MRC201SZZMast Guide Bearing – 25 mm ID, 3.000 in (76.2 mm) Roller OD, 1.000 in (25.4 mm) Width, Rubber Seals Both Faces, C2 Clearance

Product Description

What this part is

A single-row mast guide bearing: a deep groove ball bearing built with a thickened outer ring that runs directly as a roller against the channel of a lift-truck mast or a similar guide track. Bore 25 mm, outside diameter 76.2 mm (3.000 in), width 25.4 mm (1.000 in). The heavy outer ring section is what distinguishes a mast guide bearing from a standard deep groove bearing of the same bore, which would be 62 mm in outside diameter and 17 mm wide.

Decoding the designation

In the MRC scheme 305 is the series and size identity, S is the mast guide outer-ring form, and ZZ is the closure code. MRC uses ZZ for RUBBER contact seals on both faces, the reverse of the SKF, NSK and FAG convention where ZZ means metal shields. The trailing 3 is an internal construction variant. C2 in the extended carton designation is internal clearance tighter than normal, which suits a track roller where outer-ring runout controls guide accuracy.

What these specs mean in practice

The outer ring is the working wear surface, so its section thickness sets the load the bearing can take across a track edge rather than distributed around the raceway. Contact rubber seals on both faces retain a lifetime grease charge and exclude the dust, scale and water a mast channel collects; they cost a little running torque and cap the speed well below an open bearing, which suits an application turning at track speed rather than shaft speed. C2 clearance reduces radial play under load, keeping the roller from rocking in the channel.

Quantity and configuration

1 Pc. Bearing only. No mounting stud, retaining plate, spacer or shim pack.

Fitting notes

Mounting force is applied to the inner ring so the seals and the outer ring wear surface are not loaded through the balls. The seals are lifetime-charged, so no relubrication port or grease path is provided.

Interchange guidance

Interchange is by mast guide roller dimension and outer-ring form rather than by ISO base number. A standard 6305-2RS shares the 25 mm bore but has a 62 mm outside diameter and a thin outer ring, so it is a related size and not a substitute in a guide channel. Cross-brand mast guide rollers match on bore, roller outside diameter, width and outer-ring thickness taken together.