A cone crusher works in an extremely dusty environment but contains bearings that run on micron-level oil films. The part that separates these two worlds is the dust seal (dust sealing ring) and its accompanying dust collar. When this arrangement, which closes the gap between the head and the frame, fails, fine rock dust mixes with the oil; the oil effectively turns into an abrasive paste and the life of every plain bearing, from the eccentric bushing to the spherical bearing, is dramatically shortened.
In this guide we cover in detail the function of the dust seal and dust collar, different designs, signs of dust ingress, inspection and replacement steps, and spare part selection. For general cone crusher operation, see our cone crusher guide.
Function of the Dust Seal and Dust Collar
- Prevents dust ingress: Closes the moving gap between the head and the frame, preventing rock dust from entering the lubrication area.
- Keeps oil in: In some designs it also limits oil escaping.
- Tolerates movement: It is designed to be flexible enough to maintain contact during the gyrating motion of the head.
Depending on the design, the dust seal may be a rubber or polyurethane ring, a sliding sealing ring or a labyrinth-type structure. In some crushers this area is kept under slight positive air pressure by a fan or compressor, making it even harder for dusty air to enter.
Effects of Dust Ingress
| Effect | Consequence |
|---|---|
| Silicon entering the oil | The oil becomes abrasive |
| Rapid wear of bronze bushings | Eccentric, countershaft and socket liner life is shortened |
| Filters filling up quickly | Higher maintenance cost and bypass risk |
| Rising oil temperature | Friction increases and the oil degrades |
| Wear on gear tooth surfaces | Noise and tooth damage |
Signs of Failure and Wear
- A rise in silicon in oil analysis (the most reliable early warning),
- Filters filling faster than normal,
- Tears, hardening, cracks or displacement of the dust seal,
- Wear and deformation of the dust collar,
- Fan/filter failure in the positive pressure system,
- Fine material accumulated between the head and the frame.
Inspection and Maintenance Schedule
| Check | Interval | Method |
|---|---|---|
| Visual check around the dust seal | Daily | Check for build-up and tears |
| Positive pressure fan and filter | Weekly | Operation and filter cleaning |
| Silicon in oil analysis | Every 250–500 hours | Trend monitoring |
| Detailed seal and collar inspection | Every liner change | Measurement and visual check after removal |
Dust Seal Replacement Step by Step
- Planning: Replacement is scheduled for a liner change shutdown when the head group is removed.
- Safe shutdown and disassembly: The crusher is locked out; the upper group and head group are lifted out.
- Removing the old seal: The seal and its retainers are removed and the groove is cleaned.
- Inspection: The dust collar, groove surface and contact surface on the head are checked.
- Fitting the new seal: The seal is fitted in the correct orientation and fully seated; it is protected from sharp edges during assembly.
- Head installation: When lowering the head, make sure the seal does not fold or come out of place.
- Check: If there is a positive pressure system, confirm that it works; monitor the silicon value in the first oil analysis.
Common Mistakes
- Ignoring a rise in silicon in oil analysis.
- Replacing the seal only after a major failure: Renewing it according to condition at liner changes is more economical.
- Incompatible material: Rubbers not suited to the temperature and oil harden quickly.
- Cutting or folding the seal during assembly.
- Disabling the positive pressure fan.
Troubleshooting Table
| Symptom | Possible cause | Solution |
|---|---|---|
| Rising silicon in oil | Damaged dust seal or breather filter | Check the seal and breather filter, change the oil |
| Filter fills quickly | Dust ingress | Check the seal and positive pressure system |
| Seal tears quickly | Incorrect fitting, incompatible material, worn collar | Check the collar and seal type |
| Oil marks around the head | Seal or collar damage | Replace the seal |
An Example from the Field
At a quartzite quarry, the eccentric bushing of a cone crusher wore out much sooner than expected. When past oil analyses were reviewed, silicon had been rising slowly for months, but the trend had gone unnoticed. At the overhaul, the dust seal was found to be torn and the filter of the positive pressure fan completely blocked. The seal was renewed, the fan filter was added to the regular maintenance list and an alarm threshold for silicon was defined in the oil analyses. In the following period the bushing wear rate dropped markedly.
