Description
Product Overview
The 120-22-31231 steering clutch friction plate is a critical wet-clutch component for Komatsu D31 series bulldozers and compatible models including D37, D40, and D41. This friction disc operates in oil-immersed steering clutch assemblies, where it transmits torque between the clutch hub and drum through frictional engagement. When hydraulic pressure compresses the alternating stack of friction discs and steel separator plates, power flows from the transmission to the track drive; when pressure releases, the track is free to rotate independently for steering maneuvers.
Also referenced as part number 113-15-42711 in some Komatsu parts catalogs, this friction plate is interchangeably used in the steering clutch packs of D31A-17, D31A-20, D31E-17, D31E-20, D31P-17, D31P-18, D31P-20, D40A-3, D40A-5, and D41S-3 model bulldozers. It is paired with steel clutch plate 120-22-31221 in the alternating disc stack configuration.
Material Composition and Manufacturing
This friction plate uses copper-based powder metallurgy (sintered bronze) friction material bonded to a heat-treated steel core plate. The manufacturing process follows industry-standard powder metallurgy techniques:
| Process Stage | Description |
|---|---|
| Raw Material | Electrolytic copper powder (primary matrix, 70-81 wt%) combined with tin (6-11 wt%), zinc (5 wt%), silicon dioxide (5 wt%), and graphite (6-8 wt%) as solid lubricant |
| Powder Mixing | Uniform blending of metal powders and functional additives in blade mixers for consistent composition |
| Cold Pressing | Compaction of powder blend onto the steel backing plate under high pressure to form green body |
| High-Temperature Sintering | Furnace sintering under controlled atmosphere to metallurgically bond friction material to steel core and achieve final material properties |
| Finishing | Precision grinding to achieve final thickness tolerance and surface finish |
The resulting material structure is a three-layer composite: steel backing plate (rigid support and spline engagement) + transition layer (metallurgical bond) + sintered copper friction layer (torque transmission surface). This construction combines the strength and dimensional stability of steel with the superior tribological properties of sintered copper.
Technical Performance Parameters
| Parameter | Specification | Significance |
|---|---|---|
| Dynamic Friction Coefficient | 0.05 – 0.09 (wet, oil-immersed) | Determines torque transfer capacity during slip conditions |
| Static Friction Coefficient | 0.11 – 0.15 | Ensures positive engagement and holding torque when fully engaged |
| Wear Rate | Less than or equal to 1 x 10^-7 cm^3/J | Low volumetric wear per energy unit ensures long service life |
| Operating Temperature Range | Up to 300-350 deg C (intermittent peak) | Copper-based material maintains structural integrity at high thermal loads |
| Thermal Conductivity | High (copper matrix) | Rapid heat dissipation prevents glazing and thermal failure |
| Core Material | Heat-treated alloy steel | Resists warping and maintains flatness under cyclic loading |
The copper-based friction material provides several advantages over organic or paper-based alternatives in heavy-duty bulldozer applications: higher energy absorption capacity, better heat dissipation, resistance to oil contamination, and longer service life under severe duty cycles. The graphite component acts as a built-in solid lubricant, ensuring smooth engagement and preventing stick-slip behavior even during prolonged operation.
Application in Bulldozer Steering System
The Komatsu D31 bulldozer uses a wet-type steering clutch and brake system for track speed differential steering. Each track has its own steering clutch pack containing multiple friction discs and steel plates arranged alternately. The steering clutch performs two essential functions:
- Power transmission – When engaged, the clutch transfers torque from the bevel gear shaft to the final drive, driving the track forward or backward.
- Steering control – When the steering lever is pulled, the clutch on one side disengages, slowing or stopping that track while the opposite track continues driving, causing the machine to turn.
Friction plates are subject to continuous wear from cyclic engagement and disengagement, slip during steering maneuvers, and thermal loading from energy dissipation during engagement. The oil-immersed (wet) design helps cool the plates and carry away wear particles, significantly extending service life compared to dry clutch designs.
