DOOSAN Heavy Duty Undercarriage Components

TrackCarrier RollerAssembly | OEM & ODM Source Manufacturer

By JACK
Senior Undercarriage Specialist,CQC TRACK

1. Product Overview

The DOOSAN Track Carrier Roller Assembly, also referred to as theUpper Roller, is a critical support component designed for DOOSAN S140LC, DH150, and DX150 series medium-sized crawler excavators. Positioned along the upper track frame, this assembly supports the top strand of the track chain, preventing sagging and reducing friction during travel and swing operations .

CQC TRACKmanufactures this assembly as a direct OEM-quality replacement, offering both standard replacement parts and customized ODM solutions. With vertical integration spanning raw material sourcing, closed-die forging, precision machining, heat treatment, and final assembly, we operate as both a source factory and a manufacturing partner for distributors, fleet operators, and equipment dealers across global markets.

OEM Cross-Reference

Applicable DOOSAN Excavator Models

The S140LC, DH150, and DX150 represent Doosan’s established 14-15 ton class excavators. The DX150, as Doosan’s next-generation model, incorporates refined hydraulics and enhanced undercarriage durability. These machines are widely deployed across infrastructure projects, residential construction, and utility work globally .

2. Technical Specifications: Engineered for Medium-Duty Cycles

The carrier roller, or upper roller, serves a distinct function within the undercarriage system. Unlike track rollers which bear the machine’s weight, carrier rollers support the return strand of the track chain. This function is critical for maintaining proper chain alignment, reducing vibration during travel, and minimizing wear on both the chain and the track frame .

2.1 Primary Functional Responsibilities

Track Chain Support: The carrier roller supports the upper (return) run of the track chain. Without proper support, the chain would sag excessively, increasing the risk of derailment and causing unnecessary stress on the sprocket and idler .

Reduced Friction: By providing a rolling surface for the chain links, the carrier roller minimizes friction between the chain and the track frame, improving travel efficiency and reducing fuel consumption .

Chain Alignment: Carrier rollers help maintain lateral alignment of the track chain, preventing it from rubbing against the track frame side plates, which would accelerate wear on both components .

2.2 Technical Specifications

2.3 Design Considerations for S140LC, DH150, DX150

The 14-15 ton class presents specific design considerations for carrier rollers:

Mounting Configuration: Carrier rollers for these models typically feature a bolt-on mounting configuration with specific bolt patterns and thread specifications. The mounting bracket must align precisely with the track frame to ensure proper chain guidance .

Load Characteristics: While carrier rollers do not bear the machine’s static weight, they experience dynamic loads during travel over uneven terrain. The roller must withstand the chain’s weight and tension forces during acceleration, deceleration, and turning maneuvers .

3. Metallurgical Foundation & Manufacturing Excellence

3.1 Material Selection

The carrier roller operates in an environment exposed to abrasive dust, moisture, and temperature extremes. CQC TRACK selects specific alloy steel grades that achieve the optimal balance of surface hardness and core toughness:

40Mn2 / 50Mn Manganese Steel: These medium-carbon manganese steels provide excellent hardenability and wear resistance after induction hardening. The manganese content enhances toughness and promotes fine grain structure.

40Cr Chromium Steel: For applications demanding enhanced fatigue resistance, chromium steel offers improved hardenability and moderate corrosion resistance.

3.2 Closed-Die Forging Process

CQC TRACK employs closed-die hot forging for all carrier roller bodies. This process produces a dense, uniform grain structure that follows the component contour, eliminating internal voids and porosity common in cast components .

The forging process ensures:

• Continuous Grain Flow: Aligned with the roller’s geometry for maximum strength
• Superior Impact Resistance: 20-30% higher fatigue strength compared to cast alternatives
• Consistent Material Density: No porosity or internal defects

3.3 Induction Hardening

Following precision machining, the critical wear surfaces—specifically the outer diameter and flange faces—undergo localized induction hardening:

• Surface Hardness: HRC 50-56 for optimal wear resistance
• Case Depth: 4-8 mm to withstand long-term abrasion
• Core Toughness: Maintains ductility to absorb impact loads

This dual-phase structure provides both wear resistance and shock absorption essential for construction environments.

