Construction of a Gyratory Crusher: Main Parts and Functions

A gyratory crusher is a heavy-duty compression crusher primarily used to reduce run-of-mine ore and large blasted rock. Its structure is designed to withstand continuous crushing forces while allowing material to move downward through the crushing chamber.

The main components include the spider assembly, main shaft, mantle, concaves, eccentric assembly, main frame, drive system, hydraulic system and lubrication system. Each component performs a specific mechanical or protective function.

Understanding the construction of a gyratory crusher helps operators identify wear, plan maintenance and select the correct equipment for a mining or quarrying project.

Main Parts of a Gyratory Crusher

Component design and arrangement vary by manufacturer and crusher model. Always use the technical drawings and maintenance manual supplied for the actual equipment.

1. Spider Assembly

The spider assembly is installed across the top of the crusher. It supports and guides the upper end of the main shaft through the spider bearing.

Its main components may include:

• Spider hub

• Spider arms

• Spider bearing

• Spider bushing

• Spider cap

• Spider-arm liners

The spider arms are exposed to falling feed material and therefore require protective liners. The spider cap and liners reduce direct impact and abrasive wear on the structural parts.

Common inspection points include:

• Spider-arm liner wear

• Loose fasteners

• Cracks

• Lubrication condition

• Bearing clearance

• Material buildup

• Abnormal movement

The spider bearing guides the main shaft but does not contain the lower eccentric assembly. The eccentric assembly is located in the lower section of the crusher.

2. Main Shaft

The main shaft is a major load-bearing component that supports the crushing head and mantle. Its lower section interacts with the eccentric assembly, while its upper end is guided by the spider bearing.

When the eccentric rotates, the main shaft does not simply rotate around its own centre. Instead, it follows a controlled gyrating path that moves the mantle toward and away from the concaves.

The main shaft must withstand:

• Crushing forces

• Bending loads

• Repeated cyclic loading

• Weight of the crushing head

• Loads caused by uneven feeding

Important inspection areas include surface wear, cracks, scoring, lubrication condition and dimensional tolerances.

3. Mantle

The mantle is the moving crushing surface fitted around the crushing head or main-shaft assembly. It moves continuously inside the stationary concaves.

As the mantle approaches the concaves, rock and ore are compressed and fractured. As it moves away, the crushing gap opens and the material falls lower in the chamber.

Mantles are normally manufactured from wear-resistant manganese steel or another alloy selected for the material and operating conditions.

Mantle wear is affected by:

• Material hardness

• Abrasiveness

• Silica content

• Feed-size distribution

• Feed segregation

• Closed-side setting

• Throughput

• Chamber profile

A worn mantle changes the crushing-chamber profile and may affect capacity, product size and power draw.

4. Concaves

Concaves are the stationary wear surfaces installed around the inner wall of the upper shell and main frame. Together with the mantle, they form the crushing chamber.

Concaves are normally divided into multiple segments to simplify installation and replacement. Different sections of the crushing chamber may use different liner shapes or materials according to the wear pattern.

Concave design affects:

• Feed acceptance

• Crushing-chamber volume

• Nip conditions

• Product-size distribution

• Capacity

• Liner wear

Loose, cracked or excessively worn concave segments should be addressed before they expose the supporting structure or affect crusher operation.

For more information about liner inspection and replacement, see the gyratory crusher wear parts guide.

5. Crushing Chamber

The crushing chamber is the space formed between the moving mantle and stationary concaves. Its profile determines how material is received, compressed and discharged.

A correctly selected chamber should match:

• Maximum feed size

• Feed-size distribution

• Required capacity

• Required product size

• Material hardness

• Material abrasiveness

• Closed-side setting

• Eccentric throw

An unsuitable chamber profile can cause:

• Reduced capacity

• Bridging

• Poor product-size control

• Uneven liner wear

• High power draw

• Unstable crusher loading

The chamber should be selected using actual feed and production data rather than the feed opening alone.

6. Main Frame and Shell Sections

The main frame supports the crushing chamber, main shaft, eccentric assembly and drive components. Large gyratory crushers may use several frame or shell sections connected by heavy-duty fastening systems.

The structure must resist:

• Static equipment weight

• Dynamic crushing forces

• Material impact

• Drive-system loads

• Vibration

• Foundation movement

Protective liners are used in areas exposed to falling or discharged material. If these liners become excessively worn, the underlying structural surfaces may be damaged.

Inspection should include:

• Cracks

• Loose fasteners

• Abnormal movement

• Worn mounting surfaces

• Damaged protective liners

• Foundation connections

Structural repairs should follow an approved engineering and welding procedure.

7. Eccentric Assembly

The eccentric assembly is located in the lower part of the crusher. Its function is to convert the rotational input from the drive system into the gyrating movement of the main shaft and mantle.

Depending on the design, the assembly may include:

• Eccentric sleeve

• Eccentric bushing

• Gear

• Pinion

• Supporting bearings

• Thrust components

The eccentric bushing operates under high load and depends on a clean, stable lubrication supply.

