Weapon The pick-ax (found in a friend's backyard) is powered by pressurized CO2. The CO2 is stored in a large cylinder (from a paintball gun) and is fed into a pneumatic cylinder that cocks a heavy spring on windup and pushes on the pickax on release. 
Frame The frame is made of welded aluminum tubing that surrounds a tray holding all of the operating electronics and pneumatic valving. The tray is suspended on bungee cords to absorb some of the shock of being slammed during competition. The two drive wheels are wide set to give some "flip" resistance. This is an important issue when the 2 pound pick-ax  head is carried so high above the ground. 
Drive Train The Shrike is powered by standard RC car motors and  battery pack(s). The small Vantec radio  controller allows operation of both motors  from a single joystick and is used by most competitors. The motor gearboxes are surplus Pitman gearheads, modified to accept the radio control motors. The motors never run hot in practice and the Vantec is, well, overkill. 
Armor For protection from ramming, the pickax wood handle and the front of the frame are especially heavy. The body is made of  Lexan of varying thickness. Armor was added below the frame for protection from arena hazards. 

Battle History
Future Plans