The Home Machinist!

Here are some more photos showing the braking system for the Mogul.

This system allows for the boxcar to be used with a different train if desired, and if we are doing a card order event the portable compressor system may be used to hold the train while switching is being done.

really nice but ..... you really should not use pvc pipe as an air reservoir....especially where it appears you are drilling tapping the pipe wall for fittings.

Two things.
In my opinion you should always have brakes on the tender as well as the engine. The additional mass of the tender and engineer will aid in stopping. Just my two cents.

Second, and down the wormhole we go. Bill from what I've read over time you are right about not using PCV in air line service. The oils used to lubricate the compressor and anything downstream interact with the PCV and attack it, providing the potential for failure of the pcv at some point.

I know folks have been plumbing their shops for years with it, and Tom actually supplies the "air tanks" with his brake system using pcv pipe. I have seen lots of train brake installations using pcv as the reservoir.

So, it seems like a bad choice to be avoided if possible.

Having said that, I wonder if the degradation of the pcv is lessened dramatically in the train brake applications as the only lubrication presented to the system is installed at the factory that makes those little compressors we use.
I.e. I have not seen an airline lubricator installed on one of these types of train brake installations.

Harold, if I've wandered off the original thread please move to a new post.

Thanks,
Brian

Many years ago the issue of using PVC for compressed air generated a heated debate on a machinist forum. I decided to avoid speculation and called a PVC manufacturer and spoke to one of their engineers. He said they do not recommend it for air as it can become brittle with age and exposure to sunlight. I already had PVC lines in my shop and I left them there. Years later I needed to re-route the shop air lines and when pulling out the old ones, I dropped one on the cement floor. It shattered into a number of small pieces, all of which had sharp edges. I replaced all the air lines with copper. Based on these two facts, I no longer use PVC for air in any application.

What Greg said. If you choose to use plastic, the market offers green ABS, which is made specifically for compressed air use. Even if it ruptures, it doesn't create shrapnel.

So far as I'm concerned, the comments relating to the use of ABS as an air reservoir can remain in this thread. The topic has been discussed previously on this board, so having it appear in more than one venue isn't a bad idea. Folks are going to do what they wish to do, regardless of the advice to avoid the use of ABS----but having valuable information provided in several places, hopefully, will expose more to information that can spell the difference between success and failure.

Harold

To all: I bought the brake materials from Tom Bee, not knowing any of the history spoken of on the thread. If and when the cylinder fails I will try to get a metal tank to replace it, but for now I am going to use them as they are because both systems we have are enclosed in a boxcar or another type of car to set brakes when doing switching operations at a card order meet.

Thank everyone for the input, it is appreciated.

RG

the problem is that when the cylinder fails, it will fail catastrophically...completely without warning

I decided to use ABS pipe for my brakes on the electric & my LE mogul, max 60 psi. Works well. For those concerned with plastic pipe failure, Clippard offers stainless steel air tanks (link provided).

http://www.clippard.com/part/AVT-32-16

Chris Donhost
Vacaville, CA

Don

Thanks for the link--this might prove to be the easiest upgrade. I would not have known that such tanks were available so your input is greatly appreciated. I know that others have capabilities to fabricate or make tanks out of other materials but my access to tools other than hand tools is not possible.

RG

Years ago, there was an incident at one of the company printing plants. Synthetic oil was used in the pneumatic air lines to lube air cylinders, valves and such. Many of the machines in the printing line had filters, dryers, etc. with polycarbonate bowls. Found out (the hard way) synthetic oils are not compatible with the plastic bowls and eventually (1) exploded. Shards of plastic pierced a perforated sound barrier between machines some 8-10 feet from the back of the machine. Equipment specifications were amended to state such pneumatic equipment had to have metal bowls...or metal shrouded polycarbonate bowls. Equipment supplies complied. A safety bulletin went out to all plants to upgrade their equipment accordingly.

If you're looking for a relatively quick and dirty air reservoir...save those old hardware store propane cylinders. When they're EMPTY...take a pin punch and knock the valve out (you'll never get it out of the cylinder). Open the hole and tap for a 1/8 NPT fitting. Install a 1/8 NPT fitting and reduce to 10-32...and that will easily connect to Clippard type pneumatic fittings (or similar). Have had one of these kinds of "reservoirs" in service for 10 years without any issues. If it's going to rupture, don't believe it's going to be as violet as the exploding plastics. Carl B.

Happy to help, Ray. I like Clippard, and use their stuff. However, their shipping fee is steep, especially when ordering a single item. I try to group my purchases from them.

Here is another possible solution - these tanks hold around 3000psi for paintball guns. I have a couple extra tanks, and might consider ditching the ABS tanks, based on the content of this thread. Sometimes you can find used ones on Craigslist and at the local paintball shop for cheap. They have built-in pressure release valves to prevent the tank from exploding.

https://www.google.com/?ion=1&espv=2#q= ... k&tbm=shop

Chris Donhost