Solution to rotating failure of concrete pump truck arm

　　Example: A 2006 37-meter concrete boom pump truck suddenly appeared close to the boom during the pumping process. In the remote control state, the left and right sides can only be rotated unilaterally or neither side can be rotated.

　　Failure analysis

　　1. Electrical aspects:

　　(1) Whether the boom rotation limit switch is damaged

　　(2) The power status of the rotary solenoid valve of the boom and whether it is damaged

　　(3) Whether the relay is damaged

　　2. Hydraulic:

　　(1) Valve block problem of boom rotating multi-way valve

　　(2) Problem of boom rotating balance valve

　　(3) Reducer motor failure

　　(4) The reducer is damaged

　　Troubleshooting process:

　　1. Electrical:

　　(1) Check whether the I2.6 and I2.7 lights are on. If they are not on, it means that the boom rotation limit switch is not damaged. If it is lit, we disassemble the corresponding wiring to see if the fault remains: normal, it means that the limit proximity switch is damaged. If it remains, it means that the proximity switch is damaged and there are other faults.

　　(2) Check whether both solenoids are energized or not when the boom rotating solenoid valve is not rotating. Check whether Q3.0 and Q3.1 have output (check whether there is voltage output on lines 69 and 70 of the action boom). There is no output. Check whether the K31, K32 relays and modules are damaged. There is output, but the solenoid valve is not energized. Check whether there is a problem with the disconnected circuit. The solenoid valve is energized, check whether the resistance of the solenoid valve is normal, and the coil of the abnormal solenoid valve is damaged.

　　(3) Check whether the spool of the rotary solenoid valve is normal. Apply 24U voltage to the solenoid valve to see if the spool is moving. There is no action and the spool is damaged.

　　(4) If the electrical aspect is normal, perform hydraulic analysis

　　2. Hydraulic:

　　(1) Check if the multi-way valve head is damaged, and exchange the tubing with the No. 1 boom multi-way valve to see if there is no action when rotating. If there is a proof of the multi-way valve head problem, see if the orifice inside is blocked.

　　(2) Check the rotating balance valve and clean the spool to see if the card is issued.

　　(3) Check the hydraulic motor to see if it can rotate or not, the motor is damaged.

　　(4) Disassemble and inspect the reducer to check whether the bearing inside is damaged, and replace the bearing.

　　l After inspection, the fault of this boom concrete pump truck is that the coil of the rotating solenoid valve is burnt out. After replacing the solenoid valve, the equipment is normal.

　　Summary: Single-turn or non-rotation of the boom is a common fault of the boom-type pump truck, which generally appears in the electrical aspect. Therefore, first from the electrical to the hydraulic, the fault can be quickly eliminated from the easy to the difficult.