Abstract: The combine harvester is a complex agricultural machinery with precise manufacturing, especially the hydraulic system. Improper use and maintenance can easily lead to malfunctions, affecting agricultural production. The structural characteristics and key points of use and maintenance techniques for the main components of the hydraulic system of the combine harvester were emphasized.
Keywords: combine harvester; Hydraulic system; use; maintenance
The combine harvester is one of the essential equipment in modern agriculture, greatly improving agricultural productivity and reducing the labor intensity of farmers.
The hydraulic system plays an important role in the combine harvester, controlling the lifting system and walking steering system of the harvester. Once a malfunction occurs, the harvester cannot operate normally. Therefore, it is necessary to understand the structural characteristics and maintenance requirements of the main components of the hydraulic system, and use and maintain them correctly to reduce the occurrence of hydraulic system failures in the combine harvester.
1. Hydraulic oil pump
The hydraulic oil pump commonly used in combine harvesters adopts gear pumps. The oil pump housing consists of three sections, which are positioned with locating pins and fastened together with four bolts. They are sealed with O-ring seals to prevent leakage. When replacing a new pump, be sure to carefully observe the rated working pressure, flow rate, and direction of rotation of the pump. If the rated pressure and flow rate are different from the old pump, it may cause other hydraulic components to malfunction or be damaged, and pumps with opposite rotation directions cannot be used. When assembling, first check whether the O-ring seal is damaged, and then tighten the bolts. The tightening torque should be uniform and appropriate, and not too tight. After the oil pump is assembled, there should be a feeling of stagnation and not too tight when rotating the drive shaft by hand. There is a slight tightness between the four shaft sleeves and the boring holes of the housing, ensuring a tight fit between the joint planes of the two shaft sleeves and preventing oil leakage from the high-pressure chamber to the low-pressure chamber. The axial direction of the front axle sleeve has a slanted hole, which is the circulating oil passage for lubricating oil. During assembly, this type of shaft sleeve can only be installed at the front end, so that the slanted oil hole faces the suction chamber side. The axial clearance compensation of the shaft sleeve is to guide high-pressure oil to the rear end face of the shaft sleeve, and each rear axle is equipped with two O-ring seals to prevent the compensating pressure oil from communicating with the low-pressure chamber. During assembly, the technical condition of the O-ring seal and support ring should be checked, and new products should be replaced if necessary. There is a sealing ring in the protruding hole of the front cover drive shaft to prevent oil leakage and air ingress, which is fixed with a snap ring. If there is oil leakage during use, it should be replaced in a timely manner. During the trial operation, run at low speed first to check whether the oil flow direction, pump sound, and system exhaust are normal. Run at low speed and low load for 10-15 minutes, operate each working cylinder, and check if it is working properly. Gradually increase the speed and load to the rated working pressure, run for 10 minutes, and check for external leakage, sound, and temperature rise.
2. multi way valves and single way stable diversion valves
A multi way valve is composed of three slide valve directional valves and an inlet end cap. A direct acting safety valve is installed on the oil inlet cover, with 5 valve plates fastened together with bolts and sealed with O-ring seals between the valve plates. When tightening the bolts, the torque should be appropriate, otherwise the valve hole is prone to deformation, affecting the movement of the slide valve. The slide valve directional valve consists of a slide valve, a positioning spring, a hydraulic lock, a control mechanism, etc. Each slide valve controls a single acting hydraulic cylinder. The oil inlet cover is equipped with a direct acting safety valve, which can be adjusted by changing the thickness of the adjusting gasket. A steel ball is installed between the spring seat and the valve core to ensure the sealing between the valve core and the valve seat. To avoid impact, a damper is installed.
Precautions for disassembly and assembly of multi way valve: (1) The disassembled parts must not be damaged or scratched. Before assembly, burrs must be removed and cleaned and dried with diesel or kerosene. (2) Check the condition of all sealing rings and replace them with new ones if necessary. (3) When installing the oil return side cover assembly, the sealing condition of the one-way valve should be checked. The hydraulic control plunger should move freely in the bore of its housing without any jamming when there is oil. When installing the one-way throttle valve plate, precautions should be taken to prevent reverse installation. (4) When disassembling the slide valve, mark it separately from the housing to avoid incorrect installation. The slide valve is installed in its bore and can move freely without any jamming in the presence of oil. (5) The safety valve must be pressure adjusted on the test bench and should not be disassembled or adjusted arbitrarily. (6) When assembling each valve plate, be sure not to miss the sealing ring between the valve plates; Apply appropriate force when tightening the screws to prevent excessive force from deforming the valve body and affecting the normal operation of the slide valve.
A single channel stable diversion valve can ensure the stability of the output flow of a single branch when the output flow rate of the oil pump changes, in order to maintain a stable flow rate in the steering system. Precautions for use: The pressure value of the safety valve should not be adjusted arbitrarily. If necessary, it can be debugged on the test bench. Do not replace the valve core at will. The pressure difference before and after the throttle hole has been adjusted before leaving the factory. If the spring is replaced, it will affect the stable flow rate of Z small.
3. Full Hydraulic Steering Gear
The fully hydraulic steering gear is an important component in the hydraulic steering system, with precise manufacturing and complex structure. Generally, it rarely malfunctions, and even if malfunctions occur, they are caused by improper use and maintenance. Therefore, it is important to understand the fully hydraulic steering gear and use it correctly. A fully hydraulic steering gear can achieve power or manual steering, and can avoid the adverse effects of hydraulic shock during the steering process. The stator teeth of the steering gear rotor pump are in the form of rollers. The oil inlet check valve is spherical, and the bidirectional buffer valve is installed inside the housing, using a tapered valve core and a working pressure of 12 MPa.
What if the steering occurs during the use of the steering gear? When the steering wheel is heavy or malfunctioning, it is important to carefully identify the cause of the malfunction. Do not pull or forcefully turn the steering wheel, and especially do not attempt to disassemble the steering gear, as this may cause damage to the components. When installing a fully hydraulic steering system, it should be ensured that the steering gear is in the same direction as the steering shaft, and there should be a certain gap between the axial directions. After installation, we must also pay attention to whether the return is flexible. The threaded connections are also areas that we often need to inspect. If any loose nuts are found, they should be tightened immediately, and all connections should be carefully checked for oil leakage. The level of the steering oil directly determines the working efficiency of the hydraulic steering gear. If the oil level is found to be too low, it should be added in a timely manner.
4. oil cylinders and tanks
Double acting piston cylinders are used for steering cylinders. The Y-shaped sealing ring has good sealing performance. When installing, make sure to align the lip with the direction of the pressure oil and do not damage the lip. The size of the cutting platform and the lifting cylinder of the reel are different, but the structure is basically the same.
Before starting work every day, check the oil level in the fuel tank and add it to the standard level if necessary. Oil should be changed before each season's homework, and the system should be vented after oil change. After every 150 hours of work, clean the filter element only with a brush and never with sharp or hard tools. Before reassembly, check the technical status of the O-ring seal and replace it with a new one if necessary. Press the filter element into the bottom hole of the cup sleeve, so that the lower guide tube contacts the small O-ring seal. When the ambient temperature is below 0 ℃, the hydraulic oil should be preheated until it reaches normal oil temperature before it can be put into operation.
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2025-12-18