QUANCHAI N485D, Руководство по обслуживанию

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1.2 Valve timing
The valve timing, as the actual switched
represented by an annular chart of the crankshaft angle relative to the crank throw positions of the top and
bottom dead centers. Such chart is called valve timing chart.
Switched-on intake valve before top dead center 12±3°
Switched-off intake valve after bottom dead center 38±3°
Switched-on exhaust valve before bottom dead center 50±3°
Switched-off exhaust valve after top dead center 14±3°
Theoretically, the intake valve of a four
off when the crank throw turns to bottom dead center. The exhaust valve is on when the crank throw is at
bottom dead center, and off when the crank throw turns to top dead center.
account for 180° crankshaft corner. However, the actual rotating speed of the crankshaft is very high, and
each stroke of the piston is very short. Such short
inflation or incomplete exhaust, thus reducing the e
method of prolonging intake and exhaust time. That means that the switched
not exactly the time when the crank throw is at the top and bottom dead centers; instead, a cert
angle is advanced and delayed respectively to improve the intake and exhaust conditions, thus improving the
engine power.
For different types of engines, the valve timing also varies due to their different structures and rotating speed.
Reasonable valve timing shall be determined through repeated tests according to the performance
requirements of the engine.
ANHUI QUANCHAI ENGINE CO., LTD
The valve timing, as the actual switched-on and off time of the intake and exhaust valves, is usually
represented by an annular chart of the crankshaft angle relative to the crank throw positions of the top and
Such chart is called valve timing chart.
on intake valve before top dead center 12±3°
off intake valve after bottom dead center 38±3°
on exhaust valve before bottom dead center 50±3°
e after top dead center 14±3°
Theoretically, the intake valve of a four-stroke engine is on when the crank throw is at top dead center, and
off when the crank throw turns to bottom dead center. The exhaust valve is on when the crank throw is at
tom dead center, and off when the crank throw turns to top dead center. Both intake time and exhaust time
rankshaft corner. However, the actual rotating speed of the crankshaft is very high, and
each stroke of the piston is very short. Such short-term intake or exhaust process often leads to insufficient air
inflation or incomplete exhaust, thus reducing the engine power. Therefore, modern engines all adopt the
method of prolonging intake and exhaust time. That means that the switched-on and off time of the valve is
not exactly the time when the crank throw is at the top and bottom dead centers; instead, a cert
angle is advanced and delayed respectively to improve the intake and exhaust conditions, thus improving the
For different types of engines, the valve timing also varies due to their different structures and rotating speed.
Reasonable valve timing shall be determined through repeated tests according to the performance
on and off time of the intake and exhaust valves, is usually
represented by an annular chart of the crankshaft angle relative to the crank throw positions of the top and
stroke engine is on when the crank throw is at top dead center, and
off when the crank throw turns to bottom dead center. The exhaust valve is on when the crank throw is at
Both intake time and exhaust time
rankshaft corner. However, the actual rotating speed of the crankshaft is very high, and
term intake or exhaust process often leads to insufficient air
ngine power. Therefore, modern engines all adopt the
on and off time of the valve is
not exactly the time when the crank throw is at the top and bottom dead centers; instead, a certain crankshaft
angle is advanced and delayed respectively to improve the intake and exhaust conditions, thus improving the
For different types of engines, the valve timing also varies due to their different structures and rotating speed.
Reasonable valve timing shall be determined through repeated tests according to the performance