Air Brake And Train Handling Study Guide
I'm from Europe but North American freight trains have always intrigued me. I guess it has something to do with them being several times longer and heavier than the European counterparts. The closest I can come to operating these types of trains, unless I got a green card and applied to a railroad (lol), is train simulators. Until recently the simulators available to the public were pretty unrealistic, but Run8 feels (to an amateur) very realistic. A train simulator can only be so realistic unless you know the real procedures and train handling. Fortunately there is a lot of information on the Internet. I found the BNSF Air Brake and Train Handling Rules, but there are some things I'm confused about.
I thought I'd ask you all here since as far as I know this is where all the conductors and train engineers hang out and, for now, the west coast is what Run8 focuses on. I hope that is okay with the moderators. Most of my questions regards to operating GEVOs (DC variants in particular) in mountain grades. I have heard that when controlling speed on a long descending grade you should put some air under you so that you don't need more than 50% dynamic brakes. The reasoning I heard for this was that if the dynamic brakes fail or the wheels start slipping you will have to make a much bigger brake pipe reduction or there is a risk of the train running away.
Is this correct? This recommendation seems to agree with these two paragraphs (103.7.1 and 103.7.4 on page 64 and 65 of the BNSF ABTH)link:: 'Early in the braking process, achieve a balance between the level of dynamic brake and the level of air brake needed to control train speed on a descending grade.'
'When a constant level of braking is required for long distances do the following: 1. Make a minimum brake pipe reduction and make further reductions of 2 psi until the train maintains the desired speed.' Lets say you are going down a 2% grade for several miles, would you set as much air brakes so that you can main the desired speed with the dynamics at a very low effort/in setup or would you balance the two? Reading the above two quotes seems to suggest both ways are okay. If my first question is correct I have another question: Lets say you need to stop at a siding in a 2% descending grade.
You already have the brakes set to maintain your speed, would you increase the dynamic brakes to 100% (or close) or would you keep them in the mid range and make additional split reductions? If you need to slow down in level or shallow grade and full dynamic brake is enough to control the speed of the train, would you only use dynamic brakes or still make a minimum reduction and use less dynamic braking? If full dynamic brakes are enough to stop your train without any air (until below the effective range of the dynamic brakes) would you only use dynamic brakes and independent brakes or would you still make a brake pipe reduction (when?)? Some of my questions will probably be redundant if question 1 turns out to be irrelevant. Hopefully my post wasn't too long-winded, thanks in advance. Cheers, William Green. For 2% grade a good rule of thumb is set 1# of air for each 10 tons/ operative brake.
One thought on mountain grades in the 2% range is you never release the train air after you set it. You set enough air to control the train with 50%-70% dynamic braking for the speed on the hill.
If you have to stop you increase the dynamic to stop the train. This works really well with modern extended range dynamic braking.
When you stop do not set more air. When it is time to depart do not release the train air. Using light throttle pull the train to about 5 mph below the authorized speed then reduce the throttle and go into dynamic braking to control the speed. You can stop and start like this on a mountain grade all day long. It works really well if you have signal issues, mow gangs working or weed weasels out testing. Posted from Windows Phone OS 7. Tonnage will dictate some also.
How heavy is the 'test' train? Unit train or manifest? Both are going to play a part in the equation. If dynos will hold it that would be the simple way, but too much dynos will start hurting the track structure, hence the use of air to help negate that. Grain trains suck. Usually have to use more on them to control it.
The DC GEVOs dynos work so well you can't use all of them. They will start hopping at lower speeds. With DP, if your train is set up that way, you have faster recharge times between the release and next set. And is there any chance of rail contamination? Snow, rain, dust, tumbleweeds.
When all said and done, Alan's description works real well. Done it many times. But just sailing down the hill you have to practice and feel the train out. May not get that feel on simulator:( Just have to use more dynos then the 2lb reduction and reduce dynos to get where you want it to be. And if meeting somebody, start planning ahead to slow down. I run on Donner, we used to try and balance our trains for about 400 amps of dynamic braking, 600 amps would be max and after a minimum reduction had been made we take two pound reductions as needed. As the AC locomotives have taken over that translates to about 30 to 40 k of dynamic braking balanced with air.
As FBE said we stop our trains using dynamic holding the air. As UP has added a lot of track lubrication and rail wheel adhesion modifiers to reduce wear on the rail our trains are using more air and lighter dynamic to control speed. Donner is a series of steps. Norden to Cisco might require a minimum and light dynamic or throttle to keep moving. Below Cisco almost always in dynamic with a minimum set.
