Table of Contents
- 1. Introduction
- 2. How Crusher Bores Wear — The Technical Reality
- 3. The Scale of India's Stone Crushing Industry
- 4. Why Crusher Bore Repair Is Different From Excavator Bore Repair
- 5. On-Site Crusher Bore Repair — The Process
- 6. Common Indian Crusher Types and BOS Coverage
- 7. Cost of Crusher Bore Repair — On-Site vs Workshop
- 8. Where BOS Serves in India
- 9. Frequently Asked Questions
- 10. References
1. Introduction
India has one of the largest stone crushing industries in the world. Rajasthan alone has thousands of stone crushing units — granite, marble, sandstone, and limestone quarries feeding construction and infrastructure projects across the country. Maharashtra, Andhra Pradesh, Telangana, Tamil Nadu, Karnataka, and Madhya Pradesh all have significant crusher concentrations serving local construction and road building demand.
A crusher is not like a mobile excavator that can be driven to a workshop. A jaw crusher at a quarry site weighs 5 to 80 tonnes. Its eccentric shaft housing, toggle seat bores, and pitman bores are large — typically 100 to 400mm in diameter — and when they wear out, the repair options are limited. You can try to dismantle the crusher, transport the worn component to a machine shop, and wait. Or you can bring BOS on-site and have the bore repaired and the crusher back in production the same day.
This guide covers how crusher bores wear, which crusher types and bore locations BOS services, why crusher bore repair almost always requires the DS60 and sector welding, and how the repair process works at a quarry or crushing plant site.
For a broader look at on-site boring service across all heavy equipment types, see our line boring service guide for heavy equipment India.
2. How Crusher Bores Wear — The Technical Reality
A jaw crusher operates on a reciprocating motion. The moving jaw — the pitman — is driven by an eccentric shaft. As the shaft rotates, the pitman is pushed toward the fixed jaw to crush material, then swings back for the next cycle. This motion produces very specific, very predictable bore wear patterns.
Eccentric Shaft Housing Bore
The eccentric shaft sits in two bearing housing bores — one on each side of the crusher frame. These housings carry the full eccentric loading of the shaft as it rotates. The loading direction is predominantly downward and toward the crushing face — the direction of the crushing force. Over thousands of tonnes of material crushed, the housing bores wear asymmetrically: deeper on the loaded face (typically the bottom and front of the housing) than on the relief face.
This is classic asymmetric bore wear that the BOS DS60's sector welding mode addresses precisely. A 120 to 180 degree weld arc on the loaded face restores the bore without depositing unnecessary material on the unworn relief arc.
Toggle Plate Seat Bore (Swing Jaw)
The toggle plate transmits the eccentric shaft motion to the swing jaw. It seats in a bore at the bottom of the swing jaw and a bore at the toggle block. Both of these seat bores experience high impact loading with every crushing cycle. The loading is predominantly in one direction — the direction of the crushing force — producing oval, asymmetric wear on the loaded face of the bore. Toggle seat bore diameters in Indian jaw crushers range from 80mm on smaller PE-series machines to 200mm on large primary jaw crushers. Both sizes are within the DS60's 65–600mm range.
Pitman Bore (Swing Jaw Eccentric Shaft Opening)
The pitman is the swing jaw body itself. It has a large central bore through which the eccentric shaft passes. This bore is lined with a spherical roller bearing that carries the eccentric shaft load. When the bearing housing bore in the pitman wears — due to bearing failure, contamination, or shock loading from oversized feed material — the bore must be restored to its correct geometry before a new bearing can be properly seated. Pitman bore diameters in common Indian jaw crushers range from 150mm to 400mm.
