The cone crusher is the “workhorse” of crushing and screening plants, used for secondary and tertiary crushing of hard and abrasive rocks. It is the standard solution for granite, basalt, andesite, quartzite and metallic ores, in concrete and asphalt aggregate, railway ballast and ore preparation circuits before flotation. It reduces 0–150/200 mm material from the jaw crusher to the required product size, usually with a reduction ratio of between 4:1 and 6:1.
A cone crusher is a highly efficient but “sensitive” machine: incorrect feeding, inadequate lubrication or liners replaced too late not only reduce capacity but also damage expensive parts such as the eccentric bushing, spherical bearing and main shaft. This guide summarises, in a form that can be applied in the field, the operating and maintenance principles common to manufacturers’ operating manuals.
How Does a Cone Crusher Work?
In a cone crusher, the cone-shaped head on the main shaft is driven by an eccentric bushing to make a circular oscillating (gyratory) movement. The wear liner on the head is called the mantle, and the inner liner of the stationary bowl outside it is called the bowl liner / concave. As the head gyrates, the mantle approaches one part of the concave and crushes the rock there by compression; at the same time the opposite side opens and the crushed material falls. The material is subjected to successive compressions until it is small enough to pass through the closed side setting (CSS) at the bottom.
The most important feature distinguishing a cone crusher from a jaw crusher is that most of the crushing takes place by inter-particle (rock-on-rock) compression. This gives both a more cubical product and more even wear — but only when the crushing chamber is full.
Main types of cone crusher
- Spring cone crushers: The classic design; with uncrushable material, the bowl lifts on springs. Simple and durable; the setting is usually adjusted by rotating the bowl.
- Hydraulic cone crushers: Overload protection (tramp relief) and clearing are done by hydraulic cylinders; the CSS can be changed quickly with a hydraulic motor or cylinder. With automation systems, automatic adjustment based on power and pressure is possible.
- Rotating bowl (HP type) and moving main shaft (hydroset, CH/H type) designs: In the first the CSS is adjusted by turning the bowl gear, in the second by raising and lowering the main shaft hydraulically.
Main Components and Their Functions
| Component | Function |
|---|---|
| Mantle and bowl liner/concave | The manganese wear liners that form the crushing chamber |
| Main shaft and head | Carry the mantle and convert the gyratory movement into crushing force |
| Eccentric and eccentric bushing | Produce the head’s gyrating movement; run on an oil film |
| Countershaft and pinion-gear | Transmit power from the motor to the eccentric |
| Spherical bearing / socket liner | Carry the head’s axial load |
| Hydraulic cylinders / springs | Overload protection and setting |
| Lubrication unit (pump, filter, cooler, tank) | Supplies clean oil at the right temperature to bearings and bushings |
| Dust seal / dust collar | Protects the internal mechanism against dust |
| Feed plate and distributor | Distribute material evenly into the crushing chamber |
For replacement criteria and supply of these parts, see our cone crusher spare parts guide.
Choosing the Right Cone Crusher and Crushing Chamber
The same cone crusher gives very different results with different liner profiles (crushing chambers). The basic rule in choosing a crushing chamber is: the crushing chamber must be able to use the whole of the feed grading. As a practical check, with a well-graded feed:
- 90–100% of the feed should pass the closed side feed opening,
- 40–60% should pass half of this opening,
- 0–10% should pass the CSS (that is, material smaller than the CSS should be screened out before it enters the crusher).
A chamber with a larger opening than necessary runs without using its upper area when there is no coarse feed; wear concentrates in the lower area and liner life is shortened. A chamber that is too small cannot accept large rocks, leading to bridging and lost capacity.
The selection should also consider together whether there is pre-screening, whether the circuit is closed (screen oversize returned), the material’s work index (crushability) and abrasion index, the required product shape (flakiness index) and the available motor power.
Operation: Getting the Highest Efficiency from a Cone Crusher
1. Choke feeding
A cone crusher performs best when the crushing chamber is continuously full: there should be a pile of material above the chamber pressing material down into it. Choke feeding reduces voids in the chamber and increases the proportion of cubical product by reducing flaky and elongated particles. A crusher that is empty or half-fed, by contrast, breaks rocks by “impact”; the product becomes flaky and the liners wear quickly in the lower area.
