This document summarizes key information about pistons, including: 1) Pistons are a main part of engines and transmit thrust from fuel combustion to the crankshaft. They are typically made of aluminum alloy. 2) Pistons provide a closed chamber for combustion gases and allow for air intake and compression. They transfer heat energy to the crankshaft. 3) Piston parts include the head, skirt, ring grooves, ring lands, gudgeon pin boss. Proper clearances and ring types are important for sealing and reducing wear.

1. PRESENTATION
ON
PISTON
BY
SURENDRA KUMAR PATEL
JE (E&M) Course Srl No 07
158 FCPL/71 rcc/24 tf/(p)PUShPAK

2. Pistons

3. INTRODUCTION : PISTON IS ONE
OF THE MAIN PART OF ENGINE.
WHICH IS SUBJECTED TO
ENORMOUS THRUST CAUSED BY
BURNING OF FUEL AND
TRANSMITTING THIS THRUST TO
THE ROTARY MOTION OF CRANK
SHAFT. THESE ARE MOSTLY MADE
OF ALUMINUM ALLOY. TO

4. AIM :
(1) PROVIDES CLOSED CHAMBER
TO GASES TO BURN.
(2) SUCKS AIR DURING SUCTION
STROKE.
(3) COMPRESS AIR DURING
COMPRESS STROKE.
(4) IT A MEDIUM TO TRANSFER
HEAT ENERGY TO CRANK

5. FUNCTION OF PISTON :
(1) WHEN THE PISTON MOVES FORM
TDC TO BDC IN SUCTION STROKE IT
PRODUCES A PARTIAL VACUUM DUE
TO WHICH FRESH CHARGE IS SUCKED
IN I.E WORKS AS PUMP FOR TAKING
AIR IN THE CYLINDER.
(2) SOME OF THE PISTON HAVE
COMBUSTION CHAMBER MADE IN

6. PRODUCED IN THE POWER STROKE
TO CRANK SHAFT.
(4) IN EXHAUST STROKE IT PUSHED
OUT EXHAUST GASES.
(5) IT WORK AS A GUIDE FOR THE
UPPER PART OF CONNECTING
ROD.
(6) IT CARRIES RING WHICH SEAL
COMBUSTION FROM SUMP.

7. PARTS OF PISTON
(A) HEAD
(B) SKIRT
(C) RING GROOVE
(D) RING LAND
(E) GUDGEON PIN BOSS

8. Piston Construction

9. Piston Construction
 Piston head
– Round
– Approx. .040 undersized
 Ring grooves
 Ring lands
 Drain holes and slots
 Wrist pin boss

10. HEAD : IT IS THE UPPERMOST PARTS OF
PISTON WHICH IS SUBJECTED TO HOT
BURNING GASES WITH TEMPERATURE
AND PRESSURE.
SKIRT : SKIRT OF LOWER PART OF
PISTON AND WORKS AS A GUIDE FOR
THE PISTON SO THAT IT MOVES
STRAIGHT IN THE CYLINDER.
RING GROOVE : GROOVE ARE MADE IN
THE PISTON TO ACCOMMODATE
COMPRESSION AND OIL RING GROOVE

11. RING LAND : THE SPACE LEFT IN THE
CIRCUMFERENCE OF PISTON AFTER CUTTING
RING GROOVE IS CALLED RING LAND.
GUDGEON PIN BOSS : THE PLACE WHERE
GUDGEON PIN IS FIXED IN THE PISTON IS
KNOWN AS GUDGEON PIN BOSS AND IS
USUALLY REINFORCED.
THIS IS ALSO KNOW AS WAIST PIN AND IS
USED TO CONNECT PISTON WITH
CONNECTING ROD. IT IS MADE OUT OF STEEL
ALLOY AND HOLLOW FROM INSIDE SO THAT
IT IS LIGHT WIGHT AND AT THE TIME,

12. CLEARANCE OF PISTON : FOR
THE COST IRON PISTON KEEP
CLEARANCE 0.0007” (0.018 MM)
PER INCH DIA. OF PISTON AND
FOR ALUMINUM ALLOY PISTON
KEEP 0.001” (0.025 MM) PER
INCH DIA OF PISTON.

13. PISTON RING : PISTON RING ARE
USED IN PISTON TO MAINTAIN
GAS TIGHT SEAL BETWEEN THE
PISTON AND CYLINDER. PISTON
RING MOSTLY MADE OUT OF
CAST IRON.
PISTON RING IS TWO TYPE.
(A) COMPRESSION RING

14. Piston Construction
 Materials
– Cast iron (used in very old engines)
– Cast aluminum (most common)
– Forged aluminum
– Hypereutectic alloys (high silicon content
aluminum)
– Carbon Graphite (being tested)

15. Piston Construction
 Piston Pin Offset
– The piston pin is offset towards the major thrust
side of the piston to reduce piston wear, and
piston noise
– The major thrust side is the side that is loaded
during the power event
– The minor thrust side is the side loaded during
the compression event

16. Major/Minor Thrust

17. Piston Direction
Pistons should be positioned so arrow, dot or other marking
faces the front of the engine (except reverse rotation
engines)

18. Piston Head Design
 Pistons may have a dished, flat or domed
design

19. CONCLUSION : PISTON IS
VERY IMPORTANT PARTS OF
ENGINE. WITHOUT PISTON IT
IS NOT PASSABLE TO FORM A
ENGINES. PISTON IS A BACK
BONE OF ENGINE.

20. THANKS
YOU