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Hydropushers
The hydraulic valve control system is used to ensure that there was a gap in the valves and the valves are closed tightly against the seat. Hydropushers arranged between the cams of the camshaft and the end of the valve stem. Unlike systems with hydraulic adjustment - move the valve without gaps, significantly reducing noise compared with the operation of conventional valves.
PRACTICAL ADVICE Knock valves when the engine is started |
When the engine is not working for a long time, the sound of the valve is not the cause of failure. When the engine is running long hydropushers oil flows. When the engine start up, immediately hydropushers filled with oil, and the sound disappears. If the sound of the valves in the cylinder head extends to the engine is warm, it indicates a defect of one or more hydropushers. They can not be repaired and should be replaced. Causes knock valves may include the following: 1. Before starting the engine, it has been replaced by oil. 2. The engine is not running more than a day. 3. The engine starts after replacing the pushrods.
The principle of adjusting the thermal hydraulic valve clearance
| Fig. 4.18. Hydropusher cutaway: 1 - camshaft; 2 - an oil reservoir in the housing; 3 - return valve; 4 - channel oil supply; 5 - pressure zone; 6 - the valve stem; 7 - a spring; 8 - cylinder; 9 - piston; 10 - Housing hydropusher
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Hydropushers consist of two main parts - the piston and the cylinder (Fig. 4.18). The spring pushes the piston to the surface of the pusher. When the valve is closed oil flows from the engine lubrication system for the oil gallery in the cylinder head through the overflow hole in the hull of the pusher in the pusher cylinder. Check valve tappet is opened and the oil fills the grooves of the piston. When pressing on the cam camshaft tappet body it pushes the piston, under the influence of which the valve closes and stops the bypass oil. Since the liquid is not compressed in this case, the oil serves as a rigid connection between the cam of the camshaft and the valve stem, so when pressed on the valve clearance is not available. The pressure difference is then compensated bypass oil from the cylinder push rod in his body, carrying out extra lubrication of working parts of the cams of the camshaft. After closing the valve, the pressure in the housing falls pusher opens the check valve and the cylinder is filled with oil again. When long-term operation of the engine valve train parts wear out, but because of the principle of the hydropushers check valve clearance can be carried out through a relatively long period of time.
Check hydropushers 1. Warm up the engine. 2. Allow the engine to idle until the first turn on the fan. 3. Run the engine for 2 minutes at high speed (2500 min -1). 4. Turn off the engine. 5. Remove the cylinder head cover. 6. Turn the engine until a verifiable cylinder camshaft lobes will not be directed upwards.
| Fig. 4.19. Check hydropusher: 1 - pusher; 2 - Wedge
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8. If the plunger quickly and without resistance is lowered, it should be replaced. This work should be done in the workshop experts.
PRACTICAL ADVICE Work at high speed Operation at higher speeds reduces engine life. If the engine runs at higher speeds and at the same time heard a knock or noise, it shows the wear of the crankshaft and valve train. If you wear heavy, it may break the pusher. As a rule, this leads to serious damage to the engine |
. Some hydropushers faults, their causes and remedies are listed in the table.
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