At the top of the cylinder head is the camshaft. With the help of egg-shaped cams, the valves are brought into an open or closed state at a certain position of the pistons. This is determined by the so-called valve timing. The camshaft rotates on five bearings: the drive is carried out by a toothed belt from the crankshaft. The valves are thus driven along the shortest path from the camshaft: the eccentric of the shaft presses on «intermediate support» - a pusher, which further, in turn, presses down on the valve, overcoming the force of the valve spring. Thus, the gap between the plate with the valve seat becomes free - the valve opens. However, the cams do not touch the pusher exactly in the middle, but are slightly offset. This causes the valves to rotate a small distance about their axis on each downward stroke. Thus, the valves beat unevenly and leaks form over time.
The intake and exhaust valves are mirrored to each other and additionally coated with hard metal for better heat distribution (stellite) for exhaust valves. These valves are located on the front side of the engine.
Suction diesel engine sectional view:
1 - thermostat housing
2 - generator
3 - injection pump
4 - Gas-filled shock absorber (see chapter «Diesel injection system»)
5 - Crankcase ventilation pressure regulator valve
6 - nozzles
7 - piston
8 - vacuum pump for brake booster
9 - oil cooler
10 - flywheel
Attention: Strong valve noise in an engine with a hydraulic pusher may occur during the first time after the first start of the engine. who had been unemployed for a long time. This effect occurs when all the oil has flowed out of the hydraulic pushers and, as a result, a gap has reappeared in the valve drive (see next section). There is no reason to worry: the noise will disappear after a short time and the valve actuator will again work without play.
The cylinder head also has swirl rings along with injectors and glow plugs.
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