as the cart 10 is pushed pulled or turned moreover the elasticity of the flexible coupling 78 readily maintains the potentiometer shaft in a fully off rest position and compensates for any misalignment between the shaft of the potentiometer 74 and the throttle shaft 76 the throttle hand grip 54 is the principal manual control mechanism for the cart 10 two state type controls such as a forward reverse switch not shown braking mode control switch not shown may be separately mounted on the guiding arm 18 to move the cart 10 straight ahead the operator merely twists the hand grip 54 which activates the throttle 66 the circular cap 82 rotates the throttle shaft 76 and coupling 78 which in turn rotates the control shaft 74 of potentiometer 72 the resultant change of electrical resistance is communicated as an electrical signal via cable 68 to the motor power control circuit 40 fig1 the motors are each independently activated to pull the cart forward as hereinafter explained the side wheels 28 and 30 if equally loaded direct the cart 10 substantially straight ahead to turn the cart the operator may press the hand grip 54 and thereby the guiding arm 18 to the right or the left either pushing one wheel slightly faster motor speed and the speed of the other wheel or slowing one wheel and motor to permit the other motor and wheel to pull the cart 10 in the desired turning arc the frame member 70 must be a relatively sturdy construction for example the frame member 70 may include a block 88 snugly engaging the inner.