Clutch slip, oil cylinder oil leakage, distributor stuck valve, trouble of big brand tractor

Recently, I learned from the discussion with the front-line maintenance service personnel of the tractor maintenance station that the failure rate of 1204 tractor of a well-known brand in China is very high. The batch failures are mainly manifested in: the main clutch plate burns during tractor ploughing, the auxiliary clutch plate burns during rotary tillage, oil leakage from the lifting cylinder, and the force pressure on the distributor clamping valve. Due to the high failure rate of the tractor, users and dealers are not satisfied. Some users even quarrel to return the tractor.

This 1204 tractor is a high-pressure system with two double acting lift cylinders. The main fault is oil leakage. The main parts of oil leakage are piston rod oil seal, positioning valve and oil pipe joint. Other faults include: broken piston rod head of lifting cylinder, broken base of lifting cylinder and internal leakage of lifting cylinder. The failure of lifting cylinder is mainly caused by the quality of parts, some of which are caused by oversized and overweight farm tools

The clutch of this 1204 tractor is dry, butterfly spring compression and independent operation double acting. The hydraulic system adopts split strong lifting and strong pressure system, and adopts two vertical double acting lifting cylinders.
First, let's talk about the clutch failure:
In the use of tractor, clutch is one of the most common faulty parts. Once there is a problem with the clutch, it needs to be damaged. However, the newly purchased tractor soon broke down. It is difficult for users to accept psychologically, but it is difficult to judge the responsibility for clutch failure.
Manufacturers often say that the clutch damage is caused by improper use by users. Users believe that the quality problem of the clutch or improper adjustment of factory conditions have caused disputes between them. Users often quarrel with dealers and manufacturers, so why is the clutch so prone to problems? Is it more difficult to define fault liability?
Let's analyze the following:
The clutch is installed behind the engine and in front of the transmission. Its main function is to transmit and cut off the power supply to prevent overload of the transmission system.
At present, dry friction double acting clutch is widely used in the transmission system of high-power tractor. The maximum torque (i.e. static friction torque) that can be transmitted by the friction clutch is related to the maximum compression force between the friction surfaces, the size of the friction surfaces, the number of friction surfaces and the properties of friction materials (friction coefficient).
For the clutch, its static friction torque is a fixed value. If the input torque reaches this value, the clutch will slip, limiting the maximum torque of the transmission and preventing overload.
The tractor clutch also has the following properties in use:
First, it has appropriate torque reserve capacity, which can not only ensure that the maximum torque output by the engine is transmitted to the gearbox without slipping, but also prevent the transmission system from overload.
The second is to ensure fast and complete separation, smooth and soft joint and smooth start.
Third, heat dissipation should be good to prevent friction heat from fading.
Fourth, the moment of inertia of the driven part of the clutch should be as small as possible. When the clutch rotates at high speed, it should have reliable strength, good dynamic balance, absorb some vibration and be easy to operate.

There are many reasons for clutch damage, including:
The first is the problem of user operation. For example, it is customary to always press the clutch pedal. Control the vehicle speed through the half step clutch; The free stroke of the clutch pedal is improperly adjusted and the clearance is too small; The farm tools are not matched properly, and they are too big. During operation, the ploughing depth is too deep and the load is too heavy. Therefore, manufacturers will say that the user problem is causing controversy.
The second is the manufacturer's design. The clutch does not have enough capacity to transmit the maximum torque. Simply put, the clutch is "small". At present, the engine horsepower of the popular small chassis high-power tractor has increased, but the clutch itself has not been increased and strengthened in time, and the ability to transmit the maximum torque is insufficient. When the load is heavy, the clutch will slip and burn the clutch plates. For example, 1604 and 1804 tractors also use 13 inch clutches, so they are easy to slip and damage. If a 14 inch clutch is used, faults will be greatly reduced. The methods to improve the maximum torque transmission capacity of the clutch include increasing the compression force of the disc spring, increasing the size of the friction surface and increasing the friction coefficient of the friction plate.
The third is the quality of the parts, that is, the clutch itself. The clutch is produced by a professional manufacturer. Tractor manufacturers purchase only finished products for assembly. At present, German Luk clutch is mainly used for high-power tractors. It has high reliability, good quality and relatively high price. Domestic clutches include Shandong Huanghai clutch and Zhejiang Liutie clutch. They are relatively cheap but not very reliable.
Fourth, improper assembly adjustment and backward production technology. During the maintenance of High-power Tractor, it is found that there are some problems in the technical conditions of clutch when it leaves the factory, such as too small clutch clearance of auxiliary clutch, linkage between main clutch and auxiliary clutch, water ingress and rust in clutch chamber, etc. The technical requirements for clutch assembly and adjustment of High-power Tractor are relatively high. If the clutch assembly is not in the proper position and the technical conditions of the clutch are not in the proper position, it is easy to cause the film combustion used by the user.