British Standard Tapered Roller Bearing

1. Product Definition​

Imperial tapered roller bearings use inches as the unit for dimension marking. Their core structural feature lies in the fact that both the inner ring and outer ring are equipped with tapered raceways, and the rollers have a matching tapered structure. This design enables them to withstand combined radial and axial loads, with radial load being the primary one, and they are specifically adapted to imported machinery and special industrial equipment that adopt imperial standards.​

In terms of working principle, they are basically consistent with metric tapered roller bearings-both realize force transmission through the rolling of rollers on tapered raceways. However, they have uniqueness in the dimension system (e.g., outer diameter, inner diameter, width, etc., are all measured in inches) and assembly accuracy, requiring precise matching with the installation dimensions of imperial equipment.​

2. Core Features​

Separable Structure: The outer ring of a single-row imperial tapered roller bearing can be completely separated from the inner ring assembly (composed of the inner ring, rollers, and cage). Moreover, outer rings and inner ring assemblies of the same model can be internationally interchangeable. This feature greatly facilitates the installation and disassembly of the bearing, and also provides convenience for later maintenance (such as replacing worn components individually), reducing maintenance costs.​

Combined Load-Carrying Capacity: The axial load-carrying performance of the bearing is determined by the cone angle. The cone angle of conventional single-row models ranges from 10° to 19°, which can meet the needs of combined radial and axial loads in most scenarios. For models with the suffix "B", the cone angle increases to 25° to 29°, significantly enhancing the axial load-carrying capacity, making them suitable for working conditions where axial load accounts for a higher proportion.​

High Precision and Long Service Life: In terms of material selection, high-quality steel with high purity and stable mechanical properties is used. During the production process, advanced heat treatment technology is applied, endowing the bearing components with excellent hardness, toughness, and wear resistance. At the same time, strict control over dimensional accuracy and rotational accuracy effectively improves fatigue resistance, greatly extending the service life of the bearing.​

Adjustable Clearance: For double-row or four-row imperial tapered roller bearings, the radial clearance and axial clearance can be precisely controlled by changing the thickness of the inner spacers of the bearing, and even pre-interference assembly can be achieved. This adjustability allows the bearing to better adapt to the operating requirements of different equipment, reducing vibration and noise, and improving the stability of equipment operation.​

3. Key Parameters​

Dimension Unit: As a core identifier of imperial bearings, all geometric parameters such as outer diameter, inner diameter, width, and chamfer size are measured in inches. They need to correspond one-to-one with the shaft diameter, bearing housing bore diameter, and other dimensions of imperial equipment to avoid assembly errors caused by unit confusion.​

Cone Angle: The cone angle is a key parameter affecting the axial load-carrying capacity. The conventional cone angle of single-row bearings is 10°-19°, suitable for conventional combined load scenarios. For large cone angle models (with suffix "B"), the cone angle is 25°-29°, and the axial load-carrying capacity is significantly higher than that of conventional models. Selection should be based on the actual load distribution.​

Structural Type: It is mainly divided into three structures: single-row, double-row, and four-row. Among them, the single-row structure is the most basic, suitable for scenarios with relatively small loads; the double-row structure has a load-carrying capacity approximately 1.8-2 times that of the single-row structure and can withstand bidirectional axial loads; the four-row structure has the strongest load-carrying capacity, about 3 times that of the single-row structure, and is specially designed for heavy-load working conditions.​

Model Composition: The model code contains five core parts of information, facilitating quick identification and selection:​

Prefix: Represents the working condition level, e.g., "L" for light-duty working conditions and "H" for heavy-duty working conditions;​

Angle Code: Identifies the type of cone angle, distinguishing between conventional cone angles and large cone angles;​

Basic Series Number: Reflects the basic dimension series of the bearing, determining the approximate range of outer diameter and inner diameter;​

Component Number: Specifies the type of bearing component. The component number for outer rings is usually 10-19, and that for inner rings is usually 30-49;​

Suffix: Supplements additional information, such as seal type and precision grade.​

4. Typical Models​

Single-Row Model (Taking NACHI as an Example) - LM11949/LM11910​

The prefix "LM" of this model represents medium-light duty working conditions, suitable for general machinery with medium loads (such as small imported motors and light-duty transmission equipment). It adopts a separable structure, and the outer ring and inner ring assembly can be disassembled separately. There is no need to disassemble the entire equipment during maintenance, greatly improving maintenance efficiency. Its dimensions and precision have undergone strict calibration, which can meet the stable operation requirements in medium-low speed and medium-load scenarios.​

Double-Row Model - 352062​

This model adopts an integral outer ring design, and the internal clearance can be adjusted through a dedicated spacer, enabling stable bearing of bidirectional axial loads. It has a compact structure, occupying small installation space, and at the same time, it has high radial load-carrying capacity. It is particularly suitable for scenarios that require bidirectional force bearing and have limited space, such as paper machine transmission systems and small rolling mill backup rolls, which can effectively reduce equipment vibration and ensure transmission precision.​

Four-Row Model - TQIT Type (Imperial Specification)​

As a core choice for heavy-load scenarios, this model consists of four independent inner rings, matching outer rings, and four rows of rollers. It has extremely strong overall load-carrying capacity and can withstand extremely large radial loads and bidirectional axial loads. Its structural design is optimized for heavy-load working conditions, with a larger contact area between rollers and raceways and more uniform stress distribution. It is mainly adapted to heavy equipment such as work rolls of hot rolling mills and blooming mill rolls, ensuring the reliability of the equipment under high-load and continuous operation conditions.​

5. Application Fields​

Heavy Machinery Field: Four-row imperial tapered roller bearings are core components of heavy equipment such as rolling mills and blooming mills, mainly installed in the roll parts. When these devices are in operation, the rolls need to bear hundreds of tons of radial loads and bidirectional axial thrust. Relying on their extremely strong load-carrying capacity and fatigue resistance, the bearings ensure the stable rotation of the rolls and guarantee the continuity and precision of the steel rolling process.​

Paper Industry Field: Double-row imperial tapered roller bearings are widely used in paper machine transmission systems (such as the transmission parts of press rolls and dryer rolls). When a paper machine is running, the transmission system needs to bear radial loads and a certain amount of axial loads in a compact space. The compact structure and bidirectional load-carrying capacity of the bearings are perfectly adapted to this demand. At the same time, their high-precision characteristics can reduce roll runout and ensure uniform paper thickness.​

General Equipment Field: Single-row imperial tapered roller bearings are mostly used in general equipment such as imported motors, pumps, and small transmission gearboxes. These devices usually adopt imperial installation dimensions. The separable structure of the bearings facilitates later maintenance (e.g., no need to disassemble the motor rotor or pump shaft when replacing the bearing), reducing maintenance difficulty and costs, while meeting the operating requirements of the equipment under medium-low speed and medium-load conditions.​

Construction Machinery Field: For imperial transmission components (such as drive axles and gearbox output shafts) of construction machinery like loaders and excavators, imperial tapered roller bearings are often selected. When this type of equipment is in operation, the transmission components need to withstand medium-low speed and heavy-load working conditions, and also face complex environments such as dust and vibration. The wear resistance and structural stability of the bearings ensure the reliable operation of the transmission system and reduce downtime caused by faults.​

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