The gyratory crusher (on site often called the “primary gyratory”) is the largest and heaviest crusher type in the industry, used in high-capacity mining operations to reduce run-of-mine ore at the first crushing stage. Thanks to capacities reaching several thousand tonnes per hour, direct truck feeding and a continuous crushing action, it is the preferred choice in large-scale copper, iron and gold mines and in very high-tonnage quarries.
In this guide we cover the working principle of the gyratory crusher, how it differs from cone and jaw crushers, its main components, selection criteria, operating and maintenance practice, common mistakes and spare parts planning in detail. For the general working principle of cone crushers see our cone crusher guide, and for the common alternative in primary crushing see our jaw crusher guide.
What Is a Gyratory Crusher?
A gyratory crusher works on the principle of a conical crushing head (the mantle), mounted on a vertical main shaft, “gyrating” with an eccentric motion inside a fixed, inverted-cone crushing surface (the concave) that surrounds it. The shaft is suspended at its top end from an armed structure called the spider, while its lower end turns inside an eccentric bushing. As the eccentric rotates, the lower end of the shaft traces a small circle, so the gap between the mantle and the concave continuously opens and closes around the circumference. Where the gap narrows, rock is squeezed and broken; on the opposite side, the crushed material moves downwards.
This arrangement means crushing is carried out continuously around the circumference rather than in the “back-and-forth” action of a jaw crusher. As a result, for the same feed opening width a gyratory crusher offers much higher capacity than a jaw crusher, and its power draw is more even.
Difference from a Cone Crusher
Gyratory and cone crushers work on the same basic principle, but their purpose and geometry differ:
- Crushing chamber: In a gyratory the chamber is steep and long; in a cone crusher it is flatter and wider. The steep chamber allows large blocks to be nipped and reduced progressively.
- Shaft support: In a gyratory the main shaft is suspended from the spider at the top (in some designs it is supported from below by a hydraulic piston); in cone crushers the shaft is carried from below on a spherical bearing or a fixed shaft.
- Duty: The gyratory is a primary crusher; cone crushers are used at the secondary, tertiary and quaternary stages.
- Feed size: A gyratory accepts blocks of the order of a metre; cone crushers generally crush material below a few hundred millimetres.
Gyratory or Jaw Crusher?
The two machines most often compared when selecting a primary crusher are the gyratory and the jaw crusher. The choice depends not only on capacity but also on the mine plan, investment budget, the nature of the material and the plant layout.
| Criterion | Gyratory Crusher | Jaw Crusher |
|---|---|---|
| Capacity | Very high; thousands of t/h from a single machine in large mines | Medium–high; very high tonnages may need more than one machine |
| Feeding | Trucks can tip directly into the crusher hopper; a feeder is often not needed | Usually requires a hopper and a grizzly feeder |
| Investment and civil works | High machine and civil costs; deep excavation and a tall building | Lower machine and civil costs |
| Sticky and clayey material | Limited; risk of blockage | More tolerant |
| Product shape | More even thanks to continuous crushing | Flaky particle content may be higher |
| Maintenance | Heavy parts, cranes and special tooling required; long shutdowns must be planned | Simpler; faster part changes |
| Mobility | Fixed plant | Tracked mobile versions are common |
As a general approach, a jaw crusher is more economical in quarries producing a few hundred tonnes per hour, while the gyratory comes to the fore in large metal mines that need very high, continuous tonnage. When making the decision, the life of the mine, the annual production target and the capacity of the secondary crushing stages should be assessed together. For an approach to the plant design as a whole, see our crushing and screening plant set-up guide.
Main Components
| Component | Function | Maintenance Note |
|---|---|---|
| Top shell | Carries the concave segments and supports the spider | Crack inspection, flange bolts |
| Spider and spider arms | Carries and centres the top end of the main shaft | Arm guards wear and must be replaced |
| Spider bushing and seal | Bearing in which the top end of the main shaft turns | Regular greasing or oil lubrication; wear and clearance checks |
| Main shaft | Carries the mantle and transmits the crushing force | Crack scanning, bushing surfaces |
| Mantle | Moving crushing surface | Wear profile measurement, replacement plan |
| Concave segments | Fixed crushing surface (segments in rows) | Row-by-row wear tracking; backing compound |
| Eccentric and eccentric bushing | Gives the shaft its gyrating motion | Oil temperature, bushing clearance |
| Pinion and gear | Transfers power from the motor to the eccentric | Tooth contact, backlash |
| Hydroset (shaft position adjustment) | Raises and lowers the main shaft with a hydraulic piston to change the setting and relieves overloads | Pressure, sealing, oil cleanliness |
| Lubrication unit | Lubricates and cools the eccentric, gears and bearings | Filter, cooler, oil analysis |
Our detailed guides on the maintenance of parts with similar functions in cone crushers largely apply to gyratory crushers too: main shaft and head assembly, eccentric and eccentric bushing, countershaft, pinion and gear, hydraulic cylinders and lubrication unit.
