Allen Steam Brake Cylinder

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ccvstmr
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Allen Steam Brake Cylinder

Post by ccvstmr » Sat Oct 07, 2017 9:30 am

Working on some Allen steam brake cylinders. When the cylinders were opened to inspect the bore, noticed there was no spring inside (also noticed the O-rings were not as indicated on the drawings...and both O-rings were different sizes! Go figure!) Drawings indicate a stainless spring (could) be used, but no spring dimensions were provided. Question...for those that DID use a return spring in the cylinder, have any spring info (OD x ID x wire size x length)?

Also, noticed there's a "vent" hole on the lower cylinder cover. Makes sense. However, there's nothing on the drawing for draining condensate on the steam side of the piston. Have an idea to drill a #80 hole in the piston...and let condensate drain out the vent or around the piston shaft. Question...what have others done to drain the pressure side of the brake piston.

Comments, suggestions, dimensions...or other? Thanx. Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
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johnpenn74
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Re: Allen Steam Brake Cylinder

Post by johnpenn74 » Sat Oct 07, 2017 7:33 pm

On my ten there was no bleed on the steam side. It was done through the brake lap valve. It works, but takes forever since the ports in the valve are tiny. No application issue, but takes forever to release when when used as a parking brake. Lap valve is pointless on steam of course. I believe a constant bleed on the line is a good thing. My orings were so far gone that the blow by provided the steam side bleed when applied. My correction (including new orings) was to put in a tee to the steam supply line where I added a plug with a hole. This allowed me to keep up sizing the plug until I got the response time and release right. If I screwed up, just start over with a new plug.

JP
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johnpenn74
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Re: Allen Steam Brake Cylinder

Post by johnpenn74 » Sat Oct 07, 2017 7:35 pm

Can anyone explain what the prototype configuration of steam brakes is? Valve type? surely there is some kind of purging mechanism on the cylinder or steam line.

JP
John Pennington

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2 Mich-Cal Shays
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Reading A5a Camelback 0-4-0
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John_S
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Re: Allen Steam Brake Cylinder

Post by John_S » Sun Oct 08, 2017 6:43 pm

I've been running my mogul with steam brakes built as designed without any issues. No need for a drain on the steam side.

If I'm putting the loco up for a long while I'll pump the boiler up with compressed air and actuate the brake valve over and over again to get any residual water out of the lines. Otherwise I just leave it in there and have never had any issues.

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ccvstmr
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Re: Allen Steam Brake Cylinder

Post by ccvstmr » Sun Oct 08, 2017 7:27 pm

John, thanx for the info tidbits...

When I opened these brake cylinders up...had to drain the water out of the steam side of the piston. Opted to drill a #73 hole thru the piston and allow any water to migrate thru the piston and be evacuated thru the lower vent or around the piston shaft.

Do you know if your brake cylinders have internal retraction springs? ...or do you have retraction springs under the loco attached directly to the brake rigging? Carl B.
Life is like a sewer...what you get out of it depends on what you put into it!
I don't walk on water...I just learned where some of the stepping stones are!
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NP317
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Re: Allen Steam Brake Cylinder

Post by NP317 » Mon Oct 09, 2017 10:17 am

John_S wrote:I've been running my mogul with steam brakes built as designed without any issues. No need for a drain on the steam side.

If I'm putting the loco up for a long while I'll pump the boiler up with compressed air and actuate the brake valve over and over again to get any residual water out of the lines. Otherwise I just leave it in there and have never had any issues.
Same story with my Ten Wheeler.
This year I finally serviced the steam brake cylinders after 13 years of use. Disassembled them, cleaned out anything that was in there, and made sure the springs were still functioning. The best thing was smearing high-vacuum silicon grease around the pistons and o-rings. This stuff is heat and water proof, and now the brake pistons properly release from the spring force! I should have used that stuff when first built.

Several years ago I also installed a bleed valve in the steam line just above the cylinders, under the Engineer's side. Part of shutting down the loco is to open the valve to better allow the compressed air to remove the water. So far, it works well.
~RN

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