INALRA2565ZFinite-Stroke Non-Recirculating Linear Roller Bearing, 25 mm Wide x 65 mm Long x 20.6 mm Deep — Cage & Roller Assembly

Product Description

What this part is

A THK LRA-series linear roller bearing, 25 mm wide, 65 mm long, 20.6 mm deep. This is a finite-stroke, non-recirculating linear bearing, and that distinction is the whole character of the part.

Most linear guides recirculate: the rolling elements travel through the block, round a return track and back into the load zone, which allows unlimited stroke. An LRA does not. Its rollers are held in a cage that travels with the moving member, rolling between two flat raceways. Stroke is therefore limited — roughly the raceway length minus the cage length — but within that stroke it offers advantages a recirculating guide cannot match.

Why give up unlimited stroke

Three reasons, and they are the reasons this part gets specified rather than a profiled rail.

Friction is far lower. There is no return track, no direction reversal, no elements being pushed into and out of the load zone. Every roller simply rolls. That means very low and, more importantly, very consistent friction with no cyclic ripple as elements enter and leave the load path — which matters enormously on a measuring stage, a fine feed or a servo axis trying to hold a smooth low velocity.

Rigidity and accuracy are higher. Rollers give line contact rather than the point contact of balls, so deflection under load is smaller. And because there is no recirculation, there is no repeating disturbance in the motion — straightness and smoothness over the stroke are excellent. These are the bearings found in metrology stages, precision grinders, optical positioners, die-sets and short-stroke slides on machine tools.

It is very compact. At 20.6 mm deep including the raceway plates, a cross-roller or flat-roller arrangement fits where a profiled rail block will not.

The trade is stroke, and the design consequence: the raceway needs to be roughly twice the length of the required travel. On a long axis that is prohibitive. On a 30 mm fine-feed slide it is nothing.

Decoding the designation

LRA: THK’s linear roller bearing series — finite-stroke, non-recirculating, cage-guided rollers on flat raceways.

25: Width, 25 mm.

65: Length, 65 mm.

Z: A trailing designation carried on this part, reproduced here exactly as marked on the item. Match LRA2565Z, not LRA2565, against a parts list.

Published dimensions

Width: 25 mm.

Length: 65 mm.

Depth / height: 20.6 mm.

Series: LRA, finite-stroke non-recirculating linear roller bearing.

Rolling elements: Cylindrical rollers in a cage.

Motion: Finite stroke, approximately raceway length minus cage length.

Quantity and configuration

Sold individually, 1 Pc per unit. An LRA-series linear roller bearing is the cage and roller assembly, which runs between two hardened, ground raceway plates — THK’s LR-series rails, a separate part number. Finite-stroke roller bearings are normally used in opposed pairs or sets of four, since a slide needs raceways above and below, or on both sides, to be constrained. Contact us to confirm the exact packet contents against a specific requirement.

Interchange guidance

Search forms include LRA2565Z, LRA-2565-Z, LRA 2565 Z, LRA2565, LRA-2565, THK LRA2565Z. Related THK linear-motion families: the LR-series raceway plates these run on, and the RA / VR cross-roller and flat-roller ranges. Equivalent finite-stroke roller bearings from other makers — IKO’s CF and TC crossed-roller ranges, Schneeberger’s NK and RNG series, INA’s LFR and cross-roller ranges — exist at similar sizes but are different parts dimensionally: cage pitch, roller diameter and raceway geometry are all proprietary, so the cage and the raceway must come from the same manufacturer and series.