Factors Affecting Capacity and Setting
The capacity and product size of a gyratory crusher depend on the open side setting (OSS), eccentric throw, shaft speed, feed size distribution, the density and crushability of the material and the concave profile. In practice the most important variables are:
- Open side setting (OSS): In primary gyratories the setting is usually expressed on the open side. As the setting is reduced the product becomes finer, capacity falls and wear increases.
- Throw: A larger throw increases capacity and crushing force, but the machine must be kept within its design limits.
- Feed distribution: Blast quality directly affects capacity. Large blocks bridge the opening, while very fine feed can cause packing in the crushing chamber. We cover the effect of blasting on the crusher in detail in our drill and blast design guide.
- Choke-fed operation: Gyratories are generally operated with the crushing chamber kept full. This both improves particle shape and makes the mantle and concave wear more evenly.
Mantle and Concave Replacement
In a gyratory, the mantle and concave segments are the largest wear items. Concaves usually consist of several rows of segments and each row wears at a different rate; the fastest wear is often seen in the lower rows. For this reason, planning row by row can be more economical than replacing the entire concave at once.
- Wear measurement: Profile measurement is carried out with manual templates or laser scanning systems. Laser scanning captures the full profile of the crushing chamber and shows which zone is approaching its limit.
- Planning: Mantle and concave changes are planned around plant shutdowns; parts, backing compound, bolts and lifting tools are prepared in advance.
- Removal: The spider and the necessary covers are removed, and the main shaft and mantle assembly is lifted out with a special lifting tool.
- Concave installation: Segments are placed row by row and the gap behind them is filled with backing compound. Correct application of the backing prevents segments from cracking and loosening. CSP’s own backing brand Aurox is formulated for exactly this duty; for application details see our crusher liner backing compound guide.
- Mantle installation: The new mantle is seated on the main shaft, the head nut is torqued and, where required, backing is applied behind the mantle.
- Setting and commissioning: The setting is adjusted with the hydroset, and temperature and pressure values are monitored at idle and under load.
For a step-by-step description of mantle and concave replacement in cone crushers, our mantle and concave replacement guide is also a good reference for gyratory work.
Lubrication and Spider Maintenance
The key to long service life in a gyratory is lubrication. The eccentric bushing, gears and lower bearings are fed from a central lubrication unit, while the spider bushing is lubricated with grease or oil depending on the design.
- Oil supply and return temperatures, pressure and flow must be monitored continuously. A sudden rise in return temperature is the first sign of a bushing or bearing problem.
- Oil filters should be changed according to differential pressure and the oil should be analysed periodically. An increase in metal particles (especially bronze) in the oil indicates bushing wear. We explain oil analysis methods in our predictive maintenance guide.
- If spider bushing lubrication fails, the upper bushing wears rapidly and the centring of the main shaft is lost; this can lead to the mantle contacting the concave.
- Dust sealing (the dust seal and air pressurisation systems) prevents dust from the crushing chamber from contaminating the oil.
Common Mistakes
| Mistake | Result | Correct Practice |
|---|---|---|
| Running the crushing chamber empty or half-full | Uneven wear, low capacity, shock loads | Choke-fed operation, maintaining hopper level |
| Uncrushable metal (bucket teeth, etc.) entering the crusher | Hydroset overload, part damage | Metal control in the pit, operator training |
| Applying backing compound incorrectly | Cracking and loosening of concave segments | Temperature, mixing and curing in line with the manufacturer’s instructions |
| Neglecting spider arm guards | Wear of the spider arm, expensive repair | Regular inspection and replacement of guards |
| Skipping oil analysis | Bushing failure detected too late | Periodic oil analysis and trend monitoring |
Field Example: Extending Concave Life
Suppose that in a high-tonnage metal mine the lower-row concave segments wear much faster than the upper rows. Replacing the whole concave according to the life of the lower row would mean wasting usable material in the upper rows. Using laser scanning data, the wear rate of each row is calculated per tonne; options such as thicker or differently alloyed segments for the lower row, or a separate row-by-row replacement plan, are then evaluated. In addition, keeping the crushing chamber full and controlling the fines content through blasting helps distribute wear more evenly towards the upper part of the chamber. Such an approach reduces both total liner cost and downtime.
