Mechanical Engineering

What is a make or break engine?

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Wiki User
2009-08-24 01:10:39

A "make AND break engine" is an engine which controls

power/speed by making (enabling) and breaking (disabling) the

ignition cycle.

In one classic design: One or more large flywheels are attached

to the crankshaft. A flyweight governor is also attached to the

crankshaft. When the shaft speed slows, the flyweight falls inward,

releasing a mechanism which allows the exhaust valve to open. When

the piston rises to the cylinder head, the exhaust is pushed out.

When the piston pulls back, suction is created. a check valve

(one-way valve) in the exhaust closes. That resulting suction opens

the intake valve and draw fuel/air mix in. The piston then

compresses, ignition occurs, and we get a power stoke. This kicks

the crankshaft speed back up. The flyweight pushes out, covering

the exhaust valve, and thus blocking further engine cycles. The

flywheel, crankshaft, and piston run free, on momentum, until shaft

speed slows again, and the process repeats.

This is in contrast to most modern engines, which vary

speed/power with a throttle, limiting and increasing fuel/air mix,

but keeping the ignition cycle active at all times.

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