The document summarizes the key components and operation of a straight three cylinder engine. It consists of three cylinders mounted on a single crankshaft. Each cylinder has a piston connected to the crankshaft by a connecting rod. The engine operates on either a 2-stroke, 4-stroke or 5-stroke Otto cycle. Firing orders are designed to minimize vibrations, with common orders being 1-3-2 or 1-2-3. Valve timing diagrams show the opening and closing of intake and exhaust valves. Balancing shafts are required to reduce vibrations at high speeds. Applications include motorcycles, agriculture, and aviation.

1. THREE CYLINDER
ENGINE
BY
GIRISH YUVRAJ SURVE
A Presentation On

2. INTRODUCTION
• It is a straight three engine also known
as inline triple or inline three cylinder
engine having reciprocating piston, IC
engine.
• It works on the basis of otto cycle.

3. CONSTRUCTION
• It consist of three cylinder mounted on single shaft.
• Cylinder is supported in position by the cylinder block & top is
covered by cylinder head. This structure is mainly consist of cast iron.
• Piston is made of Al in small engine & of cast steel in larger slow
speed engines.
• The space between cylinder head & top of piston is called combustion
chamber.

4. • Piston is connected to crankshaft through connecting rod made of forged
steel.
• Crankshaft is supported in bearing mounted in crankcase which is the main
body of engine.
• Piston has at least three rings. Upper rings are called compression rings &
are forced outward against the cylinder wall & do not allow combustion.
The lower ring is usually an oil control ring.
• The valves are usually operated by cams.
• The straight 3 cylinder engine generally employ a crank angle of 120

5. WORKING
• The three cylinder petrol engine works on the otto cycle.
• It works on various strokes
• 1) 2 stroke
• 2) 4 stroke
• 3) 5 stroke

6. FIRING ORDER
• It is the order in which the firing impulses occur in multi-cylinder SI
engine.
• Used to minimize the engine vibrations.
• It gives uniform torque and uniform distribution of firing.
• Firing order in 3 cylinder engine is 1-3-2 or 1-2-3.

7. VALVE TIMING DIAGRAM OF ENGINE
• Valve timing is the regulation of points in the cycle at which valves are
set to open and close.
• In reciprocating IC engine, the inlet and outlet valves are opened and
closed by cam mechanism.
• Clearance between cam, tappet and valves has to be taken up slowly
in order to avoid noise and wear, the valve is lifted slowly.
• Therefore the opening and closing period of valves are spread over
considerable number of crank angles.

8. VALVE TIMING DIAGRAM (CONT.)
Valve Timing Diagram of SI Engine Valve Timing Diagram of CI Engine

9. BALANCING
• It is difficult to keep balance in triple & also in counter-rotating . So
balancing shafts are needed to keep thing revving smoothly at high
speeds.
• It is done to remove the stresses.
• In order to balance the engine flywheels are used.

10. ADVANTAGES
• Fuel Efficiency
• Lower frictional losses
• Lighter weight
• Compact size
• Cost saving

11. DISADVANTAGES
• Faster strokes are required
• Noise production

12. APPLICATIONS
• Motor cycle
• Non-automotive use
• Agricultural use
• Aviation use