Starter Controls - LUCAS: Description

Starter solenoids are electro-magnetic actuators mounted externally on the yokes of pre-engaged starting motors. These solenoids contain a soft iron plunger (linked to engaging lever), starter switch contacts and a coil with two windings (a heavy gauge pull-in winding and lighter gauge hold-in winding). Initially, both windings are energized in parallel when starter device is operated, but the pull-in winding is shorted out by the starter switch contacts at the instant of closure. Solenoids described here are sealed in a rolled steel outer case or body and cannot be disassembled. Most ground return starter solenoids have three terminals (two large and one small) with the exception having an additional small terminal marked "IGN" which is used in conjunction with the ignition coil ballast resistor. These units have an auxiliary phosphor bronze contact which serves to cut out the ballast resistor during starting, thereby ensuring that terminal voltage of the coil remains unaffected by the drop in battery voltage.