Yuba Pass is very flat most engineers release the air and recharge the brakes. Yuba Pass to Emigrant Gap a minimum set with dynamics will work. Below the Gap to Gold Run the reductions will normally be increased at a rate of 2 lbs at a time. I was always taught and agree that once a 25mph train is at 14lbs of reduction the train speed should be reduced to 20 mph max to keep the brakes from fading further due to the heat being generated (Maximum reduction on the hill is 18 lbs of air). Gold Run is Flat and brakes are recharged. Gold Run to long ravine the same process as leaving the gap.
Railroad is uphill from long ravine to Colfax, with a light down grade to west end. From MP 140 to Wiemar the railroad is flat. The railroad tips off again and grade is carried to Clipper gap On long trains I can carry the air to Bowman on short trains I release the air at Clipper gap.
Bowman to Auburn requires a set, air is released at Auburn and set again at Bloomers cut and carried all the way to Loomis. If I take the number two track from Bowman down I can cycle the air as needed all the way to Rocklin. After all that you learn to run in snow and Ice which changes everything. A couple of other factors that will dictate total brake pipe reduction on a long heavy descending grade are train consist and train length. A train that averages say 90 TOB that consists of all or mostly all loads and is 3000 ft.
Air Brake And Train Handling Manual
Long is usually going to require more brake cylinder pressure to control than a 90 TOB train that is equally split between loads and empties and is 7000 ft. The longer train will be strung out around more curves at a given time which will help bind the train up and the longer train will tend to have more braking power because it usually has more brake shoes, hence less b/c pressure required. Also, the warmer the brakes get the more effective they become so long as you don't get them hot and burn them up. I found that I could just about always save a couple three pounds of air, especially on stack trains, by drawing off a minimum reduction on top of the hill and then pulling her over the side. This allows the brake shoes to be up against the wheels and warming up by the time the majority of the train is on the down grade. Edited 1 time(s). Last edit at 03/22/14 23:40 by Chico43.
So just to make sure I get this right, it is fine to use 100% dynos when stopping (as long as the train is set up correctly and equivalent dynamic brake axles are correct etc)? There are many different types of trains available in the sim but the one I was practicing with is a 15000 ton grain train with mid and rear DPUs, 143 TPOB (if I recall correctly). Contaminants are not available as far as I know right at this time but it wouldn't feel right doing something just because you can get away with it in the sim. If you are stopping on level grade and full dynamics is enough, would you still use some air?
The ABTH manual states: 'At a sufficient distance from the stop, make a minimum brake pipe reduction and actuate.' 'Make further split reduction(s) as needed and actuate.' Maybe the extra track wear SD45X mentioned would make it a bad idea to only use dynos? Thanks again for all the answers, a lot of great information. If your running a 15000 ton grain train with a make up of 4x3 with 106 loads on heavy grade they take about 10 to 12 lbs of air to control and due to TPOB on my road they would be restricted to 20 mph. On the flat when moving at 50mph and you get a signal indicating that you will be stopping soon start with the air and follow with dynamics. The problem with simulators is that the equipment always works as designed.
In the simulator I can run max dynamics on a heavy grade and they won't fade or slide out. On the newer AC's when the dynamic slip out they can take as much as 30 seconds to a minute to recover, and a lot of things can happen in that minute. In the feather river canyon we run a normal 2x1 configuration with that tonnage on a 1 percent ruling grade, which requires what is known as a soft set and good dynamics to keep the train moving. 'If you are worried about the rules, follow them:)' Haha, well the rules were the only information I had before I asked you guys:) I know of course that rules can never make up for real world experience. 'Set the air coming in and fill with dynos to a stop.'
What if setting the air from 50mph makes you stop short of the siding? Would you release the brakes and set them again when in the siding? How come you set the air before filling with the dynos? Is there a particular reason for this order and not the opposite? Does it have to do with the dynos being less effective at higher speeds or because it takes some time to throttle down and wait 10s?
'At slow speeds the dynos get better, and they will start hopping and dropping the load on the leader hence the earlier statement you won't get 100% dynos.' What does 'hopping' mean? Mrgreen Wrote: - 'If you are worried about the rules, follow them:)' Haha, well the rules were the only information I had before I asked you guys:) I know of course that rules can never make up for real world experience. The rules are a good start.
