Freight Car Brakes

Rand posted:

Morning All,

I hope this question is in the correct place but the subject seems to overlap boundaries. I have a fairly good idea of the workings of a train air brake system. One piece of the system I can't seem to get a fundamental answer on is the retainer valve and retainer line. What are they and what are they used for? Does anyone know of a drawing on how these two are tied into a freight car brake system?

Thanks in advance.

I just did a Google search for RR air brake, retainer. Look for TG-11 Three Position Retaining Valve FM - New York Air Brake.  That should answer most of your questions to start with.

This is a long video but take a peek around the 7 minute  mark.... A crew member is putting  retainers to the on position before the train heads down the grade.    Scary stuff.

Retainers allow the brakes to remain on  the cars applied  if the train line air  becomes low & dangerous .   or in railways terms... He ****ed the air away tooo many times. ****ed  (starts with P)

During my career as a Brakeman/ Conductor I  've never heard of any crews using retainers. During my time all engines were on the head end, no dynamic brakes and stretch braking was the norm. (even in the mountains out in BC .)

Having said  that back east    ,We make a lift  on the  final stretch of  our trip, about 15 cars, we just have enough time to make it off the sub for the  "Super" CN s transcontinental passenger train. - Train order territory,  Guess what,   the train just can't get up to speed and one of the cars is smoking pretty badly, we have to stop  and sure enough the retainer is in the" on" position on a flat car.... Bottom line  We didn't make it in for the  Super . had to flag him, (we didn't fit anywhere), Talk about grumpy guys.

When we think of  retainers  it's usually about retaining the brakes going down hill. However having one on going up hill can make the difference  between doubling the hill  or not.

Yes it was  my responsibility to do up  all hose bags and release the hand brakes on the lift ... I missed the retainer.

Retaining valves were commonly used on freight trains, on heavy descending grades, in steam days.

All railroads with mountain grade territory opted for dynamic braking on their diesel-electric locomotives, and the use of retaining valves was discontinued  when dynamic braking was available.  There were a few of the most severe grade territories (such as Southern's Saluda hill) which continued to use retainers.  

When I was Assistant Supt. for territory including the Lampasas Subdivision, I issued a Special Instruction that crews coming off the rock spur at Brownwood, Texas (down a 2-mile 4% grade) would set all retaining valves to High Pressure position at the top of the hill, and, after stopping short of the split-rail derail at the bottom of the hill, set all retaining valves back to Direct Release.  They were using single GP30 and GP35 locomotives on the Brownwood Local, and the locomotives had standard -- instead of extended range -- dynamic braking.  They were brining a cut of 15-20 loaded rock cars per day, to the yard for pickup by through trains.

Al Krug's freight train brakes retainers.

Tom:

Wasn’t SP still using retainers on Cajon Pass into the late ‘80’s?  I remember there was a potash train ran away and piled up at the western foot of the pass.  Took out a bunch of houses and damaged a natural gas pipeline that exploded not long after.  It’s been quite awhile but I recollect comments at the time the crew had failed to set the retainers which led me to think it might still have been standard practice.

Curt

The one time I rode the current Grand Canyon train, I was talking with the conductor until he had to excuse himself to set up some retainers for a certain stretch...I think it was Williams bound in direction, but it has been a long time ago.

I've used retainers a few times in special situations.
Once was when I had to stop a coal train on a 1.6% grade to await MOW fixing a sunkink right ahead of me. Sat there over 2 hours and didn't notice the pressure maintaining was not working. When the MOW foreman gave me the OK to go I found I had only about 30psi brake pipe pressure on the train. The foreman gave me a FIVE mph slow order over the fixed sunkink. BN did not have extended range dynamic brakes so there was no way the DB on my 5 coal units was going to do anything at all towards holding the train speed at 5mph. I would not want to use it over a freshly tamped sunkink even if they did have extended range, that would be asking for a re-kink under the train. So I sent the headbrakeman back to set retainers on 25 cars to high pressure hold. It worked great.
Another time was early in my career when I stupidly p---d away the air in a snow storm on a long 4% grade on a mostly coal train with no DB. When I finally got the almost-a-runway stopped I told the poor brakeman to walk back in the storm and set up the retainers before I'd release the air and proceed down the hill.

The retainer principal is pretty simple. You know that the brakes apply with a reduction in BP pressure. The pistons on the cars comes out applying the brakes. When you move the handle back to the release/running position, it charges the brake pipe & brake system, releasing the brakes. When the brakes are applied with retainers set, the piston comes out on all the cars, applying the brakes, but when you go back to the release/running position to charge the system, the retainer prevents the air in the brake cylinders from releasing, "retaining" the set. The piston can't go back in. That allows the train brake pipe & train brake system to be recharged while still having the brakes set. Notice the single small 3/4" pipe at the rear of a brake cylinder. Air flows through that to push the piston out applying the brake. When the brakes are released, a spring inside the cylinder pushes the piston back, purging the air back toward the control valve, but the retainer valve in a  little 3/8" line can keep it plugged, preventing the piston from retracting. Most retainers have three or four positions. EX which is normal direct release, HP which restricts exhaust at a controlled rate then retains 20psi after about 90 seconds.  LP which has a blow down time of 60 seconds from 50-10psi then retains 10psi, and SD which has a blowdown time of 86 seconds to exhaust all the air, like a real slow direct release.

juniata guy posted:

Tom:

Wasn’t SP still using retainers on Cajon Pass into the late ‘80’s?  I remember there was a potash train ran away and piled up at the western foot of the pass.  Took out a bunch of houses and damaged a natural gas pipeline that exploded not long after.  It’s been quite awhile but I recollect comments at the time the crew had failed to set the retainers which led me to think it might still have been standard practice.

