Remote control locomotive operators. Are they required to whistle (one short) at certain times/places/people when they are working in the yards?
Air for the brakes. Figure there are air tanks on the engine. Figure there is a compressor to operate said air. Where does said air come from to get into tanks?
Grain train. Loaded. Going past slowly. Can you smell the soybeans loaded inside or do I just have a very vivid imagination? (twice!)
She who has no signature! cinscocom-tmw
Not sure on the remote whistles. With radio com nowadays whistles in yards seems to have gone the way of the dino.
Air is all around you. The compressor sucks it in either through the engines air filter or its own filter. There are basically 2 kinds of air compressors. The piston/ reed valve type and a rotary screw type.
I imagine you are smelling the old spilled grain that has been spilled and rotting.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
MookieAir for the brakes. Figure there are air tanks on the engine. Figure there is a compressor to operate said air. Where does said air come fromto get into tanks?
MookieGrain train. Loaded. Going past slowly. Can you smell the soybeans loaded inside or do I just have a very vivid imagination? (twice!)
Dan
R.C.L. operations may require the sounding of a diesel horn in some locations, but it's not a universal requirement.
----------
In most diesel locomotives air from inside the engine room is drawn through a fine mesh filter and piped into the first stage piston compressor. From there it moves to the second stage piston compressor. Lastly the compressed gas is then piped into the main reservoirs. Main reservoir pressure is regulated to fluctuate between 120 and 130 psi., possibly a little higher for Amtrak.
As covered hoppers are filled, sometimes a little grain spills over the sides and gets caught in various crevices. When exposed to the elements the grain rots. That's maybe what you're smelling.
An open top wood chip car typically has dozens of pockets where blown product accumulates. Whether loaded or empty they can smell quite nice. By contrast any car assigned to a cotton seeds pool will have a particularly pungent odor.
Perfect! I now have all 3 of my questions answered.
We have a bridge (Salt Creek) at the throat of the yard and I keep hearing an occasional one short whistle near that bridge. Today there was a yard engine and the RCO was standing on the side of the engine. Thought there might be a connection.
Was watching a coal train put out BO cars back and forth in front of us. Got to thinking about the air brakes and well, you know the rest.
Grain trains go by and once in awhile I would get a whiff of soybeans. They process them here at ADM, so know that smell. But also know where you can smell them in town and it isn't where we were parked. The only thing I could tie it to was the passing grain cars. Wasn't very strong, but definitely smelled like soybeans.
Thanks for all the answers. Now back to watching and thinking.
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
At times we'll use one short on the horn in response to a hand signal from a trainman wanting to go into the red zone. Red zone for us, establish 3-step protection (do I have that term right?) for others.
Radios may be almost universal, but there are times when hand signals are better.
Jeff
It is "three step". I've also heard of "in between."
We routinely use hand signals. Part of it is for show (albeit correct), part of it is to hold down the chatter, which the FRA mentioned to us once on a visit. Were it not for calling switches (as discussed in another thread) we could do all of our runarounds on hand signals.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
MookieRemote control locomotive operators. Are they required to whistle (one short) at certain times/places/people when they are working in the yards?
The only time the RCO has to sound the horn is at a public crossing. The RCLs, however, are programmed to ring the bell a few times, before starting to move. With ours, the bell rings when you change the speed from stop. It can get annoying though, listening to the bell ring every 2 minutes during switching. Local rules may require using the horn at other times.
Air gets sucked into the compressor from outside, and forced into the air tanks. Carl, our RC control units have a readout that display the brake pipe pressure (allegedly). Using the air from the RC units is usually far more trouble then it's worth, so most often, we just work without.
Yes. Yes. Yes. You can also smell cocoa beans, lumber, mill turnings, coke, trash, sewer sludge, etc.
Nick
Take a Ride on the Reading with the: Reading Company Technical & Historical Society http://www.readingrailroad.org/
hey sis the short answers are that yes rco are required to whistle signals like regular engineers but only for the perpose intended, First rule is when a train or engine is starting to move in yards or in switching it is to ring the bell to let others know its about to move, if crossing the bridge yes they should whistle off.
