Feb. 17, 2020
If you are tired, you need to rest. The truck is used for transportation every day. After a long run, it also needs maintenance. Don't think this is a trivial matter, small maintenance can effectively extend the life of the truck. But sometimes, the wrong way can affect the truck. Today, a custom automobile spare parts factory will introduce to you what are the methods that are easy to misuse.
Do not check plunger stroke margin
The so-called stroke allowance of the plunger refers to the amount of movement that the plunger can continue to move upward after being pushed by the cam on the camshaft to the top dead center. The reason for checking the stroke margin is because the stroke margin of the plunger is related to the wear of the plunger and the sleeve.
After the plunger and the sleeve are worn, the plunger needs to be moved up a little more to start the oil supply, which delays the start of the oil supply.
Incorrect cylinder clearance measurement
When measuring the cylinder clearance, it was not possible to measure in the direction of the piston skirt perpendicular to the piston pin hole, and in other directions. When measuring, the gap in the direction of the long axis of the ellipse is used as the reference, so the measurement is more convenient and accurate.
In the reciprocating movement, the direction of the piston skirt perpendicular to the piston pin hole is subject to greater wear due to the lateral pressure. Therefore, when measuring the cylinder clearance, the piston skirt should be measured perpendicular to the piston pin hole.
Crankshaft For Trucks
Sanding the bearing pad with emery cloth
For some inexperienced friends, the bearing bush is a difficult job. Because the scraper technology is difficult to master, it is difficult for the bearing bush to meet the technical requirements. For this reason, when replacing the bearing bush, some people increase the bearing bush and the crankshaft. The contact area, use abrasive cloth to replace the scraper.
This method is extremely undesirable in actual maintenance, because the abrasive particles on the abrasive cloth are harder, but the bearing alloy is softer. In this way, the abrasive particles are easily embedded in the alloy during grinding, and the journal wear will be accelerated when the diesel engine is working. Reduce the life of the crankshaft.
The bolt is too tight
During the disassembly and assembly of construction machinery, many parts of the bolts have specified torque requirements, such as transmission boxes, cylinder heads, tires, connecting rods, and front axles. The tightening torques are specified in the instructions. Feel free to change.
However, many users mistakenly believe that it is safer to tighten tightly, but tightening too tightly will cause the screws or bolts to break, and may also cause failure due to the thread slide fastener.
1. Coat the cylinder pad with butter. Butter is a commonly used grease in the repair of construction machinery, which can play the role of lubrication and sealing. Therefore, some repairmen will apply a layer of butter to the cylinder gasket when installing the cylinder gasket, which is believed to increase the tightness of the diesel engine. As everyone knows, this will actually affect the working performance of the diesel engine. In addition, when the butter is in a high temperature state for a long time, coke will be generated, which will cause premature aging and deterioration of the cylinder liner. Therefore, do not apply butter when installing the cylinder gasket.
2. Butter the tire nuts. In order to easily tighten the nut and prevent rust, many repairmen apply oil to the bolt and nut of the tire. This is actually a wrong approach. Because after the tire nut is tightened, there is a self-locking feature between the threads. Therefore, never grease or drip oil on the tire bolts and nuts. Doing so will loosen the nut and even cause an accident.
New cylinder liners and pistons are installed without option
When replacing cylinder liners and pistons, the new cylinder liners and pistons are considered to be standard parts and they are interchangeable. In fact, the cylinder liner and piston dimensions have a certain tolerance range.
For example, if the largest size cylinder sleeve is fitted with the smallest size piston, the fit clearance will be too large, resulting in weak compression and difficulty in starting. In addition, when the cylinders and pistons of the same group code are installed in each cylinder, pay attention to the inspection of the cylinder plug clearance before installation. In order to ensure the assembly standard, a test should be performed before installation to prevent fake and inferior products from being installed. .