Spare Parts Planning
Gyratory crusher parts are large, heavy and often have long lead times. An unplanned stoppage in a large mine can halt the entire production chain. Therefore:
- A mantle and at least one set of concave segments should be held in stock, and the replacement schedule should be updated according to wear measurements.
- The spider bushing, spider arm guards, dust seal and hydroset seal kits should be on the critical spares list.
- A risk assessment should be carried out for long-lead-time parts such as the eccentric bushing and pinion.
- The shelf life of backing compound should be tracked.
You can find wear and mechanical spare parts for your crushers on our crusher spare parts and cone crusher spare parts pages. For general wear material selection, see our wear part materials guide.
Frequently Asked Questions
Are a gyratory crusher and a cone crusher the same machine?
The principle is the same, but the gyratory is a primary crusher with a steep, long crushing chamber and a shaft suspended from the top. Cone crushers are machines with flatter chambers designed for the secondary and later stages.
Is a gyratory crusher suitable for small quarries?
Generally not. Because of the high investment and civil works costs, a jaw crusher is usually more economical in medium-sized quarries.
What does the hydroset do?
It raises and lowers the main shaft hydraulically to change the crusher setting, compensates for wear, and protects the crusher by lowering the shaft when uncrushable material enters.
Why do concave segments wear at different rates?
In the lower part of the crushing chamber the rock is smaller and compression and abrasion are concentrated, so the lower rows usually wear faster. Feed distribution and chamber fill level also affect the wear profile.
Is laser scanning necessary?
It is not mandatory, but on large machines it measures the wear profile quickly and accurately, improving replacement timing and reducing wasted parts.
Gyratory Crusher Spare Parts List
| Part | Type | Replacement Trigger |
|---|---|---|
| Mantle | Wear part | Profile measurement, setting compensation reaching its limit |
| Concave segments | Wear part | Row-by-row thickness measurement |
| Spider arm guards and spider cap | Wear part | Visual inspection, thickness |
| Spider bushing and seal | Mechanical part | Clearance measurement, temperature, grease consumption |
| Eccentric bushing | Mechanical part | Oil analysis, return oil temperature |
| Pinion and bevel gear | Mechanical part | Tooth contact, vibration |
| Hydroset seal kit and piston | Hydraulic part | Leakage, pressure drop |
| Dust seal | Sealing | Rising silica in the oil |
| Backing compound | Consumable | Every liner change |
| Head nut and locking parts | Fastening | Damage or every mantle change |
Many of these parts are manufactured and supplied on the same logic as cone crusher parts. You can request a quote with the part number or dimensions from our cone crusher spare parts page or directly via our WhatsApp line. For dust seal maintenance see our dust seal guide, and for protective parts in the feed zone see our feed plate guide.
Maintenance Record Form
| Field | Record |
|---|---|
| Mantle and concave profile | Date, tonnage, measurement method (template / laser) |
| Setting (OSS) and hydroset position | Every shift |
| Oil supply and return temperature | Continuous logging or reading every shift |
| Oil analysis | Metal particles, silica, water, viscosity |
| Spider greasing | Date, quantity |
| Tramp events | Number and type of metal found |
| Power draw and capacity | Average and peak values |
Glossary
- OSS (open side setting): The widest distance between the mantle and the concave; in primary gyratories the setting is usually expressed by this value.
- CSS (closed side setting): The narrowest distance between the mantle and the concave.
- Spider: The armed structure that carries the top end of the main shaft.
- Hydroset: The adjustment and protection system that raises and lowers the main shaft with a hydraulic piston.
- Choke feeding: A feeding mode in which the crushing chamber is kept continuously full.
- Backing: Epoxy-based material that fills the gap between the liner and its supporting surface.
More Questions
Can a gyratory crusher be bought second-hand?
Yes, but cracks in the shell, the condition of the main shaft, eccentric and gear wear, and the state of the hydroset and lubrication system must be inspected by a specialist. Parts availability should also be checked before purchase.
What is the most common failure in a gyratory crusher?
Bushing wear caused by lubrication and sealing problems, and tramp events caused by uncrushable metal, are among the most common issues.
Can concave segments be chosen in different materials?
Yes. Using a more durable alloy or thicker segments in the rows where wear is concentrated can help balance the life of the rows.
CSP Mühendislik Support
CSP Mühendislik provides engineering support to mining and quarrying operations, from primary crushing stage selection to wear part supply and maintenance planning. Contact us for mantles, concaves, bushings, seals and backing compound for your gyratory and cone crushers, as well as for our service, maintenance and repair services. You can browse our full range on our products page.
