There are lots of factors that affect the working of jaw crusher. The overload protection is the most important factor. When the material's hardness is over 300Mpa, the jaw crusher will be easy to stop if having no safety overload device. There are three common overload protection devices:
Toggle break off device
Setting a point in toggle that is easy to be broken off. If the jaw crusher is overload, the toggle will break off in order to protect the jaw crusher. But the toggle is made of cast iron, sometimes it can not protect because it's breaking off point can not be controlled exactly. What is more, if break off, the toggle must be changed which will affect the production.
Flywheel distance limit device
Hydraulic friction clutch, spring friction clutch and safety pin are the main parts of the device. It is widely used in swinging jaw crusher. Friction clutch can assure moment is in right range. If overload, the flywheel will slide to protection. The external condition like temperature will affect the device reliability, and the cleaning and maintenance is difficult if overload.
Hydraulic overload protection device
This protection device is mainly composed of working cylinder, accumulator, plunger-type oil pump, cam gear, oil pressure regulate device, operating valve, filter, oil tank, etc. The fixed jaw is fixed in the inner mantle, the electric motor drives the eccentric gear rotating through V belt, and then driving the swing jaw does compound pendulum to crush materials. The piston rod of hydraulic cylinder is connected with liner plate, and hinged spring rod at the bottom of swing jaw, which determines the size of discharge opening and the crushed materials. When the materials that the crushed granularity exceeds the set value enter into the crushing cavity, the piston quickly retracts, the discharge opening is enlarging, and the high strength materials are discharged out. After the high strength materials being discharged, the hydraulic system feed the oil to the right oil chamber, the piston moves to the limit position and recover the normal working condition. The working load of jaw crusher has large volatility, the working peak value is 3 or 4 times than the normal working value, so the hydraulic protection device must be reliable, stable and sensitive.