Product Introduction

Within the category of single row tapered Roller Bearings, the 30300 series features a design characterized by a relatively narrow width but an enlarged outer diameter. Compared to the 30200 series, and for a given inner diameter, the 30300 series offers a significantly larger outer diameter and longer rollers, resulting in substantially higher radial load-carrying capacity. It is a classic model used in automotive rear axles and the travel mechanisms of construction machinery.

Single row Tapered Roller Bearings are among the most widely used rolling bearings in industry. They consist of an inner ring with a tapered raceway and a large guide flange, an outer ring with a cup-shaped tapered raceway, and a single row of tapered rollers positioned between them. The lines of action of the tapered surfaces converge at a single point on the bearing axis, ensuring pure rolling motion for the rollers. As separable bearings, the inner ring assembly and outer ring can be mounted independently. They are capable of simultaneously supporting radial loads and unidirectional axial loads; typically, they are installed in opposing pairs to provide axial location in both directions. They find extensive application in sectors such as automotive manufacturing, construction machinery, mining, and gear reducers.

Series Positioning

The 30300 series bears the diameter series code "03" and features a contact angle of approximately 12° to 15°, classifying it as having a standard, small contact angle. Its core positioning is defined by "large outer diameter for enhanced radial load capacity"—meaning it increases the outer diameter to accommodate longer rollers without significantly increasing the bearing width, thereby boosting radial load-carrying performance.

Key Features

Superior radial load capacity: For the same inner diameter, the outer diameter is 10–20 mm larger than the 30200 series; the rollers are longer, resulting in a radial load capacity increase of approximately 30%–50%.

Moderate width: The total width is only slightly greater than that of the 30200 series, resulting in minimal additional axial space requirements.

Good speed performance: Features a small contact angle, leading to lower frictional heat generation compared to large-contact-angle series; suitable for medium-to-high-speed operating conditions.

Extensive use in the automotive sector: A preferred choice for applications involving high radial loads, such as rear axles and differentials.

Dimensional Parameter Table

The basic dimensions of WGHB Tapered Roller Bearings are listed in the dimensional data sheet

Single Row Tapered Roller Bearings: Most basic and widely used tapered bearing. Usually fitted as one of an opposing pair. During equipment assembly, can be set to the required clearance (end play) or preload condition to optimize performance. 

Single row (Type 30000): The most common type; primarily accommodates combined loads with a dominant radial component.

Inner diameter size range: 20mm~1270mm

Outer diameter range: 40mm~1465mm

Width size range: 15mm~240mm

Double Row Tapered Roller Bearings: Double row tapered bearing arrangements offer increased load capacity over single types.

Double row (Type 350000): Capable of supporting radial loads as well as bidirectional axial loads; commonly used in applications such as passenger car wheel hubs.

Inner diameter size range: 38mm~1560mm

Outer diameter range: 70mm~1800mm

Width size range: 50mm~460mm

Four Row Tapered Roller Bearings: Combine the inherent high-load, radial/thrust capacity and direct/indirect mounting variables of tapered roller bearings into assemblies of maximum load rating in a minimal space.

Four row (Type 380000): Features higher load-carrying capacity and is primarily used in heavy machinery, such as rolling mills.

Inner diameter size range: 130mm~1600mm

Outer diameter size range: 200mm~2000mm

Width size range: 150mm~1150mm

Common Suffixes

J: Pressed steel cage (standard configuration)

D / B: Designation used by some manufacturers for large-contact-angle variants (e.g., 303D has a contact angle of approx. 20°)

P5 / P4: Precision classes

C3 / C4: Increased internal clearance groups

W33: Outer ring with lubrication groove and oil holes

Common Part Numbers

30305  25×62×18.25  Small vehicle axles, agricultural machinery wheel hubs

30306  30×72×20.75  Automotive wheel hubs, light vehicle axles

30307  35×80×22.75  Automotive rear axles, transmissions

30308  40×90×25.25  Commercial vehicle axles, speed reducers

30310  50×110×29.25  Heavy-duty vehicle axles, construction machinery

30312  60×130×33.5  Crane wheels, mining machinery

30314  70×150×38  Large speed reducers, crusher auxiliary shafts

30316  80×170×42.5  Heavy-duty vehicle axles, metallurgical equipment

30320  100×215×51.5  Large speed reducers, rolling mill auxiliary rolls

Application Scenarios

Automotive Industry: 30300 This series serves as a mainstay for commercial vehicle rear axles and differentials; models ranging from 30306 to 30314 cover axle requirements for everything from light to heavy-duty trucks, with high radial load capacity being the primary reason for their selection.

Construction Machinery: Models 30310 and above are commonly used in the travel and swing mechanisms of excavators and loaders, where the large outer diameter design accommodates heavy radial loads.

Industrial Transmission: Suitable for heavy-duty gear reducers, conveyor belt drive rollers, and auxiliary shafts in mining crushers—applications characterized by high radial loads and moderate axial forces.

Lifting and Transport: Models 30312 through 30320 are frequently used in crane wheel assemblies and the travel mechanisms of port machinery.

Key Differences

The 30300 series shares similar contact angles and structural principles with the 30200 series; the primary differences lie in the outer diameter and radial load capacity. Taking the 30208 (40×80×19.75) and 30308 (40×90×25.25) as examples: for the same inner diameter, the 303 model features an outer diameter that is 10mm larger and a width that is 5.5mm greater, resulting in an approximately 40% increase in radial load capacity. If the radial load capacity of the 30200 series is insufficient but axial forces remain moderate, the 30300 series is the most straightforward upgrade option.

Selection Recommendations

The 30300 series is ideal for operating conditions involving high radial loads, moderate axial forces, and sufficient space for the outer diameter. If outer diameter space is restricted, revert to the 30200 series; if axial forces are high, consider the 31300 series; if a wider bearing and higher load capacity are required, upgrade to the 32300 series.