Old Volvo Truck

two forward and two back transmissions

differential and direction control

https://www.youtube.com/watch?v=w-I3xI22w1Q&feature=youtube_gdata_player

Step 1:

Step 2: Http://www.instructables.com/id/Knex-Differential-Version-2/

https://www.instructables.com/id/Knex-Differential-Version-2/

Step 3:

Step 4:

Step 5: Steering Wheel

Step 6: