Hey check out my recent WAR ROBOT which participated at QUARK 11 held at B.I.T.S GOA campus. this is simple in design and we have stressed more on "keep it simple rule". there is no such mechanism to damage the opponents bot. only two rammers in the rear and the front have been added. The turning mechanism is differential. For better ground grip instead of wheels belt drive is used. The robot had an excellent torque because of high velocity ratio of 125:1. The power source for this robot is 12v 100amp battery. The speed of the motor is reduced from 12500 rpm to 1500 rpm using a spur gear and then further to 100 rpm using a worm gear.