“Speed” refers to the phenomenon that the diesel engine speed is out of control and suddenly increases, exceeding the maximum allowable speed, accompanied by a loud noise. When the engine is “speeding”, if measures are not taken in time to control it, the engine may be damaged in a short period of time, even personal injury or death may occur, causing irreparable losses.
What is the reason that diesel engine is over speeding?
The reason is that the rotation of the plunger is out of control and stays at a larger or maximum fuel supply position, or the engine speed is reduced due to the load, so that the fuel injection volume per cycle increases with the acceleration of the plunger movement. The fuel injection volume of the engine promotes the speed to increase further, and this vicious circle continues until it exceeds the maximum allowable speed to an uncontrollable point. The specific reasons are as follows:
Firstly, the oil adjustment lever, namely the rack, is stuck in a certain position.
Secondly, the oil volume adjustment rod is disconnected from the connecting rod of the governor.
Thirdly, the governor spring is broken and caught.
Fourthly, the connecting pin of the governor fly hammer is stuck or pulled out.
Fifthly, the governor fly hammer is rusty.
Sixthly, the governor sliding shaft and sleeve are rusty or jammed by foreign matter.
Seventhly, the governor and the fuel injection pump are loose.
Eighthly, the oil viscosity in the governor is too high, making it difficult to open the fly hammer.
Ninethly, the axial sliding of the thrust plate of the governor is blocked.
Tenthly, the sliding of the flyweight frame and the guide plate of the governor is blocked.
After the engine generates a “speeding car”, according to the specific situation at the time, try to force the engine to stall quickly. The specific methods are as follows:
Turn on the exhaust brake button immediately, relying on the engine exhaust brake to act to prevent exhaust gas from the cylinder, force deceleration, pull out the flameout cable, force the oil volume adjustment lever, or rack, to move it in the direction of reducing oil. Cut off the fuel. For electric stalled vehicles equipped with pumps, use electrical stalls to forcefully cut off the fuel.
Put the transmission into high gear, step on the brake pedal, and slowly loosen the clutch pedal to force the engine to stop under load.
Block the air inlet to prevent air from entering the cylinder.
Loosen the high-pressure fuel pipe joint to prevent fuel from entering the cylinder.
Loosen the low pressure oil inlet pipe joint of the fuel injection pump, and disconnect the low pressure oil cavity for oil supply.
Once the engine “runaway” occurs, corresponding emergency measures should be taken on the spot to stop the engine, and then troubleshoot.
After a cold start, the engine produces “speeding”, raise the throttle, the speed is still high, and the flameout knob should be pulled to stop. First, check whether the oil in the governor is too viscous, causing the fly hammer to be difficult to open and losing the function of adjusting the speed.
For cars that have parked for a long time and start “speeding”, the inspection window cover of the fuel injection pump or the front end of the fuel injection pump should be disassembled to adjust the lever, gear lever, and end shield. Move the lever by hand to observe whether it is flexible. , Indicating that the rod and sleeve of the tie rod are corroded or poorly lubricated, they should be derusted and lubricated.
If the fuel injection pump is a “flying car” after disassembly, maintenance, and loading, check the lever and gear rod to see if it is bent and deformed due to improper storage. If it is, the correction should be removed or replaced with a new one.
When checking the lever and gear rod, if the lever moves freely but cannot move forward automatically when pushed backward, it means that the lever is disconnected from the connecting rod of the governor, and the governor inspection window cover should be removed for inspection and removal.
If the above inspections are normal, the fault is in the governor. The rear cover of the governor should be disassembled and inspected completely. After the overhaul is completed, the test bench should be debugged, and the car should be installed after being sure.