pc200-6 full hydraulic excavator work weakness reasons

pc200-6 full hydraulic crawler excavator sometimes appear whole machine weak work, the phenomenon of slow movement, we analyze the main reason is the hydraulic system failure. 1. The main pump low pressure pc200-6 excavator with double swashplate axial variable piston pump. Under normal circumstances, the main pump output hydraulic pressure ≥ 30mpa. If the amount of wear between the main pump piston and the cylinder block or between the cylinder end face and the adapter plate exceeds the standard (the clearance between the plunger and the cylinder block should be less than 0.02 mm between the end face of the cylinder block and the adapter plate Contact area should not be less than 90%), it will cause the main pump output pressure is low, reflected in the mechanical working device, there will be a whole work weak phenomenon. 2. Main pump output flow control valve group failure to the main pump and engine power to achieve the best match, give full play to the role of the engine as a precondition, the main pump output flow of the machine is as the engine power changes. If the control valve used to regulate the main pump output flow failure, such as pls feedback loop is blocked, ls valve spool stuck, pc valve spool stuck or pc-epc solenoid coil is burned inside the coil, etc. Cause the main pump is always in a state of constant flow. If the main pump has been in a low flow state, the machine will be weak at work, slow motion. Likewise, if the main pump swashplate, servo piston and other parts that directly control the main pump flow change are stuck, the output flow of the main pump will not change. 3. Low pressure control valve output Under normal circumstances, the pressure reducing valve can reduce the output of the main pump oil and stable at 3.3mpa, the formation of control oil pressure. If the oil quality is too dirty so that the valve on the valve spool closed lax, it will lead to the output pressure of the valve less than 3.3mpa. At this time, no matter how the operation handle moves, the control oil pressure is always low. The main control valves of all kinds of work devices have a small amount of movement of the valve core, resulting in a small flow rate to the work device, resulting in the whole machine being weak. 4. Low relief pressure at main relief valve The main relief valve limits the maximum pressure in the entire hydraulic system to 32.5mpa. For high pressures above this, the main relief valve opens to relieve pressure and protects the system from damage. If the main relief valve spool due to poor quality and plug the hole caused by the valve normally open, or the main relief valve set the relief pressure is low, will cause the actual overflow pressure is low, the system Low pressure. 5. Unloading valve malfunction When the driver starts the engine and the operating lever is neutral, the main pump output hydraulic oil through the unloading valve directly back to the tank, unloading pressure of 3mpa. If the unloading valve spool is not closed properly due to the dirty oil, when the machine is operating, the main pump output oil will flow through the unloading valve to the fuel tank, resulting in the system can not build high pressure; Similarly, if the unloading valve In blocking pls pressure oil and tank connected 0-ring damage, it will lead to the main pump hydraulic oil directly back to the tank. 6. ls bypass valve defective ls bypass valve through the valve body of the two small holes (slight) Leak out part of the ls loop p15 pressure oil to increase the flexibility of the operation of the machine. If the body of the o-ring damage, pl5 pressure oil will be directly connected with the tank, which indirectly leads to unloading valve normally open, resulting in the working unit weakness and slow. In short, pc200-6 excavator if the whole work weakness, largely attributable to the poor quality of hydraulic oil. Therefore, changing the hydraulic oil filter on time (regulated to be changed every 500 h) and monitoring hydraulic oil quality (viscosity, fluidity and presence or absence of suspended solids) will prevent or reduce such malfunctions.