Cone Crusher Bores
Cone crushers use an oscillating conical head driven by an eccentric shaft. The eccentric sleeve bore and the frame bearing bore in a cone crusher are both subject to high-load asymmetric wear from the gyratory crushing motion. Cone crusher eccentric bore diameters are typically larger than jaw crusher bores — 200mm to 600mm on primary and secondary cone crushers — making them firmly in DS60 territory.
| Crusher Type | Bore Location | Typical Diameter | Wear Pattern | BOS Mode |
|---|---|---|---|---|
| Jaw crusher (PE series) | Eccentric shaft housing bore | 100–200mm | Asymmetric — loaded face 2–4mm deeper | DS60 — sector welding |
| Jaw crusher (PE series) | Toggle plate seat bore | 80–180mm | Asymmetric impact wear — loaded face | DS60 — sector welding |
| Jaw crusher (PE series) | Pitman eccentric shaft bore | 150–400mm | Variable — depends on failure mode | DS60 — inner circle or sector |
| Jaw crusher (large primary) | Main frame bearing housing | 200–400mm | Uniform or asymmetric | DS60 — inner circle or sector |
| Cone crusher (secondary) | Eccentric sleeve bore | 200–450mm | Asymmetric — gyratory load direction | DS60 — sector welding |
| Cone crusher (tertiary) | Frame bearing bore | 180–350mm | Uniform wear typical | DS60 — inner circle |
| Impact crusher (VSI) | Rotor bearing housing bores | 100–250mm | Uniform — high-speed rotation | DS60 — inner circle |
| Impact crusher (HSI) | Blow bar rotor shaft bores | 120–300mm | Uniform or asymmetric | DS60 — inner circle or sector |
Table 1 — Crusher Bore Types, Diameters, and BOS Repair Mode
3. The Scale of India's Stone Crushing Industry
Understanding why BOS serves the crusher sector requires understanding the scale of crushing operations in India.
Rajasthan has over 8,000 registered stone crushing units — the highest concentration in any Indian state — feeding construction, road building, and export markets. Granite quarrying in Rajasthan's Jalore, Jodhpur, and Pali districts produces both dimensional stone and crusher aggregate. Marble quarrying in Rajsamand and Udaipur districts runs primary jaw crushers on a continuous basis.
Andhra Pradesh and Telangana have significant granite crushing operations in Karimnagar, Medak, and Khammam districts. Tamil Nadu has major limestone crushing for cement production. Karnataka's granite belt around Bangalore and Hassan runs hundreds of crusher units. Maharashtra's basalt crushing for road building is concentrated in Pune, Nashik, and Aurangabad districts.
In all of these locations, a primary jaw crusher going down with a worn eccentric shaft bore is a production emergency. The quarry stoppage is immediate. Every hour the crusher is idle is an hour the entire downstream production line — secondary crusher, screening, washing, loading — is also idle. The production loss on a mid-size quarry runs Rs. 50,000 to Rs. 2,00,000 per day depending on output volume and aggregate price.
For a detailed breakdown of what equipment downtime costs quarry and mining operations across India, read our guide on the true cost of downtime on heavy equipment.
4. Why Crusher Bore Repair Is Different From Excavator Bore Repair
The crusher cannot easily move to a workshop
An excavator can be driven onto a lowboy and transported. A primary jaw crusher weighing 30–80 tonnes is typically installed on a concrete foundation at the quarry site. Moving it requires cranes, heavy transport, and days of dismantling. The component that needs repair — the eccentric shaft housing, the toggle block, or the pitman body — can potentially be removed, but even this involves significant dismantling time, specialist rigging, and the risk of damaging adjacent components during extraction. On-site repair is not just convenient for crusher work — for many quarry crusher installations, it is the only practical repair option.
Crusher bore diameters are large
The eccentric shaft housing bores on a large primary jaw crusher (PE-1200 or PE-1500 class) are 250–400mm in diameter. These are well beyond the DS50's range and into DS60 territory. Even the smaller toggle seat bores on common Indian jaw crushers (PE-600, PE-750 class) run 120–180mm — at the upper end of the DS50's capability. For comprehensive crusher bore coverage, the DS60 is the only portable machine that handles the complete spectrum.