As far as the compressor its abeen covered and as for the beans and corn or barley or wheat yes and no some are easier to smell than others
Mookie [snip] Air for the brakes. Figure there are air tanks on the engine. Figure there is a compressor to operate said air. Where does said air come from to get into tanks? [snip]
From other answers in this thread and elsewhere, we should know that the air compressor output pressure typically ranges rom 90 PSI = Pounds per Square Inch to 140 PSI = 6 to 10 'atmospheres' = times normal atmospheric pressure of 14.7 PSI, and hence the density of the output air is similarly 6 to 10 times that of the 'free air' around us.
Now, that got me to wondering about the output volume or rating of the locomtoive air compressors in CFM = Cubic Feet per Minute, and more importantly in this context of Mookie's original question - How much air are they sucking in ? What kind of a windstorm might be encountered inside the locomotive hood near a running air compressor ?
The answer - after some research, because it's hard to find even for a specific locomotive model - is probably a pretty good gale; you'd want to hang onto your hat, scarf, and any other loose clothing. Here's the details:
A typical locomotive compressor rating might be in the 100 to 200 CFM range - and as large as 400 CFM, per the data chart on page 4 of the Gardner-Denver Locomotive Compressor brochure ''GR-LOCO-104 2nd Ed. 11/08'' at: [4 pages, approx. 651 KB in size]
http://www.gardnerdenverproducts.com/WorkArea/DownloadAsset.aspx?id=4784
See also: http://www.gardnerdenverproducts.com/LocomotiveCompressors.aspx?n=190
Interestingly, I don't see where the air pressure that's associated with those ratings is stated - so let's assume it is around 100 PSI, or 7 'atmospheres'. So, for a locomotive compressor that's putting out 200 CFM at 100 PSI, it is intaking around 7 x 200 = 1,400 CFM, or about 23.3 CFS = Cubic Feet per Second, which is about 175 gallons per second. Imagine a chunk of air that's 4 ft. wide x 6 ft. long x 1 ft. thick going past you every second - that's about what that compressor is sucking in to provide that output. If dispersed enough, it might not be more than a strong breeze - but inside that hood, I'll bet it's a pretty good gusty wind.
Any comments from those that have actually experienced it ?
- Paul North.
Paul_D_North_Jr 4 ft. wide x 6 ft. long x 1 ft. thick going past you every second
I suspect you'd hardly notice it. 6 fps is about 4 mph - barely a brisk walk.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Paul
You have thought this out very completely but. There is always a but. Out put is compressed air that has been contained and compacted into the storage vessel over time. We all know it takes a lot longer to fill that vessel than empty it. I work on trucks and heavy equipment and the 750 CFM compressors that are most common on these vehicles do not nearly suck as hard as they blow. Even our shop compressor that puts out 30 CFM @ 150 PSI only has a little piece of foam for an intake filter. I can actually hold my hand over the intake and take it away with little difficulty. To find out how much air it takes would take some math and knowledge of the compressor piston diameter and stroke. I can not remember the formula but it goes something like this. Bore diameter times bore diameter times stroke divided by Pi would give you the cubic inches than times 60 would give you the volume of air per stroke per minute times RPM.
Paul_D_North_Jr Interestingly, I don't see where the air pressure that's associated with those ratings is stated - so let's assume it is around 100 PSI, or 7 'atmospheres'. So, for a locomotive compressor that's putting out 200 CFM at 100 PSI, it is intaking around 7 x 200 = 1,400 CFM, or about 23.3 CFS = Cubic Feet per Second, which is about 175 gallons per second. Imagine a chunk of air that's 4 ft. wide x 6 ft. long x 1 ft. thick going past you every second - that's about what that compressor is sucking in to provide that output. If dispersed enough, it might not be more than a strong breeze - but inside that hood, I'll bet it's a pretty good gusty wind.
The most common type of G-D compressor applied to current locomotives is the type WLN: 2 low pressure pistons @ 7 7/8" diameter and 1 hHigh pressure piston @ 5 3/4" diameter, all with a 5 inch stroke. This compressor is rated at 213 CFM @ 1050 RPM with a BHP of 65. GE engines run @ 1050 RPM in throttle 8, but EMD engines are 900 or 950 RPM so the maximum CFM and BHP for an EMD locomotive will be proportionally lower and of course if the engine speed is less than N8 output will be lower also. The standard intake filter is about 6" wide and 18" high. If you are right next to the intake when the engine is idle or low throttle notch, you can barely feel the air flow, but at the upper throttle notches it is noticeable.
