Diagram shows a gear B, with 100 millimeter diameter, is placed above the gear C with 200 millimeter diameter. A shaft passes through gear C. A torque T in counter clockwise direction is applied on the shaft at D, a torque T subscript A in clockwise direction is applied on the shaft at A . The x-axis passes through the shaft.

The external torque T=685 N-m applied to shaft (2) creates the following torques in the system:

The torque TB is exerted on gear B by shaft (1). In turn, gear B exerts an equal but opposite torque on shaft (1).