The practical way to choke feed is to place a surge bin and a feeder controlled by a level sensor in front of the crusher. The level sensor adjusts the feed rate to keep the material level in the chamber constant.
2. Even, centred distribution
Material should be distributed evenly around the 360° circumference of the crushing chamber. Feed that falls to one side from the feed belt, or where coarse particles collect on one side and fines on the other (segregation), causes uneven wear, ring bounce on the bowl seat and fluctuating product size. The solution is to discharge the feed belt into the centre of the crusher and, if necessary, add distributor/deflector plates to the feed box.
3. The right CSS and power use
The best sign that a cone crusher is well adjusted is that motor power is used steadily at about 75–90% of the nominal value. If power is low, the crusher is either underfed or the CSS is larger than necessary. Hydraulic pressure or power constantly at the limit, with overload protection tripping frequently, shows that the CSS is too small or the feed is too fine/wet.
4. Dealing with ring bounce
On spring crushers, the bowl lifting from its seat and hammering down is very harmful to the springs and seating surfaces. The main causes are: a CSS that is too small, fine and wet feed, segregation and uncrushable metal. When ring bounce is seen, the CSS should first be opened slightly and the feed checked.
The Lubrication System: The Heart of the Cone Crusher
The eccentric bushing, spherical bearing and countershaft bearings run on a thin oil film. When this film breaks down, damage can occur within minutes. Things to monitor in the lubrication system:
- Oil return temperature: Must be within the range specified in the crusher manual. An increasing difference between return and tank temperature indicates increasing internal friction.
- Oil pressure and flow: A drop in pressure may indicate pump wear or a leak; a rise may indicate a clogged filter.
- Cold starting: In cold weather, the crusher must not be put under load until the tank heater has brought the oil to the minimum temperature specified by the manufacturer.
- Filter: Change the filter before the differential pressure indicator warns, and clean the tank opening and its surroundings before changing.
- Oil analysis: Tracking water, silicon (dust ingress), copper/tin (bushing wear) and iron (gear wear) in oil samples taken at intervals of 250–500 hours gives warning of failures before they happen.
- Tank and cooler: If the air cooler fins become clogged with dust, the oil overheats; the fins should be cleaned regularly.
For more information on lubrication elements, see our article on lubricating oil filters.
When Should Liners (Mantle and Concave) Be Replaced?
Liner replacement is the most frequent and most costly item in cone crusher maintenance. Leaving it too late leads to liners cracking and the backing compound breaking up, and ultimately to damage of the head and bowl seating surfaces. General criteria:
- A drop of 10% or more in production or capacity is the most reliable sign that the liners have lost their profile.
- Replacement should be planned when the thickness in the lower area of the liner has fallen to about 25 mm; liners tend to crack at around 16–19 mm.
- The mantle and concave should be replaced together. Fitting a new concave opposite a worn mantle (or vice versa) distorts the crushing chamber profile and restricts feed entering the chamber.
- When the mantle is replaced, connecting parts such as the feed plate and cutting ring should also be renewed.
The step-by-step procedure, setting ring and backing operations by crusher type are described in detail in our mantle and concave replacement guide, and the backing compound poured behind the liners in our crusher backing compound application guide.
