This example shows how to model a gear with backlash using the Simple Gear in series with the Foundation Library Rotational Hard Stop. The backlash is set to 0.2 degrees, and the damping adjusted so that there are a few oscillations when the torque is applied.
The Simscape Local Solver is configured so that it will provide nearly equivalent results when it is enabled. Discontinuous physical effects such as backlash require a small step size to capture the behavior accurately. The Simscape Local Solver can be enabled in the Solver Configuration block.
The plot below shows the speed of two shafts connected by gears with backlash. The input shaft is driven by a constant torque. As the input gear strikes the output gear, each impact accelerates the output shaft. Eventually, the shafts spin at the same speed.