Technical Note: How Is Thrust Plate Related To Synchronization

Truck maintenance relies on theory, experience and skills, and focuses on physical and mental strength. But is that enough? These are far from enough. You also need to have strong learning ability and analysis ability, so that you can be comfortable in maintenance. This issue will show you a fault case that needs strong “analysis ability” to be solved.

Troubleshooting Steps Are As Follows:

1. Use a diagnostic expert to read the fault code. According to the above fault code, when p0336 – crankshaft signal interference or signal loss fault code is reported, it will lead to insufficient engine power; When p0089 – pressure limiting valve is opened and the fault code is reported, it will lead to insufficient power and engine speed limit.

Tip: when the engine has a synchronization related fault, it may cause the ECU to restart. After the ECU restarts (the metering unit is normally open), the pressure limiting valve will open and report p0089 fault. Therefore, the two fault codes p0036 and p0089 are related to each other. When troubleshooting, repair the first one first.

2. Conduct in-situ test run and observe the data flow and corresponding fault codes.

In terms of data flow, the engine synchronization is normal, and the relevant sensor data is also normal. No problems related to data flow are found.

Clear the relevant historical fault codes. During the in-situ test run, the display system is normal and there is no fault code.

In other words, the fault did not reappear during the in-situ test run. Now it can be determined that the fault is an accidental fault. Next, it is planned to test run.

Tip: for this kind of accidental fault, we must find a way to make the fault reappear, so as to find the fault point faster and more accurately in combination with the fault phenomenon.

3. During the road test, when the heavy load is accelerated, the fault lamp is on, the fault reappears, and the fault code is read as shown in the figure below:

It can be seen from the above figure that two current faults are reported. First, check p0036 – crankshaft signal interference or signal loss fault.

The fault is generally caused by the following reasons:

● harness fault

● sensor failure

● signal panel fault

● installation clearance

● ECU Hardware or software problems

It is initially suspected that the crankshaft sensor and sensor harness are faulty.

4. Replace the crankshaft sensor and and the crankshaft sensor harness flying wire.

After replacement, it went out for test run, and the fault remained the same. Now it is suspected that there is a problem with the signal panel. Use the oscilloscope to read the signal panel information.

5. Use an oscilloscope to read the synchronous timing waveform.

There is no problem reading waveform with oscilloscope, indicating that there is no problem with signal panel.

Through the current troubleshooting steps, it can be determined that there is no problem with the crankshaft sensor, the harness and the signal panel. Since the fault occurred during heavy load, it is suspected that the gap between the crankshaft sensor and the signal panel changed during heavy load, resulting in p0036 – crankshaft signal interference or signal loss.

6. Remove the transmission and check the flywheel disc alignment.

Through inspection, it is found that the flywheel disc rotates well and the clearance is normal.

The clearance is normal, the signal panel is normal, the sensor is normal, and the harness is normal. There are ECU software and hardware left. The next step is to replace the ECU.

7. Replace the ECU and let the master go for a road test, or report the fault during heavy load acceleration.

After troubleshooting, the small rail has no idea for a while. Now all the things that can be checked have been checked, and the fault point has not been found.
Technical note: how is thrust plate related to synchronization
The fault occurs when the heavy load climbs and accelerates. At this time, the clutch contacts the flywheel and transmits the torque to the drive axle. At this time, the flywheel may be misaligned, resulting in the offset of the signal plate. Therefore, the next step is to disassemble the engine.
8. Disassemble the engine and check the thrust plate.
Technical note: how is thrust plate related to synchronization
Replace the thrust plate and remove the fault.
Technical note: how is thrust plate related to synchronization
Technical note: how is thrust plate related to synchronization
When it comes to the fault cases, we need to sort out the fault cases again. Why are the faults not reported during the in-situ test run, but when the heavy load is accelerated, the faults are reported?
At this time, because the clutch contacts with the flywheel when the heavy vehicle accelerates, the clutch gives a great force to the flywheel. At this time, the thrust plate has been worn and can not play a good limiting role, resulting in the movement of the flywheel plate to the inside, and the crankshaft sensor can not sense the groove of the signal plate, resulting in p0036 – crankshaft signal interference or signal loss fault.
Technical note: how is thrust plate related to synchronization
In the process of fault reporting, the synchronization status changes many times due to the crankshaft sensor fault, resulting in the restart of ECU, and p0089 – the fault that the pressure limiting valve is opened is reported.
Here I would also like to say that the wear of the thrust plate will generally lead to the falling off of the thrust plate; However, in this case, the thrust plate did not fall off, which is why the fault was not reported during light load and in-situ test run.
Technical note: how is thrust plate related to synchronization
In this issue of knowledge development, I will tell you about the thrust plate and its fault analysis.
Thrust plate, also known as thrust sliding bearing, mainly plays the role of axial support of crankshaft in the engine. It can not only ensure the circumferential rotation of crankshaft, but also prevent the axial movement of crankshaft. There are many kinds of thrust plates, which are called crankshaft thrust plates because they are used on the crankshaft. According to different shapes, the crankshaft thrust plate is called thrust plate and flanging main bearing bush.
Generally, the shape of semi-circular ring thrust plate is more, one machine has 4 pieces, and two semi-circular rings are a group, which are divided into upper and lower pieces. Generally, the lower piece is equipped with a positioning tongue or positioning hole, and there are 2 pieces of main bearing bush, which can play the function of thrust surface by turning the side.
Technical note: how is thrust plate related to synchronization
Engine bearing bush and thrust plate are the main friction pairs of the engine. They bear high dynamic load. Compared with other parts, they are the parts working under the worst working conditions.
The working conditions of the thrust plate are demanding. There are oil grooves or oil pockets on the thrust working surface, which can resist and alleviate the short oil shortage and avoid dry friction; Proper working clearance can produce a complete oil film of sufficient thickness during operation; The flowing oil film can take away the heat generated by friction and prevent the lubricating oil from deteriorating due to high temperature.
The common failure modes of thrust plate are abnormal wear and falling off.
the engine thrust plate will wear and fall off due to the following reasons:
1. Quality problem of thrust plate
The alloy material of the thrust plate is unqualified, the wall thickness of the thrust plate is out of tolerance, and the flatness and coarseness of the thrust plate are out of tolerance. The above reasons will lead to oil-free friction and dry friction when the clearance between the thrust plate and the crankshaft thrust surface is too large or too small, and the alloy surface of the thrust plate is in local contact or line contact with the crankshaft thrust surface.
Technical note: how is thrust plate related to synchronization
2. Clutch quality problem
Due to the design or manufacture of the inner cavity of the clutch pressure plate, there is not enough space to give way. When the driver steps on the clutch pedal, the clutch process interferes with the diaphragm spring, the diaphragm spring continues to deform within the stroke, and the separation force will rise sharply. The separation force is transmitted to the crankshaft, and the thrust side of the crankshaft will produce a large thrust.

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Technical Note: How Is Thrust Plate Related To Synchronization

Troubleshooting Steps Are As Follows:

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