Table of Contents
- 1. Introduction
- 2. How Crane Boom Pin Bores Wear
- 3. Crane Types and Bore Applications BOS Services
- 4. Why Crane Bore Repair Requires the DS60
- 5. Common Indian Crane Fleet and Bore Repair Applications
- 6. The On-Site Crane Bore Repair Process
- 7. Cost of Crane Bore Repair — On-Site vs Workshop
- 8. Statutory Compliance — Crane Bore Repair in India
- 9. Frequently Asked Questions
- 10. References
1. Introduction
A crane is the most expensive mobile machine on most Indian construction and infrastructure project sites. A 100-tonne mobile crane represents a capital investment of Rs. 2–4 crore. A tower crane on a Mumbai high-rise project costs Rs. 80 lakh to Rs. 1.5 crore to install and commission. A crawler crane at a major port or power project runs Rs. 3–8 crore depending on capacity.
When a crane develops a worn boom pin bore, the calculation is completely different from an excavator bore. The equipment value is higher, the rental day rate is higher — Rs. 40,000 to Rs. 1,50,000 per day depending on capacity and type — and the cost of having the crane off-hire while a boom pin component travels to a workshop and back is genuinely significant. On a project with a crane-dependent critical path, a 5-day workshop repair route can cost the contractor Rs. 2,00,000 to Rs. 7,50,000 in crane hire losses alone.
BOS portable line boring machines — specifically the DS60 with its 65–600mm bore range and sector welding capability — provide on-site crane bore repair that returns the crane to service the same day or the next morning. This guide explains how crane boom pin bores wear, which crane types and bore applications BOS services, and how the repair process works on-site without dismantling the crane. For a broader look at how on-site repair is priced, see our 2026 India line boring cost guide.
2. How Crane Boom Pin Bores Wear
Crane boom pin wear differs fundamentally from excavator bore wear in two important ways: the bore diameters are larger and the wear is almost always asymmetric.
A crane lifts loads consistently in one direction — toward the working area. The boom pivot pin is loaded asymmetrically with every lift. The face of the boom heel pin bore on the loaded side — the underside of the boom as it lifts — carries significantly greater contact pressure than the relief face on the opposite side. Over time, this one-directional loading produces a bore that is worn 2–5mm deeper on the loaded face than the relief face.
This asymmetric wear pattern is why standard inner circle welding — which deposits weld uniformly around the full bore circumference — is technically inefficient for crane boom pin bore repair.
Full-circumference welding on a crane bore deposits excess material on the unworn relief face, introduces unnecessary heat into high-strength crane steel, and adds post-weld boring time removing fresh weld from an area that did not need it.
Sector welding on the BOS DS60 deposits material precisely on the worn arc — typically 90 to 140 degrees on the loaded face — and leaves the unworn arc intact. The post-weld boring pass restores the entire bore to specification: a full-depth cut through the weld deposit on the loaded arc and a light finishing cut on the relief arc. The result is a bore restored to original specification with approximately 60% less weld material, significantly less heat input into the crane structure, and 30–40% less post-weld boring time.
- ✗ Deposits weld uniformly around full circumference
- ✗ Excess material on unworn arc — wastes wire and time
- ✗ Higher heat input into high-strength boom steel
- ✗ Longer boring pass to remove unwanted fresh weld
- ✓ Deposits weld only on the worn 90–140° arc
- ✓ ~60% less weld material per repair
- ✓ 50–65% less heat input into crane structure
- ✓ 30–40% less post-weld boring time
3. Crane Types and Bore Applications BOS Services
BOS DS60 covers the full range of crane bore applications across Indian construction, infrastructure, port, and industrial sectors.