Periodic Maintenance Schedule
| Interval | Check / task |
|---|---|
| Start of every shift | Oil level, heater/cooler operation, oil return flow, hydraulic pressure, foreign material in the feed area |
| During operation | Power (kW/amps), oil return temperature and pressure, CSS, ring bounce, unusual noise |
| Daily | Dust seal and breather filter, belts and pulleys, bolts, oil leaks |
| Weekly | CSS calibration, liner thickness measurement, oil filter differential pressure, setting mechanism |
| 250–500 hours | Oil analysis; filter change if necessary |
| At liner changes | Head and bowl seating surfaces, feed plate, locking nut, dust seal, setting gears |
| Yearly / overhaul | Measuring eccentric and countershaft bushing clearances, pinion-gear tooth contact, spherical bearing, hydraulic cylinder seals |
Troubleshooting Table
| Symptom | Possible cause | What to do |
|---|---|---|
| Capacity has dropped | Liners worn, insufficient feed, CSS increased | Measure the liners; check choke feeding and the CSS |
| Flaky, elongated product | Starved feed, large CSS, unsuitable crushing chamber | Provide choke feeding; choose the chamber to suit the feed |
| Oil temperature rising | Dirty cooler, low oil level, bushing wear, overload | Clean the cooler; have oil analysis done; reduce the load |
| Low oil pressure | Pump wear, air on the suction side, leak, overheated oil | Check the pump and lines; verify oil viscosity |
| Ring bounce / overload alarms | CSS too small, fine/wet feed, segregation, metal | Open the CSS, screen out fines beforehand, use a metal separator |
| Uneven liner wear | Poor distribution, crusher not fed centrally | Correct the feed point and distributor |
| Water or dust in the oil | Damaged dust seal or breather filter | Replace the seals; change the oil, clean the system |
| Knocking / metallic noise | Loose liner, voids in the backing, loose locking nut | Stop; check liner seating and the backing |
Safety Notes
- Work in the crushing chamber, liner changes and adjustments must be carried out after the crusher, feeder and lubrication/hydraulic unit have been locked out and hydraulic pressure has been relieved.
- Use the manufacturer’s lifting devices when lifting the head and bowl, and do not stand under the load.
- For backing compound applications, follow the personal protective equipment and ventilation requirements in the chemical safety data sheet.
Frequently Asked Questions
What is the difference between a cone crusher and an impact crusher?
A cone crusher crushes by compression on the rock-on-rock principle and gives low wear costs with hard, abrasive rocks. An impact crusher crushes by high-speed impact; it gives a cubical product and a high reduction ratio, but wear costs rise with abrasive rocks.
How often should the CSS be checked on a cone crusher?
The CSS increases as the liners wear. It should therefore be verified at least once a shift, and on crushers with an automation system, calibration should be done weekly.
Is it harmful to feed fines to a cone crusher?
Yes. Too much material smaller than the CSS fills the chamber, “packs” the crusher and causes overloads and ring bounce. The proportion of fines in the feed should be kept below 10%.
How can liner life be extended?
Choke and even feeding, a crushing chamber suited to the feed, timely replacement, quality manganese castings and correctly applied backing compound considerably extend liner life.
Capacity and Product Distribution: A Simple Calculation
When choosing a cone crusher, the capacity table in the catalogue is a starting point; actual capacity on site is determined by the feed, the closed-circuit load and the material properties. Let us take a simple example:
- Target: 0–22 mm product, 200 tonnes per hour.
- Feed: 22–150 mm material from the jaw crusher, with the minus 22 mm removed at the pre-screen.
- The cone crusher’s CSS is 20 mm, and the crusher works in closed circuit with a screen; the screen oversize (above 22 mm) returns to the crusher.
Suppose 65% of the crusher discharge is below 22 mm; the remaining 35% returns from the screen to the crusher. In this case the total load entering the crusher is about 200 / 0.65 ≈ 308 t/h. So the crusher chosen for 200 t/h of product must actually be able to handle a load of more than 300 t/h. The screen area must also be large enough to screen both the fresh feed and the returning load. This simple calculation shows that many on-site complaints that “the crusher capacity isn’t enough” actually come from not taking the closed-circuit load into account.
Reducing the CSS is the first solution that comes to mind for improving product distribution; however, as the CSS decreases, capacity falls, power and pressure rise and the risk of ring bounce increases. Very often the better solution is to choose a crushing chamber profile suited to the feed distribution and to choke feed the crusher.
