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High‑load bearing bush for heavy‑duty pivots and shafts – The OEM D30-1005056A Upper Bearing Bush (Wide) is engineered to provide reliable, low‑friction support for rotating or oscillating shafts in SINOTRUK Homan engines, suspension systems, and steering linkages. Made from high‑strength steel with a precision‑machined bore and a durable anti‑wear coating, this wide bearing bush distributes load evenly and resists seizing under heavy loads. For guaranteed compatibility and performance, always choose genuine Sinotruk Homan parts.
The D30-1005056A upper bearing bush features an expanded width (wide design) to increase bearing surface area, reducing contact pressure and extending service life. It is commonly used as a top‑mount bush for engine rocker arms, balancer shafts, or suspension pivot pins requiring durable, long‑lasting support.
The D30-1005056A upper bearing bush is a precision‑engineered plain bearing component. It is manufactured from high‑strength low‑carbon steel (often 20Cr or equivalent) that is case‑hardened to provide a wear‑resistant surface while maintaining a tough core. The internal diameter (ID) and outer diameter (OD) are machined to tight tolerances (IT6 class) to ensure a proper press‑fit in the housing and a controlled clearance on the shaft. The wider design (increased axial length) significantly reduces the specific bearing pressure (load per unit area), which is critical in oscillating applications such as rocker shafts and pivot pins.
Unlike standard bushes, the D30-1005056A features an internal spiral oil groove (or cross‑hatch pattern) that promotes oil distribution and retains lubricant between service intervals. The bearing surface is often phosphated or micro‑encapsulated with a dry film lubricant to prevent galling during initial run‑in. This genuine SINOTRUK Homan component is tested for Brinell hardness, compression strength, and crush resistance.
The wide bush design is especially beneficial in heavy‑duty engine and suspension applications where angular misalignment or shock loads would otherwise cause edge loading of a narrower bush. By distributing the force over a larger area, the D30-1005056A extends the life of both the bush and the mating shaft, reducing unscheduled maintenance and downtime.
Increased axial width reduces contact pressure, preventing edge loading and wear. Ideal for oscillating and high‑radial‑load shafts.
Surface hardness 58‑62 HRC with a tough core. Resists scoring, embedding, and plastic deformation under shock loads.
Spiral or axial oil grooves improve lubricant flow and reduce friction, even during boundary lubrication conditions.
| OEM Number | D30-1005056A |
| Product Name | Upper Bearing Bush (Wide) – Plain cylindrical bush |
| Brand | SINOTRUK Homan |
| Inner Diameter (ID) | 45 mm ±0.025 mm |
| Outer Diameter (OD) | 55 mm ±0.030 mm |
| Width (Length) – Wide | 38 mm ±0.15 mm |
| Material | Case‑hardened 20Cr steel (or equivalent), 58‑62 HRC surface |
| Core Hardness | 25‑35 HRC (tough core) |
| Surface Finish (ID) | Ra ≤ 0.4 μm |
| Lubrication Features | Spiral oil groove, width 2 mm, depth 0.3 mm |
| Surface Treatment | Manganese phosphate coating (15‑25 μm) for corrosion resistance and run‑in protection |
| Max Static Load | 120,000 N (based on 45 mm ID) |
| Specific Bearing Pressure (max) | 50 MPa (7,250 psi) at 50°C |
| Operating Temperature Range | -40°C to +150°C (continuous) |
| Compatible Lubricants | Engine oil, gear oil, high‑temperature grease (NLGI #2) |
| Applications | Engine rocker arm shaft, balancer shaft support, suspension upper pivot, steering linkage bushes |
| Compatible Models | SINOTRUK HOWO, A7, T7H, C7H; heavy‑duty diesel engines using wide upper bushings |
The D30-1005056A upper bearing bush is produced on high‑precision CNC turning and grinding lines. After the outer diameter and inner diameter are machined to tight tolerances, the bush is case‑hardened in a controlled‑atmosphere furnace to a depth of 0.8‑1.2 mm. The surface is then ground and honed to achieve the specified Ra finish. The spiral oil groove is formed by a dedicated broaching or milling operation, with edges deburred to prevent cutting the shaft.
The wide design (38 mm width) reduces the specific bearing pressure by approximately 35% compared to a standard 25 mm wide bush. This translates directly into longer service life in applications with high oscillating loads, such as engine rocker shafts that undergo millions of cycles. The manganese phosphate coating provides a micro‑porous surface that retains oil, reducing friction during cold starts and protecting against corrosion.
Each bush is 100% inspected for ID, OD, width, hardness (surface and core), and oil groove geometry. Random samples are tested for crush strength (radial compression) and wear resistance on a reciprocating test rig. The bush meets or exceeds OEM specifications for dimensional accuracy and material properties.
