Passenger Trains > Air Brake Pressure on Amtrak Trains Using Freight Power

I've been curious about something and hope someone on TO might know the answer(s). The usual air pressure used on Amtrak passenger trains is 110 psi vs. the usual 90 psi for freight service. When Amtrak substitutes a freight locomotive, does the engineer run the train at 90 psi, or is there a way to raise the brake pipe pressure to 110 psi from the cab of the freight locomotive? I'm aware of one case where the engineer was prohibited from raising the air pressure (like in the old days) due to the locomotive software not providing for a 110 psi option. Can anyone enlighten me? Thanks in advance.

CFG,

It is a little more complicated than that.

Passenger trains run in graduated release and freight trains run in direct release.

If you stick a freight engine on top of a passenger train you have to select graduated release and 110 psi. This can be done, but freight rules may say no in which case the train will be operated in direct release at 90 psi.

Amtrak engineers are trained to operate in graduated release and freight engineers are taught to operate in direct release. If the engine is to be operated by a freight engineer he, or she, will want direct release. If an Amtrak engineer then graduated release is preferred.

Direct release means that when you make a release the brake pipe is fully recharged and the brakes are fully released.

Graduated release means that if you take more than a minimum set, say 20 lbs, you can release part of the set as you are coming to a stop.

The single car test for a passenger car operating in graduated release requires that 3 releases can be made from a 25 lb set to a full release.

Since all passenger trains oerated by Amtrak today are operated today, except for the Autotrain, are operated in graduated release the locomotive will have to be set up for grauated release.

Changing the train over to direct release requires the resetting of each car on the train.

hope this confusing diatribe helps.

CFG Wrote:
-------------------------------------------------------
> I've been curious about something and hope someone
> on TO might know the answer(s). The usual air
> pressure used on Amtrak passenger trains is 110
> psi vs. the usual 90 psi for freight service.
> When Amtrak substitutes a freight locomotive, does
> the engineer run the train at 90 psi, or is there
> a way to raise the brake pipe pressure to 110 psi
> from the cab of the freight locomotive? I'm aware
> of one case where the engineer was prohibited from
> raising the air pressure (like in the old days)
> due to the locomotive software not providing for a
> 110 psi option. Can anyone enlighten me? Thanks
> in advance.


Newer power can be dialed up to 110 PSI and operated in Passenger mode (Graduated release). The only two times we've had to used freight power to get over the road on my trains the units were equipped with a passenger setting on the brake valve and were able to be set at 110 PSI, so as far as what happens when the freight unit doesn't have those settings is beyond me.

That said, one of those times we ended up with a freight motor we had coasted to a stop on single main track, and the dispatcher had the whole freight train flag up behind us, couple on, and yank us back about a mile and a half to the last siding where they were able to run around us and set out one of their units for our use. With the 90lb release all but one of the cars was able to completely release the brakes and roll freely, so I'm sure it's possible to run a passenger train at 90lbs in an emergency.

Passenger equip will run at either pressure. Your condition was caused by not dropping the brake pipe far enough to allow the 90lb setting to initiate a full release. I would have had the pass train draw the pipe down to 62 lbs or even plug it, and then cut out the brake stand on the pass engines and take control from the freight the cars would then be fully released.

In my experience, it is relatively simple to adjust the BP to 110 with the feedvalve handle or key, or thru the airbrake settings on the computer. The equipment will work fine at 90 psi if needed, either in graduated or direct. Our instructions regarding adding UP power is to set it at 105 psi,due to a slightly lower Main Reservior pressure found on some UP units. I did have one UP unit one time that only had direct release, and had to change all the graduating caps on the car control valves to direct release.

UP25198 Wrote:
-------------------------------------------------------
> In my experience, it is relatively simple to
> adjust the BP to 110 with the feedvalve handle or
> key, or thru the airbrake settings on the
> computer. The equipment will work fine at 90 psi
> if needed, either in graduated or direct. Our
> instructions regarding adding UP power is to set
> it at 105 psi,due to a slightly lower Main
> Reservior pressure found on some UP units. I did
> have one UP unit one time that only had direct
> release, and had to change all the graduating caps
> on the car control valves to direct release.

What sort of training or 'blessing' do you have to have to reset the car brakes? Is this something that any engineer can do? Just an Amtrak engineer? An Amtrak conductor?

John Gezelius
Tustin, CA

Per the latest rule, it is no longer needed to adjust the car brakes when you have a freight engine that will not operate in graduated release. You leave the train in graduated and run the loco in direct, and make a note of it on the paperwork.

