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Re: CN (xDMIR) Two Harbors runaway and Orinoco brake system
Author: Dr Zarkoff
Date: 12-30-2013 - 10:27
>As I suspected, this isn't anything new, just a new nickname for it. Westside Lumber used this same type of system that came on the skeleton cars they got from Swayne Lumber, Hutchinson Lumber/Feather River #3 (now Cass #11) had 6ET with a S3A for a similar system, no doubt there were many others.
I first ran into this on a Pickering Lbr engine.
>A mini-quad diagram in the 1976 DMIR rule book shows an AB-1 double check mounted on the AB pipe bracket connecting the brake cylinder and straight air line. While not actually controlling the retainer, the combined straight-air and automatic brake pipe system would enable either the use of the retainers in the normal manner or allow the straight air pipe to mimic the use of retainers with the engineer having a wider degree of control.
Thanks for looking up the details; I gave up after finding about four sites which did little more than quote each other. From what you say, the so-called "Orinoco system" isn't remote controlled retainers but the combined straight and train air system, re-animated for AB ("Night of the Living Brake System"), which is what I suspected. Having a remote controlled retaining valve makes no sense because of all the complicated (and expensive to buy and maintain) gee-gaws that would be involved.
>When using the straight air system as retainers, the automatic brake should be applied first in an amount sufficient to control train speed. Then a straight air application can be made. The automatic brake may then be released. The advantages of making the automatic application first include a more rapid buildup of brake cylinder pressure and improved seating of packing cups in the brake cylinders in cold weather.
This makes sense when viewed in the light of slack action. However, going downhill all the slack would be bunched, so applying the straight air first wouldn't be a very big problem.
>but the electro-pneumatic PS-68 system uses somewhat the same theory by using a magnet valve to control the brake cylinder exhaust but at each car (commuter use only).
The same is true for a UE-18 control valve used with the UC system of c1914 for main line passenger cars.
I first ran into this on a Pickering Lbr engine.
>A mini-quad diagram in the 1976 DMIR rule book shows an AB-1 double check mounted on the AB pipe bracket connecting the brake cylinder and straight air line. While not actually controlling the retainer, the combined straight-air and automatic brake pipe system would enable either the use of the retainers in the normal manner or allow the straight air pipe to mimic the use of retainers with the engineer having a wider degree of control.
Thanks for looking up the details; I gave up after finding about four sites which did little more than quote each other. From what you say, the so-called "Orinoco system" isn't remote controlled retainers but the combined straight and train air system, re-animated for AB ("Night of the Living Brake System"), which is what I suspected. Having a remote controlled retaining valve makes no sense because of all the complicated (and expensive to buy and maintain) gee-gaws that would be involved.
>When using the straight air system as retainers, the automatic brake should be applied first in an amount sufficient to control train speed. Then a straight air application can be made. The automatic brake may then be released. The advantages of making the automatic application first include a more rapid buildup of brake cylinder pressure and improved seating of packing cups in the brake cylinders in cold weather.
This makes sense when viewed in the light of slack action. However, going downhill all the slack would be bunched, so applying the straight air first wouldn't be a very big problem.
>but the electro-pneumatic PS-68 system uses somewhat the same theory by using a magnet valve to control the brake cylinder exhaust but at each car (commuter use only).
The same is true for a UE-18 control valve used with the UC system of c1914 for main line passenger cars.
