IKO SB12A Spherical Plain Bearing, Steel-on-Steel, Without Seals, 12 mm Bore

This page covers the IKO SB..A spherical plain bearings (spherical bushings) for 12 to 55 mm shafts, 10 sizes from SB12A to SB55A. Choose the shaft diameter from the drop-down; each variant has its own dimensions, load capacities and mass in the Model Details.

SB..A is a steel-on-steel type: inner and outer rings of high carbon chromium bearing steel, with phosphate-treated sliding surfaces that are dry-coated with molybdenum disulfide (MoS2). The outer ring is split at one position only, so the outer and inner rings do not separate, which keeps handling before mounting and fitting to the housing simple. Its boundary dimensions are the same as the SB type (outer ring split in halves and held by a snap ring), with smaller radial internal clearances. Each ring has an oil groove and two oil holes.

Where this product is used

• Pivots and linkages in industrial machinery and construction machinery
• Joints with alternate loads and shock loads
• Mountings where the shaft and housing can be slightly out of line and the bearing must self-align
• Joints that carry a radial load and an axial load in both directions at the same time

Features

• Steel-on-steel: high carbon chromium bearing steel rings, phosphate-treated and dry-coated with molybdenum disulfide (MoS2) for low torque, wear resistance and large load capacity
• Self-aligning spherical sliding surfaces that carry a radial load and a bi-directional axial load at the same time
• Without seals (SB..A has no sealed version)
• Oil groove and two oil holes on the inner ring and on the outer ring
• Dynamic load capacity Cd 15.9 to 314 kN and static load capacity Cs 95.3 to 1,880 kN across the 10 sizes on this page
• Permissible tilting angle 4 to 7°

Key specifications

Available sizes

Selecting the right option

The drop-down is the shaft diameter in mm, which is the bore of the bearing: the number in the part number is the bore size (for example SB12A has a 12 mm bore). Every size on this page is a metric size.

SB..A and the plain SB type share boundary dimensions. The plain SB type is numbered from its bore, outside diameter and width (SB122211 for the 12 mm size), has an outer ring split in halves and held by a snap ring, and has larger radial internal clearances. Every part number on this page ends in A.

Steel-on-steel or maintenance-free is chosen from the operating conditions: load, lubrication, temperature and sliding velocity. This is a steel-on-steel type, which needs periodic grease lubrication and suits alternate loads and shock loads. If you are unsure, send AIMS the load, motion and environment and we will help you choose.

Fitting and use

Recommended fits for steel-on-steel bushings: shaft h6 or j6 with housing bore H7 or J7 for normal operation, and shaft m6 or n6 with housing bore M7 or N7 when the load direction is indeterminate. N7 is recommended for light metal housings.

When the load is large, the shaft can slip in the inner ring bore: prepare the shaft to a hardness of 58 HRC or greater and a surface roughness of 0.8 μm Ra or less.

When mounting, set the split plane of the outer ring at right angles to the direction of the load, so that the load does not act on the split.

Steel-on-steel bushings need periodic grease lubrication as a general rule, and a shorter interval is recommended during initial operation. Lithium soap based grease (NLGI consistency No. 2) containing molybdenum disulfide is widely used.

For steel-on-steel bushings the recommended load is up to 0.3 x Cd for a constant load and up to 0.6 x Cd for an alternate load. Radial and axial loads can act together. The equivalent radial load is P = Fr + Y x Fa, where Y is 1, 2, 3, 4 and 5 for an Fa/Fr of 0.1, 0.2, 0.3, 0.4 and 0.5; an Fa/Fr above 0.5 is marked unusable.

The maximum allowable temperature of steel-on-steel bushings without seals is +180 °C. The dynamic load capacity is multiplied by a temperature factor ft: 1 up to +150 °C and 0.7 from +150 to +180 °C.

Cd is the dynamic load capacity (the maximum allowable load under oscillating motion, based on the contact pressure on the spherical surfaces) and Cs is the static load capacity.

Related products

Other IKO spherical plain bearing pages: SBB inch series spherical plain bearings (1/2 and 5/8 in) and SBB..-2RS inch series sealed spherical plain bearings (3/4 to 4 in).