When operating a truck-mounted crane, have truck-mounted crane owners ever encountered a diesel engine runaway failure? Runaway failure refers to a situation where the speed of the diesel engine becomes uncontrollable or keeps escalating. Next, the editor will elaborate on the causes of diesel engine runaway failure intruck-mounted cranes for everyone. Generally, diesel engine runaway failure in truck-mounted cranes occurs either when the vehicle is just started or when the load suddenly vanishes or decreases during operation. Moreover, runaway can lead to severe accidents such as cylinder pounding and shaft breaking in the diesel engine of the truck-mounted crane. Therefore, it is of paramount importance to promptly grasp the causes of the runaway accident and subsequently take appropriate measures to eliminate the malfunction.
The causes of diesel engine runaway failure in truck-mounted cranes are as follows:
The fuel injection pump’s fuel quantity adjustment teeth are stuck at the maximum fuel supply position or the rack is disengaged from the governor pull rod, losing control and causing runaway.
Let’s explore this cause in more detail. The fuel quantity adjustment teeth of the fuel injection pump play a crucial role in regulating the amount of fuel injected into the engine cylinders. When they get stuck at the maximum position, an excessive amount of fuel is continuously supplied, bypassing the normal control mechanisms. This can result in a sudden and uncontrollable increase in engine speed. The disengagement of the rack from the governor pull rod disrupts the communication between the governor and the fuel injection system, leading to a loss of control over the fuel supply and subsequent runaway.
The plunger pairs of the fuel injection pump are stuck due to incorrect installation or being jammed by grease and dirt and cannot rotate. Especially for multi-cylinder fuel pumps, when the load decreases, the fuel supply amount cannot be changed, causing runaway.
Incorrect installation of the plunger pairs can cause misalignment or binding within the fuel injection pump, preventing them from moving freely. Grease and dirt can accumulate and obstruct the movement of the plunger pairs, affecting their ability to adjust the fuel supply accurately. In multi-cylinder fuel pumps, the inability to adapt the fuel supply in response to a changing load can result in an imbalance and excessive fuel injection, triggering a runaway condition.
The transmission sliding sleeve of the governor of the single-cylinder fuel pump of the single-cylinder truck-mounted crane is stuck, causing the governor to malfunction and resulting in a runaway failure.
The transmission sliding sleeve in the governor is responsible for transmitting control signals and adjusting the fuel supply based on engine speed and load. If it becomes stuck, the governor loses its ability to regulate the fuel injection accurately, leading to an uncontrolled increase in engine speed. This malfunction can have significant implications for the stability and safety of the engine’s operation.
Excessive lubricating oil is added in the governor housing, affecting the governing effect; the friction clutch of the governor slips; the high-speed limit screw and safety gear of the governor are loose; they come out or get stuck quickly; the governor spring is broken, the thrust bearing or the governor bearing is damaged, causing the governor to malfunction and resulting in runaway.
An excessive amount of lubricating oil in the governor housing can create resistance and interfere with the smooth operation of the internal components. A slipping friction clutch fails to transfer the necessary control forces, while loose or malfunctioning limit screws, safety gears, and broken springs compromise the governor’s ability to regulate the engine speed effectively. Damaged bearings further disrupt the precise movement and control within the governor system.
Excessive engine oil in the inertia oil bath air filter is sucked into the cylinder for combustion, which is equivalent to increasing the fuel supply amount and will also speed up the rotation speed, causing runaway.
When there is an excessive amount of engine oil in the inertia oil bath air filter, it can be drawn into the cylinders during the intake process and combusted along with the fuel. This additional source of fuel effectively increases the overall fuel supply, leading to an increase in engine speed beyond the normal range and potentially causing a runaway situation.
For some fuel injection pump plunger sleeves, the inlet and return oil holes are in the same planar position. If the positioning screw of the plunger sleeve is too long and blocks the return oil hole, causing poor return oil, resulting in a sharp increase in the fuel supply amount, it can also cause runaway.
The alignment and functionality of the inlet and return oil holes in the plunger sleeves are critical for maintaining the proper fuel pressure and flow. A too-long positioning screw blocking the return oil hole disrupts the normal oil circulation, leading to an abnormal increase in the fuel supply. This imbalance can cause the engine to accelerate uncontrollably and result in a runaway failure.
The above six points provide possible causes of diesel engine runaway failure in truck-mounted cranes for owners to understand and study!
By being aware of these potential causes and conducting regular inspections and maintenance of the fuel injection system, governor components, and related parts, truck-mounted crane owners can take proactive measures to prevent runaway failures. Early detection and timely repair of any abnormalities can ensure the safe and reliable operation of the diesel engine, minimizing the risk of costly damages and dangerous situations.