| Crane Type | Bore Applications | Typical Bore Diameter | BOS Machine |
|---|---|---|---|
| Mobile cranes (all-terrain, rough-terrain) | Boom heel pin bore, luffing pin bore, jib attachment bores, outrigger pad bores | 80–200mm | DS50 (smaller) or DS60 |
| Crawler cranes | Boom foot pin bore, upper works slewing bore, crawler side frame bores, ring and pinion housing bores | 100–400mm | DS60 |
| Tower cranes (self-erecting, top-slewing) | Slewing ring gear housing, mast section pivot bores, jib attachment pin bores | 80–300mm | DS60 |
| Port cranes (ship-to-shore, RTG) | Gantry pivot bores, boom hinge bores, spreader attachment bores, travel wheel housings | 150–600mm | DS60 |
| Overhead EOT cranes (industrial plant) | End carriage wheel bearing housings, crane bridge pivot points, hoist drum shaft bores | 80–350mm | DS60 |
| Piling rigs and derrick barges | Leader mast pivot bores, spud barge pin bores, derrick boom foot joints | 150–500mm | DS60 |
Table 1 — Crane Types and Bore Applications Serviced by BOS. DS60 bore range 65–600mm covers the full scope of crane bore repair. DS50 (55–160mm, extension to 300mm) covers smaller mobile crane applications only.
4. Why Crane Bore Repair Requires the DS60
There are three specific reasons why the DS60 is the correct machine for crane bore repair and the DS50 is not adequate for most crane applications.
Bore Diameter
Most crane boom heel pins and crawler crane pivot bores exceed 160mm in diameter — the DS50's standard upper limit. A 30-tonne mobile crane has a typical boom foot pin bore of approximately 140–160mm. A 100-tonne mobile crane's boom foot bore runs 180–220mm. Crawler cranes, port cranes, and tower crane slewing bores regularly exceed 250–400mm. The DS60's 65–600mm range is the only portable machine that covers this spectrum completely.
Asymmetric Wear — Sector Welding Required
Crane boom pin wear is almost always asymmetric due to consistent one-direction loading during lifts. Sector welding on the DS60 addresses this correctly — depositing material only where wear occurred. The DS50 supports inner circle welding only, which deposits material uniformly around the full circumference regardless of where wear is concentrated. On crane bores where the unworn arc is still within tolerance, inner circle welding wastes material, introduces excess heat, and produces a bore where the boring pass must remove fresh weld that was not needed. See the DS50 vs DS60 comparison for the full specification difference.
High-Strength Steel — Lower Heat Input Critical
Modern mobile crane booms are manufactured from high-strength steel grades — structural members at 355–690 N/mm², boom tip sections sometimes higher. While the bore pin housing itself is typically a lower-grade structural steel, the surrounding boom structure must not be exposed to excessive heat during repair. Sector welding on the DS60 reduces heat input by 50–65% compared to full inner circle welding on the same bore, because only the worn arc receives weld deposit. This is a meaningful structural protection for the crane's load-bearing integrity.
5. Common Indian Crane Fleet and Bore Repair Applications
India's crane fleet spans a wide range of equipment types and manufacturers. The table below shows the most common crane types in Indian infrastructure, construction, and industrial operations and their typical bore repair requirements.
| Make / Model | Type | Common In India | Typical Bore Repair |
|---|---|---|---|
| ACE Mobile Cranes (various) | Mobile crane | Pan-India construction sites | Boom heel pin 80–120mm, jib pin 60–100mm |
| Escorts Cranes | Mobile crane | Infrastructure projects India | Boom pivot 100–150mm |
| Tadano ATF series | All-terrain mobile | Port, power, infrastructure | Boom foot pin 140–200mm, luffing pin 120–180mm |
| Liebherr LTM series | All-terrain mobile | Major infrastructure, oil and gas | Boom foot pin 180–250mm, superlift bores |
| Kobelco crawler cranes | Crawler | Power projects, ports, heavy lifts | Boom foot 200–350mm, upper works slewing 200–400mm |
| Manitowoc crawler cranes | Crawler | EPC project lifts, refinery | Boom foot 250–400mm, crawler side frame bores |
| Potain tower cranes | Tower, top-slewing | Mumbai, Delhi, Bengaluru high-rise | Slewing ring housing 150–300mm, mast pivot bores |
| ZPMC port cranes (STS, RTG) | Port crane | Major Indian ports | Gantry pivot 200–500mm, boom hinge bores |
Table 2 — Common Indian Crane Fleet and Bore Repair Applications. Contact BOS to confirm bore diameter and access requirements for your specific crane model.
