This Bendix starter drive is the engagement mechanism that connects the starter motor pinion to the engine flywheel ring gear when the ignition key is turned. It sits on the starter motor output shaft and uses a solenoid-actuated lever to push the pinion forward into mesh with the flywheel. A worn or sticking drive causes a grinding noise during cranking or a failure to engage, which prevents the engine from starting. The manufacturer machines the drive to the same tooth profile and spring force as the original assembly, so the pinion retracts cleanly after the engine fires without overrunning the armature. On reinstall, ensure the drive slides freely on the starter shaft and that the solenoid plunger travel is adjusted to spec.