For additional technical background on drivetrain component maintenance, see our excavator final drive system guide and center joint diagnostic analysis.
Maintenance Intervals and Wear Limits
Proper maintenance of steering clutch friction plates is essential for reliable bulldozer operation. Recommended inspection and service intervals:
| Service Interval | Maintenance Action | Key Check Points |
|---|---|---|
| Every 250 hours | Inspect rear axle / steering clutch oil | Check oil level, color, and for metal particles; change oil if contaminated |
| Every 500 hours | Measure clutch pack wear | Inspect friction plate thickness; replace if single plate wear exceeds 1mm |
| Every 2,000-3,000 hours | Complete clutch overhaul | Replace full set of friction plates, steel plates, and seals; 2,000 hours for heavy mining/rock duty |
Always replace the complete set of friction plates rather than individual worn discs. Mixing new and worn plates causes uneven pressure distribution, accelerated wear on the newer plates, and reduced torque transfer capability. The clutch pack clearance (released position) should be 2.0-2.5mm when measured with a feeler gauge after assembly.
Replacement and Inspection Checklist
Steering clutch replacement is a significant repair requiring 4-8 hours per side depending on model and technician experience. During replacement, inspect the following components and replace as needed:
| Component | Inspection Criteria | Replace If |
|---|---|---|
| Friction discs (120-22-31231) | Measure thickness, check surface condition | Worn beyond limit, cracked, glazed, or delaminated |
| Steel separator plates (120-22-31221) | Check flatness, surface scoring, heat discoloration | Scored, warped beyond tolerance, or heat-damaged (blue/brown discoloration) |
| Pressure plate / platen | Inspect friction surface, check for warping | Scored, worn, or warped beyond flatness specification |
| Clutch piston seals | Inspect seal condition, hardness, and wear | Leaking, hardened, cracked, or grooved |
| Steering clutch shaft / hub | Check spline condition, shaft wear | Splines worn, shaft scored or bearing surfaces damaged |
| Return springs | Measure free length and tension | Weakened, broken, or not returning piston fully |
| Clutch drum / housing | Inspect inner splines, check for cracks | Spline wear, cracks, or distortion |
Our replacement parts selection and maintenance guide provides additional systematic inspection procedures for construction equipment components.
Compatibility Verification
Before ordering, confirm compatibility with your specific machine:
- Machine model: Verify your bulldozer model is in the compatibility list: D31A-17, D31A-20, D31E-17, D31E-20, D31P-17, D31P-18, D31P-20, D40A-3, D40A-5, D41S-3
- Part number: Cross-reference with 120-22-31231, 120-22-31233, or 113-15-42711
- Count required: Each steering clutch typically uses 10-14 friction discs (varies by model); both sides require the same number
- Steel plates: Order corresponding steel separator plates (120-22-31221) for complete clutch rebuild
If you are uncertain about fitment, send us your machine model and serial number for confirmation.
Ordering and Supply Information
| Parameter | Detail |
|---|---|
| Part Numbers | 120-22-31231, 113-15-42711, 120-22-31233 |
| Compatible Models | Komatsu D31, D37, D40, D41 series bulldozers |
| Material | Copper-based powder metallurgy (sintered bronze) |
| Origin | Made in China |
| Warranty | 6 months |
| Minimum Order | 1 piece |
| Unit Price | Negotiable (contact for quotation) |
| Bulk Pricing | Available for orders of 50+ pieces |
| Lead Time | 1-5 business days |
| Monthly Capacity | 1,000 pieces |
| Packaging | Neutral export packaging / wooden cases |
| Payment Methods | T/T, PayPal, Western Union |
We ship worldwide from China with multiple logistics options: express courier (5-10 days to Southeast Asia), air freight (7-14 days), and sea freight (15-30 days). Both single-piece sample orders and bulk container orders are accepted.
Browse our complete agricultural loader and construction equipment parts catalog or read our guide to evaluating reliable parts suppliers before purchasing.