For crane-related construction applications, see our construction and earthmoving equipment applications page. For the full on-site service offering across equipment types, see our line boring service for heavy equipment India guide.
6. The On-Site Crane Bore Repair Process
BOS on-site crane bore repair follows the same weld-and-bore process used for all heavy equipment, with specific considerations for crane structure access and high-strength material.
Bore Assessment and Wear Pattern Analysis
Before any repair work begins, the worn bore is measured at multiple points around the circumference using an internal bore gauge. For crane boom pin bores, measurements are taken at 45-degree intervals — at 0, 45, 90, 135, 180, 225, 270, and 315 degrees. The difference between the maximum and minimum readings reveals the extent of asymmetric wear. A difference of more than 1.5mm confirms sector welding is the appropriate mode. The worn arc is identified — typically the bottom face of the bore relative to the direction of lift loading.
Machine Setup and Bar Alignment
The DS60 boring bar is threaded through the boom pivot pin hole from one side, supported by a self-centering bracket on the opposite side. Alignment is verified using a dial indicator. For crane boom bores where access to both sides of the boom pivot may be restricted, BOS technicians assess access requirements before mobilisation to confirm the correct bar length and support configuration for that specific crane model. Setup time for a mobile crane boom heel bore: typically 45–90 minutes.
Sector Welding
Welding parameters are programmed on the DS60 numerical control panel: start angle, end angle (defining the worn sector), feed rate, rotation speed, and number of passes. The welding head deposits material only within the programmed arc — the worn loaded face — advancing along the bar axis on each pass. For a typical mobile crane boom pin bore with 3–4mm asymmetric wear on a 120-degree arc, weld time is typically 1.5–2.5 hours. The heat-affected zone is confined to the weld deposit area, not distributed around the full circumference.
Controlled Cooling
After welding, the bore must cool before boring begins. For crane bores, cooling time is typically 45–75 minutes depending on bore diameter and ambient temperature. This stage must not be rushed — boring into a hot weld deposit produces inaccuracy as the material contracts during cooling, and on high-value crane components the consequence of an out-of-specification bore is significantly more serious than on a standard excavator.
Line Boring to Specification
Without disturbing the bar setup, the welding head is replaced with the boring head. The boring pass machines the bore back to original specified diameter. On the sector-welded arc, the full weld deposit is removed to reach the target diameter. On the unworn arc, only a light finishing cut brings the surface to the correct Ra 3.2 finish and ensures overall bore roundness. Boring time for a typical 160–200mm crane bore: 1.5–2.5 hours. Final diameter tolerance: ±0.05mm.
Quality Verification and Crane Return to Service
Final bore measurements verify diameter, circularity, and surface finish. The replacement pin is trial-fitted to confirm correct clearance. Grease is applied and the crane is ready to return to service. For cranes subject to statutory inspection — which includes most lifting equipment in India under the Factories Act and applicable state industrial safety regulations — the bore repair should be noted in the crane maintenance log. BOS provides a job record documenting bore diameter before repair, welding mode used, bore diameter after repair, and date.
