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Precision support for driving bevel gears in heavy-duty axles – The OEM 31311 Bearing – Driving Bevel Gear is a single‑row tapered roller bearing specifically engineered to support the driving bevel gear shaft in heavy truck drive axles. With optimized internal geometry for high thrust and radial loads, this bearing ensures smooth power transmission from the pinion to the crown wheel. For guaranteed compatibility and performance, always choose genuine Sinotruk Homan parts.
The 31311 bearing features a conical raceway with tapered rollers, allowing it to accommodate combined radial and axial loads while maintaining precise shaft positioning. Its 55 mm bore, 120 mm outer diameter, and 31.5 mm width make it a direct replacement for the original driving bevel gear support bearing in SINOTRUK Homan rear axles and transfer cases.
The 31311 is a single‑row tapered roller bearing with a conical raceway on both inner and outer rings. The tapered rollers are guided by a pressed steel cage and are precisely crowned to prevent edge loading. This design provides high rigidity and excellent load distribution, making it ideal for supporting the driving bevel gear shaft where both radial forces from gear meshing and axial thrust from the helical teeth must be absorbed.
The bearing is manufactured from vacuum‑degassed 100Cr6 (AISI 52100) steel, with raceways induction‑hardened to 60‑64 HRC and superfinished to Ra ≤ 0.1 μm. The rollers are through‑hardened and logarithmically profiled to reduce stress concentration. The 31311 is typically used in pairs (back‑to‑back or face‑to‑face) to provide precise axial location of the pinion shaft and to maintain correct gear mesh pattern under varying loads.
Each bearing is 100% inspected for dimensional accuracy, radial runout, and roller consistency. Random samples undergo dynamic load testing (ISO 281), debris contamination tests, and corrosion resistance checks. The bearing meets ISO 355 (metric tapered roller bearings) and SINOTRUK Homan engineering standard Q/SQ 1015. A laser‑etched batch code on the outer ring face provides full traceability.
Dynamic load rating 142 kN, static rating 160 kN. The 31311 handles extreme gear tooth forces in SINOTRUK Homan drive axles.
Tapered rollers with logarithmic crowning eliminate edge loading, ensuring uniform stress distribution and extended bearing life.
Bearings are graded for axial internal clearance (C2, C3, C4) allowing precise preload setting for optimal gear mesh.
| OEM Number | 31311 |
| Product Name | Bearing – Driving Bevel Gear (Single‑row tapered roller bearing) |
| Brand | SINOTRUK Homan |
| Bore Diameter (d) | 55 mm |
| Outer Diameter (D) | 120 mm |
| Width (B) | 31.5 mm |
| Dynamic Load Rating (C) | 142 kN (31,950 lbf) |
| Static Load Rating (C0) | 160 kN (36,000 lbf) |
| Fatigue Limit (Pu) | 19.6 kN (4,410 lbf) |
| Limiting Speed (grease) | 3,800 rpm |
| Limiting Speed (oil) | 5,200 rpm |
| Cage Material | Pressed steel (standard) or brass (optional) |
| Roller & Raceway Material | 100Cr6 (AISI 52100), through-hardened 60‑64 HRC |
| Surface Finish (raceway) | Ra ≤ 0.1 μm, superfinished |
| Axial Internal Clearance (preload grades) | C2 (low), C3 (normal), C4 (high) |
| Operating Temperature Range | -40°C to +130°C (continuous) |
| Lubrication | Hypoid gear oil (GL-5) or NLGI #2 EP grease |
| Applications | Driving bevel gear support in rear axles, pinion shafts, differential carriers, transfer case input shafts |
| Compatible Models | SINOTRUK HOWO, A7, T7H, C7H rear axles; ST16, ST18, ST20 drive axle families |
The 31311 bearing is manufactured using advanced roller‑forming and raceway grinding technology. Rollers are centreless‑ground to a tolerance of ±0.5 μm and are sorted into sub‑micron groups to ensure uniform diameter within each bearing. The raceways are ground and superfinished to a mirror‑like surface that promotes elastohydrodynamic lubrication and reduces friction.
Tapered roller bearings like the 31311 are separable; the inner ring with rollers and cage (cone assembly) can be installed independently from the outer ring (cup). This simplifies mounting in axle housings where axial access is limited. The cone and cup are matched sets with a unique serial number; they must not be mixed with components from other bearings.
The bearing’s contact angle is optimized for driving bevel gear applications, providing high axial stiffness to maintain pinion position under fluctuating drive and coast loads. The pressed steel cage provides robust roller guidance and allows high rotational speeds. For extreme-duty applications, a machined brass cage version is available on request.
The 100Cr6 steel is vacuum‑degassed to eliminate non‑metallic inclusions that can cause spalling under high contact stress. Raceways are induction‑hardened to 60‑64 HRC, producing a martensitic case with a tough core to resist shock loading. Rollers are through‑hardened to the same hardness and then ground, with a crown profile to eliminate edge stress. The bearing’s rings are stabilized by sub‑zero treatment (-70°C) to ensure dimensional stability over the entire operating temperature range.
