The FK series is the standard rigid flange-coupling arrangement for joining two shaft ends. Its split at the flange joint allows the individual flange halves to be mounted on their shafts before the final bolted connection is made. The arrangement is intended for heavily loaded drives where a compact frictional shaft connection and practical service separation are required.
Connection principle and load path
TAS Schäfer rigid flange couplings connect shaft ends through backlash-free frictional shaft-hub connections. Each shrink disc supplies the radial clamping force that presses a flange hub onto its shaft. Torque passes through the shaft-to-flange friction interface and the bolted flange connection; the shrink disc itself is outside that load path. The flange connection can be separated directly at the mating faces, which supports assembly and maintenance of the drive.
Configuration and identification
| Configuration item | Details |
|---|---|
| Series | FK |
| Complete arrangement | Two flange halves and two shrink discs |
| Function | Rigid connection of two shaft ends |
| Service separation | Directly at the flange joint |
| Clamping element | Three-part shrink-disc construction in the standard catalog design |
| Catalog designation example | TAS FK-090/085/095 |
Assembly and connection principle
Slide each flange half onto its respective shaft end and position it as required. Clamp the shrink discs in accordance with their own installation instructions, then bolt the flange halves together. The catalog notes that the cylindrical clearance fit permits precise positioning and that the clamping process does not produce an axial shift of the flange on the shaft. Assembly does not require the hub to be expanded by heating or by hydraulic pressure in this standard mechanical arrangement.
Published product-group range
| Characteristic | Published flange-coupling product-group information |
|---|---|
| Transmittable torque | 830–2,742,000 Nm across the product group |
| Nominal diameter | 38–500 mm across the product group |
| Load duties | Torque and dynamic loads; assess axial force and bending where present |
| Connection | Rigid, backlash-free frictional shaft-hub connection |
| Special options | Application-specific designs and corrosion protection |
| Range interpretation | Confirm the actual series, size and configuration rating |
The published group range covers several sizes and constructions. It does not mean that every nominal size or special configuration achieves the maximum listed torque. Brake-disc options, half couplings, different shaft diameters and adapted hubs require the values for their exact assembly.
Standard FK/FKB catalog dimensions and ratings
The table below reproduces the standard FK/FKB catalog entries for nominal sizes 75–500. Its torque and dimensions refer to the listed combination of shaft diameter and shrink disc; they are not universal ratings for different bores, brake discs or special flange arrangements. The separate product-group range is broader than this table. Footnote 1: the shrink disc for the FK 200 entry is type 3071.4.
| FK nominal size | d_w (mm) | M_t,max (Nm) | Shrink disc 3071-d | Shrink-disc M_A (Nm) | A (mm) | D (mm) | D_z (mm) | L (mm) | a (mm) | b (mm) | z (mm) | Flange bolts Z | Flange bolt S | Flange bolt M_A (Nm) | I (kgm²) | Weight (kg) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 75 | 75 | 7300 | 100 | 30 | 210 | 240 | 170 | 136 | 44 | 44 | 4 | 6 | M16 x 70 | 210 | 0.165499 | 26 |
| 90 | 90 | 13100 | 125 | 59 | 265 | 305 | 215 | 160 | 54 | 48 | 5 | 6 | M20 x 80 | 420 | 0.487699 | 48 |
| 100 | 100 | 17900 | 140 | 100 | 286 | 340 | 230 | 190 | 64 | 56 | 5 | 5 | M24 x 90 | 720 | 0.829143 | 63 |
| 120 | 120 | 38700 | 165 | 250 | 356 | 400 | 300 | 228 | 75 | 72 | 5 | 8 | M24 x 110 | 720 | 2.126131 | 120 |
| 130 | 130 | 42600 | 175 | 250 | 356 | 400 | 300 | 228 | 75 | 72 | 5 | 8 | M24 x 110 | 720 | 2.246611 | 120 |
| 150 | 150 | 79500 | 195 | 250 | 420 | 475 | 350 | 278 | 90 | 90 | 6 | 10 | M30 x 130 | 1450 | 5.408399 | 215 |
| 165 | 165 | 103000 | 220 | 250 | 440 | 510 | 370 | 314 | 108 | 90 | 6 | 14 | M30 x 130 | 1450 | 7.692146 | 270 |
| 180 | 180 | 144000 | 240 | 490 | 475 | 540 | 405 | 322 | 113 | 88 | 6 | 16 | M30 x 130 | 1450 | 10.247474 | 310 |
| 200 | 200 | 193000 | 260¹ | 490 | 500 | 560 | 430 | 368 | 125 | 110 | 8 | 16 | M30 x 150 | 1450 | 14.889123 | 395 |
| 220 | 220 | 251000 | 280 | 490 | 530 | 590 | 460 | 392 | 139 | 104 | 8 | 18 | M30 x 150 | 1450 | 18.392262 | 445 |
| 240 | 240 | 318000 | 300 | 490 | 555 | 615 | 485 | 408 | 147 | 104 | 8 | 20 | M30 x 150 | 1450 | 22.627586 | 500 |
| 260 | 260 | 435000 | 340 | 490 | 640 | 710 | 570 | 450 | 161 | 118 | 8 | 24 | M30 x 160 | 1450 | 45.880687 | 780 |
