GBC-SCS25 Aluminum Clamp Type Shaft Collar – 25mm Bore
The GBC-SCS25 aluminum clamp-type shaft collar fits the internationally standardised 25 mm bore shaft diameter. OD 45 mm, face width 12 mm, M5 screw, 8 mm DIN keyway option. The definitive collar for helical gearbox outputs, belt conveyor head pulleys, and agricultural PTO-driven shaft assemblies worldwide.
MOQ: 50 pcs. Minimum order value USD 1,500; mixed orders and trial quantities welcome.
25mm Bore Aluminum Clamp Shaft Collar with 8mm Keyway – International Standard for Gearbox & Drive Coupling Shafts
| Parameter | Value | Note |
|---|---|---|
| SKU / Model | GBC-SCS25 | GBC SCS Series |
| Bore Diameter (d) | 25 mm | Nominal; shaft h6 tolerance recommended |
| Outer Diameter (D) | 45 mm | |
| Face Width (B) | 12 mm | Extended width for higher axial bearing area |
| Clamping Screw | M5 socket-head cap screw | 5 mm hex key required |
| Slot Width (W) | 1.5 mm | Radial flex gap for clamping action |
| Keyway Width (K) | 8 mm | DIN 6885 Form A; plain bore is default |
| Shaft Fit (ISO h6) | 25.000 / 24.987 mm | Sliding fit before clamping |
| Material | Aluminium alloy | Hard-anodize & electroless nickel available |
| MOQ | 100 pcs | Custom engineering drawings accepted |
Product Overview
Twenty-five millimetres is the single most internationally standardised shaft diameter across the entire spectrum of power transmission components — it is the reference bore for ISO and DIN coupling series, the most common output journal on helical and bevel-helical inline gearboxes from 0.37 kW to 2.2 kW, and the standard shaft size for belt-conveyor head pulleys in the 500 mm belt-width class. The GBC-SCS25 is engineered to match this breadth of application. Its 45 mm OD maintains a compact radial envelope that clears most standard coupling flanges and bearing housings, while the 12 mm face width delivers adequate axial bearing area for the continuous thrust loads generated in conveyor and pump drives. The 8 mm keyway — the widest in the SCS series up to this size — is consistent with DIN 6885 for 25 mm bore and enables direct bolt-free torque coupling to sprockets, pulleys, and cam discs without secondary fasteners.
Key Features
Zero Shaft Surface Damage
The split-clamp design wraps clamping force uniformly around the shaft circumference, eliminating the localised indentation and fretting fatigue caused by set-screw contact. This is particularly valuable on ground or hard-chrome shaft surfaces where any surface damage accelerates seal and bearing wear adjacent to the collar.
M5 High-Capacity Clamping
The M5 socket-head cap screw is the correct choice for bore diameters in the 25 mm range, delivering clamping torque capacity and proof load matched to the wall section and surface area of the 45 mm OD collar body for reliable retention under the heavy-duty axial loads at this shaft size.
12 mm Extended Face Width
The 12 mm face width provides a wider axial contact band on the shaft than smaller SCS collars. This distributes the axial reaction force over a greater shaft surface area, reducing contact pressure and enabling the collar to hold higher sustained axial loads without risk of bore deformation under long-term service.
Field-Adjustable Axial Positioning
Collar position can be changed during commissioning or maintenance using only a 5 mm hex key — no shaft removal, no bearing housing disassembly, no machining. This makes SCS collars significantly faster to reconfigure than machined shaft steps or welded thrust collars.
8 mm DIN Keyway — Torque Locking Option
The 8 mm keyway follows DIN 6885 Form A for 25 mm bore, enabling simultaneous axial location and rotational torque transmission. Default supply is plain bore — specify keyway at time of order.
Typical Application Scenarios
Helical Gearbox Output Shaft Location
Inline helical gearboxes with 25 mm output shafts are the workhorse of conveyor drives, agitator drives, and pump drives across food, beverage, and logistics facilities. The SCS25 positions the driven coupling half against the gearbox flange bearing, prevents coupling walk under sustained axial misalignment forces, and allows the coupling hub to be repositioned without shaft disassembly when drive ratios change.
