The adjustable moving jaw (more accurately, the adjustable discharge port gap) is one of the core mechanisms that enables jaw crushers to operate stably for extended periods and extend their lifespan. However, this function’s purpose is not merely to “increase lifespan,” but primarily to control product particle size.

1. Core Function: Controlling the Discharge Port Gap The space between the moving and fixed jaws is called the “discharge port.” This gap can be changed using an adjustment device (usually a wedge or hydraulic system). When a finer product is needed: reduce the discharge port size. When a coarser product is needed: increase the discharge port size.

2. How to Indirectly “Increase Equipment Lifespan”?

a) Preventing Overload and “Stalling”

Scenario: If the material contains extremely hard foreign objects such as iron blocks, or if too much or too large a quantity of material is fed in at once, it will cause a sudden increase in pressure within the crushing chamber. Consequences of lacking an adjustment function: If the discharge port is fixed and too small, large materials cannot be discharged, severely jamming the moving jaw, leading to motor overload, burnout, and even damage to critical components such as the eccentric shaft and connecting rod.

Advantages of having an adjustment function: Operators can quickly widen the discharge port to allow these oversized foreign objects or materials to pass smoothly, thus preventing equipment damage due to overload. This is an important self-protection mechanism.

b) Optimizing crushing efficiency and reducing ineffective wear

Principle: The ideal crushing state is that the material is squeezed multiple times in the crushing chamber and then just able to be discharged from the discharge port. If the discharge port is set too small: The material needs to be over-crushed before it can be discharged, which increases unnecessary and intense friction and squeezing between the jaw plates. “Material blockage” easily forms in the crushing chamber, leading to a decrease in crushing efficiency, while increasing energy consumption and wear per unit output.

Advantages of having an adjustment function: Setting a reasonable discharge port size based on the material hardness and feed particle size allows the material to be crushed in the most economical way. While ensuring product particle size, it minimizes wear on vulnerable parts such as jaw plates and bearings, thereby extending their service life.

c) Compensating for Normal Liner Wear

Process: The jaw plate (liner) is the component that directly contacts the material and suffers the most wear during crushing. With increasing usage time, the jaw plate gradually thins, leading to a larger actual discharge opening size (due to the increased distance between the moving and stationary jaws).

Consequences of No Adjustment Function: The discharge opening will become increasingly larger, resulting in coarser product particle size, failing to meet production requirements. At this point, the only solution is to stop the machine and replace the jaw plate.

3. Advantages of Adjustment Function: Operators can periodically and gradually reduce the discharge opening to compensate for the increased clearance caused by liner wear. This maintains a stable product particle size for a long period until the liner wears to the point of requiring replacement. This means the liner is fully utilized, replacement frequency is reduced, overall maintenance costs are lowered, and the equipment’s effective operating time is longer.