Curt

The short answer is "No".

The Espee runaway you refer to was caused by the Engineer mishandling the air brakes, and retainers were not being used.  A contributing factor was some units in the consist not having operable dynamic brakes, but that should not have resulted in this wreck.

He waited until speed was getting to high, set too much air, and was going to stall.  He released the air, speed immediately picked up and then he set way too much again.  He basically burned off the brake shoes and the train ran away and derailed on a curve at the bottom end of the grade.  There was a housing tract there, and the derailment wrecked a couple of houses.  The wreckage caused a buried pipeline to catch fire, and more houses burned.  That's the short version.

The Engineer had insufficient understanding of heavy grade train handling to realize that he was getting into trouble with a very heavy train, and the train crew did not do anything to help.  A competent Engineer would have realized that something was not right, before speed built up.

There were contributing factors, but the Engineer mishandling the air brakes was the root cause.

Wyhog posted:

I've used retainers a few times in special situations.
Once was when I had to stop a coal train on a 1.6% grade to await MOW fixing a sunkink right ahead of me. Sat there over 2 hours and didn't notice the pressure maintaining was not working. When the MOW foreman gave me the OK to go I found I had only about 30psi brake pipe pressure on the train. The foreman gave me a FIVE mph slow order over the fixed sunkink. BN did not have extended range dynamic brakes so there was no way the DB on my 5 coal units was going to do anything at all towards holding the train speed at 5mph. I would not want to use it over a freshly tamped sunkink even if they did have extended range, that would be asking for a re-kink under the train. So I sent the headbrakeman back to set retainers on 25 cars to high pressure hold. It worked great.

Those who are not railroaders can see what I meant about being competent and understanding safe, heavy grade train handling.  Wyhog thought it all out in advance and used skill and knowledge to get a good result.  I would have enjoyed working with him, any day.

Anyone remember a wreck caused by hose bags part parting   between 2 cars with cushioned draw bars .Instead of an emergency brake application it happen so fast , the hose bags lodged   in a   position that  closed the air from either direction. , almost as if someone had gone in between the cars and close both cocks. Unfortunate the train still had a tail end crew with caboose and failed to take action.

Hey Tom  Did you ever have a radar gun? Gregg  

Gregg posted:

Hey Tom  Did you ever have a radar gun? Gregg  

Yes, but I did not ever "catch" anyone speeding by using it.  

I used it to prevent speeding by making sure crews frequently saw me holding it as they passed.  If people know that you care, they will try to do good work.  If they think that you are okay with careless work, then a good number of them will do whatever they think they can get away with.

Another prevention practice was to go out to a remote location in the middle of the night and, after a train passed, call the crew on the radio and report "all black."

If you can be a coach, you don't need to be a policeman.

Thanks everyone for this great information.   Makes you appreciate the job of the engineer.

Gentlemen,

Thank you all very much for the detailed education on retainer lines and valves and how they relate to the brake system. The technical information and personal recollections were awesome!

Number 90 posted:

Wyhog posted:

I've used retainers a few times in special situations...

...Wyhog thought it all out in advance and used skill and knowledge to get a good result.  I would have enjoyed working with him, any day.

And I would have enjoyed working with both of you guys. I’m sure I would have learned a lot from you two pros.

The SP derailment on 5/12/89 near San Bernandino,  CA, occured when a train loaded with trona was unable to maintain proper speed down hill.  The NTSB concluded that the accident was primarily caused by two factors. The engineer believed the train had 6150 trailing tons. It was actually 9000 tons. The engineer believed, when he started down the grade that he had 24 axles of dynamic brakes.  It was only half that much. The NTSB blamed the accident on poor communication between the dispatcher, helper engineer, and head end engineer. Four people died in this accident, two of the head end crew members and two children who lived in a house near the tracks which was covered by the spilled trona. 

On 5/25/89 a pipeline used to transport gasoline was damaged by earth moving equipment helping to clean up the derailment.   Two more near by residence died in the fire.   The pipe line company seems to have gotten most of the blame for this because they were aware of the derailment and were to have pressured the pipe line down. A defective valve in the pipe line prevented this. 

Given the information the engineer had about the train, retainers were not required.  Had the engineer had accurate information about the brakes and train weight, the train would not have been allowed to travel down the hill.  The melting of brake shoes and damage to brake heads was a result the effort to stop the train after it was already out of control.  It was not a cause of the accident.