7. Cost of Crane Bore Repair — On-Site vs Workshop
Crane bore repair costs more than excavator bore repair for two reasons: larger bore diameters require more weld material and longer boring time, and crane hire rates are significantly higher than excavator rates, making every idle day more expensive.
| Cost Factor | Workshop Route | BOS On-Site Service |
|---|---|---|
| Crane hire rate (example: 100T mobile crane) | Rs. 80,000 – Rs. 1,50,000 per day | Rs. 80,000 – Rs. 1,50,000 per day |
| Machine idle time | 5–8 days | 8–10 hours maximum |
| Lost crane hire value | Rs. 4,00,000 – Rs. 12,00,000 | Rs. 40,000 – Rs. 60,000 (same-day return) |
| Transport cost (boom section) | Rs. 25,000 – Rs. 80,000 (oversize load) | Nil |
| Workshop machining fee | Rs. 40,000 – Rs. 1,00,000 | — |
| BOS service fee (crane class) | — | Rs. 20,000 – Rs. 60,000 per bore |
| Total estimated cost | Rs. 4,65,000 – Rs. 13,80,000 | Rs. 60,000 – Rs. 1,20,000 |
Table 3 — Crane Boom Pin Bore Repair: Workshop vs On-Site Cost Comparison. Estimates based on 100-tonne mobile crane class. Actual costs vary by crane type, bore diameter, site location, and wear severity.
The saving per crane bore repair using BOS on-site service versus the workshop route is typically Rs. 4,00,000 to Rs. 12,00,000 for a 100-tonne mobile crane class — primarily driven by the elimination of idle hire cost during the workshop repair period. For a crane owner or contractor who owns their crane, the production value loss during 5–8 days of downtime replaces the hire cost in this calculation, and the magnitude is similar. For the full cost picture across equipment types, read our 2026 India line boring cost guide.
8. Statutory Compliance — Crane Bore Repair and Inspection in India
Cranes in India are subject to statutory inspection requirements under the Factories Act 1948, the Indian Electricity Act (for EOT cranes), and applicable state industrial safety regulations. Key points for fleet managers:
Maintenance Records Required
All maintenance work on lifting equipment — including bore repair — should be recorded in the crane maintenance log with date, scope of work, and who performed the work. BOS provides a written job record for every crane bore repair documenting bore diameter before repair, welding mode used, bore diameter after repair, and date of service.
Load Testing After Structural Repair
If the bore repair involves the crane's primary structural pin joints (boom foot pivot, upper works slewing), the crane operator or owner may need to perform a proof load test after repair before returning the crane to full rated capacity service. Consult your statutory inspector or Approved Examiner for guidance specific to your crane and jurisdiction.
Bore Repair Is Not Structural Steel Repair
BOS line boring service restores pin bore geometry — diameter, roundness, and surface finish — to original specification. It does not address structural damage to the boom or jib itself (cracks, deformation, corrosion). Structural repairs to crane booms require separate assessment by a qualified structural engineer and are outside BOS service scope.
BOS DS60 covers the full spectrum of crane bore applications across India — mobile, crawler, tower, port, and industrial EOT cranes. No dismantling. Same-day return to service.
9. Frequently Asked Questions — Crane Bore Repair
10. References
- → Rusch Cranes — At What Point Is a Crane Boom Beyond Repair? (ruschcranes.com, June 2026)
- → Rusch Cranes — What Are the Signs That a Crane Boom Needs Repair? (ruschcranes.com, June 2026)
- → Mitchell Crane — Complete Crane Overhaul and Bore Repair (mitchellcrane.com)
- → FieldFix — Heavy Equipment Line Boring Repair Guide (fieldfix.ai, July 2026)
- → PR Crane and Earthmovers / BOS — Bore On Site: Crane bore repair field records and DS60 product specifications
- → ISO 286-1 — Geometrical Product Specifications: Limits and fits (H7 tolerance system)
- → Factories Act 1948 (India) — Lifting machine inspection and maintenance requirements
Prakhar Bhardwaj is the founder of BOS — Bore On Site, India's portable line boring machine brand. He leads product development for the DS50 and DS60 machines and drives BOS's technical content on bore repair processes for mining, construction, crane, and marine applications.