8275

The 8275 bulldozer has by lego design a motor for the legt track and a motor for the right track. Because the two motors will never be the same there will be small drift if going in a staight line. 

Differential steering solves this problem; by using one motor for forward reverse and the other for steering straight will be straight. 

The trick is to have two differentials. The first one is moved by the drive motor the second one with the steer motor. By having an uneven gear train and even gear train the gears coming together in the steering diff cancel each other out and the diff doesn't move. 

p.
dijkstra 
    @         
yahoo.
co
.uk