OSK – Original Schlegel Clamping System

The "OSK“ system is unlike any other available clamping system. It has been designed for screw terminals with wire-protection bracket, and due to its special construction it provides the so-called "six securities", including reliable wire insertion, security against tilting of the clamp and increased security against wire loosening. The underlying functional principle: The conductors are pressed to the bottom of the conductive clamping body by means of a clamping screw that leads through the wire-protection bracket.


1. Secure Wire Insertion due to:

  1. guiding walls next to wire insertion opening of the metal body
  2. reliable opening of the clamp when loosening the screws (because wire protection bracket snap-fits below screw head)  and
  3. limitation of clamping space by the lower part of the wire protection bracket, thus no slipping of single wires or strands.

2. Security against screw loosening under vibration by the resilient wire protection bracket that presses against the screw head (this makes the screws captive).

3. Direct clamping pressure transmission to the wire at full bearing of the screw and protection of the wire (no damaging or piercing by the screw).

4. High Tightening Torque
The Schlegel terminals have rolled screws which, contrary to turned screws, feature a high-compressed structure with unbroken fibres in the thread area. The very high mechanical strength properties are achieved by thread rolling and assure high tightening torques.

5. Security against tilting of the clamp (the solid metal clamping body prevents the connection "cages" from tilting when using thin wires).

6. Security against wire loosening thanks to the resilient wire protection bracket and elastic deformation properties of the clamping body.