Use of Gaskets

Use of gaskets

The gasket on the tractor is a seemingly simple structure, but it has a great role. The paper pad, asbestos pad, copper skin asbestos pad, cork paper pad, steel pad, inscription pad, and other gaskets are to pay attention to the use of matters to be highlighted in order to improve the quality of tractor maintenance.

Tractor gaskets according to the different materials can be divided into many kinds, there are paper pads, asbestos pads, copper asbestos pads, cork paper pads, steel pads, aluminum pads, felt pads, etc. These gaskets seem to be simple in structure, but they have a great role in sealing, and preventing oil, water, and gas leaks; changing their thickness can realize the adjustment, such as the adjustment of oil supply time. In maintenance, if not pay attention to the gasket material, size, and installation method, often will affect the normal work of the tractor, and even cause accidents.

Can The Thickness of The Gasket be Changed at Will?

If the thickness of the gasket is changed, the original performance of the machine will be changed. For example, the paper gasket between the fuel pump and the side cover is used to adjust the oil supply time (oil supply advance angle), the thickness of the gasket is 0.1 MM 9 gaskets for each increase or decrease of 0.1 mm, the oil supply angle changes by 1.7°. The axial clearance between the crankshaft tile and the crankshaft is also achieved by adjusting the paper pad between the side cover and the body between the flywheel. Another example is the shim on the back of the differential planetary gear and the thrust shim between the differential half-shaft end face and the large bevel gear hub when overhauling, pay attention to the consistency of its thickness. If these shims are not the same thickness, will change the planetary gear and differential half-shaft gear mesh clearance, some will also cause the large bevel gear excessive axial clearance, so should be repaired according to the specific requirements of each type of tractor. Inspection, if the overhaul gasket is too thick, will make the planetary gear and half-shaft gear clearance too small, resulting in inflexible differential work; such as the thickness of the shim difference, will cause the differential skew, failure, and even damage to the gear, so the shim thickness to be consistent. 

Do Not Just Add or Subtract Shims on Tractors

There is a tractor start after the oil pressure dropped significantly. Because the mechanic prevented oil leakage, in the pump cover and the pump casing joint plane added a 0.2 mm thick paper gasket. This oil pump joint plane is of high precision, the original design without the gasket. Now the paper pad is added, which is equivalent to increasing the end gap of the gear so that the oil supply of the gear oil pump is greatly reduced. However, there is a paper gasket (asbestos gasket) on the oil pump assembly and cylinder block joint surface, if it is missed, it will make the pressure oil pumped by the oil pump leak here, causing the oil pressure to drop and the oil channel to be short of oil.

Precautions for the Use of Asbestos Pads

Asbestos gaskets and copper-skin asbestos gaskets are high-temperature resistant and cannot be replaced by gaskets of other materials. The S195 diesel engine gear chamber cover gasket is made of rubber asbestos with a standard thickness of 1 mm, which is easily damaged when disassembling the gear chamber cover and cannot be replaced by other paper gaskets after damage. Otherwise, it will cause poor sealing of the gear chamber cover and oil seepage, the diesel engine speed is high and low, and the work is not normal. If a thick paper gasket is used instead of a 5195 diesel engine gear chamber cover gasket, one is to increase the axial clearance of the camshaft, which will cause abnormal gas distribution and oil supply; the other is to change the compression force between the end face of short arm fork of speed control lever and thrust bearing, which will cause the oil supply to increase and be uneven; the other is to increase the axial clearance of starting shaft, which will make the axial run and sound easily when working and accelerate the gear wear. Thus, the shim cannot be replaced by other shims.

Asbestos gaskets are prone to errors when using gaskets that are installed backward and gasket holes that are cut too large. These do not only refer to the asbestos pad, other gasket production and use will also appear when this situation. A newly repaired tractor, test drive when the oil pressure is always less than 98 kPa after an inspection found to be the oil filter and the cylinder body joint surface of an asbestos pad installed backward. The pad of the fixed screw hole left and right symmetrical, flip 180°can also be installed, but its oil pressure is less than the specified value, so the installation needs attention.

Cork Paper Pad Use Precautions

Cork pad has a certain toughness, generally used in the water tank, oil sump, and the body between. When making the gasket, it should be punched first and then undercut, i.e. use a pencil to mark out the exact size on the cork paper, take a suitable hollow punch to finish punching the hole, and then cut the undercut with a sharp knife blade according to the scribed line. When installing, scrape the dirt on the contact surface of the parts concerned, wipe a layer of lead oil or butter on both sides of the gasket, and then tighten the fixing bolts evenly according to the specified order, and generally, there will be no oil leakage.

Copper Pads and Aluminum Pad Use Precautions

The use of copper gasket parts requires higher pressure, as the injector nozzle gasket must be used copper flat gasket, and tightened as specified; the oil valve gasket should be made of softer materials such as purple copper (aluminum or nylon material can also be used instead), and tighten the adjustable seat of the oil valve according to the specified torque. Purple copper gasket surface hardening or grooves, to grind flat after heating, softened by dipping in cold water. The aluminum flat gasket has a certain toughness, repeated use is not easy to damage. Tractor diesel and oil pipeline coupling are used in the aluminum flat gasket, aluminum flat gasket should be checked before installation of its plane whether there are dents or cracks, otherwise, it will produce micro-leakage or oil circuit sucked into the air.

After a diesel engine is started, it stalls after running for a while. After pumping the oil with a hand pump, it can start again, but it still stalls automatically. We determined that there was air in the fuel line. Checked all the oil pipes and joints, and finally found that the purple copper washer at the pump screw plug was not pressed tightly. When the oil pump piston is in the suction stroke, air enters from it, forming a pneumatic resistance in the low-pressure oil circuit, so that the oil pump loses its pumping function. Hand pump into the injection pump of the point of diesel sprayed, and the diesel engine is off. Some tractors are using the above structure of the piston oil pump, the screw plug gasket should be made of softer metal materials such as purple copper, and aluminum, and pay attention to the screw plug tightening degree to ensure that the seal is.

Notes on the Use of Felt Pads

A felt pad has certain wear resistance and shock absorption, tractor oil coarse filter inside and outside the filter element, the upper, middle and lower, each a felt pad. Less installed one of them or not pressed between each other will make the coarse filter lose the filtering role, and the impurities in the oil may enter the main oil channel, the shaft tile, and crankshaft strains. Felt pad will lose elasticity after a period of use, reducing the degree of sealing, and should be replaced regularly. When processing the felt gasket, the thickness should be appropriate. The gasket is too thick and will indent the inner and outer cartridge; too thin will cause the oil to short circuit, so that the cartridge does not work. There is an iron washer is used to compress the outer felt pad and make it evenly stressed to avoid squeezing through, so it should not be missed. In addition, if the copper washer and asbestos pad on the outer cover are not tightened enough, the oil will also leak from the place, so the bolts of the outer cover should not be over-tightened.