3.4 Precision Machining

All critical dimensions are CNC-machined to achieve tolerances of ±0.02 mm, including:

• Shaft diameter: For bearing fit
• Mounting bolt holes: For proper alignment with track frame
• Flange geometry: For consistent chain guidance

3.5 Bearing & Sealing System

The carrier roller incorporates a robust bearing and sealing system designed for medium-duty applications:

The advanced sealing system prevents the ingress of abrasive contaminants, ensuring long bearing life even in dusty construction environments.

4. Quality Assurance Protocols

CQC TRACK implements multi-stage quality verification throughout production:

5. Regional Market Coverage & Logistics Support

CQC TRACK maintains a global supply chain with strategic stock locations and regional expertise.

5.1 Australia & Oceania

5.2 Japan & Northeast Asia

5.3 South America

5.4 North America

5.5 Russia & Central Asia

5.6 South Africa & Sub-Saharan Africa

5.7 Europe

5.8 Korea

6. OEM & ODM Manufacturing Capabilities

CQC TRACK offers comprehensive manufacturing services beyond standard replacement parts:

OEM Manufacturing

• Standard Specifications: Production according to OEM dimensions and material specifications
• Quality Certification: ISO 9001:2015 certified processes
• Full Traceability: Documentation from raw material to finished product

ODM Customization

• Custom Branding: Private label packaging and component marking
• Custom Specifications: Modified dimensions, materials, or coatings to meet specific requirements
• Design Collaboration: Engineering support for unique applications

Manufacturing Capacity

• Production Capacity: High-volume manufacturing with scalable output
• Lead Times: 15-20 working days for standard production
• Quality Control: 100% inspection of critical dimensions

7. Undercarriage System Context: The Complete Solution

While this article focuses on thecarrier roller assembly, CQC TRACK manufactures the full spectrum of undercarriage components for DOOSAN S140LC, DH150, and DX150 excavators:

8. Wear Indicators & Maintenance Guidelines

8.1 Critical Wear Indicators

• Outer Diameter Wear: Reduction in outer diameter affects chain support and alignment
• Flange Wear: Thinning flanges reduce lateral guidance capability
• Bearing Play: Excessive radial or axial play indicates bearing wear
• Seal Damage: Grease leakage indicates seal failure and potential contamination

8.2 Common Symptoms

• Excessive track chain sag on the upper run
• Unusual noises from the undercarriage during travel
• Visible wear or damage to the roller surface
• Grease leakage from the roller assembly

8.3 Maintenance Best Practices

• Regular Inspection: Check for wear, cracks, or bearing play during scheduled maintenance
• Track Tension Verification: Ensure proper tension to avoid unnecessary stress on carrier rollers
• Lubrication: Follow OEM-recommended service intervals
• Professional Installation: Proper bolt torque and alignment are critical for longevity

9. Quality Certifications

10. Ordering Information

Incoterms

• FOB – China main port (Shanghai, Qingdao, Tianjin, Xiamen)
• CIF – Any major port worldwide
• DDP – Qualified customers in select regions

Lead Times

• Stock Items: 24-72 hours
• Factory Production: 15-20 working days
• ODM Custom Orders: 25-30 working days

11. Contact Information

CQC TRACK – Heavy Duty Undercarriage Division

• Email: cqc@cqctrack.com
• Website: www.cqctrack.com
• Factory Location: Fujian / Shandong, China

Regional Contact Points

12. Technical Support Services

CQC TRACK provides comprehensive technical support:

Pre-Sales

• Fitment verification by machine serial number
• Application assessment for operating conditions
• Complete undercarriage kit recommendations

Installation Guidance

• Bolt torque specifications: Grade 10.9 bolts, 120-150 Nm
• Alignment verification procedures
• Seal inspection guidelines

After-Sales

• Wear analysis and replacement interval recommendations
• Failure diagnosis and root cause analysis
• Maintenance optimization guidance

About the Author

JACK is a Senior Undercarriage Specialist at CQC TRACK with over 15 years of experience in heavy equipment undercarriage systems. He has provided technical support and supply solutions to construction and mining operations across Australia, South America, Europe, Central Asia, North America, and Africa.

© 2025 CQC TRACK. All rights reserved. This content is original and proprietary to CQC TRACK.