Force on the piston

= FP = FG – FI ; FG = (PG – Po) AP ; FI = MP a

Piston moving from TDC to BDC

(shown by the red arrow)

Piston moving from BDC to TDC

(shown by the red arrow)

Direction of inertia force (FI) on the piston pin is shown by the blue arrow

TDC

45 0 aTDC

90 0 aTDC

BDC

BDC

90 0 aBDC

135 0 aBDC

BDC

Variation of piston position, velocity and acceleration