The PNWC Blog

One of the things that gets done every year before the Holiday Express train runs is the air brake test.

The primary purpose of the test is to make sure the brake equipment under each of the cars works – which means the brakes set, hold, and release as expected. Another big part of the air brake test is measuring the leakage rate.

This is important, because with a steam engine, the air pumping capacity is limited, and the more leaks we have, the more wear and tear on the steam powered air pumps.

There are Carmen (such as myself) that spend a lot of the waiting time during the air test crawling around under the cars with a spray bottle filled with bubble soap. Every potential leak in the entire brake system gets sprayed with bubble soap. And there are a lot of things to check: connectors, welds, gaskets, valve stems, hoses, all kinds of connectors and fittings – each of which has the potential to leak.

A leak hit with bubble soap will blow bubbles. Finding the leak is the first challenge: most of these things are too small to make any noise. Once found, it’s a matter of figuring out how to fix the problem. In most cases, the solution is to take the joint apart, clean everything up, replace the gasket or seal, put everything back together, and then test again. It takes a lot of patience, a bunch of big heavy wrenches of various sizes, and a collection of spare parts. Teflon thread sealant tape is wonderful stuff in fixing threaded joints that leak.

This year we replaced all of the sealing washers in the glad hands that connect the brake hoses between each of the cars. I’ve attached a photo of one of the washers that was removed. The problem here is part of the sealing face of the washer is chewed up. (See Figure 1 attached: The sealing face should be smooth like the area at “A”, the general poor condition and cracks such as the one at “B” are the concern.) When the brake hoses are connected, the two washers come together, and are supposed to make a tight seal. Those defects in the face of the washer will cause a leak. It’s not a big leak, and lots of little leaks add up.

I’m very pleased with the performance of our air brake equipment. And I’m also pleased that we have a near zero leakage rate – something that has taken a long time and a lot of work to achieve. It’s not very glamorous, or very exciting, and there is a certain satisfaction in the hunt for and repair of leaks in the air brake system.

Special thanks to Forest LeCain, who supplied the new brake hose washers, and to Pete Rodabaugh, who assisted with installation.

Regards,

gnh

I went down tonight and isolated the fault to the 371 power plant. The fault was isolated to the starter relay.

When I attempted to disconnect the starter motor lead from the relay, something went click, and the fault went away.

I took the relay off, brought it home, opened it up and so far have not found the fault. I’m still looking.

The relay does have some obvious problems. It will need some repair, I’ll see what I can find in the way of repair parts.

gnh

I discovered over the weekend that we still have a ground fault in the PNWC 6800 electrical system. It appears to be a dead short between the positive and the car body.

I went back down tonight and started on the process of isolating the fault.

It is between the battery box and the electric locker. The path is two parallel 500 MCM cables, effective resistance to ground is zero.

I’ll try and get down again later in the week and start by disconnecting the starter motor for the 3-71 from the battery, and go from there.

gnh

You may recall we reported in April that the diaphragm on the 6800 was damaged. Figure 1 was taken in April when the damage was found.

The 6800 & Round End have been spotted with workspace between the cars. Phil Barney built a bridge between the cars that has been helpful with the repair work so far.

This weekend, Keith & I went down to make further progress on the demo of the diaphragm. Keith used his angle head grinder to cut the diaphragm assembly away from the car. When we let it loose, it fell against the diaphragm on the Round End. The Round End moved away from the 6800, and the bridge collapsed. See Figure 5.

We made a little progress on cutting the pieces apart, and then it started to rain and we went home for the day.

I went back tonight and finished cutting the diaphragm apart and loaded up the remains. See Figures 6 & 7.

Figure 4 is a shot taken of the end of the Zimmerman baggage car that has the type of tube diaphragm we hope to put in place on the end of the 6800.

gnh

Figure 1 attached shows the overhead heat control valve under the PNWC 6200 during Holiday Express 2010. The steam leak visible in the photo comes from the stem seal in the control valve.

Figure 2 is a photo of the bellows assembly that is used to seal the valve stem. It’s a complex assembly that includes a copper bellows that allows the stem to move, a brass inner piece, and a stainless steel stem. The stem has broken loose and that is the origin of the steam leak.

Repair is complicated because the bellows has to be compressed in order to expose the joint. There is also a soft solder joint at the end of the bellows that must be kept cool in order to avoid having the whole assembly come apart. The stem has to be held in position as well as in alignment so that the assembly will fit within the valve body.

Figure 3 shows the bellows in the jig that I built ready for repair. Silver solder and flux have been applied after the joint has been carefully cleaned of all dirt and oxide. The silver solder is a special alloy that contains nickel and is specifically recommended for joining stainless steel & brass. A strip of terry cloth towel will be wound around the bellows and soaked with water before the oxygen – propane torch is used to heat the joint. The aluminum jig and wet towel will prevent the soft solder joint from melting.

Figure 4 shows the joint after brazing has been completed. The assembly has been washed in hot water to remove the flux. This is expected to be a permanent repair.

Figure 5 shows the jig used to make the repair. The bottom of the assembly has a post with a spring that supports the stem for soldering. The concentric hole in the bottom holds the end of the bellows in alignment. The compression plate is made in two layers, the concentric hole holds the top of the bellows in position. The top bar holds the stem in alignment for soldering.

(I repaired two of these bellows assemblies, both had the same problem. The first one took six tries before I was able to get the solder to flow where I wanted it. It’s difficult in part because the stainless steel is very thick and a very poor conductor of heat, while the brass is very thin and tends to wick the heat away. The whole assembly has to be cleaned and flux applied after each attempt.  I was being very cautious to avoid overheating the whole assembly, and it the end found I was not using nearly enough heat. The second assembly only took two attempts to complete the silver soldering.)

The next step is to reassemble the valve and then test the complete assembly before re-installation under the PNWC 6200.

Special thanks to Ron McCoy who provided the hole saw and drilled one of the holes used in the jig.

gnh

On Friday, April 8, 2011, a special train operated on the OPR. The train was used in a movie shoot for the series Leverage.

The train consisted of locomotive OPR 100, coaches Mt Hood, Plum Creek, Red river, Baggage Car Gordon Zimmerman, and OPR Caboose.

Operations with the production company concluded at about 1:30 PM, at which time the train returned to Site 1 behind the locked gate.

On Saturday, 4/9/2011, OPR switched the consist to return the cars to their original positions in the string, with the exception of the Zimmerman which remains next to the South Gate. Before switching started, I was met by George Lavacot, who reported the diaphragm on the PNWC 6800 Red River had been damaged, apparently by the buffer assembly on the Zimmerman baggage car.

The car has been positioned with a gap between the 6800 & the Round End to permit access for repair purposes.

I’ve attached a few photographs as follows: Figures 1 & 2 are views of the B end of the PNWC 6800 where the diaphragm is damaged. Figure 3 is a view of one end of the Baggage Car that shows the buffer plate and tube diaphragm.

gnh

Figure 1 attached is a photo I took during HE2010, showing a steam regulator valve under the PNWC 6200 leaking steam around the flow limit valve stem.

Figure 2 is a photo of the metal bellows that provides the stem seal for the leaky valve. The stem is supposed to be attached to the bellows, the joint has failed and the stem has broken loose from the bellows. That is the source of the leak.

I have a surplus valve that I can use to obtain the part needed to fix the leaking valve.

I’ll send another update after repairs are completed.

gnh

The blog is starting in the middle of a project-installing new wheelsets on the Mt. Hood. As part of that work we’re doing some repairs to the trucks on Saturday October 30 we installed new bushings in the brake beam.