1. Piston Pin Semi-Floating Pins are used to a limited extent
Modern engines mainly use Fully Floating Pins
Semi-Floating Pins are used to a limited extent
Important Parameters
Bending Stresses
Shearing Stresses
Stresses and Strains due to the Ovalization of the pin 1

2. Piston Pin
The Height and mass of a piston is influenced by the diameter of the piston pin
Failure occurs due Fatigue stresses arising from ovalization and by tangential shear
Carburizing increases the endurance limit by %
Nitriding by % 2

3. Loading of the Piston Pin3

4. Loading of the Piston Pin4

5. Loading of the Piston Pin
The Following Forces are considered
The maximum force due to combustion (a > 360 ) and the inertia force toward TDC (a<360)
Inertia forces at the end of the exhaust stroke toward TDC (a<720) 5

6. Checking Dimensions Against Bending
mp= mass of piston assembly
r = S/ l’ = r/l l = Connecting rod length
s = Bending stress < x 105 kN/m2
w = radial velocity of the crankshaft (rad/s) 6

7. Checking Against Pressure in Projection Area7

8. Checking against Tangential Shear Stress8