Four-row recirculating ball bearing linear guide unit SSR series

25 mm30 mm35 mm

Overview
Compact radial-type LM guide designed for horizontal guide units. Balls contact the raceway at 90° in the radial direction, providing high planar running accuracy and suitability for large radial loads. Available sizes: 15, 20, 25, 30, 35. Manufacturer: THK.

Types / Models

• Models SSR-XW / SSR-XWM — Bolts mounted from above. Basic dynamic load rating (kN): 14.7 to 64.6. Basic static load rating (kN): 16.5 to 71.6.
• Models SSR-XV / SSR-XVM — Bolts mounted from above; short block (LM Guide). Basic dynamic load rating (kN): 9.1 to 48.3. Basic static load rating (kN): 9.7 to 46.7.
• Model SSR-XTB — Flange; bolts mounted from below. Basic dynamic load rating (kN): 14.7 to 64.6. Basic static load rating (kN): 16.5 to 71.6.
• Model SSR-XSB — Flange; bolts mounted from below; short block (LM Guide). Basic dynamic load rating (kN): 9.1 to 48.3. Basic static load rating (kN): 9.7 to 46.7.

Structure and Features
Balls circulate in four rows of precision-ground raceways on the LM rail and LM block, guided by ball cages and end plates integrated in the block. The cage reduces ball-to-ball friction and increases grease retention.

• Compact, Radial Type — Low cross-sectional height and ball contact suited to large radial loads; optimal for horizontal guide units.
• Superb Planar Running Accuracy — Radial contact structure minimizes radial displacement under load for stable, accurate linear motion.
• Self-Adjustment Capability — Front-to-front configuration of circular-arc grooves (DF set) absorbs mounting errors even under preload for smooth, precise motion.
• Stainless Steel Option — Models with LM block, LM rail, and balls in stainless steel (‘M’ suffix) available for improved corrosion/environmental resistance.

Dimensional notes / Key dimensional data (unit: mm)
LM rail standard lengths (selected values per model):
SSR 15X | 160, 220, 280, 340, 400, 460, 520, 580, 640, 700, 760, 820, 940, 1000, 1060, 1120, 1180, 1240, 1300, 1360, 1420, 1480, 1540
SSR 20X | 220, 280, 340, 400, 460, 520, 580, 640, 700, 760, 820, 940, 1000, 1060, 1120, 1180, 1240, 1300, 1360, 1420, 1480, 1540, 1600, 1660, 1720, 1780, 1840, 1900, 1960, 2020, 2080, 2140
SSR 25X | 220, 280, 340, 400, 460, 520, 580, 640, 700, 760, 820, 940, 1000, 1060, 1120, 1240, 1300, 1360, 1420, 1480, 1540, 1600, 1660, 1720, 1780, 1840, 1900, 1960, 2020, 2080, 2140, 2200, 2260, 2320, 2380, 2440
SSR 30X / 35X | 280, 360, 440, 520, 600, 680, 760, 840, 920, 1000, 1080, 1160, 1240, 1320, 1400, 1480, 1640, 1720, 1800, 1880, 1960, 2040, 2120, 2200, 2280, 2360, 2440, 2520, 2600, 2680, 2760, 2840, 2920

Standard pitch F: SSR 15/20/25 = 60; SSR 30/35 = 80
G, g dimensions: 20 (for SSR 15–35)
Standard maximum rail length: 3000 mm (varies with accuracy grade; stainless models may have different maxima)

Rail mounting hole dimensions (summary)
Model | Standard rail | Semi-standard rail
SSR 15 | For M4 (symbol Y) | For M3 (no symbol)
SSR 25 | For M6 (symbol Y) | For M5 (no symbol)

Tapped-hole LM rail (notes)

• A tapped-hole LM rail is available only for High Accuracy or lower grades.
• Select bolt length to leave clearance at the bolt tip relative to effective tap depth.
• Standard pitches for taps correspond to the LM rail standard lengths above.

Additional notes

• Balls are circulated by ball cages and end plates; the cage eliminates ball-to-ball friction and increases grease retention.
• ‘M’ in the model number indicates stainless steel LM block, LM rail, and balls for improved corrosion resistance.
• Maximum rail length and other dimensional limits vary with accuracy grade; special lengths or joined rails may be possible but affect stability and accuracy.

Specifications / Technical data

• Product family / Series: SSR (Radial Type LM Guide)
• Manufacturer / Brand: THK
• Nominal sizes available: 15, 20, 25, 30, 35
• Recirculation/rolling elements: Balls in four rows with ball cages and end plates
• Contact type: Balls contact raceway at 90° in radial direction (radial-load optimized)
• Load ratings (examples): SSR-XW / XTB: Basic dynamic 14.7–64.6 kN, basic static 16.5–71.6 kN; SSR-XV / XSB: Basic dynamic 9.1–48.3 kN, basic static 9.7–46.7 kN
• LM rail standard pitch F: 60 mm (SSR15/20/25), 80 mm (SSR30/35)
• G, g dimensions: 20
• Standard maximum LM rail length: 3,000 mm (varies with accuracy grade)
• Options: Flange types, tapped-hole rails, contamination protection accessories, seals/lubricant options, stainless steel models