The model also multiplies transmission speed by gear ratio, which loops back to the torque converter. A transmission model consists of a torque converter model and a transmission-ratio model. System models often require loops that feed the results of a computation back into a block in the model. The model simulates a dynamic system. Not all loops provide feedback to the system.
Some loops can simulate mathematical expressions.
For example, you can evaluate a differential equation using integrals and loops. The bottom diagram in Figure 1 is a state diagram with feedback. It simulates the logic in a transmission that decides when the transmission should shift gears. The shift logic tries to reach a steady state based on external inputs of throttle position and vehicle speed. In the steady state, the transmission is in the proper gear.