Possible signs of eccentric or bushing problems include:

• Rising oil temperature

• Metal particles in the oil

• Abnormal vibration

• Increased clearance

• Irregular main-shaft movement

• Unusual noise

The eccentric bushing should not be described as being inside the spider hub. The spider assembly is at the top of the crusher, while the eccentric assembly is in the lower section.

8. Drive System

The drive system transfers power from the electric motor to the eccentric assembly.

A typical system may include:

• Electric motor

• Coupling

• Drive shaft

• Pinion

• Gear

• Bearings

• Protective guards

As the motor drives the pinion and gear, the eccentric assembly moves the main shaft and mantle in a gyrating path.

Drive-system inspection should include:

• Alignment

• Coupling condition

• Gear contact

• Bearing temperature

• Lubrication

• Fasteners

• Abnormal noise

• Guard condition

The motor power and drive arrangement depend on crusher size, chamber design and expected crushing load.

9. Hydraulic Adjustment System

The hydraulic system supports or adjusts the main-shaft position, depending on the crusher design. Raising or lowering the main shaft changes the closed-side setting.

The system is used to:

• Adjust discharge size

• Compensate for mantle and concave wear

• Maintain the required CSS

• Support the main shaft

• Provide overload protection in suitable designs

The hydraulic system may increase the discharge opening when an uncrushable object enters the chamber. However, hydraulic protection does not replace upstream metal detection and removal equipment.

Typical hydraulic components include:

• Hydraulic cylinder or support piston

• Oil tank

• Pump

• Valves

• Accumulator

• Pressure sensors

• Pipes and hoses

10. Lubrication and Cooling System

The lubrication system supplies clean oil to critical moving components, including bearings, bushings, gears and the eccentric assembly.

A typical system may contain:

• Main oil pump

• Standby oil pump

• Oil tank

• Filters

• Oil cooler

• Temperature sensors

• Pressure sensors

• Flow sensors

• Alarms and interlocks

The system should be operating before the main crusher motor starts. Correct oil pressure, flow and temperature must be confirmed before crushing begins.

Poor lubrication may lead to:

• Bearing damage

• Bushing wear

• Gear damage

• High temperature

• Abnormal vibration

• Unplanned shutdown

Detailed inspection requirements are available in the gyratory crusher maintenance checklist.

11. Dust-Sealing System

The dust-sealing system helps prevent fine particles from entering the eccentric, bearing and lubrication areas.

The system may use:

• Dust seals

• Seal rings

• Covers

• Pressurized air

• Oil-based sealing arrangements

Seal condition is particularly important when the crusher processes dry, dusty or abrasive material. Damaged seals can contaminate the lubricating oil and accelerate internal wear.

Oil analysis may help identify dust, water and abnormal metal contamination before serious damage occurs.

12. Protective Liners

Protective liners are installed on structural surfaces exposed to falling material, abrasive flow or repeated impact.

These may include:

• Spider-arm liners

• Bottom-shell liners

• Feed-area liners

• Discharge-area liners

• Internal frame liners

Protective liners should be replaced before the underlying frame or shell becomes exposed. Replacing a liner is generally less complex than repairing structural damage.

How the Components Work Together

Run-of-mine ore or blasted rock enters through the upper feed opening and falls into the chamber between the mantle and concaves.

The drive system rotates the eccentric assembly, causing the main shaft and mantle to move in a gyrating path. Material is compressed when the mantle moves toward the concaves and moves downward when the gap opens.

This process repeats until the material is small enough to pass through the bottom discharge opening.

The hydraulic system controls the main-shaft position and closed-side setting, while the lubrication system protects the bearings, bushings and drive components.

For a complete process explanation, see how a gyratory crusher works.

Which Parts Are Wear Parts?

Not every crusher component is a regularly replaced wear part.

Regular wear parts

• Mantle

• Concave segments

• Spider cap

• Spider-arm liners

• Bottom-shell liners

• Other protective liners

Components subject to mechanical wear

• Eccentric bushing

• Spider bushing

• Main-shaft sleeve

• Bearings

• Dust seals

• Gear and pinion

Mechanical components should be inspected and measured. They should not automatically be replaced at the same interval as the mantle and concaves.

How Construction Affects Crusher Selection

The construction of a gyratory crusher determines its feed capacity, crushing performance, installation requirements and maintainability.

Before selecting a model, consider:

• Maximum feed size

• Feed-size distribution

• Material hardness

• Abrasiveness

• Required capacity

• Required product size

• Chamber profile

• CSS range

• Motor power

• Foundation requirements

• Maintenance access

• Available lifting equipment

A larger feed opening alone does not guarantee that the crusher is suitable for the project. The chamber, eccentric throw, drive power and discharge system must also match the application.

The X Series Primary Gyratory Crusher is available in multiple sizes for different feed openings and capacity requirements. Final selection should be based on actual feed and operating data.

Conclusion

A gyratory crusher is built around a heavy-duty main frame, a gyrating main shaft and mantle, stationary concaves and a lower eccentric assembly. The spider guides the upper end of the main shaft, while hydraulic and lubrication systems control the setting and protect critical components.

Understanding the function of each part makes it easier to identify abnormal wear, plan shutdown work and select the correct crusher for a project. Equipment selection should consider the complete chamber, drive, hydraulic, lubrication and installation system—not only the feed opening or nominal capacity.