The pilot relief valve of the Kato excavator is installed in the pilot gear. As shown in Figure 3-14, the pilot gear pump is connected in series with the two main pumps. The hydraulic system continuously generates pressure to supply different equipment
(1) Hydraulic pressure is supplied to the left and right pilot control valve and the travel pilot valve.
(2) The hydraulic pressure supply solenoid valve controls the rotary parking brake, high power function and walking speed.
(3) The hydraulic pressure is supplied to the signal of straight forward walking pressure increase.
(4) Hydraulic pressure supply arm contact valve
(5) Hydraulic pressure is supplied to the upper turntable and walking pressure switch.
(6) APC proportional decompression control valve.
Therefore, if the circuit pressure is too low or too high, it will result in a series of faulty pressure measurement methods
1. Pressure measurement method
(1) Stop the engine, as shown in Figure 3-15, press the air vent rubber plug on the fuel tank to reduce the air pressure of the fuel tank.
(2) Install the pressure gauge 0~98MPa to the sensor connector at the inlet of the pilot filter
(3) Turn on the start switch to start the engine
(4) Check if there is oil leakage at the connection of the pressure gauge.
(5) Turn on the working mode to "Heavy duty", APC mode to "H", automatic deceleration mode to "OFF" and "OFF".
(6) Run the engine and heat it until the oil temperature reaches (50±5)℃
(7) Fully rotate the accelerator knob to the low idle and high idle stop positions, and read the pressure gauge reading at each position.
[note]
① The pilot relief valve pressure at low idle speed is 314~343MPa.
② The pressure of the pilot relief valve at high idle speed is 343~422MPa 2. The pressure adjustment method uses the relief valve installed in the pilot gear pump to adjust the pressure as shown in Figure 3-16, loosen the lock nut and turn the adjustment screw to adjust Pressure, and then set the lock nut.
note
①When the tightening torque reaches 294N·m, the pressure of the relief valve will reach (300kgf/m2).
②Adjust the screw to the left and rotate it once, increasing the pressure by about 1.7MPa, and turn the screw to the right and reduce the pressure by about 1.7MPa.
