Tractor hoist shell cracking: structural defects, rear double cylinder pressure system security risks

Release time：2023-05-23    Click：201

In one case, a 2004 tractor in Anhui Province, heavy press type lifter with two rear double acting oil cylinders, share 435-share plow plow, the lifter housing cracked during plowing operation. The tractor hoist shell from the appearance, give a person's intuition is very strong, strength should not be too much of a problem, the shell cracking this kind of failure makes people feel very strange, seems to have its cause.

After careful observation of the tractor, it is found that the limit cover plate on the two pressure cylinder of the elevator is not the same height. According to the fault diagnosis principle of the tractor: combined with the structure, the contact principle; Understand the signs, specific analysis; From simple to complex, from the outside to the inside; According to the system segmentation, inference screening. According to the structure and working principle of the type of pressure elevator, after careful analysis, the author thinks that the type of rear double cylinder pressure elevator has major safety risks, there are structural defects, such as the use of adjustment, it may cause serious failure of tractor hoist shell cracking, not only high cost, but also delay field operations, affect farming time.

Each double acting cylinder of the rear double cylinder pressure lifting system is equipped with a positioning valve. If you need to use the positioning clamp cover plate in the work, a basic requirement is to adjust the two positioning clamp cover plate in a plane at the same time, only in this way can ensure that the two double acting cylinders are positioned at the same time. If the two positioning clamp cover plate is not in the same plane when adjusting, the two cylinders will be out of sync.

When the tractor is equipped with a large machine, due to the heavy machine, in the fall limit, because the positioning cover plate of the two cylinders is not in the same plane, the work is not synchronous, the oil circuit of the lower chamber of one cylinder is cut off and stopped, the other cylinder can still fall, under the action of pressure oil and the impact of the larger dead weight of farm tools, It is possible to directly damage the pressurization mechanism itself, causing major failures such as the cracking of the elevator shell, and bringing safety risks to the operation and use. The type 2004 tractor rear double cylinder hydraulic hoist shell cracking is caused by this reason, when the hoist shell cracking, must be replaced with a new hoist shell, the cost is high, delay the operation time is long.

After market research, at present, the domestic mainstream tractor manufacturers of the pressure elevator system, mostly adopt rear dual cylinder configuration, each cylinder has an independent positioning valve, independent positioning cover plate, the structure is much the same. As we analyzed above, the rear double cylinder pressurization system of this structure has the hidden danger of using the positioning cover plate to locate, such as the two positioning cover plates are not in a plane, which will cause the two cylinders to be out of sync, thus directly damaging the pressurization mechanism itself. After market research, this hidden danger is not only theoretical existence, but has already occurred in the practical use of many cases, especially on the high-horsepower tractors, many 1804, 2004, 2204 high-horsepower tractors in the use of the elevator shell cracking phenomenon and the positioning cover plate on the two cylinders are not in the same plane. The positioning valves on the two cylinders close asynchronously.

This type of rear dual cylinder pressure system market quantity is huge, but fortunately, the user in use of the positioning valve function is not many people, which is the problem although serious consequences, but the actual amount of failure is not a big reason. To avoid the occurrence of this problem in use, to solve this problem, one is to train the user, inform the user in use, must ensure that the adjustment of two positioning cover plate in a plane; The second is to improve the structure, completely solve the problem. When the structure is improved, the independent control of the positioning valve on the two cylinders can be improved to a unified control of the positioning valve, and the two double acting cylinders can be controlled by a positioning valve at the same time, so as to avoid the safety risks caused by the use of two positioning valves out of sync, and simplify the operation method. In this way, the hidden danger problem of two double acting oil cylinders forced into the soil mechanism can be solved well, and the problem of control incoordination between two double acting oil cylinders can be solved.