Crusher wear is more severe than excavator wear
Jaw crushers crush rock. The forces involved are enormous — a PE-900 jaw crusher generates approximately 1,600 kN of crushing force. This load is transmitted through the eccentric shaft and its bearing housings with every crushing cycle, at rates of 200–300 cycles per minute. Bore wear rates on crusher eccentric shaft housings under high-production conditions can be 3–5 times faster than on equivalent-size excavator pin bores. Crusher bore wear inspection intervals should be 3–4 months maximum on high-production units.
5. On-Site Crusher Bore Repair — The Process
BOS DS60 crusher bore repair follows the same weld-and-bore process as all BOS on-site work, with crusher-specific considerations for setup access, bore diameter, and wear pattern.
Crusher Shutdown and Bore Assessment
The crusher is locked out and tagged out. BOS technician accesses the bore — either the eccentric shaft housing with the shaft removed, or the toggle seat bore with the toggle plate removed. Internal bore gauge measurements are taken at multiple points around the circumference: 0, 45, 90, 135, 180, 225, 270, and 315 degrees. For crusher eccentric housing bores, the difference between maximum and minimum readings is typically 2–5mm for bores operating past their optimal repair window. This measurement confirms the wear pattern and determines the sector welding arc.
Machine Setup and Bar Alignment
The DS60 boring bar is threaded through the worn bore. For crusher frame bores where both sides of the housing are accessible, the bar is supported by a bracket on the far side. Self-centering setup cones align the bar concentrically. Alignment is verified with a dial indicator. Setup time for a crusher eccentric shaft housing bore: typically 60–90 minutes depending on access.
Sector Welding
Welding parameters are programmed on the DS60 numerical control panel. For typical jaw crusher eccentric housing bore asymmetric wear (120–180 degree worn arc on the loaded face), sector welding deposits material only within the programmed arc. For a PE-900 jaw crusher eccentric housing bore of approximately 220mm diameter with 3mm asymmetric wear on a 150-degree arc, typical weld time is 2.5–4 hours. Sector welding reduces heat input to the crusher frame by 55–70% compared to full inner circle welding on the same bore — critical for cast iron crusher frames.
Controlled Cooling
After welding, the bore must cool for 45–90 minutes before boring begins. Crusher eccentric shaft housings are typically cast iron or high-grade steel. Cast iron components are particularly sensitive to rapid thermal cycling — controlled cooling is not optional for cast iron crusher frames. BOS technicians do not skip or abbreviate the cooling period on crusher bore repairs.
Line Boring to Specification
The boring head machines the weld deposit back to the original bore diameter. For crusher eccentric shaft housing bores, the target diameter is the original shaft bearing outside diameter plus the required bearing clearance — typically H7 fit tolerance. Diameter tolerance achieved: ±0.05mm. Surface finish: Ra 3.2 micrometres. Boring time for a 200–250mm crusher bore: typically 1.5–2.5 hours. On the sector-welded arc, the full weld deposit is machined back to specification. On the unworn arc, a light finishing cut brings the full bore to uniform roundness.
Verification and Crusher Return to Production
Final bore measurements verify diameter, circularity (roundness), and surface finish. The shaft or bearing is trial-fitted to confirm correct clearance. The crusher reassembly proceeds — toggle plates, swing jaw, guards — and the unit is returned to production. Total downtime from crusher shutdown to first production: typically 10–16 hours for a standard jaw crusher eccentric shaft housing bore repair. For the workshop route, 7–14 days is the realistic expectation at most Indian quarry locations.