Spare Part Selection
- Material: Rubber or polyurethane with suitable wear, temperature and oil resistance.
- Dimensions: Inside/outside diameters and cross-section profile must match the crusher model exactly.
- Dust collar: Should be assessed together with the seal; a worn collar quickly ruins a new seal.
- Positive pressure system parts: Fan, filter and hoses.
CSP Mühendislik supplies dust seals, dust collars and sealing elements as part of its cone crusher spare parts range. We also recommend reading our guides on the eccentric bushing and lubrication unit, which are most affected by dust ingress.
Pre-Purchase Checklist
- Have the crusher model and seal part number been identified?
- Has the condition of the dust collar been checked?
- Are positive pressure system parts needed?
- Has the replacement been scheduled for the liner change shutdown?
Frequently Asked Questions
How often should the dust seal be replaced?
It depends on condition rather than a fixed period; it is recommended to inspect it at every liner change and renew it when damage, hardening or wear is seen.
Does the dust seal also prevent oil leaks?
Partly, in some designs; but its main job is to stop dust entering. There may be separate seals for oil sealing.
Is a positive pressure system essential?
It depends on the design. In crushers with this system, the fan must run continuously and its filter must be clean.
What should the silicon value be?
The exact value depends on the crusher and the oil; what matters is establishing your own baseline and monitoring increases in the trend.
Sealing Designs in Cone Crushers
| Design | How it works | Maintenance point |
|---|---|---|
| Rubber/polyurethane dust ring | Seals by contact between the head and frame | Wear and hardening |
| Dust collar + ring | The collar forms the surface the ring runs on | Collar wear and deformation |
| Labyrinth seal | Traps dust with narrow, winding passages | Keeping the passages from filling |
| Positive air pressure system | A fan blows clean air inside | Fan, filter and hoses |
The Role of the Breather Filter
Another entry point as important as the dust seal is the breather filters on the oil tank and crusher housing. As the crusher heats up and cools down, the internal air volume changes and the breather points take in and release air. If the filter at these points is saturated or damaged, dust and moisture enter the system directly. Desiccant breather filters can noticeably reduce the amount of water in the oil in humid climates. The dust seal and breather filter should always be checked together.
Effect of Operating Conditions
- Very dry, dusty rock: The dust load on the seal is high; a positive pressure system is very beneficial.
- Plants with washing: Water and mud splash strain the seal; moisture ingress shows up as water in the oil.
- Hot climate: Rubber elements harden faster.
- Frequent ring bounce: Irregular head movement fatigues the seal mechanically.
Maintenance Record Form
| Field | Record |
|---|---|
| Silicon in oil analysis | Trend chart |
| Seal condition | Observation at liner changes |
| Dust collar | Wear and deformation |
| Positive pressure system | Fan operation, filter cleaning |
| Breather filter | Replacement date |
OEM or Aftermarket?
For dust seals, the correct cross-section profile and material determine how effective the sealing is. For an aftermarket seal, verify inside/outside diameters, cross-section dimensions, material hardness (Shore), and temperature and oil resistance. A seal with the wrong dimensions either comes out of place or restricts the head’s movement and wears quickly.
Stock Planning
- Keep one dust seal in stock ready for each liner change.
- The dust collar lasts longer than the seal but should be on the critical spares list.
- Breather filters should be ordered regularly as consumables.
More Questions
What should be done first when silicon rises?
Check the dust seal and breather filters; after removing the source, change the oil, clean the system and confirm the decrease with the next analysis.
Can a positive pressure system be added to any crusher?
It depends on the crusher design; some models offer it as an option. It should be assessed together with the manufacturer.
Can the seal be replaced without removing the head?
In most designs the head group must be lifted to access the seal, so it is scheduled for the same shutdown as the liner change.
Spare Parts and Service for Dust Seals
CSP Mühendislik supplies cone crusher sealing elements as part of its cone crusher spare parts range, and supports seal replacement and sealing checks together with liner changes through our service team. Share your crusher model on WhatsApp for a quick quote.
