KOYO B 1812 28.58x34.92x19.05 - Drawn Cup Needle Roller Bearing

KOYO B 1812 28.58x34.92x19.05 - Drawn Cup Needle Roller Bearing

KOYO B 1812 is a drawn cup needle roller bearing with a cage, featuring compact dimensions of 28.58x34.92x19.05 mm, equivalent to approximately 1 1/8 x 1 3/8 x 3/4 inch. The thin-walled drawn outer cup provides a very small radial cross-section, while the needle roller and cage assembly is designed primarily to support radial loads. The bearing is open at both ends and is normally used without a separate inner ring.

Technical Specifications - KOYO B 1812

Manufacturer: KOYO / JTEKT
Designation: B-1812 / B 1812
Product type: Needle roller bearing
Series: B inch series
Design: Drawn cup needle roller bearing
Rolling elements: Needle rollers
Needle guidance: Cage
Inner ring: Not included
Ends: Open
Raceway diameter Fw: 28.575 mm
Outside diameter D: 34.925 mm
Width C: 19.05 mm
Rounded dimensions: 28.58x34.92x19.05 mm
Imperial dimensions: 1 1/8 x 1 3/8 x 3/4 inch
Primary load direction: Radial
Installation: Press fit in the housing

Dimensions 28.58x34.92x19.05 mm

The nominal dimensions of B 1812 are:

Fw: 28.575 mm = 1 1/8 inch
D: 34.925 mm = 1 3/8 inch
C: 19.05 mm = 3/4 inch

For this reason, the bearing may be listed as either 28.58x34.92x19.05 mm or with the more precise imperial conversions 28.575x34.925x19.05 mm.

Both dimensional descriptions identify the same nominal inch-size bearing.

Drawn Cup Needle Roller Design

The outer ring of KOYO B 1812 is manufactured as a thin-walled drawn cup. This design minimizes the radial installation space required by the bearing.

The difference between the nominal needle roller raceway diameter of 28.575 mm and the outside diameter of 34.925 mm is only 6.35 mm.

This compact cross-section makes the B series particularly useful where conventional roller bearings would require too much radial installation space.

Needle Roller and Cage Assembly

A key characteristic of B 1812 is its caged needle roller construction.

The cage separates and guides the needle rollers, reducing direct contact between adjacent rolling elements. This construction is suitable for applications requiring compact radial dimensions together with good operating speed capability.

This is also one of the major differences between the B and BH series.

B 1812 vs BH 1812 - Important Difference

Although the designations are similar, KOYO B 1812 and BH 1812 are different bearings.

KOYO B 1812:
Dimensions: 28.575x34.925x19.05 mm
Outside diameter: 34.925 mm
Design: caged needle rollers
Series: B

KOYO BH 1812:
Dimensions: 28.575x38.1x19.05 mm
Outside diameter: 38.1 mm
Design: full complement needle rollers
Series: BH

Therefore, B 1812 and BH 1812 are not direct dimensional replacements. The housing bore and internal bearing construction must be verified before substitution.

Bearing Without an Inner Ring

KOYO B 1812 is normally supplied without a separate inner ring.

In this arrangement, a suitably prepared shaft surface acts directly as the inner raceway for the needle rollers. This allows an even more compact bearing arrangement.

The shaft raceway must therefore provide suitable hardness, dimensional accuracy, roundness and surface finish for direct rolling contact.

Where the shaft cannot provide an appropriate raceway, the bearing arrangement may require a suitable separate inner ring.

Radial Load Capability

Needle rollers have a relatively large contact length compared with their diameter. This allows a needle roller bearing to support substantial radial loads while maintaining a small radial cross-section.

KOYO B 1812 is intended primarily for radial loading.

If significant axial forces are present in the application, they should be supported by an appropriate separate axial bearing arrangement.

Open-Ended Construction

B-1812 is an open-ended drawn cup bearing, allowing the shaft to pass completely through the bearing position.

The open design is an important identification characteristic because closed-end drawn cup needle roller bearings are also available for applications where the shaft terminates inside the bearing arrangement.

Typical Applications

KOYO B 1812 can be used in appropriately designed:

• industrial gearboxes
• agricultural machinery
• transmission mechanisms
• compact drive systems
• mechanical power transmission
• shaft assemblies
• material handling equipment
• industrial machinery

The final bearing selection should consider radial load, rotational speed, lubrication, shaft hardness, shaft surface quality and housing accuracy.

Replacement Identification - KOYO B 1812

When selecting a replacement, verify:

Brand: KOYO / JTEKT
Designation: B-1812
Bearing type: Needle roller bearing
Construction: Drawn cup
Dimensions: 28.575x34.925x19.05 mm
Imperial size: 1 1/8 x 1 3/8 x 3/4 inch
Rolling elements: Caged needle rollers
Inner ring: Not included
Ends: Open
Primary loading: Radial

Matching only the 28.575 mm raceway diameter is not sufficient. The outside diameter, width, cage design and housing fit must also correspond to the original application.

FAQ - KOYO B 1812

What are the dimensions of KOYO B 1812?
The nominal dimensions are 28.575x34.925x19.05 mm, equivalent to 1 1/8 x 1 3/8 x 3/4 inch.

What type of bearing is KOYO B 1812?
It is a drawn cup needle roller bearing with a cage.

Does B 1812 have an inner ring?
No. The standard bearing is supplied without an inner ring, allowing a suitably prepared shaft to act as the inner raceway.

Does KOYO B 1812 have a cage?
Yes. The needle rollers are guided and separated by a cage.

Is B 1812 the same as BH 1812?
No. B 1812 has an outside diameter of 34.925 mm, while BH 1812 has an outside diameter of 38.1 mm. Their internal constructions are also different.

What does the 28.575 mm dimension represent?
It corresponds to 1 1/8 inch and is the nominal needle roller raceway diameter.

What loads is B 1812 designed to support?
The bearing is primarily designed to accommodate radial loads.

Why is the B 1812 bearing so compact?
Its thin-walled drawn outer cup and needle roller construction provide useful radial load capacity with a very small radial cross-section.