Pneumatic Proximity Switch

The Kuhnke pneumatic sensor is often referred to as a pneumatic reed switch. It is a magnetically operated 3/2 valve originally designed to fit to pneumatic cylinders as a position sensor. The underside of the body is moulded for round cylinders 8mm - 100mm diameter.

Connect using 3mm i/d (5x1) tubing. When "on" the blue indicator button pops up.

Senses magnetic pistons or FE (iron). Has many other applications such as end rod sensing, float sensing, general proximity etc etc.

Proximity switch Pneumatic Proximity Switch
Kuhnke part number 33.21.326 (0.499.300) available with mounting strap. Push on tube fittings. Use as cylinder sensor or proximity sensor.

(595Kb)

How do I mount it?

Use a standard Kuhnke strap 33.006(or 1.490.205) for round cylinders 8 - 100mm. For other applications such as tie-rod or profile cylinders use the M4 through body threading as a mounting point.

Air Supply

Oil Free. 5 micron. 2 - 6 bar. Note that 6 bar is the absolute maximum pressure. We recommend system pressures below 5 bar to avoid dangerous pressure surges from step-up effects etc.

Biggest Operating Problems

  • Oil in Air.
  • Overpressurisation. Keep below 5 bar.
  • Clamping of body too tightly (it flexes in & seizes).
  • Unsuitable applications (See installation hints).

Installation Hints

  • The unit is supplied with a small piece of foam plastic packing. Use this when fixing to a cylinder with a diameter of < 16mm.
  • Make sure that there is no other ferous material within 15mm. This includes swarf that might collect in operating conditions.
  • Make sure there is at least 20mm between adjacent switches.
  • This versatile switch can be used in 3 switching directions, x, y & z. So it can be used to sense an outstroked piston rod.
  • It will scan a passing ferous item a speeds upto 1m/s, so it can be used to scan intermediate positions on a moving cylinder.
  • The sensor is designed to sense the magnetic material in the piston ring of a pneumatic cylinder. It is generally suitable for all standard manufacturers cylinders. Occasionally the material used by certain manufacturers may not sufficient to operate the switch. If this is the case then changing you cylinder source is the only solution. If in doubt please ask Kuhnke.
  • To sense the proximity of a piston rod or other product simply ensure that there is ferous material for the sensor to operate.