'Set the air coming in and fill with dynos to a stop.' What if setting the air from 50mph makes you stop short of the siding? Would you release the brakes and set them again when in the siding? You don't set all the air at once. Common practice is called a split reduction. You set the minimum reduction of about 7# and see how that works. Then set another 2-3# and wait then set more as needed.
If you are using air to stop in a siding you may not have enough room to set the air, release the air, let it charge and set it again. No air applies immediately and the next application is not as strong as the first without going deeper. How come you set the air before filling with the dynos? Is there a particular reason for this order and not the opposite? Does it have to do with the dynos being less effective at higher speeds or because it takes some time to throttle down and wait 10s? Yes, setting the air early allows the brakes to warm up and become more effective.
Especially with older units the dynamic hrakes are most effective between 45mph and 20mph. 'At slow speeds the dynos get better, and they will start hopping and dropping the load on the leader hence the earlier statement you won't get 100% dynos.' What does 'hopping' mean? Hopping is another form of wheel slip. The wheel is trying to go slower than the locomotive is going. When it actually does that on slippery rail due to water, frost, oil or control it almost locks up then hops when the wheel regains adhesion with the rail.
William Posted from Windows Phone OS 7. It depends upon whether you need to remain stretched or bunched.
If you are pulling in power your slack is stretched if all is going well. If you set the air while in power the slack stays stretched.
If you throttle off then set the air the head end cars start to set up first and the trailing cars start to bunch against them. DPU operations reduce this a little bit but you end up with the slack scattered throughout the train which is not good. If you want to stop with the slack bunched then you get out of power, bunch the train with dynamic braking then set the air to stop. The engineers job is to be thinking two miles ahead and a mile or a bit more these days behind. Your immediate work area is about 3 miles long. Posted from Windows Phone OS 7. Power braking is running in a high throttle notch and setting the air and never going to a lower throttle until ready to stop.
Setting the air in run two and stretching your train to a stop in the siding or at a absolute signal is not considered power braking even if I have to go back to run 4 to get the train to clear. The reason I always start with air on heavy trains and Auto trains is to get something working for me. I have to work the throttle down gradually and wait 10 seconds before I can go into dynamic, then gradually bunch the train up before going into heavier settings.
The most important thing when coming to a stop is to not get by the signal, everything else can be forgiven. Thanks, I always thought you wanted to use the dynos first, but what you said definitely makes sense. So you usually want to stop with the couplers stretched on ascending grades and bunched on descending grades but where is the point of change between these two situations?
Amtrak Air Brake And Train Handling
For example on level grade or just a slight ascending grade, does it vary a lot or is there some kind of rule of thumb? Another thing I'm wondering about is: I read that when going over a railroad crossing at grade you want to notch down to N4 or lower before passing the crossing (it has something to do with the risk of flash over I think?) If the train you are running have mid and/or rear DPUs, do you wait until the whole train has passed before you throttle back up or do you fence the DPUs and use the distance counter as a guide when to notch down the DPUs? Mrgreen Wrote: - Thanks, I always thought you wanted to use the dynos first, but what you said definitely makes sense. So you usually want to stop with the couplers stretched on ascending grades and bunched on descending grades but where is the point of change between these two situations? For example on level grade or just a slight ascending grade, does it vary a lot or is there some kind of rule of thumb?
Another thing I'm wondering about is: I read that when going over a railroad crossing at grade you want to notch down to N4 or lower before passing the crossing (it has something to do with the risk of flash over I think?) If the train you are running have mid and/or rear DPUs, do you wait until the whole train has passed before you throttle back up or do you fence the DPUs and use the distance counter as a guide when to notch down the DPUs? William Just to clarify William. Crossing at grade is a railroad diamond or where two railroad cross each other. Not a road crossing. Bunched with dynamic is preferred on downhill or level track. If you try that going uphill the rear end will run out when you release the brakes and you may get a break in two.
DPU power might hold it together but why risk it. Slowing down and reducing the load going over a crossing at grade is to keep the brushes on the traction motors from bouncing on the armature creating pits in the armature or even flashing over the motor which is an expensive fatal failure. Neither is as likely with AC traction motors but the axle and traction motor is all unsprung weight. Anything you can do to reduce impacts to the motor and track structure is desirable. The special instructions probably cover procedures to be complied with. Posted from Windows Phone OS 7.