MRC9209U5Precision Single-Row Ball Bearing, 50 x 85 x 19 mm, ABEC 5, Universally Ground, Open

Product Description

What this part is

An MRC 9209 U5 precision single-row ball bearing, 50 mm bore, 85 mm outside diameter, 19 mm width, open on both faces. MRC is part of the SKF group, and “annular ball bearing” is MRC’s own catalogue term for its single-row precision ball bearing programme.

Decoding the designation

The 9200 block is MRC’s precision annular ball bearing series and the trailing 09 identifies the size within it. U marks the bearing as universally ground, so that any two of the same designation assemble as a matched pair without shims or measurement. The trailing 5 is the tolerance class, ABEC 5, and the catalogue title carries the same ABEC 5 reading independently. There is no closure suffix, so both faces are open. The numbers 524718-IB and K500A016V are distributor and customer stock references rather than part of the MRC designation.

What these specs mean in practice

ABEC 5 narrows bore and outside diameter tolerance and, more importantly, radial and axial runout, against a normal-class bearing. That is what a shaft needs when its position is a specification rather than a consequence — a machine-tool feed screw, a grinding head, an instrument spindle. Universal grinding is what lets two bearings be stacked in a duplex mounting and produce a repeatable preload from the grinding itself, rather than from a shim stack measured at assembly. With both faces open, lubrication and sealing are provided by the housing.

Quantity and configuration

1 Pc. Single row, straight bore, open both faces, universally ground for pairing.

Fitting notes

A precision-class bearing expects ground and measured shaft and housing seats, and is handled clean. Mounting force is applied through the ring being fitted and never transmitted across the balls from one ring to the other. On a paired mounting the outer-ring face marks are lined up so the ground offset closes as the set is clamped.

Interchange guidance

The genuine interchange is another MRC 9209 U5, or the same MRC number in a matching universal grind and class. Precision ball bearings of the same nominal envelope from other schemes differ in class notation and in whether they are universally ground, so an equivalent has to match on bore, outside diameter, width, class and grinding together before it is a substitution rather than a related size.