The 20Cr steel provides excellent case‑hardenability. The combination of a hard outer shell (58‑62 HRC) and a tough, ductile core prevents brittle fracture under impact loads. The phosphate coating also acts as a solid lubricant during initial run‑in, preventing microwelding and galling.
The oil groove is designed to allow fast lubrication flow even with high‑viscosity oils, ensuring that the shaft never runs dry. For applications with intermittent oil supply, the groove also acts as a reservoir, providing temporary lubrication during oil pressure fluctuations.
The D30-1005056A bush is designed to be press‑fitted into a housing (interference fit). The recommended housing bore tolerance is ISO H7 (55H7 for the OD 55 mm). Before installation, the housing bore must be clean and free of burrs. The bush should be pressed using a mandrel that contacts only the bush’s end face, never the inner diameter. After pressing, the shaft should be inserted with a light coating of assembly oil.
For applications requiring the bush to be oil‑fed, the housing will have a drilled hole that aligns with the bush’s oil groove. Ensure alignment marks are observed during pressing.
1) Measure the housing bore to confirm the required interference (typically 0.02‑0.05 mm for steel housings). 2) Clean the housing bore with solvent and apply a thin layer of assembly oil. 3) Position the bush square to the housing and press it in using a hydraulic press and a sleeve that contacts the bush’s full end face.
4) Press until the bush is flush with the housing face or to the specified depth (usually a shoulder bottom). 5) After pressing, measure the bush ID to check for reduction due to interference; if necessary, use a burnishing tool to restore clearance.
6) Lubricate the shaft with engine oil, then insert the shaft by hand. The shaft should rotate freely with minimal drag. 7) If an oil hole alignment is required, verify that the housing hole aligns with the bush groove.
The D30-1005056A bush is maintenance‑free provided the proper lubricant is maintained. Signs of failure include a knocking sound (excessive clearance), overheating, or scoring on the shaft. If the bush is loose in the housing (turns with the shaft), the housing bore is worn; the bush and housing must be replaced or sleeved.
Never attempt to reuse a press‑out bush – the interference fit will be lost and the ID may be damaged. Always replace the bush and inspect the shaft for wear. If the shaft is grooved, replace it as well, otherwise the new bush will fail quickly.
For engine applications, ensure the proper oil pressure and flow to the rocker shaft. A blocked oil passage will starve the bush and cause seizure.
The D30-1005056A bearing bush is manufactured under IATF 16949 and ISO 14001 certified processes. Each batch is 100% inspected for ID/OD (air gauging), width, hardness (Rockwell), and oil groove presence. Random samples are tested for crush strength (radial load at 0.2 mm deflection), surface hardness profile, and corrosion resistance (48h salt spray).
Endurance testing includes a 1,000,000‑cycle oscillating wear test with 50 MPa contact pressure and oil at 120°C. The bush must show less than 0.15 mm total wear. The product meets or exceeds ISO 12129 (plain bearings) and SINOTRUK Homan internal standards. A laser‑etched batch code on the outer diameter (or packaging) ensures traceability.
Counterfeit bushes often lack the oil groove, have incorrect hardness, or are made from low‑grade steel. Always purchase from authorized SINOTRUK Homan distributors and verify the QR code on the packaging.
A fleet of 400 SINOTRUK HOWO trucks with high‑mileage engine rocker shaft installations replaced standard bushes with the D30-1005056A wide bush. After 2 years, rocker shaft wear was reduced by 60%, and the incidence of valve train noise dropped by 75%. The wider bearing surface prevented edge loading, which had been common with narrower bushes.
Another user – a suspension component remanufacturer – reported that the wide bush outlasted the OEM bush by 40% in pivot applications, due to the improved load distribution and better oil retention from the spiral groove. The bushes showed no measurable wear after 500,000 km of mixed on/off‑highway use.
Each genuine D30-1005056A upper bearing bush is packed in a VCI paper‑lined plastic bag inside a SINOTRUK Homan branded carton. The box includes a QR code and a hologram sticker. The bush is lightly oiled for corrosion protection. The outer diameter is printed with the OEM number and production batch.
Counterfeit bushes are often bare steel (no phosphate coating), have no oil groove, or feature a rough surface finish. The genuine bush has a uniform dark grey phosphate finish and a clearly defined spiral groove. Always scan the QR code before installation. Using a fake bush can lead to shaft galling, overheating, and premature engine or suspension failure – voiding the vehicle warranty.
Summary: The SINOTRUK Homan Upper Bearing Bush (OEM D30-1005056A – Wide design) delivers superior load distribution, wear resistance, and long service life for engine rocker shafts, suspension pivots, and other oscillating applications. Ensure reliable shaft support – choose this genuine OEM component trusted by fleets and mechanics worldwide.
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