In graduated release (passenger) mode, the loco will increase brake pipe pressure as you move the brake handle closer and closer to release. On direct release (freight) mode, you will not see any increase in brake pipe pressure until the handle is moved all of the way to the "release" position, when it will then increase all the way to the maximum pressure.

If the freight loco is set for direct, the cars set to graduated will act appropriately. After all, as far as the car is concerned, you kept applying the brakes, applying a bit more, and eventually just releasing completely (which happens to be exactly what you did).

What will NOT work is running a direct-release train with a locomotive set for graduated release. If you attempt that, as soon as you move the brake handle back even a smidge and get a couple pound increase on the brake pipe, the train brakes will release completely and the brake pipe will NOT go to maximum pressure to recharge (since the engineer did not move the brake handle to release). That would be a Bad Thing, since it would essentially be an uncommanded release of the train brakes, and furthermore would not charge the car reservoirs appropriately.

Per the Amtrak Air brake book AMT-3 if on the UP you set the Brake Pipe pressure to 105psi. This is a rule the UP has which is noted in the book as a "non-conforming" railroad rule which we must follow.

When a freight unit is used on a passenger train NOTHING changes at all. Per rules you operate the freight unit at passenger speeds unless otherwise restriced. Ex. unit is geared for 70 mph then you would run 70 mph on all track with a speed greater than 70 for passenger. Basically run the engine at the fastest speed it is allowed to operate at. Another ex. is the unit is geared for 75mph then you would run 75 mph on all 75mph track and on any segment over 75 mph you obviously continue at 75mph.

Amtrak Engineers are trained to operate in both direct and grad. release. The P-42's have a freight and pass setting on their pilot valves and the control valves are always set with their release caps in GRAD. Rel. The main thing to be cognicent of is if the cars control valves are set for direct rel. and the engine brake stand is put into GRAD. Rel. This is when you can have major trouble because if you graduate off the brake valve when the control valves in direct relase see a 1 to 1 1/2 lb increase in BP pressure they will "think" you called for a release when infact you graduated off and at that point your BP gage will show a reduction in BP still but the cars will be in release.

Lastly, when adding a freight unit and the BP pressure will be set below 110 psi it is required per rule to put the train into emergency. This is to reset the control valves. After putting train into emerg and control valves are reset you can dial any pressure below 110 psi and the control valves will now be "set" for that new BP pressure.

I remember many years ago I was the fireman on the circus train out of SLO. We had to add a unit out of the house so the engineer cranked the pressure up to 110 lbs. Well, the circus train is 90 lbs, its all over the cars. Well 3 hours later we finally got the train bled of the overcharge and charged to 90 lbs so we could make an air test and go.

Same thing when you had an official car on the end of a freight. It would work fine on 90 lbs.


Nudge

The AMT3 also has rules in it as to how many direct release only cars may be on the train before it must be operated in direct release, which Amtrak is reluctant to do. Some private cars when rebuilt had freight brake valves installed in them, like the old captive AutoTrain pool. Even with the freight valves, like ABDW, a relay valve is installed in the system and that controls the brake cylinder pressure.

Operating at 110 psi brake pipe vs 90 psi brake pipe has no effect on a passenger car's ability to brake in a service situation, but in emergency there will be some additional cylinder pressure, owing to the increased reservoir pressure.

Amtrak long-distance trains used Direct Release for several years beginning, I think, in 1997 when the boxcars showed up.

They switched back to Graduated Release when Amtrak Express service ended in 2005.

As I understand it, Auto-Train equipment is all direct release because of the auto racks. Most private passenger cars are equipped with a changeover feature so they may be operated either way.

RailNet802, out

Add the freight power, keep the pressure maintaining valve in the FRT position and dial up the feed valve to the prescribed pressure. The passenger equipment will only release when the handle is in the release position. Amtrak engineers know what to do and how to do it. However, freight engineers probably don't know anything about graduated release (especially the newer ones) and most carriers forbid their engineers to operate passenger equipment. Do not touch the DIR/GRA caps on the cars. You must maintain a 15# differential between brake pipe and main reservior pressure is the CFR law.

No one talked about "transition" from series to parallel as a major passenger vs. freight power issue.

This is generally done by the mechanical people, by unbolting and repositioning the graduating cap on the control valve on each car.

Here's a question- on the Amtrak reroutes we've had on my line- they just slap an SD70M on front with the feed valve set with the higher brake pressure (I think it was 105psi), and you cut in the auto brake for graduated release- since the Wabco brake valve on these units has a setting for both Passenger and Freight. My question is on the electronic brakes like the AC4400s have I know you can turn up the pressure of the braking system, but does it even have an option for graduated release? I've never found one anywhere.