There are two sounds emmitted from two different locomotives, in which I think are pretty darn cool and make IMHO those units prett darn cool. The sounds maybe made by other units, but I will always associate the sounds with the units in particular. OK; the sounds:
GP7
There is a certain “whirr” sound I hear. You can hear it when the prime mover revs up almost in sync. Then the prime mover noise subsides and you can distinctively hear this sound whirr “down” Is this the generator or prime mover?
DASH 9
The only way I can describe this sound is by a “whoop” DASH 9’s seem to do it when ever. the last time I heard this was with a DASH 9 on the point of a 4 engine loco, going through a yard at about 20MPH. Any clues?
The Dash 9 “whoop” is the motor driven air compressor motor starting up - usually followed by the sound of the air compressor pounding away - “da-da-da-da-da…”
if your certain its a GP7 my guess would be the noise is the beating exhaust of a non-turbo 567 series…no better sound in the world other then a Pere Marquette Berkshire westbound outa Plymouth from a dead stop…
I think it might be both. Just used one (WSOR 702) for switching last night. You can definitely hear the main gen whirring. 702 has a four-stack manifold, so it is a little louder. Switch mode works as well, very nice.
Unless I am sadly mistaken, he is referring to the very distinctive sound of the Roots blowers on the ‘non-turbo’ 567. The idle of these locomotives is among the most pleasant sounds I know.
For the record, these blowers aren’t ‘superchargers’ in the sense a turbo is. These are two-stroke engines, and the crankcase itself is pressurized (by the pair of Roots blowers) to provide the scavenge air at sufficient volume in the (comparatively short) time the scavenge ports are exposed at the bottom and the four exhaust valves are open.
These function exactly the same as a supercharger, a turbo-supercharger is mearly an exhaust gas driven supercharger. The blowers do not pressurize the crankcase but the airbox which is a seperate piece from the crankcase on an EMD engine. There is a device that measures crankcase pressure on most any medium and slow speed engine. Anytime the crankcase pressure exceedes 1 inch of water pressure (very very general number, individual builder specs are all fairly close to this) they will trigger an alarm and kill the engine or warn the operator.
Personally, I love the GE Whoop and air compressor sound. Only thing I like about them really. And I haven’t heard enough 567s to really hear the whir. Does the 645E in the GP38 sound similar? Does the sound change when the 567 is upgraded with the 645 parts? I always associate the popping Air valves with EMD 2nd gen units. chit chit chit chit chit chit. And the whine of the engines. And of course the gentle chugging sound of an Alco.
I know exactly what you are referring to as the “whirr” sound of the GP7. I would call it a whine sound. I don’t know exactly what is making that sound, but it does not sound like the exhaust sound of the engine. You can hear it as the throttle is opened several notches, and especially when the engine slows down after a full throttle is closed. It is almost a musical note as if it were being played on an organ or music synthesizer. And, as a musical chord, the sound is a distinctly minor sounding chord.
You can hear that whine sound with this GP9 at about 1.00 minutes, and again when he throttles down about 1.30 minutes.
I know what you mean. My guess is the gear drive train for the blowers. Might be more discernible compared to a GP38 because there isn’t the gear driven traction motor blower on a GP7. But, I really don’t know.
That is the GERL (GE railfan locator). Patent pending, it is linked with the GPS system. The Whoo-oop sound is the transmission being sent to the company’s headquarters reporting your suspicious activity and location. The RRs appreciate it if you stay at that location and wait for authorities to arrive.
