Troubleshooting and solution for excavator grabs’ opening and closing

INDUSTRY NEWS 2023-10-31

The opening and closing failure of excavator grabs means that the fingers of the grab can not be opened or closed, the grasping weak, and so on. When the user mentions that the grab is not moving, it is very likely that he has encountered this opening and closing failure.

By consulting Jiangtu engineers, we summarized the causes and solutions of the opening and closing failure of the grab as follows.

  • When the grab does not open and close

First of all, check whether the solenoid valve voltage has electricity (whether the induction light is on), and whether the pilot solenoid valve is electrified by pressing the button (if there is electricity, pressing the button will have the sound of “dang” suction). Whether the handle button is flexible and electric, and whether the control box has a response.
If all of the above is no problem, then Let’s check if there is a problem with the hydraulic oil circuit.


Induction light of solenoid valve


Control box and its Indicator light

The best way to check the oil problem is to check with the hydraulic gauge, which is fast and accurate. Measure the pressure on the main inlet pipe, if it is normal, it means that the excavator multi-way valve and pilot valve are all right. Measure the pressure on the forearm pipe,if normal, it means that the large solenoid valve and relief valve are fine, on the contrary, the large solenoid valve is stuck.

What if there is no hydraulic pressure gauge? Whether it is normal or not can also be judged by observing the reaction of the main inlet pipe and the arm oil pipe.


Pressure measurement by hydraulic gauge.

If all of the above is normal, it means that the cylinder is damaged and the oil seal or cylinder assembly needs to be replaced. The chance of damage to both cylinders at the same time is very small and almost impossible.

  • One finger moves and the other doesn’t move.

First of all, check whether the balance valve is damaged: mark the two balance valves and exchange them for installation. if the problem becomes motionless can move and the active finger cannot move, it means that the balance valve is damaged and needs to be replaced; on the contrary, if the oil cylinder or oil seal is damaged, the oil seal or cylinder assembly needs to be replaced.


balance valve



  • When the grab is weak

1. The grasping is weak and the rotation is normal. When grasping objects, the two fingers are synchronized at the same speed. Most cases are caused by a large solenoid valve stuck and need to clean a large solenoid valve.

2. The grasping is weak, the rotation is normal, the object does not fall off, and there is a slow speed and signs of weakness in opening or closing a finger. By exchanging valves, we can judge whether it is the problem of the valve or the leakage in the cylinder.

If you do not press the corresponding button on the handle when grasping the item, it will fall off, then check the large solenoid valve and clean it on the basis of the above scheme.

The above are several points of analysis and solutions to the opening and closing failure of the grab, hoping to help the users of our grab.

The above problem-solving steps are in basic sequence. In practice, they can be used flexibly.
If still need help, please feel free to contact us at whatsapp +86-15653818637.

If you choose Jiangtu Excavator Grab, the failure rate is low. Our grabs win nice word of mouth by working well for 6-9 years. With One year warranty and 6 months free replacement after-sales policy you can rest assured to choose.



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