THKHSR25CA1SSLM Guide Carriage Block, Size 25 for 23 mm Rail, 36 mm Height, Four-Row 45° Ball Contact, C 27.6 kN, GK Interchangeable Series, Block Only

Product Description

What this part is

This is a THK LM Guide carriage block, model HSR25CA — a four-way equal-load linear bearing block running on a 23 mm wide HSR size-25 LM rail. HSR is THK’s flagship full-ball linear guide series: four rows of balls at a 45° contact angle, giving equal load capacity downward, upward and to both sides.

Block only

This is the block on its own, with no LM rail. THK marks standard LM Guide blocks and rails with matching serial numbers and states that “an LM rail and LM blocks used in combination must have the same serial number,” because preload and running parallelism are set as a pair.

This part carries the (GK) designation. THK’s GK series exists specifically so blocks and rails can be bought separately — in THK’s words, the GK series “features a lineup of interchangeable LM blocks and LM rails that can be combined freely as long as they have the same model number.” Any HSR25 GK rail of matching accuracy and preload grade makes a correct assembly.

Decoding the designation

HSR: four-way equal-load full-ball LM Guide series.

25: size, corresponding to a 23 mm wide rail.

CA: block type, flanged, tapped mounting holes, mountable from top or bottom.

1: THK’s coding field for the number of LM blocks used on the same rail, not a pack quantity.

SS: end seal plus side seal. DD is double seal, UU is end seals only.

GK: the interchangeable block-only / rail-only series.

Published dimensions and ratings

Assembly height M: 36 mm.

Block width W: 70 mm.

Block length L, with UU or SS seals: 83.1 mm. Block body L1: 59.5 mm.

Block mounting hole pattern B x C: 57 x 45 mm; taps 6 x M8.

Mating rail width W1: 23 mm (±0.05). Rail height M1: 22 mm.

Rail hole pitch F: 60 mm; hole d1 x d2 x h: 7 x 11 x 9 mm.

Basic dynamic load rating C: 27.6 kN.

Basic static load rating C0: 36.4 kN.

Static permissible moment MA: 0.324 kN·m (one block) / 1.8 kN·m (two blocks).

Static permissible moment MB: 0.324 kN·m (one block) / 1.8 kN·m (two blocks).

Static permissible moment MC: 0.366 kN·m (one block).

Rolling elements: four rows of balls, 45° contact angle, full complement with retainer plates.

Block mass: 0.59 kg. Rail mass: 3.3 kg/m.

Grease nipple: B-M6F. Maximum rail length: 3000 mm.

Accuracy grades available: Normal, H, P, SP, UP. Preload grades: Normal, C1, C0.

The 45° contact angle

The four-row 45° geometry is the reason to choose HSR over a two-row guide. With the contact lines at 45°, capacity is identical in all four radial directions and moment stiffness is symmetrical, so wall, inverted and vertical rail mounting carry no derating, and a single block resists roll, pitch and yaw.

The trade is friction and speed. A full-complement ball guide has balls contacting each other in the circulation path, which runs warmer and noisier at high speed than a caged-ball design. Caged-ball series are smoother for fast light duty; HSR is the family for heavy, shock-loaded, orientation-agnostic duty.

Reading the moment figures

MA and MB are quoted for one block and for two blocks on the same rail, and the two-block value is roughly five times the single-block value rather than double. Two blocks spaced along a rail react a moment as a couple between them, so capacity scales with their spacing. A single-block axis is sized on the one-block column.

Interchange guidance

Cross-references: HSR25CA1SS, HSR25CA1SS(GK), HSR-25-CA1-SS, HSR25CA1UU, HSR25CA, HSR 25 CA, HSR25-CA1-SS-GK. Related block types in the same size: HSR25A, HSR25B, HSR25C, HSR25R. Adjacent sizes: HSR20CA, HSR30CA.