Spur planetary Bevel planetary Spur and pinion Pinion Driven gear Bell gear Sun gear Drive gear Crank shaft Figure 1-34. Reduction gears.  mixture is ignited, the resultant gases of combustion expand  very rapidly and force the piston to move away from the  cylinder head. This downward motion of the piston, acting  on the crankshaft through the connecting rod, is converted to  a circular or rotary motion by the crankshaft. A valve in the  The operating cycle of an internal combustion reciprocating  engine includes the series of events required to induct,  compress, ignite, and burn, causing expansion of the fuel/ air charge in the cylinder and to scavenge or exhaust the  byproducts of the combustion process. When the compressed  1-25