WG9012570062 Sinotruk Howo Truck Parts Engine spare parts WG9012570062 Fuel stopper stick

Relevant Knowledge

Working principle of fuel injection pump:

1. Oil suction process: the plunger is driven by the cam of the camshaft. When the convex part of the cam leaves the plunger, the plunger moves downward under the action of the plunger spring, the oil chamber volume increases and the pressure decreases; When the radial oil inlet hole on the plunger sleeve is exposed, the fuel in the low-pressure oil chamber flows into the pump chamber along the oil inlet hole;

2. Oil pumping process: when the convex part of the cam pushes up the plunger, the volume of the pump cavity decreases, the pressure increases, and the fuel flows back to the low-pressure oil cavity along the radial oil hole on the plunger sleeve; When the plunger goes up to completely plug the radial oil hole on the plunger sleeve, the pressure on the pump cavity increases rapidly; When the pressure overcomes the preload of the outlet valve spring, the outlet valve moves up; When the pressure reducing ring on the outlet valve leaves the valve seat, high-pressure diesel oil is pumped into the high-pressure oil pipe and injected into the cylinder through the fuel injector;

3. Oil return process: as the plunger continues to move up, when the chute on the plunger is connected with the radial oil hole on the plunger sleeve, the fuel in the pump cavity will flow back to the low-pressure oil cavity through the axial oil passage on the plunger, the inclined oil passage and the oil hole on the plunger sleeve, and the pump oil will stop.

Symptoms of broken fuel injection pump:

1. The diesel engine galloping is mostly caused by the clamping of the fuel supply gear rod or the failure of the governor. It is definitely necessary to repair the fuel injection pump;

2. Fake runaway refers to that the idle speed of the diesel engine is normal after starting, and the engine does not slow down after it is increased to high speed and the throttle is released. This is the idle fuel quantity of the gear rod at the idle position after the fuel injector plunger is worn. Once the fuel is added and the speed is increased, the gear rod can return to the idle position after the throttle is released, but the moving parts and transmission device of the governor are stuck at the high speed position due to excessive wear, and the speed cannot be reduced. In case of this phenomenon, the fuel injection pump must be repaired;

3. The high pressure oil pipe does not produce oil, but the low pressure oil pipe has oil, and the diesel engine cannot start, indicating that the fuel supply gear rod is stuck in the position of no fuel supply. At this time, it is also necessary to repair the fuel injection pump in time;

4. The rotating speed fluctuates from high to low, which is the result of inflexibility of the oil supply gear rod, or excessive wear of the internal parts of the governor, and the increase of the fit clearance. Therefore, it is also necessary to repair the fuel injection pump;

5. When accelerating, the speed of diesel engine remains unchanged or changes little. This indicates that the fuel supply toothed rod is stuck in a certain position, and the fuel injection pump must be repaired.

The screw is generally scrapped due to long-term wear and the gap between the screw and the barrel is too large to be extruded normally, but there are also cases where the working stress caused by improper design or operation exceeds the strength limit and is damaged. Therefore, the screw should also meet certain strength requirements.

1) For the case of floating connection between the screw tail and the main shaft of the reducer, the bending stress caused by the dead weight of the screw is equal to zero because the screw is floating in the barrel, so the calculation is only based on the compression stress and shear stress of the screw. 2) Because the bending stress caused by the dead weight of the screw is very small (the screw is full of materials), even in the former case, it can be omitted, so the two methods are actually the same. 3) Screw diameter is also estimated by torque.