1. Valve springs

Valve springs are subject to high temperature and periodic high-frequency alternating forces. After a period of use, they will wear and plastically deform, weakening the elastic force, resulting in poor valve closure, engine power reduction, exhaust black smoke, and difficulty starting. Therefore, the elastic force of the valve spring should be checked regularly. A small piece of iron sheet can be placed between the old spring and the new spring, clamped in a bench vise and pressurized to compare the shortening degree. When the new spring is compressed to 2/3 of the original length, if the old spring is 2mm shorter than the new spring, it should be replaced. If there is no spare part for the time being, a flat washer of about 2mm can be placed on the old spring to make up for its lack of elastic force. Under normal circumstances, the valve spring should be replaced after 2500-3000 hours of use.

2. Fuel injection pump plunger springs

The fuel injection pump plunger spring will also be subject to periodic high-frequency alternating forces and wear and deform, thereby shortening its free length and weakening its elastic force. After the elastic force is weakened, the return speed of the plunger slows down. In this way. When the engine is running at high speed, the reciprocating motion of the plunger cannot maintain a coordinated relationship with the high-speed rotary motion of the oil pump cam, thereby reducing the lift of the plunger. The oil supply is reduced accordingly, causing the engine power to drop. Therefore, the plunger spring should be replaced in time after 3600-4500 hours of use.

3. Oil outlet valve spring

After the elastic force of the oil outlet valve spring is weakened. It will cause serious leakage of high-pressure oil, reduce the residual pressure in the high-pressure oil pipe, and the oil outlet valve will not seat quickly, resulting in a reduction and instability of oil supply, and the engine will work weakly and "wandering". In addition, it will also make the injector weak at the beginning of the spray, the oil cut-off is not clean, and the phenomenon of after-drip occurs. This will lead to deterioration of combustion, engine overheating, and black smoke from the exhaust. Therefore, the oil outlet valve spring should generally be replaced after 3600-4500 hours of use. If there is bending and deformation, it should be replaced in time.

4. Speed ​​regulating spring

The following points should be noted when using the speed regulating spring of a small diesel engine.

(1) After the diesel engine is stopped, the speed control handle should be placed in the stop position to prevent the speed control spring from being in a long-term stretched state, which will weaken the elastic force.

(2) The speed control spring and other parts should be cleaned frequently to prevent dust and debris from blocking them, causing jamming and affecting the normal operation of the speed governor.

(3) It is not allowed to increase the engine speed by "tying up" the speed regulating spring, otherwise it may cause serious consequences.

(4) When the speed regulating spring's elastic force becomes smaller after long-term use, the diesel engine will not reach the required speed. At this time, the adjusting screw can be used for adjustment. When adjusting the adjusting screw, the engine speed must be measured with a tachometer.

5. Clutch spring

The clutch spring is under the action of static pressure most of the time. When it is used for too long, it will undergo plastic deformation, shorten the free length, and weaken the elastic force. When the elastic force of the clutch spring is weakened. The torque that the clutch can transmit will be reduced, and the power of the engine cannot be fully exerted, resulting in the locomotive's powerlessness. When it is found that the elastic force of the clutch spring is weakened, a gasket of appropriate thickness can be added to the pit of the part in contact with the spring to adjust it. When adding the gasket, it should be noted that the free length (including the thickness of the gasket) of each spring on the same clutch assembly should be consistent. If the spring cannot restore its original elastic force after adding the gasket, a new set of springs should be replaced. Generally, after the spring is used for 2500-3000 hours, a 1-2mm thick gasket should be added to adjust the pressure; after 5000 hours of use, all springs should be replaced at the same time.

6. Steering spring of hand-held tractor

When installing the steering spring, you should first identify whether it is a left-handed spring or a right-handed spring. The left side should be equipped with a right-handed spring, and the right side should be equipped with a left-handed spring. If the left and right springs are installed incorrectly, when the tractor turns, the steering spring will be subjected to a reverse torsion force, which will deform the spring, even break the spring, or scrape and damage the inner step of the steering gear. Once the spring breaks, the steering gear loses thrust after the steering handle is relaxed. The teeth cannot return to their original position, which may cause a serious accident. How to identify left-handed and right-handed springs: Hold the spring with your left hand, with your thumb facing up, and the direction of the other four fingers is exactly the same as the direction of the wire rotation. It is a left-handed spring: otherwise, it is a right-handed spring. In

addition, insufficient elasticity of the steering spring may cause the hand-held tractor to lose its steering stability. Therefore, the steering spring should be checked regularly. The inspection and adjustment methods are the same as those for valve springs, but flat washers of the same thickness should be placed on both sides. Generally, they should be inspected and adjusted once every four years.

7. Springs with adjustable elasticity

When the spring force of the injector pressure regulating spring weakens, the fuel injection atomization is poor, the combustion deteriorates, the engine power decreases, and the fuel consumption increases; when the spring force of the speed regulating spring of the speed governor weakens, the engine speed decreases. The power decreases, and the "wandering" phenomenon will also occur: when the spring force of the pressure regulating spring of the lubrication system and the safety valve spring of the hydraulic system weakens, it will cause accelerated wear of the parts and deterioration of the technical status of the engine; when the spring force of the shift fork positioning spring weakens, the gearbox cannot be reliably positioned, and automatic jump and random gear shifting will occur. Therefore, the pressure of the above adjustable springs should be adjusted in time.