Two stage starter drive system

A device for supplying dual electrical power levels to the cranking motor and solenoid actuator of a positive shift starter drive system for cranking the crankshaft of an engine, said device comprising:

• a source of electrical power;
• a starter switch connected to said source of electrical power;
• a cranking motor having an output shaft rotatable in response to receiving electrical power from said source of electrical power;
• a pinion gear attached to said output and rotatable therewith, said pinion gear axially translatable along said output shaft;
• a cranking gear attached to the engine's crank shaft;
• solenoid actuator means having a resiliently biased armature movable therein from a first to a second position, a pull-in coil and a hold-in coil receiving electrical power from said source of electrical power through said starter switch, said armature movable from said first position against the force of said resilient bias to said second position in response to said pull-in coil receiving electrical power and operative to remain in said second position as long as said hold-in coil receives electrical power, said pull-in and hold-in coils each having an input lead connected to the starter switch and an output lead, said output lead of said hold-in coil connected to a common electrical ground;
• shifting means mechanically linking said armature with said pinion gear for axially displacing said pinion gear into engagement with the engine's cranking gear when said armature is in said second position and for axially displacing said pinion gear to disengage from the engine's cranking gear when said armature is in said first position;
• and
• switch means attached to said solenoid actuator means for controlling the electrical power received by the cranking motor and the pull-in coil as a function of the position of the solenoid actuator means armature, said switch means applying full electrical power to the pull-in coil and no power to the cranking motor with the armature in said first position for applying reduced electrical power to said pull-in coil and to said cranking motor after said armature has moved to a predetermined intermediate position between said first position and said second position, and for applying full electrical power to the cranking motor and no electrical power to the pull-in coil when said armature is in said second position.

In combination with an external source of electrical power;

• a second electrically activated device;
• and a solenoid actuator of the type having a pull-in coil;
• a hold-in coil;
• a resiliently biased armature, said armature being movable from a first position to a second position in response to said external source of electrical power energizing said pull-in and hold-in coils;
• and a dual mode power switch, the improvement comprising:
• two normally open electrical switches sequentially closed by movement of the armature of said solenoid actuator from said first position to said second position, the first of said two switches having an input terminal for receiving electrical power from the external electrical power source, and an output terminal, said first switch closing in response to the resiliently biased armature of said solenoid actuator being displaced to a predetermined intermediate position between said first and second position and the second of said two switches having an input terminal for receiving electrical power from the external source and an output terminal connected to the output of said hold-in coil and to the input of said second electrically activated device, said second switch closing in response to the armature being in its second position;
• and
• a resistance having a predetermined value connected between the output terminal of said first switch and the input of said second electrically activated device.