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Working Principle and Internal Forces of Jaw Crusher

Working Principle of Jaw Crusher

The core working principle of a jaw crusher is crushing materials through the relative motion and extrusion of the movable jaw and fixed jaw.

Core Structure

• Fixed Jaw: Vertically or obliquely fixed on the frame, serving as one side wall of the crushing chamber.
• Movable Jaw: Connected via an eccentric shaft, connecting rod and other mechanisms, capable of reciprocating swing.
• Eccentric Shaft: The core driving component, rotated by the motor through a pulley.

Working Process

1. After the motor starts, it drives the eccentric shaft to rotate, which in turn drives the movable jaw to perform periodic swing.
2. When the movable jaw approaches the fixed jaw, the materials between the two jaw plates are crushed by extrusion and shear forces.
3. When the movable jaw moves away from the fixed jaw, the crushed materials fall by gravity and are discharged from the discharge port, completing one crushing cycle.

Key Features

• Large Crushing Force: Relying on extrusion, it is suitable for processing high-hardness materials (such as ore and rock).
• Intermittent Operation: The swing of the movable jaw is periodic, with crushing and discharge carried out alternately.

What Internal Forces Act on a Jaw Crusher?

A jaw crusher is mainly subjected to three types of core internal forces: reaction force from material crushing, inertial force from moving parts, and acting force from the transmission mechanism.

1. Material Reaction Force (Main Working Force)

• When the movable jaw extrudes materials, the materials exert a reverse extrusion force on the movable jaw and fixed jaw, which is the main internal force of the equipment.
• The force magnitude is related to material hardness, particle size and crushing chamber pressure. The higher the hardness and the fuller the materials, the greater the reaction force.

2. Inertial Force of Moving Parts

• Moving parts such as the movable jaw, eccentric shaft and connecting rod perform periodic reciprocating motion or rotational motion, generating inertial force.
• Inertial force affects equipment stability and needs to be offset by designs such as counterweights to avoid excessive vibration.

3. Transmission and Support Forces

• Torque force transmitted from the motor to the eccentric shaft through the pulley, driving the components to move.
• Support reaction force from bearings and the frame on the eccentric shaft and movable jaw, used to balance the force on moving parts and ensure stable motion trajectory.

Other Auxiliary Forces

• Frictional force between materials and jaw plates, which hinders material sliding and exerts wear force on the jaw plates.
• The equipment's own gravity, as well as additional dynamic loads generated by vibration during operation.