Four Stroke Gas Engines. The four strokes of a internal combustion engine are:. Intake. Compression. Power. Exhaust. Each stroke = 180 ˚ of crankshaft revolution. Each cycle requires two revolutions of the crankshaft (720˚ rotation), and one revolution of the camshaft to complete
The four strokes of a internal combustion engine are:
Each stroke = 180˚ of
Each cycle requires two revolutions
of the crankshaft (720˚ rotation), and
one revolution of the camshaft to complete
The piston moves down the cylinder
from TDC (Top Dead Center) to BDC
(Bottom Dead Center).
This movement of piston causes low
air pressure in the cylinder (vacuum)
Mixture of Air and Fuel in the ratio
of 14.7 : 1 (air : fuel) is drawn into
Intake valve stays open and the
Exhaust valve stays closed during
The piston moves from BDC to TDC
Intake and exhaust valves stay closed
Air and fuel mixture is compressed
8:1 to 12:1
The pressure in the cylinder is raised
At the end of compression stroke
the sparkplug fires, igniting the air/fuel
Both the valves stay closed in
The expanding gases from the
combustion in the cylinder
(with no escape) push the piston
The piston travels from TDC to BDC.
Fourth and last stroke
The momentum created by the
Counter-weights on the crankshaft,
move the piston from BDC to TDC.
The exhaust valve opens and
the burned gases escape into the
Intake valve remains closed.
All four strokes
The ratio of cam to crank sprocket is 2:1
For every two revolutions of
Crankshaft, the Camshaft turns once.
The job of the carburetor is to
accurately meter extremely tiny
quantities of fuel and mix it with
the air entering the engine, so that
the engine runs properly.
It works on the principle of
High and low pressure
High and low pressure is created
with the help of Venture
Provides high voltage surges – as high as 47,000 volts to the spark plug
In the engine, dippers on the connecting-rod bearing caps enter
the oil pan with each crankshaft revolution to produce the oil splash.
A passage is drilled in each connecting rod from the dipper to the
bearing to ensure lubrication.(used only on 4-stroke small engines)
Fins are used to dissipate heat
Coolant is used to dissipate heat.