The R-80 hydrodistributor is operated on MTZ tractors, designed to redistribute the circulating fluid of these units. The mixture flows from the pump into the working space of the cylinder. The design of the device makes it possible to adjust the oil pressure in the system, to fix the attachments in the required position. In fact, with the help of the unit, the working equipment of the equipment is controlled.
Device
The P-80 valve is equipped with a housing, a spring mechanism, an upper and lower cover, a locking element, channels for the passage of fluid, several types of valves, an adjusting screw, spools, a booster and a clip holder. The node is controlled by levers with spherical bearings.
Spools
Spools are cylinders in the form of cylinders, subjected to careful processing. In specific places, there are provided recessed nests. They are placed in suitable and prepared locations on the hull. During installation, the spools pass through special channels and cavities in the direction of the axes. As a result, the spool elements open one channel, closing the other working holes. This design helps to change the direction of fluid flow. The spools are moved by a lever operating in four positions:
- Neutral position.
- Work on the rise.
- Free swimming.
- Forced lowering.
The indicated positions of the P-80 directional valve have a certain fixation. Holding the lever by hand is provided only in the "forced lowering" position. Spool devices are equipped with an automatic return to neutral from fixed modes.
Operating principle
The P-80 control valve allows the spools in a neutral position to remain under the force of the springs. They block the discharge compartment from the working grooves, while the liquid does not get to the cylinders. In addition, the oil path to the drain holes is cut off. The piston in this situation remains in a strictly fixed position. After the start of the oil supply through the pump to the discharge cavity, the lower part of the bypass valve acts. Under this directed force, the element opens, the oil fluid is transported to the lower part of the P-80 directional valve and enters the drain channels.
The control groove remains ajar, while part of the oil is drained, without interfering with the opening of the bypass valve. If the spool is in a floating position, both compartments communicate with each other via a drain line. The working fluid from the pump flows freely through the dispenser and enters the reservoir through the channels that are activated in the neutral position. In this mode, the piston is able to move under the influence of the rod load due to the aggregation of both cylinders.
Features
The P-80 hydrodistributor, the diagram of which is shown below, working for lifting or forcing lowering, communicates one working cavity with a drain system, and the second analogue with a discharge element. The control channel is blocked by the spool belt, the oil pressure in both parts of the bypass valve piston is equalized. In this case, the valve of the redistributing mechanism goes down under the influence of its own spring. The flow of oil to the drain is completed.
Under the influence of liquid, the piston in the cylinder moves, bringing into operation the equipment and working elements of the equipment. The automatic return of the spools from the "rise" mode is due to the created pressure. Its value is identical to the same indicator observed when the safety valve is activated. It connects to the drain line, after which the pressure parameters drop slightly. In the opposite channel, it remains stably high, since the bypass valve is in the closed position.
Due to the pressure difference in the channels of the assembly, an opening is observed, after which the oily liquid begins to flow under the booster. The spool is no longer fixed, returning under the action of the spring to the neutral mode. In the forced lowering position, the working channel is connected to the waste compartment. The pressure indicator at which the spool fixation stops is only 2 MPa.
Connection
Connection of the P-80 control valve to pipelines or hoses is carried out exclusively through fittings, flanges and other intermediate elements. The working fluid in the system must have a purity of at least category 16 according to GOST 17216. Oil is cleaned with a fine filter (25 microns).
Spool controllers that are not involved in the maintenance of tractor equipment should preferably be set to neutral. During technical maintenance and routine inspection, it is recommended that the pressure of the safety valve be adjusted to the values indicated in the machine manual. Data is checked using a pressure gauge connected to the pressure part of the distributor. Correction is performed at the maximum crankshaft speed, taking into account the calculated pressure value.
The outlet pressure should not exceed 0.5 MPa, and the level of the distributor should not be lower than the same indicator of the upper point of the oil reservoir. The devices under consideration with any kind of spools are operated in the hydraulic systems of tractors and agricultural machinery.
Repair of the R-80 hydrodistributor
Repair of the part in question requires certain knowledge in the field of hydraulics. Otherwise, the inadequately conducted recovery process can only aggravate the situation.
Having studied the device of one hydraulic distributor of the system, you can easily deal with similar drives of similar designs. All of them have an almost identical structure with a similar principle of operation, including modifications with several levers or controlled by a joystick. When diagnosing and repairing, special attention is paid to the spool, valves and housing.
Frequent malfunctions
A rather serious problem of the distributor is the development in the landing nests between the body and the spool. You can detect such a defect by touch. Its appearance is indicated by longitudinal scratches and scores, vibration of the spool. It is worth noting that spool elements are not interchangeable. Some craftsmen, repairing the P-80 hydraulic distributor with their own hands, adjust the spool in size from another distributor. This makes it possible to extend the life of the part. Experts do not recommend this approach, despite the fact that the professional restoration of landing clearances is a very time-consuming and expensive process.
The main reasons for unauthorized lowering of working equipment (bucket or boom) are lack of tightness in rubber seals or clogging (wear) of the valve needle. If a similar problem occurs, the diagnosis should begin with the valve.
System Check
If the malfunction is associated only with attachments, the reason may lie in additional valves, cylinders. Check the elements by turning off one by one. If the working system refuses to work completely, it is necessary to increase the pressure in the valve, check the needle, pump, plug, presence of foreign objects in the pipelines and the distributor of the system.