Belt Conveyor Head Pulley Shafts
Head-pulley shafts in 500 mm and 650 mm belt-width conveyors terminate at 25 mm journals in pillow-block bearings. The SCS25 provides the axial shaft location that prevents the pulley from walking under the lateral belt-tension component, which is amplified by any belt-tracking misalignment during commissioning.
Agricultural Machinery PTO-Driven Shafts
Compact baler feeder rolls, round-baler pickup shafts, and forage-harvester cross-auger drives frequently output through 25 mm shafts. The SCS25 with keyway locks feed rollers and auger flights at their design pitch positions, maintaining consistent crop-feed rates across the variable-load cycles of field harvesting operations.
Dimensional Guide & Shaft Fit Specification
The GBC-SCS25 is defined by bore d = 25 mm, outer diameter D = 45 mm, and face width B = 12 mm. The slot width W = 1.5 mm runs the full face width, providing the radial flex gap that closes as the M5 screw is tightened. Specify the mating shaft to ISO 286 h6 (25.000 / 24.987 mm) for a sliding pre-installation fit and maximum post-clamping retention. Tighter shaft tolerances such as g6 will reduce retention force; looser tolerances such as h8 should be avoided for duty cycles involving sustained axial loads.
GBC accepts custom specifications including extended face widths up to 25 mm, reduced OD profiles for confined housing installations, twin-screw clamping configurations for maximum holding force, and specialised surface treatments for corrosive or food-contact environments. Submit your engineering drawing via the GBC contact page for a fast quotation.
Model Selection Guide
For 22 mm shafts in machine-tool auxiliary and cam-drive applications, the GBC-SCS22 provides the same 45 mm OD at a 6 mm keyway. Stepping up to 30 mm bore — where the M6 screw and 55 mm OD together handle significantly higher axial loads — the GBC-SCS30 is the appropriate choice for agricultural and heavy conveyor applications.
| Model | Bore | Relation |
|---|---|---|
| GBC-SCS22 | 22mm | ← Smaller |
| GBC-SCS25 | 25 mm | ◀ Current |
| GBC-SCS30 | 30mm | → Larger |
Installation Procedure
- Shaft preparation: Measure the shaft diameter with a calibrated micrometer to confirm it falls within h6 tolerance (25.000 / 24.987 mm). Degrease the clamping zone and remove burrs with a flat file.
- Collar placement: Slide the GBC-SCS25 onto the shaft to the required axial position. For heavy assemblies, use a mallet and a soft brass drift to move the collar if shaft features resist free sliding.
- Progressive clamping: Insert a full-length 5 mm hex key and tighten in three incremental steps — 30%, 60%, then full torque — checking position after each step. Torque M5 screw to 4.5 N·m. For conveyor head-pulley applications, check belt-tracking alignment with the collar in place before final tightening. Adjust collar position laterally by no more than 1 mm between sides to correct minor belt tracking without realigning the entire conveyor frame.
- Operational verification: After initial operation under load, re-check screw torque. For high-vibration environments, apply medium-strength threadlocker before final tightening and mark the screw head for visual drift detection during inspections.
Frequently Asked Questions
Why is 25mm the most common shaft size for coupling specifications?
What keyway size does the SCS25 use, and how do I select the correct key?
Can two SCS25 collars be used to replace a machined locating shoulder on a conveyor head-pulley shaft?
Related Products
Browse adjacent sizes and related drive components in the GBC SCS series:
- GBC-SCS22 – 22mm bore aluminum clamp shaft collar — smaller bore for lower shaft diameter requirements
- GBC-SCS30 – 30mm bore aluminum clamp shaft collar — next larger size with higher axial load capacity
- Full GBC SCS Shaft Collar Range — bore sizes 6 mm to 60 mm, all available with custom specifications
Request a Quote or Submit a Custom Drawing
Minimum order quantity is 100 pcs. GBC supplies custom bore tolerances, keyway options, extended face widths, twin-screw configurations, and corrosion-resistant surface treatments. Provide your engineering drawing for an accurate quotation.
The GBC-SCS25 aluminum clamp-type shaft collar fits the internationally standardised 25 mm bore shaft diameter. OD 45 mm, face width 12 mm, M5 screw, 8 mm DIN keyway option. The definitive collar for helical gearbox outputs, belt conveyor head pulleys, and agricultural PTO-driven shaft assemblies worldwide.
MOQ: 50 pcs. Minimum order value USD 1,500; mixed orders and trial quantities welcome.
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