Safety couplings

The ST4 heavy-duty safety coupling from R+W Couplings features an integral toothed arc coupling and is used for direct drive with torque overload, accommodating both lateral, axial, and angular misalignments. The ST4 coupling has a robust, compact, and simple design, and offers highly precise overload protection. The industrial coupling is torsionally rigid and features an integral heavy-duty bearing for support. The maximum torque of the industrial coupling can also be manually adjusted using an adjusting wrench. This wrench can be ordered separately. For specific inquiries about safety couplings or other industrial couplings, please contact VARIODRIVE.

Torque limiter with toothed coupling and keyway
Limiting torque
200 - 250.000 Nm
tot 4000 rpm
Temperature Range
-30 tot +120 oC
Reinforced nitro-carburized steel
Safety elements
Evenly distributed
no service
ATEX, adjusting wrench, adjusting plate

  • ATEX instructies
  • Uitleg veiligheidssystemen
  • Datasheet ST4
  • Manual ST Koppelingen
ST4 drawing
ST4 Series2510254060100160250
Overall length A12803503904605806507808601060
Fit length / keyway length (mm) C1/2627690105135150190220290
Bore diameter Ø bis Ø F7 (mm) D1/230-7832-9842-11246-13260-17470-190110-233120-280200-340
Bolt circle diameter ST (mm) O154171220270350376490532630
Moment of inertia (approx.) D max. + max. sgmnt (10-3 kgm2) 108244529111743636650206113382084926
Moment of inertia (approx.) D max. + max. sgmnt (10-3kgm2) 2,545651002252935707181280
Distance (mm) L110138159,5202238275318360458
Distance (mm) M148188209,5252306343408450534
Hub diameter (gear coupling) (mm) B4130,5158,4183,4211,5275,5307367423553
Speed max. (rpm) 40003900370035502750242019501730950
Length (mm) E263,578,592,5108139154194225296
Flange outside diameter (gear coupling) (mm) B3168200225265330370438525639
Flange outside diameter (ST portion) (mm) B1198220270318428459592648740
Axial (mm) 1,52,52,5344456
Angular (degree) 2×0,35°2×0,35°2×0,35°2×0,35°2×0,35°2×0,35°2×0,35°2×0,35°2×0,35°
Tightening torque of the fastening screws (mm) F186565150150220400520670
Adjustment range available from - to (KNm) 0,2-0,5 | 3xST10 0,5-1,0 | 6xST10 1,0-1,5 | 6xST100,7-2 | 3xST15 1,2-4 | 6xST15 3,2-6 | 6xST152-5 | 3xST15 4-10 | 6xST15 6-14 | 9xST156-12 | 6xST15 9-18 | 9xST15 15-25 | 12xST1512-21 | 6xST30 22-32 | 6xST30 32-45 | 9xST3011-18 | 3xST30 22-36 | 6xST30 30-55 | 9xST3024-50 | 3xST70 45-90 | 6xST70 80-110 | 9xST7025-55 | 3xST70 50-110 | 6xST70 80-165 | 9xST70100-170 | 8xST71 160-250 | 12xST71
Actuation distance (mm) N3,54,54,54,588101010
Mounting flange outside diameter (ST portion) (mm) B2192209259300399418560618724
Screw (mm) F6xM810xM1212xM1212xM1614xM1614xM1814xM2216xM2422xM24
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Frequently Asked Questions

You can place an order with VARIODRIVE by sending your request to Your request will then be processed directly by our internal sales team.

By choosing VARIODRIVE’s complete solution, you won’t need to worry about integrating different drive components into the machine’s drive chain. We stand behind our complete solution and can guarantee its functionality.

Due to our in-depth knowledge of our products and their integration into applications, we can provide a system warranty. At that point, we guarantee that the application will function using our motion control and traction solutions.

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