There is a problem with the limit device of the hydraulic grab bucket

1. Limit high contact current and frequently malfunction. The original limit used a fire extinguishing limit, but this limit did not have an arc extinguishing device. Due to the high current, arc short circuits often occur, resulting in the limit not working.
2. Due to the irregular grasping of materials by hydraulic grab buckets, larger diameter materials often get stuck on the grab bucket jaw plate and cannot be closed properly, resulting in the failure of the travel switch and causing the wire rope to break or the motor to burn out.
Improvement and transformation plan for hydraulic grab limit device
1. The improved limit device cannot use a travel switch due to irregular materials, so a heavy-duty limit device installed on the rope is selected, which has a simple structure and is easy to modify. Regardless of whether the grab bucket is closed properly, as long as the tension of the steel cable exceeds the set value, the overload limiter can be activated.
2. The control line is modified to use an overload limiter to control the contactor, achieving small current control and large current control. The normally closed contact of the overload limiter S is closed. When it opens or closes the button, the contactor KM will have electricity, the motor will start, and the time relay KT will work. After the delay action is completed, the electrical delay disconnection contact of the timing relay will disconnect; When the tension of the steel wire rope exceeds the set value, the contactor releases electricity, the motor stops running, and a warning sound and light alarm is issued. When shutting down, the relay contact KT is closed. Open again, as the time relay is powered on, the delayed disconnect contact KT closes, KM is powered on, the grab opens, and after the delayed action, the overload limiter is released and the time relay contact KT disconnects.