There are certain mechanisms that we want to remain
locked once they have stopped—for example, a winch on
a crane or a rail-crossing barrier. If such mechanisms are
motorized, a stopped motor will keep them stopped, but
only until the load on the mechanism overcomes the motor’s
resistance and starts to drive it backward. This scenario is
likely in the case of a heavy load, such as what a crane might
carry.
Figure 8-8: The angle of the pawl should be such that the line coming out
of its mounting point aims slightly below the gear’s rim.