Crushing Chamber Profiles: Which One When?
| Profile | Feed | Use |
|---|---|---|
| Extra coarse / coarse | Coarse, jaw crusher discharge | Secondary crushing, high capacity |
| Medium | Medium size, pre-screened | Secondary or tertiary, balanced product |
| Fine / extra fine | Small, narrowly graded feed | Tertiary crushing, before chippings and sand |
| Short head design | Small feed | Fine product, high reduction ratio |
The golden rule in choosing a profile is that the largest particle in the feed should enter the chamber’s closed side feed opening comfortably and the lower half of the chamber should not be left empty. Before ordering a new set of liners, photographing and measuring the wear profile of the old liners provides the most reliable data for choosing the right profile.
Critical Spare Parts Stock: The Way to Shorten Downtime
In an unplanned cone crusher stoppage, what wastes most time is often not the part itself but waiting for it to arrive. Although it varies with crusher type and intensity of use, the parts recommended to keep on site are:
- Always in stock: One set of mantle and concave, sufficient backing compound, feed plate, dust seal, oil filters, breather filter, belt set.
- Critical spares (long lead time): Eccentric bushing, countershaft bushings, pinion (or pinion-gear set), socket liner, hydraulic cylinder seal kits.
- Can be shared with regional stock: Main shaft, countershaft, head, large castings.
When choosing spare parts, check the original dimensions and tolerances, the material certificate and casting quality. A bushing with unsuitable tolerances can show itself within a few days through oil temperature problems.
When and How Should an Overhaul Be Planned?
Cone crushers undergo a comprehensive overhaul at certain operating hours or when condition monitoring data requires it. Signs supporting an overhaul decision:
- A continuously rising trend of copper/tin values in oil analysis,
- Rising oil return temperature at normal load,
- A changing sound and increasing vibration from the pinion-gear area,
- Eccentric and bushing clearances approaching the measurement limit,
- Progressive damage on the bowl seating surfaces.
An overhaul includes dismantling, cleaning, measurement and inspection (bushing clearances, shaft ovality, gear tooth contact, seating surfaces), replacement of worn parts, assembly and commissioning. Recording the measurement results in an overhaul report provides the most valuable data for planning the next overhaul.
An Example from the Field: The Real Cause of Uneven Wear
At a basalt aggregate plant, the cone crusher’s liners were being replaced at about half their expected life; wear was markedly greater on one side of the crushing chamber. The first solution that came to mind was to try a higher-alloy liner. The site investigation, however, found that the feed belt discharged towards the edge of the crusher rather than its centre, and that coarse particles collected on one side and fines on the other. A simple distributor and deflector plate was added to the feed box and level control was installed ahead of the crusher. As a result, liner wear became even, product distribution stabilised and liner life increased considerably. This example shows that with liner problems, feed conditions should be examined before metallurgy.
Pre-Purchase Checklist
- Have the compressive strength, abrasiveness and moisture content of the material been determined?
- Are the feed distribution and largest particle size known?
- Has total capacity including the closed-circuit load been calculated?
- Have the CSS and crushing chamber profile been determined for the required products?
- Have a bin and level control been planned ahead of the crusher for choke feeding?
- Is there metal separation (magnetic separator, metal detector)?
- Is the cooling capacity of the lubrication unit suited to the regional climate?
- Are spare parts and service support available in the region?
More Questions
Can a cone crusher run empty for a long time?
Running empty for a long time is not recommended. When empty, the head may tend to spin, and liners and lubrication conditions can be affected undesirably. When there is no feed, the crusher should be stopped quickly.
How is a cone crusher started in cold weather?
The oil should be brought to the minimum temperature specified by the manufacturer with the tank heater; after oil circulation has started and return flow is seen, the crusher should be run empty and the load increased gradually.
The bowl is turning or the setting drifts by itself; why?
Insufficient locking system pressure, a leaking lock cylinder seal or wear on the adjustment ring teeth can cause this problem. The locking pressure and setting mechanism should be checked.
Cone Crusher Solutions from CSP Mühendislik
CSP Mühendislik supplies cone crushers, selects crushing chambers and optimises plants; it supplies cone crusher spare parts such as mantles, concaves, eccentric bushings, countershafts, socket liners and seals, as well as Aurox crusher backing and Nordbak backing compounds. Contact us for on-site liner changes, overhauls and service.
