Air Governor Question

[paul102a3]

I am trying to get a better understanding of the air governor. I think I understand the basic operation but am confused on several points.

Am I correct in thinking there is no pressure to the unloader port until the piston inside overcomes the spring pressure or does the unloader port see the same pressure as the inlet until the piston moves?

Is the purpose of the exhaust port to relieve the pressure in the unloader valve itself?

Thanks for any clarification,

Paul

[bevans6]

Your first thought is correct.  Air comes into the governor through the reservoir port (bottom port if you consider the adjusting spring end as the top).  When the reservoir port pressure reaches the cut-out set pressure the piston moves and reservoir pressure is applied to the unloader ports.  The unloader ports are connected to the compressor unloader and to the air dryer purge valve if there is an air dryer.  Once the reservoir port pressure drops to the cut-in point the piston moves back down and the pressure in the unloader port is vented out via the exhaust port.  This is a great description of how it all works.  http://beamalarm.com/Documents/haldex_d2_governor_service_data.html

Brian

[paul102a3]

Brian,

Thanks for the confirmation. I appreciate it.

Paul