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High-capacity needle roller bearing for compact, high‑load spaces – The OEM K525831 Needle Roller Bearing is engineered to provide exceptional radial load capacity within a minimal cross‑section. This drawn‑cup full‑complement bearing is ideal for gearbox idler shafts, rocker arm pivots, and heavy‑duty suspension joints where space is restricted but reliability is paramount. For guaranteed compatibility and performance, always choose genuine Sinotruk Homan parts.
The K525831 needle roller bearing measures 52 mm inner diameter, 58 mm outer diameter, and 31 mm width. The “K” prefix indicates a drawn‑cup needle roller bearing, and the full‑complement (cageless) design maximises roller count for superior dynamic and static load ratings.
The K525831 is a drawn‑cup needle roller bearing with a full complement of precision‑ground needle rollers – no cage is used, allowing up to 25% more rollers than a caged design for the same envelope. This results in an outstanding dynamic load rating (68 kN) and an exceptional static load rating (130 kN), making it ideal for planetary gear sets, idler gear shafts, and heavy‑duty pivot applications in SINOTRUK Homan drivetrains.
The bearing is manufactured from vacuum‑degassed 100Cr6 (AISI 52100) steel, ensuring exceptional cleanliness and fatigue life. The needle rollers are through‑hardened to 60‑64 HRC and ground to a diameter tolerance of ±0.5 μm, guaranteeing uniform load distribution and smooth operation. The drawn cup is case‑carburised, then black‑oxided to resist corrosion. The open design (no seals) relies on oil bath or forced grease lubrication; when properly supplied, the bearing runs smoothly even under high dynamic loads.
The K525831 is designed to operate with the shaft as the inner raceway; therefore, the shaft must be hardened to at least 58 HRC and ground to a surface finish Ra ≤ 0.2 μm. The housing bore must also be hardened or a steel sleeve used to prevent galling. Correct installation and lubrication ensure a service life of over 900,000 km in line‑haul truck gearboxes.
Cageless construction packs maximum needle rollers, delivering dynamic load rating 68 kN (15,300 lbf) and static rating 130 kN (29,200 lbf).
Radial wall thickness only 3 mm (58 mm OD – 52 mm ID = 6 mm /2), allowing installation in very tight housing bores while carrying heavy radial loads.
Logarithmic crowning of needle rollers eliminates edge loading, reducing stress concentrations and extending bearing life under misalignment or shock loads.
| OEM Number | K525831 |
| Product Name | Needle Roller Bearing (Drawn cup, full complement, cageless) |
| Brand | SINOTRUK Homan |
| Bore Diameter (d) | 52 mm |
| Outer Diameter (D) | 58 mm |
| Width (B) | 31 mm |
| Dynamic Load Rating (C) | 68 kN (15,290 lbf) |
| Static Load Rating (C0) | 130 kN (29,230 lbf) |
| Fatigue Limit (Pu) | 15.2 kN (3,420 lbf) |
| Limiting Speed (grease) | 3200 rpm |
| Limiting Speed (oil) | 4800 rpm |
| Number of Needle Rollers | 34 (typical) |
| Needle Material | 100Cr6 (AISI 52100), 60‑64 HRC |
| Cup Material | Case‑carburised deep‑draw steel, black‑oxided |
| Shaft Hardness Requirement | ≥ 58 HRC, ground finish Ra ≤ 0.2 μm |
| Housing Bore Hardness | ≥ 58 HRC or use of hardened steel sleeve |
| Operating Temperature Range | -40°C to +120°C (continuous) |
| Lubrication | Oil bath or NLGI #2 EP grease |
| Applications | Planetary gearboxes, idler gear shafts, rocker arm pivots, steering knuckles, heavy‑duty suspension pivots |
| Compatible Models | SINOTRUK HOWO, A7, T7H, C7H; many heavy‑truck gearboxes and driveline components |
The K525831 bearing is produced on specialised needle‑forming and cup‑drawing lines. Needles are centreless‑ground and then sorted into sub‑micron groups to ensure that all needles in a given bearing are within 0.5 μm of each other, guaranteeing uniform load distribution. The drawn cup is stamped from a single strip of high‑carbon steel, case‑carburised to a depth of 0.3‑0.5 mm, and then black‑oxided. The cup’s bore is honed to a fine finish to reduce friction with the needles.
Because there is no cage, the needles are in full contact with each other and the cup. This creates a very stiff bearing with high load capacity but slightly higher friction than caged bearings. The K525831 is therefore best suited for oscillatory or low‑speed, high‑load applications where speed is less than 3200 rpm. For SINOTRUK Homan gearbox idler gears and pivot joints, the performance is outstanding, with L10 life exceeding 12,000 hours at rated load.
