Since the mid-1970s, the Minsk Tractor Plant has been developing MTZ universal-row-wheel wheeled vehicles of the Belarus family. Tractors of this brand are characterized by a small cab, stiffer suspension and all-wheel drive. Today, the MTZ 82 Belarus is considered the most advanced technical modification. According to the manufacturer, this version has unification with the first prototype up to 70%. But, there are significant differences, which, in particular, relate to the management system of the working bodies. The MTZ 82 hydrodistributor, represented by the P80-3 / 1-222 node, is responsible for this function. This is the basic version of the hydraulic system, which provides the ability to control suspended equipment directly from the cab.
Mechanism device
The basis of the design is a metal block with a system of channels providing the movement of the working fluid. The basic functional part contains the sockets of the oil supply circuits from the pump to the drain lines to the cylinders. It also provides control channels for overflow valves. Control of fluid return, its fixation and centering in blocks is provided by spools with elements of automated control. In the upper part, the device of the MTZ 82 hydraulic distributor is formed by the control bodies in the form of integrated levers. For insurance of unforeseen overflows, a special safety complex is also provided. Small accessories that provide the processes of mechanical control of functional elements are represented by sleeves, balls, springs, adjusting screws and clamps.
Hydroallocator Features
The modification of the hydraulic system P80-3 / 1-222 has many differences not only from the similar units that equipped the MTZ 50 line of equipment , but also from modern spreaders as part of competitive tractors. Basically, these features are due to the fact that in 1998 the MTZ 82 control valve began to be massively provided with non-return valves with wide control capabilities. Today, this control mechanism is known as a hydraulic lock, increasing the functionality and reliability of the system. One distributor can contain no more than four hydraulic locks (there are three of them in the MTZ 82 standard). As a rule, a frontal arrangement is used, and in an expanded configuration, a lateral fourth spool is additionally introduced. All components are unified and can be interchanged with similar elements within the P80 family of hydraulic systems.
Principle of operation
The main function of the control valve is to direct the pump fluid into the cylinder cavity, which ensures the operation of the target mounted organ that is currently relevant. After the session, the technical oil is transferred back to the tank as a result of automatic switching. As an additional control option, a mechanism for fixing the working equipment in a certain position is also provided. But before using this function, one should take into account the pressure limitations that, in principle, the MTZ 82 hydrodistributor can withstand. The connection scheme of the mechanism to different cylinder channels implies the separation according to purpose:
- For lowering.
- To lift.
- For regulation.
Each of the fluid supply circuits is associated with a central pipeline, a control system, and a drain channel. In the process of control, functional blocks with hydraulic locks are brought into active or inactive operating position. Now it’s worth familiarizing yourself with the specific operating conditions of the unit.
Work in a neutral position
In the initial position, the spools are held by springs with sufficient force, which is calculated in the process of factory assembly. This is the normal inactive position of the hydraulic locks. At the same time, the sleeve cups emphasize the lid located in the upper region of the structure. On the other hand, emphasis is placed on the lower part of the block. The fundamental difference between this condition is also the overlapping of the word and discharge channels. The belts and levers of the MTZ 82 hydrodistributor prevent the penetration of oil into the working cavities, therefore the pistons are in a fixed state. The lower channel can open at the moment of activation of the pump, which directs the oil to the working circuits.
Work of lifting units
The function of the lifting mechanisms assumes that pressure will be provided to the spool spring from the side of the lower barrel sleeve. A special sleeve holds the fixed ball elements, against which the body also rises to the upper position. As the channels overlap with the nozzle hole, the hydraulic belt rises above the oil injection line, connecting it to the cylinder. There is also a convergence of the liquid drain circuit with the drain hole, that is, the mechanism is prepared for drainage into the tank. Lifting of the equipment can be carried out until the cylinder of the MTZ 82 hydraulic distributor rests against the housing cover. After that, switching to the neutral position will automatically work. But, as a rule, the lifting process is completed by the operator himself, who stops the movement of the working bodies manually from the cab. By the way, the automatic control system is formed by a separate infrastructure, consisting of a fixing screw, a ball valve, a pusher and a special spring.
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Lowering process
In this mode, the working pressure is equalized across all hydraulic circuits. Balancing is achieved by shutting off the valves with the spools initially connected. At the same time, the flow of liquid also stops. The system gradually switches to a neutral position, as a result of which the draining process is completed and the contours are unloaded. In some cases, lowering may be automatic. This happens when the pressure on the fluid supply lines exceeds the maximum allowable load. Further, the MTZ 82 tractor’s hydraulic distributor even without the operator’s participation moves the spools to their original position, releasing the safety valves. If the system maintains an active lifting position even under conditions when the load on the valve exceeds a critical level, this indicates an incorrect adjustment, which can lead to breakdown of the mechanism.
System Maintenance Recommendations
During operation, the technical condition of the hydraulic system and its components should be regularly monitored. At the first sign of wear, the elements are replaced with new ones or repaired. The most common problems include valve damage, deformation of seals and jamming of individual parts of the assembly. In most cases, repairing a structure requires dismantling. Accordingly, the question arises of how to remove the valve on the MTZ 82? Work begins with the cab platform, where the panel with the dashboard of the attachment control system is disconnected. Next, the side flap on the hood is removed, cylinder tubes disconnecting the fittings and pressure hoses are disconnected. Directly, the valve body is removed after unscrewing the bolts from the side member. On the disassembled base of the mechanism, it is possible to replace individual elements, clean the channels with spools, check the condition of the oil vents, etc.
New directional control valves
The mechanism does not undergo drastic changes, but certain improvements still take place. In particular, the P80-3 / 1-222G modification is characterized by improved leakage protection. The design provides more reliable seals and regulators of valves. Also, the MTZ 82 hydraulic valve of the new sample was able to ensure the circulation of liquids under high pressure. The operator can start, stop and fix executive bodies in an intensive mode. At the same time, an updated overload protection system will insure the mechanics. Like previous versions, this valve is universal and can be integrated into the design of tractors MTZ, YuMZ-6, DT, T-150, etc.
Unit cost
There are not so many universal solutions in the segment of tractor hydraulic systems, therefore, there is no need to talk about a wide choice among alternative options for MTZ 82 owners. At most, we can talk about structural improvements of the mechanism, after which it can be fully used as part of the working bodies. But this does not make much sense due to the operational attractiveness of the standard MTZ 82 hydraulic distributor, whose price is on average 5.5-6 thousand rubles. This is a modest cost, since similar systems for similar equipment cost 7-8 thousand. However, there may be additional costs for accessories, levers and consumables - on average, 1-2 thousand.
Conclusion
The optimal combination of technical parameters with well-thought-out functionality made the P80-3 / 1-222 hydraulic system successful in terms of operation. It facilitates the tasks of the tractor driver and the work of the service engineer. But there are also weaknesses in the MTZ 82 hydrodistributor associated with a low level of automation. If similar nodes from other manufacturers are increasingly provided with automated controls in terms of control of working bodies, then almost the entire P80 line can independently solve only safety-related tasks. In particular, this applies to safety and protective functions. Partly for this reason, structural reliability is still one of the main advantages of this valve. Durability is confirmed by technical tests and the practice of using the unit in the field.