grounding engages the bendix, which pushes the starter gear out,
to engage the flywheel. As current flows through the starter windings,
the starter spins. When the ignition switch is released from start
to run, the ground is opened releasing the solenoid, stopping current
flow from the battery. Springs return the bendix, which disengages
the gear from the flywheel. With the ignition switch is in the run
position, R is supplying power to the coil.