Locomotive air dryers

D.Carleton wrote:With the air problems Amtrak has been having getting across the Northern Plains the question has arisen concerning air dryers. What type of air dryers are installed in Amtrak's P42 fleet? Is there one type or brand of dryer common to Amtrak or any specific railroad? Thank you in advance.

Air dryer?? what's that? please explain about them. thanks.

Anytime you compress air you get condensation, air dryer pulls the water out before it puts it to the train.

Does the air tank/dryer have to be manually drained of water like some trucks?

crash575 wrote:Does the air tank/dryer have to be manually drained of water like some trucks?

Air dryers have a timed cycle that emits a purge blast of air to eject the collected water. Newer diesel truck have them too...

Thats the spitting sound you hear from idling (and moving) locomotives.

Notice it in this video (not sure if this is the "air dryer, but it is spitting condensation from the line)

Or this video @2:13 (I'm thinking this is what it's referring to)

In the video of the CSX B36-7 the air dryer is the cylindrical appurtenance seen between the fuel tank and the forward truck. It is a mechanism with twin 'towers' filled with a moisture adsorbent called desiccant. Normally one tower is in service with air flow from the air compressor to the air reservoirs. The other tower is will be in "purge" with a small amount of dry air flow purging the moisture. Depending on design either a timer or a moisture sensor swaps the towers.

These are two of the more popular makes of locomotive air dryers:
http://techinfo.wabtec.com/DataFiles/O& ... 21,S.3.pdf
http://www.grahamwhite.com/main/product ... 1=43&P2=-1

The 'spitting' sounds are separate valves on the air reservoirs. At a low point on the reservoirs are the spitter valves which periodically blow down any accumulated moisture.