Ok, this is driving me crazy…what IS the noise coming from diesel locomotives that sounds like an electronic spitting noise (for lack of a better description)? Is it compressed air being released to avoid overloading the brake lines? Is it something electrical? The noise seems to happen regardless if the engine is sitting, idling or hauling freight. Sometimes I hear it even if the engine is off.
Thanks
Locomotives have automatic, mechanical drain valves that spit out the condensed water from the compressed air system. They are located near the main reservoirs. They make a sort of ticking sound. The frequency of operation of these valves can vary up to a couple times a second. Do you think that’s what you’re hearing
Conrail used them. NS did not. It’s one way of recognizing an ex-Con unit. I’m not sure about other railroads.
electronic spitting noise !
What, you never heard an electronic spitting noise before??? [;)]
My point was that the electronic spitting noise is just that … electronic spitting noise … Actually they are not electronic all (the spitter valves) there are electric blowdowns that operate either off a timer or of the CRL (compressor relay) they usually cycle each time the aircompressor starts or stops, but these are distunguished by one long blast of air rather that several (hundred) little blasts of air. Sometimes you will see wires going into the spitter valves but most of the time these are little heaters to prevent the things from freezing up . Then there are airdryers of the salem, grahm white type that make different noises altogether.
I haven’t seen a robot camel yet.[;)]
I am not completely certain about the locomotive application, but the principles are the same as in automotive use; The ‘Spitter Valve’ [slang] is a diaphragm valve, in which the moisture is evacuated from the air system. The moisture from the heated air (compressed air) is cooled in the air resevoir and runs down to the lowest point in the tank; generally, the location of the spitter valve, where it builds up in the chamber of the diaphragm and that weight causes activation of the valve and the condensation is blasted out by the release of the air by the action of the diaphragm valve. Many of these valves carry an electrical connection to a heater element to prevent the moisture from freezing and blocking the release of the condensation. This valve gained popularity in trucking by removing the ‘human factor’, having the driver crawl under the truck and twist open the valve to manually drain the condensate, a messy, and highly unpopular task among big riggers, but a very necessary duty to maintain a dry air supply, particularly in colder climates…