| 290 | 290 | 519000 | 360 | 490 | 660 | 720 | 590 | 450 | 167 | 106 | 8 | 24 | M30 x 160 | 1450 | 76.717692 | 790 |
| 310 | 310 | 697000 | 390 | 840 | 735 | 805 | 660 | 484 | 180 | 114 | 8 | 28 | M30 x 160 | 1450 | 81.558246 | 1060 |
| 340 | 340 | 891000 | 420 | 840 | 770 | 835 | 690 | 530 | 198 | 122 | 10 | 30 | M30 x 160 | 1450 | 102.444238 | 1230 |
| 380 | 380 | 1198000 | 460 | 840 | 845 | 920 | 770 | 556 | 208 | 128 | 10 | 35 | M30 x 170 | 1450 | 166.038502 | 1420 |
| 410 | 410 | 1431000 | 500 | 1250 | 940 | 1030 | 850 | 618 | 225 | 156 | 12 | 32 | M36 x 200 | 2400 | 283.051874 | 2200 |
| 440 | 440 | 1961000 | 530 | 1250 | 1000 | 1100 | 900 | 696 | 258 | 160 | 14 | 36 | M36 x 200 | 2400 | 382.170457 | 2680 |
| 470 | 470 | 2397000 | 590 | 1250 | 1080 | 1180 | 980 | 744 | 280 | 164 | 14 | 40 | M36 x 200 | 2400 | 553.092493 | 3340 |
| 500 | 500 | 2742000 | 620 | 1250 | 1110 | 1210 | 1020 | 744 | 280 | 164 | 14 | 42 | M36 x 200 | 2400 | 638.288490 | 3620 |
Recommended fits and surface roughness
The catalog recommendations below are a general calculation basis. Increased clearance and roughness can reduce transmittable torque and increase hub stresses. Confirm the bore and shaft fit for the selected nominal size; the wider fit table is not an extension of the standard coupling-size table.
| Shaft diameter > (mm) | Shaft diameter ≤ (mm) | F_S,max (mm) | Hub / shaft fit | Rz (µm) |
|---|---|---|---|---|
| 9 | 18 | 0.022 | H6/h6 | 10 |
| 18 | 30 | 0.026 | H6/h6 | 10 |
| 30 | 50 | 0.032 | H6/h6 | 10 |
| 50 | 80 | 0.049 | H7/h6 | 16 |
| 80 | 120 | 0.057 | H7/h6 | 16 |
| 120 | 150 | 0.065 | H7/h6 | 16 |
| 150 | 180 | 0.079 | H7/g6 | 16 |
| 180 | 250 | 0.090 | H7/g6 | 16 |
| 250 | 315 | 0.101 | H7/g6 | 16 |
| 315 | 400 | 0.111 | H7/g6 | 16 |
| 400 | 500 | 0.123 | H7/g6 | 25 |
| 500 | 630 | 0.136 | H7/g6 | 25 |
| 630 | 800 | 0.154 | H7/g6 | 25 |
| 800 | 1000 | 0.172 | H7/g6 | 25 |
Drawing and torque terminology
| Symbol | Meaning |
|---|---|
| d_w1 / d_w2 | Shaft diameters at flange sides 1 and 2 |
| M_t,max | Maximum transmittable torque for the specified connection |
| A / D / D_z | Pitch-circle diameter / outer diameter / flange-centering diameter |
| L / a / b / z | Coupling width / shrink-disc width / flange thickness / centering depth |
| Z / S / M_A | Bolt quantity / bolt size / required tightening torque |
| I | Mass moment of inertia |
The tightening values for the shrink-disc screws and for the flange bolts belong to separate fastener groups. Use the actual size-specific value for each. Mass moment of inertia I is expressed in kgm², while weight is listed in kg; these are different selection parameters.
Surface preparation and assembly
Keep the shaft-to-hub contact surfaces and the mating flange faces clean, dry and free of grease. This differs from the functional surfaces of the shrink disc, its screw threads and under-head bearing surfaces, which require the specified lubricant. The flange-hub-to-shrink-disc contact surfaces are oiled as described in the installation documentation. Mixing these surface-preparation requirements can change the intended friction conditions.
Combined loads and operating conditions
Check the shrink connection and the flange bolting separately. Torque, bending moment and axial force may act together at the shaft-hub interface, while the flange bolts and flange body must also be assessed for their actual load. A static torque check alone does not cover cyclic bending or other dynamic duties. Provide the load spectrum and operating speed so the complete assembly can be evaluated.
Configuration and ordering example
The catalog example TAS FK-090/085/095 identifies nominal coupling size 090 with shaft diameters of 85 mm and 95 mm. This demonstrates that the complete ordering designation must include both shaft diameters. The dimensions and ratings for a different bore combination require the corresponding assessment rather than direct substitution of a standard table row.
Application information
Listed application areas include marine drives, wind-power equipment, conveying systems, mixing and process machinery, hydropower, crushing plants and elevators. The appropriate configuration depends on the machine interface and operating duty. Special corrosion protection and individual designs can be specified, and hydraulic shrink-disc arrangements are also available as a separately defined configuration.
Selection and ordering
Specify the complete coupling type, nominal size, both shaft diameters, shaft tolerances, material properties, speed, torque and any axial or bending loads. Include available space, tool access, assembly sequence, surface protection and maintenance requirements. Confirm the type-specific drawing and the required screw tightening values before finalizing the selection.