D and D-AM Automatic Valve

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Chalwyn D Valve


The Chalwyn D and D-AM automatic valves are self-contained with flow actuated overspeed shutdown. They require no external electrical or mechanical input devices. The closing force is provided by the intake air flow passing through the valve. The valve closes automatically when the engine speed exceeds a pre-set point. The valve automatically resets open soon after the engine has stopped, so the engine is ready for re-starting.

The Model D is the basic version of the automatic valve. The D-AM is the automatic valve with a manually operated pull “T” handle cable stop. The cable is available in lengths of 1.0, 1.5, 2.0, and 3.0 meters. 

The valves are available in 3 size ranges and are selected by combination of the engine power at its rated speed and the air intake line bore size.

D Valve Range

Engine Power

Air Intake Hose Size





Mini (Mini-Bendix)



25 - 58

1 - 2¼

Standard (Bendix)



40 - 108

19/16  - 

Large (Spindle)

80 – 600

107 - 805

76 - 229

3 - 9

Features and Benefits

  • Easy to install
  • No external power source or speed signal required
  • Air flow actuated
  • Automatic reset after engine stops
  • Option for remote pull "T" handle close
  • Trip setpoint calibrated on engine