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Heavy‑duty plain bearing for high‑load lower positions – The OEM D30-1005057 Lower Bearing Bush (Wide) is engineered to provide a durable, low‑friction interface for rotating or oscillating shafts in SINOTRUK Homan engines, transmissions, and suspension systems. With a widened design that distributes load over a larger area, this bush reduces specific contact pressure and resists wear under extreme conditions. For guaranteed compatibility and performance, always choose genuine Sinotruk Homan parts.
The D30-1005057 lower bearing bush is a precision‑machined, case‑hardened steel component with an internal spiral oil groove and a manganese phosphate coating. Its wide format (increased axial length) is specifically designed for high‑load lower positions such as crankshaft journals, balancer shaft supports, and heavy suspension pivots.
The D30-1005057 lower bearing bush is a cylindrical plain bearing machined from high‑grade 20Cr case‑hardening steel. Its wide design (increased width) significantly increases the load‑carrying surface, lowering the effective bearing pressure. This is particularly important in lower positions such as engine crankshaft journals and suspension lower pivots, where static and dynamic loads are highest. The wider bush also helps accommodate slight angular misalignment without edge loading, extending both bush and shaft life.
The bore is precision‑ground to an Ra ≤0.4 µm finish, and a spiral oil groove (width 2 mm, depth 0.3 mm) is machined into the inner diameter to distribute lubricant evenly. The bush is then case‑carburised to a depth of 0.8‑1.2 mm, achieving a surface hardness of 58‑62 HRC while maintaining a tough, ductile core (25‑35 HRC). A manganese phosphate coating (15‑25 µm) is applied for corrosion resistance and to provide a micro‑porous layer that retains oil during initial run‑in.
Unlike standard bushes, the D30-1005057 is designed for press‑fit installation. The recommended housing bore tolerance is ISO H7, and the interference fit ensures the bush rotates with the housing, while the shaft rotates inside the bush. This design is proven in thousands of heavy‑duty applications, including SINOTRUK Homan diesel engines and planetary gearboxes.
Increased width (38 mm) reduces specific bearing pressure by 35% compared to standard 25 mm bushes. Prevents edge loading under high loads.
Surface hardness 58‑62 HRC resists scoring and wear; tough core absorbs shocks. Manganese phosphate improves run‑in.
Spiral groove ensures continuous oil film, reduces friction, and prevents seizure during momentary oil starvation.
| OEM Number | D30-1005057 |
| Product Name | Lower Bearing Bush (Wide) – Cylindrical Plain Bearing |
| 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, 58‑62 HRC surface / 25‑35 HRC 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) |
| Max Static Load | 130,000 N (based on 45 mm ID, 38 mm width) |
| Specific Bearing Pressure (max) | 48 MPa (6,960 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 | Crankshaft main bearing (lower half), balancer shaft support, lower suspension pivot, steering linkage bushes |
| Compatible Models | SINOTRUK HOWO, A7, T7H, C7H; heavy‑duty diesel engines and drivetrains |
The D30-1005057 lower bearing bush is manufactured using high‑precision turning, grinding, and broaching processes. After the ID and OD are machined to tight tolerances, the bush is case‑hardened in a sealed quench furnace with a carbon‑rich atmosphere to produce a deep, uniform case. The spiral oil groove is then milled or broached, and the edge burrs are removed by tumbling. Finally, the bush is manganese phosphated and oiled for storage.
The wide design (38 mm width) is specifically intended for lower bearing positions that experience higher loads than their upper counterparts. For example, in many overhead‑valve engines, the lower half of the rocker shaft bush sees greater force because of valve spring resistance. The increased surface area reduces wear and prevents the bush from rocking in its housing. In suspension applications, the lower bush absorbs a larger portion of the vehicle weight and road shocks.
Each bush is 100% inspected for ID/OD (air gauging), width, hardness (Rockwell), and groove presence. Random samples undergo crush strength testing (radial compression until 0.2 mm deflection), wear testing on a reciprocating test rig (1,000,000 cycles at 50 MPa contact pressure), and salt spray corrosion testing (48 hours). The bush meets or exceeds SINOTRUK Homan’s internal engineering standard Q/SQ 1002.
The 20Cr steel used in the D30-1005057 provides an excellent combination of case hardenability and core toughness. The phosphate coating acts as a solid lubricant during initial run‑in, preventing micro‑welding between the bush and shaft. The spiral oil groove orientation is optimised for unidirectional rotation; for oscillating applications, an axial groove pattern is available on request.
The bush is compatible with all conventional engine oils, gear oils, and EP greases. When used in heavy‑duty truck engines, the high oil flow through the groove ensures that the bush never runs dry, even during cold starts or low‑oil‑pressure conditions.