6. Common Indian Crusher Types and BOS Coverage
The table below covers the most common crusher makes in India's quarrying and mining sectors and their bore repair coverage under the BOS DS60.
| Crusher Make / Model | Type | Common Bore Repair | BOS Machine |
|---|---|---|---|
| Terex Jaques (formerly Goodwin-Barsby) | Jaw crusher | Eccentric housing 150–300mm, toggle seat 100–180mm | DS60 |
| Sandvik CJ series | Jaw crusher | Eccentric housing 200–400mm | DS60 |
| Metso C series | Jaw crusher | Eccentric housing 180–350mm, pitman bore 200–400mm | DS60 |
| PE series (Chinese — widely used in India) | Jaw crusher | Eccentric housing 100–250mm, toggle seat 80–160mm | DS60 |
| Sandvik CH/CS series | Cone crusher | Eccentric sleeve bore 200–450mm | DS60 |
| Metso HP series | Cone crusher | Frame bearing bore 180–400mm | DS60 |
| Terex Canica VSI | VSI impact crusher | Rotor bearing housing 100–200mm | DS60 |
| Local fabricated crushers (India) | Jaw crusher — varies | Eccentric housing 100–300mm (varies) | DS60 |
Table 2 — Common Indian Crusher Types and BOS DS60 Coverage
For mining applications broadly — including crushers, underground loaders, and surface drill rigs — see our mining equipment line boring application page.
7. Cost of Crusher Bore Repair — On-Site vs Workshop
The economics of on-site crusher bore repair are compelling — particularly for quarry operations where the crusher is the production bottleneck and every idle day halts the entire production chain.
| Cost Factor | Workshop Route | BOS On-Site Service |
|---|---|---|
| Crusher shutdown and dismantling | 2–3 days for component extraction | None — repair performed in-situ |
| Transport (oversize heavy component) | Rs. 20,000 – Rs. 80,000 | Nil |
| Production loss at Rs. 1L/day (mid-size quarry) | Rs. 5,00,000 – Rs. 10,00,000 | Rs. 50,000 – Rs. 1,00,000 |
| Workshop queue and machining time | 3–5 days minimum | Same-day repair (10–16 hours total) |
| Reassembly and recommissioning | 1–2 days | Included in same session |
| Workshop machining fee | Rs. 30,000 – Rs. 1,00,000 | — |
| BOS service fee (crusher class) | — | Rs. 15,000 – Rs. 50,000 per bore |
| Total Estimated Cost | Rs. 5,50,000 – Rs. 11,80,000 | Rs. 65,000 – Rs. 1,50,000 |
Estimates based on mid-size jaw crusher (PE-900 class) at a Rajasthan granite quarry. Production loss estimate: Rs. 1,00,000 per day for an 8-hour production shift. Actual costs vary significantly by crusher size, location, and wear severity.
For a detailed breakdown of line boring service costs across all equipment types, see our 2026 India line boring cost guide.
8. Where BOS Serves in India
BOS provides on-site crusher bore repair service across India's major stone crushing and mining states. Key crusher belt locations served:
Contact BOS at +91 9901585506 or wearebos.in for crusher bore repair anywhere in India. BOS responds same business day for emergency quarry breakdown calls.
Talk to our team before the next breakdown. We'll confirm the repair approach for your specific crusher make, model, and bore diameter.
9. Frequently Asked Questions
10. References
- → ScienceDirect Topics — Jaw Crushers: Engineering and Applications (sciencedirect.com)
- → McLanahan Corporation — Jaw Crusher Design and Operating Principles (mclanahan.com, 2025)
- → Fote Machinery — Most Practical Jaw Crusher Repair and Maintenance Manual (ftmmachinery.com, 2023)
- → Diamond Crusher India — Jaw Crusher Maintenance and Repair Guide (diamondcrusher.in, May 2025)
- → JXSC Machine — Jaw Crusher Parts: Eccentric Shaft, Toggle Plate, and Bearing (jxscmachine.com)
- → PR Crane & Earthmovers / BOS — Bore On Site: Crusher bore repair field records and DS60 specifications
- → ISO 286-1 — Geometrical Product Specifications: Limits and fits (H7 tolerance system)
Prakhar Bhardwaj founded BOS with a modern approach to on-site machining and bore repair solutions. With 6+ years of hands-on field experience, he leads BOS's product development and customer operations across India and international markets.