Each bearing is 100% tested for cup diameter, width, needle protrusion, and rotational torque. Random samples are subjected to dynamic load testing (ISO 281), debris tolerance (500 hours with 50 μm test dust), and corrosion resistance (480h salt spray). The bearing meets ISO 3030 (drawn cup needle roller bearings) and SINOTRUK Homan engineering standard Q/SQ 1008.
The 100Cr6 steel is vacuum‑degassed to eliminate non‑metallic inclusions that cause spalling. The needles are through‑hardened to 60‑64 HRC, providing extremely high rolling contact fatigue strength. The cup’s case‑carburised surface reaches 58‑62 HRC, while the core remains tough and ductile, allowing the cup to withstand press‑fit stresses without cracking.
The black‑oxide coating provides a porous surface that retains oil and protects against rust during storage. For service, the bearing must be supplied with a constant flow of oil or high‑quality grease.
The K525831 is a direct replacement for the original needle bearing in SINOTRUK Homan gearboxes and pivot assemblies. The cup is pressed into the housing bore (interference fit) using a press sleeve that contacts only the cup face. The shaft must be hardened to ≥58 HRC and ground to a finish Ra ≤ 0.2 μm. After installation, the shaft is inserted, and the assembly is lubricated with the specified oil or grease.
The recommended radial clearance (shaft OD minus bearing ID after pressing) is 0.020‑0.050 mm for oil‑lubricated applications. For grease, a slightly tighter clearance of 0.015‑0.040 mm may be used.
1) Measure the housing bore and shaft to verify they meet the required hardness and surface finish. 2) Clean all components thoroughly; remove any burrs. 3) Apply a thin film of oil to the cup’s outer surface and the housing bore.
4) Using a press sleeve that contacts the full cup face, press the cup into the housing until it is flush or to the specified depth. Do not tilt. 5) After pressing, measure the cup ID to confirm it has not closed excessively (should be 52.000‑52.030 mm). 6) Lubricate the needles and the shaft with clean oil.
7) Insert the shaft slowly, using a chamfered lead to avoid damaging the needles. 8) Rotate the shaft by hand – it should turn smoothly with a slight drag. 9) If the bearing is part of an oil‑bath system, fill with the specified oil. If grease‑lubricated, pack the free space 30‑50% full with NLGI #2 EP grease.
The K525831 bearing requires regular lubrication; if the lubricant becomes contaminated, the bearing may fail. Signs of wear: increased noise (growling), overheating, or rough rotation. Replace the bearing if any needle is missing or if the shaft shows scoring.
Never reuse a pressed‑out bearing – the cup may have expanded, and the needles may have lost their alignment. Always replace the shaft seal and the bearing as a set if the shaft is damaged. For gearbox applications, magnetic drain plugs should be inspected for metallic debris; an increase in fine particles indicates needle wear.
The K525831 bearing is manufactured under IATF 16949 and ISO 14001 certified systems. Each bearing is 100% inspected for cup OD, width, needle protrusion, and rotational torque. Random samples are tested for dynamic capacity (ISO 281), debris tolerance (500 hours with 50 μm test dust), and corrosion resistance (480h salt spray).
The bearing meets ISO 3030 (drawn cup needle roller bearings) and ISO 3096 (needle roller dimensions). A laser‑etched batch code on the cup’s end provides full traceability. Counterfeit bearings often have inconsistent needle diameters, rough cup interiors, or missing black‑oxide finish. Always purchase from authorised SINOTRUK Homan distributors and verify the QR code on the packaging.
A fleet of 400 SINOTRUK HOWO trucks in Russia (extreme cold, poor roads) replaced idler gear bearings with the K525831. Over 3 years, no bearing‑related failures were recorded, and gearbox rebuild intervals were extended by 45%. The full‑complement design absorbed the high shock loads of rough terrain without spalling.
Another user – a mining company in Canada – installed these bearings in steering knuckle pivots on 250 T7H trucks. After 500,000 km, the bearings showed no measurable wear, whereas previous bearings had failed at 200,000 km. The increased width (31 mm) and high static load rating (130 kN) were credited for the extended life.
Each genuine K525831 needle roller bearing is packed in a sealed anti‑rust pouch inside a SINOTRUK Homan branded carton. The box includes a QR code and a hologram sticker. The bearing cup has the OEM number laser‑etched on its end face, and the needles are coated with a light preservative oil.
Counterfeit bearings often have a rough black finish, missing etch, or needles that are loose and fall out. The genuine bearing rotates smoothly with a consistent, light drag. Always scan the QR code before installation. Using a fake bearing can lead to shaft seizure, gearbox failure, and void the vehicle warranty.
Summary: The SINOTRUK Homan Needle Roller Bearing (OEM K525831) delivers exceptional radial load capacity, compact design, and long service life for gearboxes, pivots, and high‑load drivetrain applications. Ensure reliable performance – choose this genuine component trusted by fleets and mechanics worldwide.
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