The D30-1005057 bush is pressed into the housing with a hydraulic press. The housing bore should be machined to ISO H7 tolerance (55H7 for the 55 mm OD). A small chamfer on the housing bore helps guide the bush. Use a press sleeve that contacts the full end face of the bush; never press against the inner diameter. After pressing, verify that the oil groove aligns with any lubrication hole in the housing. If no alignment hole exists, the bush can be oriented arbitrarily.
The shaft should have a hardness of at least 45 HRC and a surface finish Ra ≤ 0.8 μm. Lubricate the shaft with engine oil before assembly. The recommended radial clearance (ID of bush minus OD of shaft) is 0.040‑0.080 mm for oil‑lubricated applications.
1) Measure the housing bore to ensure it is within H7 tolerance (55.000‑55.030 mm). 2) Clean the bore with solvent and remove any burrs. 3) Apply a light film of assembly oil to the outer diameter of the bush.
4) Position the bush square to the housing. Using a press sleeve that contacts the full end face, press the bush into the bore until it reaches the bottom shoulder or the specified depth. 5) After pressing, check the ID for any reduction due to interference. If the ID is below 45.000 mm, use a burnishing tool to adjust the clearance.
6) Lubricate the shaft with engine oil. Insert the shaft carefully, rotating it slightly to engage the oil groove. 7) Verify that the shaft rotates freely without binding. If binding occurs, check for misalignment or excessive interference.
The D30-1005057 bush is maintenance‑free as long as the lubricant is regularly changed. Signs of wear include a knocking sound (excessive clearance), overheating, or a polished shaft surface. If the bush spins in the housing (instead of staying press‑fitted), the housing bore is worn – replace the housing or machine it for an oversized bush.
Do not reuse a bush after it has been pressed out – the interference fit is compromised. Always replace the bush and inspect the shaft for scratches or ovality. If the shaft is damaged, replace it at the same time to avoid premature failure.
For engine applications, ensure the oil feed hole is not blocked by a misaligned bush. The spiral groove should be positioned to receive oil from the housing gallery; if no gallery exists, the orientation is not critical.
The D30-1005057 lower bearing bush is manufactured under IATF 16949 and ISO 14001 certified processes. Each batch is 100% inspected for ID/OD (air gauging), width, surface hardness (Rockwell C), and groove presence. Random samples are tested for crush strength (radial load at 0.2 mm deflection), corrosion resistance (48 h salt spray), and wear resistance (1,000,000‑cycle oscillating test).
The bush meets or exceeds the requirements of ISO 12129 (plain bearings) and SINOTRUK Homan engineering standard Q/SQ 1002. A laser‑etched batch number on the end face (or the outer diameter) provides full traceability. Counterfeit bushes often lack the phosphate coating, have incomplete oil grooves, or are made from low‑grade steel with insufficient hardness. Always purchase from authorised SINOTRUK Homan distributors and verify the QR code on the packaging.
A fleet of 350 SINOTRUK HOWO trucks in central Asia (extreme temperature variations and rough roads) replaced lower rocker arm bushes with the D30-1005057. Over 2 years, valve train wear was reduced by 55%, and rocker shaft scoring was eliminated. The wider bush prevented edge loading caused by a slight misalignment in the rocker pedestal.
Another user – a heavy‑duty suspension rebuilder – installed these bushes in lower control arms on 200 T7H trucks. After 600,000 km of mixed highway and construction site use, the bushes showed no measurable wear, whereas the original narrower bushes required replacement at 400,000 km. The fleet saved approximately $40,000 in labour and parts.
Each genuine D30-1005057 lower bearing bush is packed in a VCI paper‑lined plastic bag, then placed in a SINOTRUK Homan branded carton with foam inserts. The box contains a QR code and a holographic seal. The bush itself is lightly oiled; its outer diameter is laser‑etched with the OEM number and a batch code.
Counterfeit bushes are often bare steel (no phosphate coating), have no oil groove, or feature a shallow, poorly defined groove. The genuine bush has a uniform grey‑black phosphate finish and a clearly visible spiral groove. Always scan the QR code before installation. Using a fake bush can cause shaft seizure, bearing overheating, and catastrophic engine or suspension failure – and will void the vehicle warranty.
Summary: The SINOTRUK Homan Lower Bearing Bush (OEM D30-1005057 – Wide design) delivers superior load distribution, wear resistance, and reliability for lower bearing positions in engines, transmissions, and suspension systems. Ensure lasting shaft support – choose this genuine OEM component trusted by fleets and mechanics worldwide.
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