The main reservoir pressue is set by the Chief Mechanical Officer of the railroad. FRA does not specify it. North American standard has been 135 psi for a very long time. The FRA does have requirements for the safety valve: "shall prevent the accumulation of pressure of more than 15 pounds per square inch above the maximum working pressure fixed by the chief mechanical officer of the carrier operating the locomotive" Rule 229.49(a)(1). This puts the safety valve setting at 150 psi. Rule 229.49(b) requires that the compressor governor "stops and starts or loads and unloads the air compressor within 5 pounds per square inch above or below the maximum working pressure fixed by the carrier." This puts the standard main reservoir pressue between 130 and 140 psi. Rule 229.49(c) states "the compressor will start when the main reservoir pressure is not less than 15 pounds per square inch above the maximum brake pipe pressure fixed by the carrier and will not stop the compressor until the reservoir pressure has increased at least 10 psi.
Union Pacific is one of a few railroads that operate their main reservoir pressue between 120 and 130 psi. This significantly increases service life of the compressor. This would also require that the safety valve setting to be reduced to 140 psi. FRA issues a waiver to the railroad to allow the safety valve to remain at 150 psi so that locomotives with a lower main reservoir working pressure won't pop their safety valve if put into a locomotive consist with 130-140 psi compressor settings.
Railroads can order EMD and GE locomotives with either Gardner-Denver or WABTEC compressors, however current practice is to apply water cooled G-D compressors on EMD and air cooled WAB compressors on GE. GE since Dash8 has used a motor driven compressor that runs 2X engine speed in the lower throttle notches and same as engine speed in the upper throttle notches. Older GE and all (with few exceptions) EMD compressor are engine shaft driven and compressor capacity is relative to throttle notch postions. That is why it is common practice to "pump up" a train by putting the Gen FLD switch in OFF and the throttle to N4. Motor driven compressors however do not need to be "boosted" to provide sufficient air at any time.
N4 never its always N5 or N6 and motor driven dont need to be boosted,, LOL yea right.
I think MoPac started the 120-130 psi main res setting.
I usually only go up to N4 to pump up. One time I ran some CN SD75Is. They automatically revved up to recharge after the train dumped. Fun watching the engine RPMs on the computer screen.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
WSOR 3801 I usually only go up to N4 to pump up. One time I ran some CN SD75Is. They automatically revved up to recharge after the train dumped. Fun watching the engine RPMs on the computer screen.
EMD locomotives 60 series and newer are equipped with a Main Reservoir Pressure Switch (MRPS) that speeds up the engine if the main reseroir pressure drops below 110 psi for 120-130 main reservoir pressure and 115 for 130 - 140 psi main reservoir pressure. The MRPS was applied per my specification to solve a problem that occurs when a long train with only 1 or 2 units is moving in medium levels dynamic brake and the low engine speed is not turning the shaft driven compressor fast enough to keep up with train air pressure maintaining and horn usage. "I blow the horn 3 times and my brakes set up" complaints. Tried to apply MRPS on Dash2 locomotives, but the engine speed-up caused the dynamic brake to be unstable. Dash2 excitation control cannot "turn down" the main generator excitation enough to get along with the increased generator rotation speed and there were long periods of no excitation which caused dynamic brake to "hunt". Micro-processor excitation control has a wider range of control over excitation. GE's with motor driven compressors doe not need MRPS, however if there is a motor control problem on a single leading unit that delays the start-up of the compressor, main reservoir pressure can get low enough to cause train brakes to set-up when the horn is blown and to release the train brakes when the compressor starts to pump - without the engineer touching the automatic brake handle.
tleary01/ DPman - Now there's a couple of answers ! Thanks much for your time and effort in replying with that much detail.
