Calma hoisted his arm up and down slowly

Recently, a Tianjin customer Kalmar DRF450-60S5K front crane appeared fast lifting function reaction is normal, the big arm slow lifting, lifting speed becomes slower with the increase of load failure to lift the heavy box, and the cab display terminal KID no fault code. Let's work it out.

Maintenance process:

The first step is to check:

Hydraulic parts: arm lifting maximum pressure 160Bar, and spreader or steering action when the pressure can rise to 200 Bar; the arm retracted, the maximum pressure of 140 Bar, 35 Bar normal pressure servo, sling action normal, normal steering action.

By entering the kharma diagnosis system view: air lifting handle electrical part of the input signal 2.5V ~ 4.5V normal, lifting control solenoid valve with current output of 700mA is normal, the length of the sensor input signal of 0.5 ~ 4.5V, the angle sensor input signal of 0.5 ~ 4.5V normal.

The second step, tune:

Adjust the lifting control solenoid valve output current to the maximum, no improvement; re calibration weighing system (calibration length and angle sensor), no improvement; adjust the initial hydraulic pump pressure, no improvement.

The third step, change:

Part of the hydraulic schematic diagram is as follows:

图1

The replacement of the unloading electromagnetic valve (43), no improvement; the replacement of the shuttle valve (36), no improvement; the replacement of the shuttle valve (39), no improvement; replacement of priority valve assembly (31), no improvement; the replacement of the main pressure limiting valve (42), no improvement; replacement about lifting oil blocking valve assembly, no improvement; the replacement of the main valve or solenoid valve control, no improvement.

The fourth step, dismantle:

Remove hydraulic pump (41) pressure control valve, check the spool and spring are normal;

Remove the lift cylinder, C- return line, test during lifting operation, no leakage of pressure is found;

Remove the boom, control the main valve, lift the stem and check for no excessive wear and hold;

Remove the hydraulic pump (41) and check inside for no excessive wear.

The fifth step, than:

Measure the LS (load signal) pressure of the car owner's valve and measure the pressure of the LS (load signal) of another valve of the same type. Compare the two:

When the fault car rises, the 50-90-160bar rises when the normal car is 50-90-200bar

图2

The sixth step, repair:

Check found that the main valve LS (load signal) between the outlet to T port LS pressure release valve stem is stuck by metal chip, resulting in LS signal pressure leakage is too large, oil pump fuel flow is not enough. Remove the metal scraps, clean the main valve and assemble, and connect the control pipe to test.

LS (load signal) hydraulic schematic diagram is as follows:

图3

Through this article we can see that some engineering machinery fault in the solution, is must have professional knowledge and judgment, so the working principle of on-site maintenance personnel must be familiar with the whole system, according to the standard locomotive first obtain actual data changes. Of course, in the positive hanging work, must maintain good equipment, especially machinery and hydraulic system, and in strict accordance with the maintenance service operation procedures, must not be arbitrary.