Generally speaking, grabs can be divided into hydraulic grabs and mechanical grabs. These two grabs have their own characteristics and scope of application. Let us introduce a hydraulic grab, mainly its concept, structure, maintenance and how to deal with some shortcomings. The specific content is as follows:
1. The concept of hydraulic grab
Hydraulic grab, as the name implies, is to provide power through a hydraulic power source, and then drive the opening and closing of two combined buckets or multiple jaws on the left and right to achieve the purpose of grabbing or unloading materials. It is an operating equipment.
2. Hydraulic grab structure
The hydraulic grab is mainly composed of a bucket, an upper beam, a lower beam and a hydraulic system. The upper and lower beams are hingedly connected by connecting rods, and two buckets are hinged on the lower beam and equipped with a hydraulic system. There is a hook on the upper part, which is connected to the lifting organization.
The hydraulic system of the hydraulic grab consists of an oil tank, an oil pump, a control valve group and a hydraulic cylinder. The piston rod is tightly matched with the tapered hole of the upper beam and fixed with a nut. Four connecting rods connect the upper beam and the grab.
3. Maintenance of hydraulic grab
(1) Regarding hydraulic oil, pay attention to the oil level, oil temperature, oil quality and oil type. The grab should be closed before measuring the oil level in the tank; when the ambient temperature is below -10℃, the grab should also be closed.
(2) Clean or replace the filter in time. When replacing the hydraulic oil, use the same brand of hydraulic oil.
(3) Each hinge should be refueled on time, especially when it is out of use for a long time.
(4) Pay attention to cleaning the top of the piston rod to prevent solid particles from entering. If the top of the piston rod is excessively worn, the piston rod should be replaced in time.
4. Disadvantages of hydraulic grab
Disadvantage 1: The grab cannot be opened when it is full of cargo.
First check the circuit. If the circuit is normal, loosen the oil pipe joint on the oil cylinder, and then use two hoists to place the grab on the deck. Then remove the cable connector, motor cover and oil pipe, lift out the motor and oil pump, check whether the suction check valve is normal, whether the relevant joints are loose or cracked, and remove the oil pump or control valve group if necessary.
Disadvantage 2: The grab cable is loose or even clamped.
When the oil volume is insufficient, the driving torque is reduced, the cable is loose and easy to break; when the oil volume is too much, the motor is overloaded. If the cable cannot be tightened, the hydraulic oil should be replaced, and the oil pressure of the hydraulic oil can be adjusted if necessary.