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Post by domh245 on Apr 26, 2013 18:35:15 GMT
Hi all,
I've been wondering what the large whirring fan noise is in the saloon. It appears to randomly come on and off, especially on hotter days (and thinking about it, mostly around wimbledon!?). I would imagine that this is some sort of saloon cooling, kicking in above certain temperatures. I must admit, I did laugh when a lady said that the noise was the "air conditioning, if that's what you can call it". Everyone knows that the D78s don't have AirCon!
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Post by Deleted on Apr 26, 2013 19:34:06 GMT
They have forced air ventilation fans, don't they?
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Post by Deleted on Apr 26, 2013 20:00:13 GMT
I thought they didn't work because they were wired in backwards?
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Post by Dstock7080 on Apr 28, 2013 22:11:31 GMT
The fresh-air (axil) fans at the far ends of each car were removed upon refurbishment, they brought-in air from outside.
When the opening windows were installed the operation of the fans was changed as new extractor fans were added towards the centre of each car.
The recirculating fans, behind the longitudinal grilles, just used to blow the risen stale/hot air back down again! These were disabled when the windows were installed and removed upon refurbishment.
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Post by Deleted on May 14, 2013 15:29:49 GMT
Hi all, I've been wondering what the large whirring fan noise is in the saloon. It appears to randomly come on and off, especially on hotter days (and thinking about it, mostly around wimbledon!?). I would imagine that this is some sort of saloon cooling, kicking in above certain temperatures. I must admit, I did laugh when a lady said that the noise was the "air conditioning, if that's what you can call it". Everyone knows that the D78s don't have AirCon! I think you're probably referring to the air compressors that compress the air into tanks to operate the pneumatic doors and brakes |
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Post by Deleted on May 14, 2013 15:45:53 GMT
+1 on luke94's point
Probably usually happens around termini as the train probably 'shuts down' when the drivers are changing ends and the compressed air may be lost whilst sitting there.
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Post by domh245 on May 14, 2013 15:53:53 GMT
No, definately not air compressors. Air compressors (at least on the D stock) are rather "thumpy" with a sort of fragmented pulsing noise. The noise I'm talking about is a solid whoosh (and in the DM cars - which don't have air compressors) a little bit similar to the 95TS cooling fans for the IGBT drives which you sometimes hear.
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Post by v52gc on May 14, 2013 21:40:25 GMT
Possibly the Motor Alternaters, but they should always be on. It's what splits the voltage to different circuits (lighting, doors, controls...)
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Post by domh245 on May 14, 2013 22:30:17 GMT
No, definitely not the MA's either. They are a sort of "always on" noise. This noise sort of "spooled up", ran for a bit, and then "spooled down". This then kept on happening. When I next encounter it, I'll try and record it
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Post by Deleted on May 15, 2013 17:12:43 GMT
Could be the cab air conditioning unit?
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Post by domh245 on May 15, 2013 17:15:05 GMT
I'm doubtful that it was. It was clearly above the grilles, and very audible even towards the rear of the DM
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