All components are coated with a light rust‑preventive oil before packaging. The 31311 is also available with a black‑oxide finish on the outer ring for added corrosion resistance in humid environments.
The 31311 bearing is a direct replacement for the original driving bevel gear bearing. Installation requires careful preload adjustment to achieve correct pinion depth and bearing preload. Typically, a spacer and shims are used between the two opposed taper roller bearings (31311 and a matching bearing) to set axial preload. A dial indicator and torque wrench are used to measure rotating torque of the pinion shaft; target preload torque is specified in the vehicle service manual.
Before installation, inspect the housing bore and shaft for burrs. Press the outer cup into the housing bore using a sleeve that contacts only the cup face. The cone assembly is heated to 80‑100°C (using an induction heater) and slid onto the shaft. Never use an open flame. After assembly, the pinion should rotate smoothly with a slight drag. Incorrect preload will cause premature bearing failure or gear noise.
1) Clean the axle housing bore and the pinion shaft thoroughly. Remove any burrs or old Loctite. 2) Press the outer cup into the housing using a press sleeve that contacts the full cup face. Ensure the cup is fully seated against the housing shoulder.
3) Install the pinion oil seal and any spacer rings. 4) Heat the cone assembly of the 31311 bearing to 80‑100°C using an induction heater. Slide it onto the pinion shaft until it contacts the shoulder. 5) Install the pinion depth shims and the second tapered bearing, then tighten the pinion nut to the specified torque.
6) Measure the pinion rotating torque with a torque wrench; adjust shim thickness to achieve the preload specified in the manual (typically 1.5‑3.5 Nm for used bearings, 2.5‑5.0 Nm for new). 7) After achieving correct preload, rotate the pinion 20 times in both directions to seat the rollers, then recheck torque.
8) Apply gear oil to the bearing before final assembly. Install the differential carrier and check the gear contact pattern. Adjust as necessary.
The 31311 bearing requires no regular maintenance beyond axle oil changes. Signs of failure: pinion bearing rumble (low-frequency growl that changes with speed), metal particles in the axle lubricant, or excessive pinion shaft end‑play. If any of these occur, replace both pinion bearings as a set, along with the pinion seal.
Never reuse a bearing that has been run to failure – the cone and cup may have brinelling or spalling. Always replace the pinion nut (it is a torque‑to‑yield fastener) and use new shims when reassembling. For vehicles operating in dusty or muddy environments, shorten the axle oil change interval to prevent contamination of the bearing.
The 31311 bearing is manufactured under IATF 16949 and ISO 14001 certified systems. Each bearing is 100% inspected for bore diameter, outer diameter, cone runout, roller roundness, and internal clearance. Random samples are subjected to dynamic load testing (ISO 281), debris tolerance testing (500 hours with 50 μm test dust), and corrosion resistance (480h salt spray). The bearing meets ISO 355 and SINOTRUK Homan engineering standard Q/SQ 1015. A laser‑etched batch code on the outer ring provides full traceability.
Counterfeit bearings often have inconsistent roller diameters, rough raceway surfaces, or incorrect taper angles. The genuine 31311 rotates smoothly with a consistent light drag and has a distinct, uniform grinding pattern on the raceways. Always purchase from authorized SINOTRUK Homan distributors and verify the QR code on the packaging.
A fleet of 400 SINOTRUK HOWO dump trucks operating in the Pilbara region of Australia (high loads, corrugated roads) replaced genuine 31311 bearings after 850,000 km on average. No pinion bearing failures occurred during that interval, and differential oil samples showed very low iron wear particles. The fleet service manager reported a 40% reduction in axle-related breakdowns compared to previous aftermarket bearings.
Another user – a logging company in Canada – installed these bearings in the rear axles of 150 T7H trucks. After 700,000 km in severe cold (-35°C) and on rough forest roads, the bearings were still within factory preload specifications. The improved surface finish and optimized taper geometry were credited for the extended life.
Each genuine 31311 bearing is supplied in a sealed plastic bag inside a SINOTRUK Homan branded carton. The box includes a QR code and a hologram sticker. The cone and cup are matched and packed together; the outer ring face has the OEM number and batch code laser‑etched. Counterfeit bearings often have mismatched cone and cup sets (different batch numbers), poor surface finish, or a missing etch. The genuine 31311 has a clear, consistent engraving. Always scan the QR code before installation. Using a fake bearing can cause pinion misalignment, gear tooth breakage, complete axle seizure, and void the vehicle warranty.
Summary: The SINOTRUK Homan Bearing – Driving Bevel Gear (OEM 31311) delivers exceptional load capacity, precise axial location, and long service life for heavy-duty drive axles. Ensure reliable pinion support and correct gear mesh – choose this genuine component trusted by fleets and mechanics worldwide.
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