Common sense of spring use and maintenance

1. Valve spring
Under the action of high temperature and periodic high frequency alternating force, the valve spring will wear and plastic deformation after using for a period of time, which will weaken the elastic force, resulting in the valve closing laxly, engine power decreasing, exhaust emitting black smoke, starting difficult and so on. Therefore, the valve spring force should be checked regularly. A small piece of iron sheet can be placed between the old spring and the new spring, which is clamped on the bench vice for pressure comparison to see its 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 a while, a flat washer of about 2mm can be padded on the old spring to make up for its insufficient elasticity. In general, the valve spring should be replaced after 2500-3000 hours of service.

2. Plunger spring of fuel injection pump
The plunger spring of fuel injection pump will also be worn and deformed under the action of periodic high frequency alternating force, which will shorten its free length and weaken its elastic force. When the elastic force decreases, the return speed of plunger slows down. So. When the engine is running at high speed, the reciprocating motion of the plunger can not keep a harmonious relationship with the high-speed rotary motion of the oil pump cam, thus reducing the lift of the plunger and the corresponding reduction of the fuel supply, resulting in the decrease of engine power. Therefore, when the plunger spring is used for 3600 ~ 4500 h, it should be replaced in time.

3. Outlet valve spring
After the spring force of the oil outlet valve decreases. It will cause serious internal leakage of high-pressure oil, reduce the residual pressure in the high-pressure oil pipe, and the oil outlet valve does not seat quickly, resulting in the reduction and instability of fuel supply, and the engine is unable to work and “travel”. In addition, it will make the fuel injector start to spray powerless, cut off the fuel not simply, and drop after the phenomenon, resulting in combustion deterioration, engine overheating, exhaust smoke. Therefore, the spring of the oil outlet valve should be replaced after 3600-4500 h of use. If there is bending deformation, it should be replaced in time.

4. Speed regulating spring
Attention should be paid to the following points when using the speed regulating spring of small diesel engine.
(1) after the diesel engine stops and fires, the speed regulating handle should be placed at the stop position, so as to prevent the speed regulating spring from being stretched for a long time, resulting in the weakening of the elasticity.
(2) The speed regulating spring and other parts should be cleaned regularly to avoid blockage of dust and sundries, resulting in jamming and affecting the normal operation of the governor.
(3) It is not allowed to use the method of “locking” the speed regulating spring to increase the engine speed, otherwise serious consequences may be caused.
(4) The speed regulating spring can not reach the speed of diesel engine due to its small elastic force after long-term use. At this time, the adjusting screw can be used to adjust it. When adjusting the adjusting screw, the engine speed must be measured with a tachometer.

5. Clutch spring
Most of the time the clutch spring is under the action of static pressure. If the clutch spring is used for a long time, plastic deformation will occur, the free length will be shortened and the elastic force will be weakened. When the elastic force of clutch spring is weakened, the torque transmitted by clutch will be reduced, and the power of engine can not be fully exerted, resulting in the powerlessness of locomotive. When it is found that the elastic force of the clutch spring is weakened, it can be adjusted by adding a gasket of appropriate thickness in the pit of the parts in contact with the spring. When shimming, it should be noted that the free length (including gasket thickness) of each spring on the same clutch assembly should be consistent. If the spring cannot recover its original elasticity after adding gasket, a new set of springs shall be replaced. Generally, when the spring is used for 2500-3000h, 1-2mm thick gasket should be added to adjust the pressure; after 5000h of service, all springs should be replaced at the same time.

6. Steering spring of walking tractor
When installing the steering spring, first identify the left-hand spring or the right-hand spring. The left side should be equipped with a right-hand spring, and the right side should be equipped with a left-hand spring. If the left and right springs are installed wrongly, the steering spring will be subjected to a reverse twisting force when the tractor turns, which will deform the spring, even break the spring, or scrape the inner step of the steering gear. Once the spring is broken and the steering handle is released, the steering gear will lose its thrust and the jaw will not return to its original position, which may lead to serious accidents. Identification method of left and right rotation spring: hold the spring with left hand, thumb upward, and the other four fingers with the same direction of rotation as the steel wire are left-handed spring; otherwise, it is right-handed spring.
In addition, the insufficient spring force of the steering spring may cause the walking tractor to lose its handling stability. Therefore, the steering spring should be checked regularly. The inspection and adjustment method is the same as that of valve spring, but flat washer of the same thickness should be padded on both sides. Generally, it should be checked and adjusted once every four years.

7. Adjustable spring
When the spring force of the pressure regulating spring of the injector is weakened, the atomization of the fuel injection is poor, the combustion is deteriorated, the engine power is reduced and the fuel consumption is increased; When the spring force of the governor speed regulating spring is weakened, the engine speed and power will decrease, and at the same time, the “traveling block” phenomenon will occur; When the elastic force of the positioning spring of the shift fork is weakened, the gear position of the gearbox can not be reliably positioned, and the phenomenon of automatic shifting and disorderly shifting will occur. Therefore, the pressure of the adjustable spring should be adjusted in time.