Offset Crankpins; Balance Shaft Timing - International VT 275 V6 Manual

Offset Crankpins

• The 4-stroke engine requires 720° of
crankshaft rotation to complete all four
strokes of the cycle. In a multi-cylinder
engine dividing the 720 degrees by the
number of cylinders will equal the ideal
crankshaft rotation between combustion
events in the firing order. The VT 275
achieves equal spacing of the combustion
events by splitting the crankpins and
staggering the individual journals 30º.

Balance Shaft Timing

• The crankshaft counterweight, flywheel,
and damper are used to offset the rotating
and reciprocating forces developed in the
90° V6 engine, but these components
alone will not offset the couple imbalance.
Couple imbalance is created when two or
more forces act on the crankshaft at
different points along its length. Couple
imbalance, if not offset, results in pitch and
yaw forces on the engine that are felt by
the vehicle occupants as a vibration.
• Couple imbalance forces in the engine are
offset by the balance shaft forces as it
rotates at crankshaft speed but in the
opposite direction.
B B A A L L A A N N C C E E R R S S H H A A F F T T
B B A A L L A A N N C C E E R R S S H H A A F F T T
C C O O U U N N T T E E R R W W E E I I G G H H T T E E D D
C C O O U U N N T T E E R R W W E E I I G G H H T T E E D D
B B A A L L A A N N C C E E R R S S H H A A F F T T G G E E A A R R B B A A L L A A N N C C E E R R S S H H A A F F T T G G E E A A R R
International ® VT 275 V6 Engine
VT 275 DESIGN FEATURES
# # 4 4 C C R R A A N N K K P P I I N N
# # 3 3 C C R R A A N N K K P P I I N N
C C O O U U N N T T E E R R W W E E I I G G H H T T
C C O O U U N N T T E E R R W W E E I I G G H H T T
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