I’ve read where the DMIR and now CN use straight air (third set of piping)on the old and new ore jennies. What does this mean?
Thanks!!
Orinco Straight Air. Erie Mining used this also. CN now very rarely uses it, except on Proctor Hill. I will try for a more detailed description later tonight.
All air brake systems require one train line, not two, not three.
? Its a separate set of piping…
Is the extra pipe for brakes? Somewhere I remember something about air being used to power the dump mechanisms.
Think of the Orinocco brake as a remote retainer set up system. The locomotive Engineer sets up the train brake with the Automatic brake valve. Then he can apply the Orinocco to hold the set he just made, following which he can make a release of the Automatic brakes while the Orinocco holds the application on the train. It does this via an additional set of brake cylinders attached to the car’s brake rigging. Trains ran a feature on the DM&IR mini-quads and the Orinocco Brake in the '80s IIRC. At any rate they covered it along with a photograph showing the additional brake cylinder setup. After trying air dumping again on the first batch of new ore cars, CN has again gone back to the tried and true manual trapping to dump the ore cars.
Yes, two sets of air hoses. Air is used for extra braking on hills.
The Orinocco or straight air, uses a second air hose (and second independent valve) which allows the engineer keep a constant pressure on every brake cylinder in the train, although he may be recharging the train line at the same time.
The DMIR/Erie Mining straight air system works a bit different. On a normal automatic brake, when you release the brake, everything releases.
With the straight air, you can recharge the reservoirs on the automatic system, yet keep a set on the train, which can be adjusted. Makes coming down big hills with heavy trains a lot easier. You could turn retainer valves for a similar effect, but it takes a lot of time to walk the train, turn the retainer valves, come down the hill, walk the train again to return the retainer vales to normal, and continue. The ore trains were pretty much dedicated trains, so adding the Orinocco system was seen to increase safety and productivity.
DMIR 193 Big picture, but shows the hookups fairly well. Straight air pipe is marked. Ore cars have the air hose hookups high, as the cars couple up closely, and the wheels get in the way.
Just remember that our #193 has the high hoses removed. The new ore cars do not have high hookups. The Missabe trains with old ore cars do not use the bottom hose at all, main res and straight air are both up top.
In Queensland, we use a three pipe system on some of our coal trains.
Train line,main resivior and B brake,train line is 500Kpa,main res is 900Kpa and is only used to charge the main res,B brake is 350 Kpa and is direct air from the loco air brake.
The B brake is used to hold the train on a falling grade to allow the train to recharge the train line.
RAYMOND T
On DM&IR, 4 cars=1 car
Duluth, Missabe & Iron Range quads four cars drawbarred together
by Morgan, David P.
from Trains February 1976 p. 12
brake DM&IR ore
Here is a view from between the ore cars, note that one of the hoses isnt laced at the moment, it will be when they depart:
On the cabeese, you can see they have a normal low train line hose down below, but also one above for when in ore service. They do not have a straight air hose, as they have no need for it.
On the locomotive you will see the straight air hose, which is a little smaller, on the right side. Train line air is the hose on the left, while the lower train air hose is to the left of the coupler, for non ore train service.
Thanks for those photos and explanations, Max. Here’s a link to one more (not mine) of the cab/ control stand of DM&IR 406, an SD40T-3, which shows the 2 independent brake valves:
http://www.railpictures.net/viewphoto.php?id=187852
EDIT: See also the explanation near the bottom of Page 1 of 2 of this short thread:
http://www.railroadforums.com/forum/showthread.php?t=10081
and on this one:
http://www.railroad.net/forums/viewtopic.php?p=430909&sid=4400c2296488f9f7e11c84889c4cff54
The “Orinocco” brakes apparently originated on a US Steel iron ore road in Venezuela - until this thread, I’d not seen or heard that term for them before.
- Paul North.
Also all of the true Missabe units, and SOME of the IC SD40-3’s on the Missabe (IC 6250-6264) have 6 cylinder air compressors, as opposed to 4 on normal units, which allows quicker air charging, especially during the bitter cold winter months.
Thank You.