ARMY TM 9-2815-257-24 AIR FORCE TO 38G1-128-2 MARINE CORPS TM 10155A/2815-24/3 2-3 1. Solenoid 2. Dust Cover 3. Dust Cover 4. Torsion Spring 5. Shift Lever 6. Over-Running Clutch 7. Gear Case 8. Pinion Stopper 9. Gear Case Bearing 10.   Pinion 11.   Armature 12.   Yoke 13.   Rear Cover 14.   Dust Cover 15.   Rear Cover Bearing 16.   Brush Holder 17.   Brush 18.   Field Coil    Figure 2-1.  Engine Starter Motor (Side View) c.     Power Stroke.  The combustion of the air and fuel mixture forces the piston (8) downward, causing the piston connecting rod to turn the crankshaft (6).  The crankshaft is coupled to the end item and drives the end item as designed. d.    Exhaust Stroke.  As the crankshaft (6) turns, it pushes up on the connecting rod, forcing the piston (8) to rise to its high point again.  Once the piston begins to rise, the exhaust valve (9) opens.  Exhaust gases (a result of the air / fuel combustion) are forced out of the cylinder through the exhaust valve.  The valve closes just before the piston reaches it high point. e.     Intake Stroke.  As the piston (8) moves downward again, the inlet valve (10) opens.  Air is drawn through the open valve and into the cylinder.  The inlet valve closes just before the piston reaches the end of its stroke (low point in the cylinder).  The piston moves upward once more to repeat the combustion cycle. A decompression lever (1) installed in the rocker arm cover is utilized during manual start operations.   A  breather  (2)  regulates  the  amount  of  pressure  built  up  on  the  chamber  and  opens  to  release  pressure  as required.  An air cleaner (3) ensure that air entering the combustion chamber is free of particles that could cause damage to engine components.