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Brand: KTR
KTR CLAMPEX KTR 603 External Clamping Set
Description
Three-part external clamping set for keyless shaft-hub joints
The KTR CLAMPEX KTR 603 is an external clamping set, also called a shrink disk, for connecting hubs to cylindrical shafts without a keyway. It is also used on hollow shafts. Tightening the clamping screws pushes the conical rings against each other so that the inner ring contracts onto the shaft and the outer ring expands against the hub bore. The result is a friction-locked connection that transmits torque and axial force and has no backlash, no fretting at a keyway and no weakening of the shaft by a slot. KTR gives the transmittable range of the product family on its product page as 28 Nm up to 1,460,000 Nm.
The data below is taken from KTR operating and assembly instructions KTR-N 40821 EN for CLAMPEX KTR 603 clamping sets. The document is edition 4 from 2016, and KTR remains the reference for any later revision.
Technical specifications
| Parameter | Specification |
|---|---|
| Manufacturer | KTR Systems GmbH, Rheine, Germany |
| Product type | Three-part external clamping set (shrink disk) for keyless shaft-hub connections |
| Series | CLAMPEX KTR 603 |
| Shaft types | Cylindrical shafts without keyway, and hollow shafts |
| Loads transmitted | Torque and axial force |
| Size range, table 1 | 14 x 38 mm up to 500 x 850 mm (shaft diameter x outer diameter) |
| Weight range | Approximately 0.1 kg up to 575 kg |
| Clamping screws | DIN EN ISO 4014, property class 10.9 |
| Surface pressure | Approximately 190 to 390 N/mm2 |
| Shaft tolerance | H6/j6 for 10 to 30 mm; H6/h6 for 31 to 50 mm; H6/g6 for 51 to 80 mm; H7/g6 for 81 to 500 mm |
| Lubrication | Taper surfaces, threads and contact surfaces with a molybdenum disulphide paste (Molykote) |
| Storage | Keep in dry conditions; the instruction gives a storage period of 6 to 9 months for original packing |
Where a clamping set is used
Clamping sets are common where a hub has to be fixed to a plain shaft without changing the shaft: couplings on gearbox outputs, pulleys, sprockets, gears and brake discs on drive shafts. A keyless joint also makes it easy to adjust the angular position of the hub during commissioning and to release the connection later without damage. For shafts that are machined with high accuracy it gives concentric running and avoids the imbalance of a key. Because it can be released again, it is also useful on machines that are modified or serviced frequently.
Mounting and tightening
The shaft and hub bore must be clean and free from grease before assembly, apart from the lubricant specified for the taper surfaces and screws. The clamping screws are tightened gradually and in sequence, going round several times, until the rated tightening torque is reached for all screws. Skipping the sequence leads to uneven pressure and a shifted hub. To dismantle, the screws are slackened evenly and the rings are released as described in the instruction. The shaft tolerances in the table above must be observed, since the clamping set only works within these limits.
The transmittable torque depends on the shaft diameter, the hub material and wall thickness, and on the set size. Hub strength and the pressure of the clamping set on the hub bore should be verified for the application, particularly with thin-walled hubs or cast iron.
Documents and quotation
The attached PDF is the KTR operating and assembly instruction containing the dimension table for all sizes. For a quotation send the shaft diameter and tolerance, hub outer diameter and material, the torque and axial force to be transmitted and the load type. Related coupling ranges are listed under Electric Motors.
Datasheets & Documents
- Operating Instructions KTR CLAMPEX KTR 603 operating and assembly instructions KTR-N 40821 EN (edition 4, 2016) Download
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About brand
KTR Systems is a German manufacturer of power transmission couplings, brakes and hydraulic components, based in Rheine, Westphalia. It was founded on 30 September 1959 by Franz Tacke, grandson of the founder of the older coupling maker F. Tacke KG, which dated from 1886. KTR's ROTEX jaw coupling, introduced in 1967, became the first brand coupling to be standardised in DIN.
Seven Star LLC is an independent supplier in Muscat. We list KTR coupling ranges with the technical data from the manufacturer operating and assembly instructions, for machine builders and maintenance teams in Oman and the GCC.
KTR company profile
| Founded | 30 September 1959, Rheine, Germany, as Kupplungstechnik GmbH |
|---|---|
| Founder | Franz Tacke |
| Roots | F. Tacke KG, coupling maker in Rheine since 1886 |
| Headquarters | Rheine, Germany |
| Product families | ROTEX jaw couplings, BoWex curved-tooth gear couplings, RADEX-N disc couplings, POLY-NORM couplings, brakes, torque limiters, torque measuring systems, oil coolers and hydraulic bell housings |
Milestones
- 1886: Franz Tacke founds F. Tacke KG in Rheine.
- 1959: Kupplungstechnik GmbH, later KTR, is founded.
- 1967: The ROTEX coupling is introduced.
KTR product series
Flexible couplings include the ROTEX torsionally flexible jaw coupling, the POLY-NORM torsionally flexible coupling, the REVOLEX KX pin and bush coupling for heavy drives, the ROFLEX fail-safe coupling and the MONOLASTIC flexible flange coupling. Torsionally rigid couplings include the BoWex curved-tooth gear coupling and the RIGIFLEX-N steel laminae coupling.
For servo and precision drives there are the ROTEX GS backlash-free jaw coupling, the RADEX-NC servo laminae coupling and the TOOLFLEX metal bellows coupling. The CLAMPEX KTR 603 clamping set provides a keyless shaft-hub connection.
Where KTR couplings are used
Pumps and compressors, fans, gearboxes and conveyors, hydraulic power units, machine tool and servo axes, and heavy drives in steel, mining and cement plants.
KTR products we list
Ordering KTR couplings: what we need
Send the coupling type and size, or the motor power and speed, the shaft diameters and keyways, the torque and shock loads, the shaft displacement expected and the operating temperature. The instructions state rated torque, maximum torque, speed and displacement for each size.
Facts checked against KTR's own history and company profile pages (ktr.com), October 2026.
Browse KTR products by category: Electric Motors, Couplings & Shaft Locking Devices.
FAQ
Questions about the KTR CLAMPEX KTR 603 External Clamping Set
Answers from our engineering team on installation, compatibility and integration.
01What is a CLAMPEX KTR 603 used for?
It connects hubs, couplings, gears or pulleys to smooth cylindrical shafts or hollow shafts without a keyway, using friction.
02Can it transmit axial force as well as torque?
Yes. The instruction states that the clamping set transmits both torque and axial forces.
03Which shaft tolerances are required?
H6/j6 for 10 to 30 mm, H6/h6 for 31 to 50 mm, H6/g6 for 51 to 80 mm and H7/g6 for 81 to 500 mm.
04What size range does the document cover?
Table 1 lists sizes from 14 x 38 mm up to 500 x 850 mm, with weights from about 0.1 kg to 575 kg.
05Which edition of the instruction is attached?
KTR-N 40821 EN, edition 4 from 2016. Newer editions may exist on the KTR website.
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