Now, a couple of follow-up questions, if you'll indulge mea little further:
1. Someplace else I read about another pressure switch and Multiple-Unit cable assignment that - when the main reservoir pressure drops low enough on any of the units in a consist to start its compressor running - then turns on all of the compressors in the consist. The purpose of that is to avoid having a single unit carrying that entire load - whether it's charging the train line, or releasing the brakes - thus getting the pressure up faster and spreading the wear and tear and workload. Otherwise, the unit with the lowest setting or most sensitivity in its switch would be doing all the work. That's something that apparently couldn't be done with double-headed or helper steam locomotives 'back in the day'. Any comments or insights on that ?
2. How long/ how much air - in CFM at the trainline pressure - does it take to charge, say, a 100 car train about 6,000 ft. long, from a complete empty/ no pressure condition ? I would guess that the typical brake cylinder - main and emergency reservoir - on each car might be 3 to 5 cubic feet in volume, plus another cubic foot or so for the train line and hoses - call it 6 cubic feet per car ? So a 200 CFM rated compressor running at 85 % capacity would be providing about 170 CFM, or enough for almost 30 cars a minute - hence the train would completely charge in a little over 3 minutes, plus more for leakage, which is worse in cold weather, etc. But somehow that's much shorter than it usually seems to take - like 10 minutes or so, or longer. What am I missing here ?
Thanks again for sharing your expertise and insights.
The Conrail EC-99 brake book gives the following charging times:
Single Car - 7 minutes - 50 cars - 8-11 minutes - 100 cars - 18-25 minutes - 150 cars - 35-50 minutes Times based on 50 ft. uncharged cars. Shorter times shown are for minimum brake pipe leakage, longer times are for maximum allowable brake pipe leakage.
Times based on 50 ft. uncharged cars. Shorter times shown are for minimum brake pipe leakage, longer times are for maximum allowable brake pipe leakage.
Obviously that's going to vary, but it might help you with your computations. Al Krug's North American Freight Train Brakes may also provide some insight.
Paul_D_North_Jranother pressure switch and Multiple-Unit cable assignment that - when the main reservoir pressure drops low enough on any of the units in a consist to start its compressor running - then turns on all of the compressors in the consist. The purpose of that is to avoid having a single unit carrying that entire load - whether it's charging the train line, or releasing the brakes - thus getting the pressure up faster and spreading the wear and tear and workload. Otherwise, the unit with the lowest setting or most sensitivity in its switch would be doing all the work.
The pressue switch that you are referring to is the compressor control (compressor governor) switch on locomotives without micro-processor control. On decreasing main reservoir pressure the switch energize the compressor control relay to start the compressor pumping. If the compressors are synchronized, the compressor control relay will also energize trainline wire 22 which will make all of the other compressors in the locomotive consist start pumping even if their main reservoir pressure is above their start pressure. Each will also energize TL22 and the all of the compressors will pump until the locomotive with the highest compressor control switch setting reaches its stop pressure. If locomotives with 130-140 psi main reservoir pressure are in consist with locomotives with 120-130 main reservoir pressure the all compressors will start to pump at 130 psi and stop at 140 psi which negates the advantage of 120-130 psi (see my previous post). The compressor switch on locomoties set 120-130 have a limit switch that stops only that compressor at 135 psi even if the synchronous command TL22 is still there. On locomotives with micro-processor control a main reservoir transducer provides the main reservoir pressure to the micro-processor and it is programmed to start and stop pumping and to energize/deenergize TL22 via its output drivers.
Compressor sync is actually an option and some locomotives do not employ compressor sync, the TL22 wire runs straight through without a connection. It would seem logical to synchronize the compressors to get the benefit of all compressors in the locomotive consist helping to maintain the main reservoir pressure. On some SD60 locomotives EMD applied a clutch to the engine/compressor drive shaft. The compressors were un-synchronized because when they were'nt pumping they were'nt rotating. When the clutches started to have chronic failures, EMD just bolted the parts together and made a solid drive shaft and the compressors were like all the others - constantly rotating and periodically pumping but only if the locomotives were lead units. As trail units the un-synchronized compressors would spend long hours between pumping cycles. The compressor's unloded pistons would pump crankcase oil out of the open intake vales where it would "coke-up" the valves. When the main reservoir pressure got very low the trailing unit compressor would finally get a command to pump but the intake valves were clogged open = no air compression. After as few close call incidents that proved my point, EMD restored synchronization and never tried a clutch again.
Our community is FREE to join. To participate you must either login or register for an account.