Q: Engine power machinery speeding accident emergency measures and handling methods?
A: Power mechanical overspeed accident refers to the engine speed lost control and suddenly increased beyond the maximum speed allowed, accompanied by a loud sound phenomenon. Engine “flying”, if not timely measures to control, in a short period of time can lead to engine damage, and even personal injury or death, resulting in irreparable damage.
(1) Cause
The reason why the engine produces power mechanical overspeed accident is due to the loss of control of the rotation of the plunger, stagnant in the larger or maximum oil supply position, or the engine speed due to load reduction, so that the amount of oil injection per cycle with the plunger movement speed and increase, the increased amount of oil injection and promote further increase in speed, so vicious cycle, until the maximum allowable speed to reach the point of no control.Â
What is the plunger rotating out of control
- In diesel engines, fuel pumps (such as the common dispensing pumps) are used to inject fuel into the engine combustion chamber through the operation of a plunger pump. A plunger pump works by compressing and injecting fuel through a single plunger. The plunger is usually composed of actuators, springs, valves and oil holes. When the plunger is compressed and moved from its position (oil pump) to its working position, the valve located in the lower part of the plunger is opened at the same time. Fuel flows from the pump into the plunger, while a compression coil spring pushes the plunger upward. During the plunger movement, fuel is slowly injected into the cylinder either equally or proportionally. In general, the plunger pump works in a cyclic process: compression, chamber mixing, injection and acceleration periods, etc.
- Out-of-control plunger is usually a plunger that does not move smoothly or has problems with the synchronization of transmission parts due to wear, deformation, looseness, etc. during use, resulting in fuel not being injected into the combustion chamber according to the normal injection pattern. If the plunger is not fully released while receiving oil pressure, it may cause errors in injection timing and volume, and may lead to engine “jumping” and other abnormal combustion and performance problems, which in extreme cases may lead to engine overspeeding, fuel leakage, combustion chamber explosion and other serious dangers.
Specific reasons are as follows.
- oil volume adjustment lever (i.e. rack) jammed in a position.
- The oil quantity adjusting lever is disconnected from the speed governor connecting rod.
- The governor spring is broken and stuck.
- The speed governor hammer connection pin is stuck or disconnected.
- The governor hammer is rusted.
- Â The governor sliding shaft and sleeve are rusted or stuck by foreign objects.
- The governor and injection pump are loose.
- The oil viscosity in the governor is too large, so that the flying hammer is difficult to open.
- The thrust disk of the governor axial sliding blocked.
- The governor’s hammer frame and guide plate sliding obstruction.
(2) Emergency measures
Engine “power mechanical overspeed accident”, should be based on the specific circumstances, quickly try to force the engine off, the specific methods are as follows.
-  immediately open the exhaust brake button, rely on the engine exhaust brake to play a role in preventing the cylinder exhaust gas discharge, forced deceleration; pull out the flameout cable, forced oil adjustment lever (or gear lever) to reduce the direction of oil movement to make it cut off; for the installation of “VE” pump electric flameout vehicles, the use of electric flameout, forced to cut off oil.
- Put the transmission into high speed gear, depress the brake pedal, slowly release the clutch pedal, so that the engine with load forced off.
- Block the air inlet to stop the air from entering the cylinder.
- Loosen the high-pressure fuel line connector to keep the fuel from entering the cylinder.
- Loosen the injection pump low pressure inlet pipe connector and disconnect the low pressure oil chamber supply.
(3) Diagnosis and treatment method
Once the engine “power mechanical overspeed accident”, should take the appropriate emergency measures in place to make the engine off, and then troubleshoot.
- cold start engine “flying”, lift the throttle, the speed is still high, should pull the flameout pull button to make it flameout. First of all, you should check whether the oil in the governor is too sticky, causing the flying hammer is not easy to open, lose the function of adjusting the speed.
- parked for a long time after the start of the car “flying car”, should be removed from the injection pump inspection window cover or injection pump front oil volume adjustment tie rod (tooth rod) end cap, move the tie rod by hand, observe whether flexible, if astringent, indicating that the tie rod (tooth rod) and the set of rust, or poor lubrication, should be removed rust lubrication.
- If the injection pump is in the disassembly and maintenance of the car after the installation of the “flying car”, it is necessary to check whether the tie rod (gear rod) due to poor storage caused by bending deformation stuck. If so, it should be removed and corrected or replaced with new parts.
- Â In the inspection of the tie rod (gear rod), if the tie rod movement freely, but backward push can not automatically move forward, indicating that the tie rod and governor connection rod disconnected, should be removed from the governor inspection window cover to check to exclude.
- If the above checks are normal, the fault in the governor, should be disassembled governor back cover, completely decomposition check. After the repair is completed, the test bench commissioning should be carried out to ensure that there is no doubt before loading.