Upper Side Guard / Upper Cheek Plate

In the spare parts system of jaw crushers, the upper side guard (upper cheek plate) and the lower side guard together form the side-wall protection system of the crushing chamber. Typically installed on the inner upper left and right sides of the frame, it is a critical wear-resistant component that protects the core structure of the equipment from direct impact and friction caused by the material.

Below is a detailed breakdown across four dimensions: core functions, materials and manufacturing processes, replacement standards, and installation and maintenance guidelines.

1. Core Functions: The "Upper Shield" for the Frame

Protecting the Frame Side Walls

During the operation of a jaw crusher, massive compressive forces are generated between the swing jaw plate and the fixed jaw plate. The upper side guard directly withstands the friction and impact from the material in the upper part of the crushing chamber, preventing the frame side walls from wearing out. Once the frame is damaged, repair costs are extremely high, and it may even lead to the scrapping of the entire machine.

Withstanding High-Intensity Impact

Unlike the lower side guard, which primarily endures sliding friction, the material size at the top of the crushing chamber is the largest. Therefore, the upper side guard bears the most intense initial impact loads. It must possess extremely high impact resistance and toughness to prevent deformation or fracture when crushing large blocks of material.

Assisting Feed and Guiding Material

Located directly below the feed inlet, the surface profile and installation angle of the upper side guard help guide large blocks of material smoothly into the core crushing zone of the chamber, reducing material retention in the upper section.

2. Material Selection

Since the upper side guard primarily endures intense impacts from large blocks of material, its material must possess excellent toughness and work-hardening capabilities:

High Manganese Steel: The most mainstream choice. After being subjected to intense impact, high manganese steel undergoes rapid work-hardening on its surface, significantly increasing its hardness, while the core maintains high toughness. This perfectly suits the high-impact conditions at the top of a jaw crusher.

Medium Manganese Steel: Some manufacturers also use medium manganese steel, which provides a more cost-effective wear-resistant solution while maintaining adequate toughness.

Casting Processes: Processes such as lost-foam casting, quartz sand molding, or resin sand molding are typically used to ensure there are no internal defects like porosity or shrinkage cavities in the casting, thereby guaranteeing overall strength.

3. Replacement Standards

The upper side guard is a high-frequency wear part and must not be used until it is completely worn through, which would compromise the frame:

Thickness Wear Limit: It must be replaced immediately when the wear volume reaches 25% of its original thickness or dimensions.

Surface Damage: If severe pits, significantly thinned areas, or penetrating cracks appear on the surface, it must be replaced.

Decreased Sealing Performance: If wear leads to a decrease in the sealing of the crushing chamber, resulting in a noticeable increase in dust leakage, it also needs to be replaced.

Time Cycle: Under normal operating conditions, the replacement cycle is typically around half a year (6 months), depending on the hardness of the crushed material and the production volume.

4. Installation and Daily Maintenance Guidelines

Replace in Pairs

When replacing the upper side guard, it is highly recommended to replace the left and right sides simultaneously. Replacing only one side will cause asymmetry in the feed gap at the top of the crushing chamber. This not only leads to poor feeding but also causes eccentric loading on the swing jaw, accelerating the wear of the bearings and the main shaft.

Fastening and Anti-loosening

The upper side guard is usually secured to the side wall of the frame with high-strength bolts. Due to the extreme vibration of the jaw crusher, spring washers or lock nuts must be used, and the bolts must be tightened to the specified torque during installation. During daily inspections, it is essential to tap-check the bolts to ensure they are not loose.

Clearing Accumulated Material

Regularly inspect the gap between the side guard and the frame for trapped small rocks or dust. If found, it must be cleared immediately; otherwise, these hard particles will act like sandpaper, accelerating the wear on the back of the side guard and the frame.