The jaw crusher is the primary piece of equipment for the primary (coarse) crushing stage in mineral processing plants. Known for its simple, robust, and durable design, it is highly adaptable and capable of handling almost any type of ore—making it particularly well-suited for the primary crushing of large, run-of-mine ore. The key to selecting the right model lies in ensuring a proper balance between the feed opening dimensions, the maximum feed particle size, and the required processing capacity; simply choosing the largest available unit is not necessarily the best approach.

Taking the PE series compound-pendulum jaw crusher as an example, this text describes its structure, working principle, and the methods for selection and calculation.

I. Structural Components
The main components of a compound-pendulum jaw crusher are described below. The term "compound-pendulum" refers to the motion trajectory of the moving jaw, which involves both vertical movement and a back-and-forth swinging motion, resulting in high crushing efficiency.

II. Operating Principle
An electric motor drives an eccentric shaft via a V-belt, causing the moving jaw to oscillate periodically. As the moving jaw swings toward the fixed jaw, material within the crushing chamber is subjected to compression, splitting, and fracturing. As the moving jaw swings away, the crushed material is discharged through the outlet. This continuous cycle enables ongoing crushing.

A characteristic of the compound-pendulum jaw crusher is its complex moving-jaw trajectory, which combines compression with a grinding (abrasive) action, leading to high efficiency. However, this also results in relatively rapid wear of the jaw liners (wear plates), which require periodic replacement. Understanding this is essential for proper operation and maintenance.

III. Three Core Parameters for Equipment Selection
Selecting a jaw crusher centers on balancing three key parameters: the dimensions of the feed opening, the maximum feed particle size, and the processing capacity.

Feed Opening Dimensions and Maximum Feed Particle Size
The width of the feed opening must be greater than the maximum particle size of the feed material. Generally, it is recommended that the maximum feed particle size does not exceed 80%–85% of the feed opening width—meaning the feed opening should be approximately 1.1 to 1.25 times the size of the largest feed particles. If the feed material is too large, it may become lodged in the feed opening, reducing processing capacity or even causing damage to the equipment. Feed opening width B ≈ (1.1–1.25) × maximum feed particle size (Dmax).
For example, if the maximum feed particle size is 500 mm, the feed opening width should be at least 550–625 mm; a model with a feed opening of 600 mm or larger would be appropriate. Selection should be based on the actual maximum feed particle size, not the average particle size.

Throughput capacity
Throughput capacity should align with the design production target, with an appropriate margin included. The capacity of a jaw crusher is influenced by feed particle size, material hardness, discharge opening size, and the uniformity of the feed. The capacity figures provided in product literature are typically reference values ​​based on specific conditions; in practice, these should be adjusted according to actual operating conditions.

Discharge opening and product particle size
The size of the discharge opening determines the product particle size. A smaller discharge opening results in a finer product, but also leads to reduced throughput and increased energy consumption. When selecting equipment, the discharge opening should be set based on the requirements of the downstream secondary crushing or grinding process, rather than simply minimizing the opening size.