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What is the role of the excavator Idler?

What is the role of the excavator Idler?

What is the role of the excavator Idler?

1- The main pump pressure is low
PC200-6 excavator adopts double swash plate type axial variable piston pump. Excavator maintenance and repair Under normal circumstances, the output oil pressure of the main pump is greater than or equal to 30 small MP.

Excavator Idler-001

If the amount of wear between the plunger of the main pump and the cylinder body or between the end face of the cylinder body and the valve plate exceeds the standard (the gap between the plunger and the cylinder body should be less than 0.02, and the gap between the end face of the cylinder body and the valve plate should be less than 0.02). The contact area should not be less than 90%), which will cause the output pressure of the main pump to be low, which will be reflected in the working device of the machine, and the whole machine will be unable to work.

2- The main pump output flow control valve group is faulty
On the premise that the power of the main pump and the engine can be optimally matched and the role of the engine can be fully utilized, the output flow of the main pump of the machine changes with the change of the engine power. If the control valve group used to adjust the output flow of the main pump fails, if the PLS feedback loop is plugged, the LS valve spool is stuck, the PC valve spool is stuck, or the internal coil of the P°C-EPC solenoid valve is burned out In other cases, the main pump will always be in a state of constant flow.

If the main pump is always in a small flow state, the machine will be weak and slow when working:
Similarly, if the swash plate, servo piston and other parts of the main pump that directly control the flow change of the main pump are stuck, the output flow of the main pump will not change.

3- The control pressure output by the pressure reducing valve is low
Under normal circumstances, the pressure reducing valve of the excavator maintenance company in Chongqing can reduce and stabilize the output oil pressure of the main pump at 3.3P, forming a control oil pressure. If the push spool on the pressure reducing valve is not closed tightly because the oil is too dirty, the output pressure of the pressure reducing valve will be lower than 3.3MPā. At this time, no matter how the operating handle moves, the control oil pressure is always low, and the movement of the spool of the main control valve of various work equipment is small, resulting in a small flow to the work equipment, resulting in the powerlessness of the whole machine.

Excavator Idler-002

4-Relief pressure of the main relief valve
The main relief valve with low force limits the maximum pressure of the entire hydraulic system to 32.5MP. For the high pressure exceeding the ratio, the main relief valve will open to relieve pressure. Hitachi Excavator Repair Chongqing Company will protect the system from damage. If the small hole on the main relief valve spool is blocked due to poor oil quality and the spool is normally open, or the set relief pressure of the main relief valve is low, the actual relief pressure will be low, that is, the system Pressure is low.

5- The unloading valve is faulty
When the driver starts the engine and puts the operating lever in neutral, the hydraulic oil output from the main pump returns directly to the fuel tank through the unloading valve, and the unloading pressure is 3MP. If the spool of the unloading valve is not closed tightly due to the dirty oil, the output oil of the main pump will pass through the unloading valve directly to the oil tank when the machine is in operation. When the O-ring seal on the load valve used to block the connection between the PS pressure oil and the oil tank is damaged, it will also cause the main pump hydraulic oil to flow back to the oil tank directly.

Excavator Idler-003

6-LS bypass valve faulty
The LS bypass valve can leak a part of the P15 pressure oil on the LS circuit through the two small sub-holes on the valve body (slightly) to increase the stability of the machine operation. If the O-ring seal on the valve body is damaged, the PL5 pressure oil will directly communicate with the fuel tank, which will indirectly cause the unloading valve to open normally, resulting in weak and slow movements of each working device.

In a word, if the PC200-6 excavator is incapable of working as a whole, it can be largely attributed to the poor oil quality of the hydraulic oil. Therefore, replace the hydraulic oil filter element on time (required to be replaced every 500) and pay attention to the recovery


Post time: Jul-20-2022