This article describes in detail the adjustment of the valve clearance of the top type engine of the Kobelco excavator camshaft, the adjustment of the valve clearance of the common top valve engine and the quick adjustment of the valve clearance.
Adjustment of valve clearance for A Kobelco excavator camshaft top one engine
1 because the camshaft top mounted engine can not be adjusted in operation, it is necessary to shut down the engine and adjust it in the cooler condition (around 20 degrees Celsius).
2 unload the cover of the valve chamber;
3 make the first cylinder piston at the upper dead center of the compression stroke. When the vehicle is adjusted, the crankshaft can be rotated, the fan belt can be pressed with the right hand and the fan is turned with the left hand.
4 adjust the cam clearance of the L cylinder. Most of the engine adjustment operation should be done according to the following method, that is, first unlock the locking nut of the swing arm bolt, and rotate the screw (support shaft) to insert the thickness gauge into the cam and the rocker arm at the same time. The clearance value specified by each manufacturer is 0.15 to 0.35 millimeters, and the exhaust valve is 0. .25 ~ 0.43 mm. If the clearance of the inlet valve is too small and the valve is jacked up, it is easy to blow back together. In addition, when the aluminum cylinder head is used, the gap between the exhaust valve and the valve is smaller because of the thermal expansion.
5 cam clearance adjustment, do not tighten the cylinder head bolts, otherwise it will cause cam gap changes.
6, tighten the lock nut tightly to avoid changing the gap due to loosening.
7 after adjusting the cam clearance of the above cylinders and cylinders, install the valve chamber cover and adjust the operation to the end.
Adjustment of valve clearance for B top mounted valve type engine
1 insert thick thin gauge in the gap of valve rod and rocker arm to adjust the gap to the degree of gently pulling out the thickness of the gauge, tighten the adjustment screw, the final fine adjustment, the valve clearance is too small, the valve is easily jacked up, the valve can be leaked, the valve face will be ablated, or the valve jammed, the abnormal sound and so on.
2 the tappet can automatically eliminate the gap between the tappet as the engine temperature increases, but the clearance should be adjusted to the manufacturer's specified value (as well as the ordinary tappet) in the cold machine.
The action principle of the hydraulic tappet
When the cam starts to push the Tingxuan, the pressure of the oil storage room is raised because the ball valve is closed, even though there is a trace of oil leaking, or pushing the stem through the plunger. Thus, the movement is carried out with the transfer of the rocker arm to push the engine valve open.
After the cam passes through the apex, the tappet also begins to fall, but the oil pressure in the oil storage chamber does not decrease before the valve is completely closed. As the valve closes, the plug spring is extended, but also the top push rod, only the tappet body drops. And the oil pressure drops from the cylinder body through the oil hole flowing through the cylinder body out of the oil pressure of the cylinder body. Oil in the oil storage room is supplemented. As this action is repeated, the valve is often closed automatically without clearance. The failure of the hydraulic tappet is usually mostly oil clogging. In the decomposition repair and adjustment of the valve clearance, the valve clearance should be carried out in the condition of the cold car and the clearance of the valve is adjusted to the specified value of the factory. Thus, despite the engine When the engine is warm, the valve has a sound, but when the engine returns from cold to normal working temperature, the sound will disappear.
Fast adjustment method of C valve clearance
1 out of the method of finding the dead point on the compression stroke of each cylinder piston, the working efficiency of the cushion clearance is very low, so the rapid adjustment method of adjusting the valve clearance according to the different working stroke of the engine is introduced here.
2 for the 4 cylinder engine, it can be seen from table 3-1 that when the first cylinder piston is at the dead point on the compression stroke, the valve which can be adjusted at the same time is the inlet valve and the exhaust valve of the first cylinder (at this time, the piston is at the dead point on the compression stroke).
The intake valve of the second cylinder is finished, the exhaust starts, and the intake valve is still closed.
The exhaust valve of the third cylinder (when the suction stroke is made, the exhaust valve must be closed).
3 the crankshaft is turned 360, so that the fourth cylinder piston is at the dead point on the compression stroke, at the same time the valve can be adjusted at the same time; the inlet valve and the exhaust valve of the fourth cylinder (the piston is in the dead point on the compression stroke).
The intake valve of the third cylinder (the end of the work stroke, the exhaust valve opens, the intake valve closes).
The exhaust valve of the Z cylinder (the exhaust valve must be closed when inhaling).
