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Top dead center in a gasoline engine. In a reciprocating engine, the dead centre is the position of a piston in which it is either farthest from, or nearest to, the crankshaft. The former is known as top dead centre (TDC) while the latter is known as bottom dead centre (BDC). [1] Position of pistons
BDC = Bottom dead centre; IO = Inlet valve opens; IC = Inlet valve closes; EO = Exhaust valve opens; EC = Exhaust valve closes; Either valve opens before the piston head reaches top dead centre or bottom dead centre. The amount in crankshaft degrees by which the valves open before top dead centre or bottom dead centre is reached is known as ...
This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing a partial vacuum (negative pressure) in the cylinder through its downward motion.
This position is also known as the bottom dead center (BDC), or where the piston forms the largest volume in the cylinder. The piston is returned to the cylinder top (top dead center) (TDC) by a flywheel , the power from other pistons connected to the same shaft or (in a double acting cylinder ) by the same process acting on the other side of ...
Just as with a boxer-four, piston pairs from opposite banks reach top-dead-centre at the same time, but with a crankpin split of only 60° instead of 180°, potentially giving a shorter and stronger or stiffer crankshaft. For 60° V6s, the crankpins are usually split the other way causing the paired pistons to reach top-dead-centre 120° apart.
From top dead center to 34% of stroke, the crank turns through an angle of about 71°. In the six cylinder engine, one piston reaches top dead center every 360°/6 = 60°. The three cylinder WHE-DR engine only has a piston reach TDC every 120°, so its admission valve must be open over a much larger angle to ensure the engine is self-starting.
As the piston moves toward the valve plate, fluid is pushed or displaced through the discharge port of the valve plate. Effect of precession. When the piston is at the top of the reciprocation cycle (commonly referred to as top-dead-center or just TDC), the connection between the trapped fluid chamber and the pump's discharge port is closed ...
This is because the big end of the connecting rod swings from side to side, so that the motion of the small end deviates from ideal sinusoidal motion between top and bottom dead centre on each swing, i.e. twice per crank revolution, and the distance the small end (and a piston connected to it) has to travel in the top 180° of crankshaft ...