeping track of the robots movement.

The picture below shows the mounting of a typical encoder (click on it for a larger view). All the hardware shown is included to mount two encoders. Several different sized nylon spacers are included so you can space the plate off the ATR frame based on your encoder.

The Pair of wheels include the following:

• (1) Pair 6.75 Wheels
• (2) Custom Made hex Shafts matched for wheels
• (2) Laser Cut Encoder Mounting Plates
• (4) 1/2"ID sealed bearings
• (4) 1/2"ID shaft collars
• (2) Set Screws (with 1/4" bore option)
• (1) Hardware to mount the encoder
• (2) Bolts for Mounting the Tires to the Shaft