The Composition of the Double-Swing Jaw Crusher
The hydraulic jaw crusher consists of three main components: the double-swing jaw crusher main unit, the hydraulic protection device, and the electrical control cabinet.
The structure of the hydraulic jaw crusher is basically the same as that of a conventional simple swing jaw crusher, with the following differences: the safety mechanism and adjustment mechanism of the hydraulic cylinder replace the original safety device and adjustment device of the conventional jaw crusher. The principles of the three major devices of the hydraulic jaw crusher—segmented start-up, hydraulic safety, and hydraulic adjustment—are described below.
1. Hydraulic staged start-up
To reduce power consumption during the start-up of large jaw crushers, two hydraulic friction clutches are installed at both ends of the eccentric shaft. One clutch is mounted between the pulley and the eccentric shaft, while the other is mounted between the flywheel and the eccentric shaft. Due to the action of springs, the clutches are normally engaged, keeping the flywheel, pulley, and eccentric shaft tightly meshed. Before starting the crusher, hydraulic oil is pumped into the two cylinders located at both ends of the eccentric shaft. When the oil pressure reaches 29 kg/cm², the cylinder pistons move toward both ends of the eccentric shaft, compressing the springs and disengaging the clutches. At this point, the main motor is started, driving the pulley to rotate. After 20 seconds, the pulley reaches normal operating speed, At this point, the oil in the oil cylinders of the pulley is depressurised and flows back to the oil tank, the clutch engages, and the eccentric shaft rotates together with the pulley. After another 20 seconds, the oil in the oil cylinders at the flywheel end is depressurised, the clutch engages, and the flywheel rotates together with the eccentric shaft, completing the three-step start-up of the crusher.
2. Hydraulic safety device
The hydraulic safety cylinder is installed in the connecting rod body. Before starting the crusher, the hydraulic oil pump is first activated to fill the piston of the connecting rod body cylinder with oil, ensuring the oil pressure does not exceed 200 kg/cm². Then the main motor is started, and the crusher operates normally. When non-crushable objects enter the crushing chamber, the oil pressure in the lower cylinder of the connecting rod exceeds the specified pressure, forcing the high-pressure relief valve to open. This causes the oil from the lower cylinder to flow into the upper cylinder to relieve pressure, thereby stopping the movement of the lower part of the connecting rod, the thrust plate, and the moving jaw that are currently in operation. Meanwhile, the main motor, eccentric shaft, and upper part of the connecting rod continue to operate normally, thus protecting the machine from damage. The machine is then stopped, the non-crushable objects are removed, and the machine is restarted.
3. Hydraulic Adjustment Device
Before adjustment, first loosen the nuts connecting the slide block seat to the rear frame and the spring nuts on the tie rod. then start the oil pump to fill the cylinder with oil, causing the piston to push the slide block seat forward. Add or remove shims between the slide block seat and the rear frame to adjust the size of the discharge opening. After adjustment, drain the oil, tighten the nuts connecting the slide block seat and the rear frame, and re-adjust the nuts of the tie rod spring. The adjustment of the discharge opening is now complete.
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