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Locomotive Brake Shoe Force on Wheel
https://rypn.org/forums/viewtopic.php?f=1&t=37547		 Page 1 of 2
Author:  Rick Rowlands [ Mon Jan 12, 2015 12:55 am ]
Post subject:  Locomotive Brake Shoe Force on Wheel
Jones & Laughlin 58, our 23" gauge Porter 0-4-0T, was never equipped with engine brakes and none of the cars it handled had brakes either. I suppose braking was handled with the johnson bar or they just banged around a lot. We are planning to add a rudimentary steam jam brake to the locomotive which will use two brake shoes pushing against the rear drivers.

I am trying to figure out what the braking force should be for cast iron locomotive brake shoes on standard gauge locomotives and how it is determined. Is there one value that is desired, or is there a formula that takes into account the weight of the locomotive in caclulating the braking force?

If I can understand the engineering behind locomotive braking, I can do the math and figure out the braking force that I will need.

The photo is of a brake shoe and holder mocked up in place. To the left you can see where we are missing the entire rear end of the locomotive, which will be rebuilt. The brake system will consist of two brake hangers tied to a crosswise brake beam and pushed from the middle by a cylinder placed between the frame.

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Author:  David Johnston [ Mon Jan 12, 2015 4:00 am ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
Normally you would want 100% of the weight of the locomotive as the force on the brake shoes, gross. Since the plan is to brake only half of the axles, 50% gross would be used. Applying the force at the brake beam will reduce rigging losses, so the gross and net will be nearly the same, so maybe a 35% force will be more appropriate. This is based on cast iron shoes. There are other considerations. I would recommend you get a copy of the book Engineering and Design of Railway Brake Systems, put out by the Air brake Association.
Author:  Rick Rowlands [ Mon Jan 12, 2015 10:24 am ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
Thank you David. I am going to defer spending $75 for the book for now, but based upon your 35% number that gives me 32,000 lbs. of braking force , exactly what an 8" steam cylinder at 160 psi would provide.

Anyone have insight on how the plumbing for a stream brake should be set up? What should I use for a brake valve, and how is condensation bled off? I'm afraid I've never seen a steam brake system in person to study its components.
Author:  Mike Tillger [ Mon Jan 12, 2015 11:40 am ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
Rick,
a copy of the 1921 book titled "The Principles and Design of Foundation Brake Rigging" bu the Air Brake Association is available in Google books
https://books.google.com/books?id=DoNBAQAAMAAJ&pg=PA94&lpg=PA94&dq=designing+brake+rigging+for+railroad&source=bl&ots=bl8zxJtb0c&sig=soyOYE_h4RFXLXaQlhMS82aUBPg&hl=en&sa=X&ei=lOSzVIzYGYm1sQTevIDQCg&ved=0CDIQ6AEwBTgK#v=onepage&q=designing%20brake%20rigging%20for%20railroad&f=false

Mike Tillger
Author:  Dave [ Mon Jan 12, 2015 1:18 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
The brake valve is a simple 3 way steam valve that has the center connected to the cylinder, one side to the boiler and the other to exhaust to the atmosphere. The drain valve is located at the lowest point where the steam line enters the bottom of the cylinder head, and consists of a poppet similar to a cylinder cock with a light compression spring to hold it open until an application is made, at which time the steam pressure coming to the cylinder to apply the brake acts on the top of the poppet and closes the drain. When released, the light spring lifts the poppet off its seat and lets the condensation drain out of the system.

dave
Author:  Kelly Anderson [ Mon Jan 12, 2015 5:37 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
.
Author:  Mike Tillger [ Mon Jan 12, 2015 6:25 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
I would have some concern maintaining that high of a braking ratio on a single set of wheels using the short length of brake shoe shown in the photo. Also would there not be some concern with wear of the tread and changing wheel tape sizes on rod connected drivers. Would it be possible to install the brakes to operate between the drivers with a shoe on each wheel using a wedge or cam mechanism ala the early American type locomotive steam jam brakes.

Mike Tillger
Author:  Rick Rowlands [ Mon Jan 12, 2015 7:10 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
Mike, I understand your concerns about premature wear of one set of drivers with brakes on only one axle. The frame is SOLID and there are 4" slabs that sticks out between the drivers too. Of course that is what makes this locomotive unique, but at the same time it complicates what otherwise would be simple matters. It may be possible to add two additional shoes in front of the front drivers. I have to be very careful to do it in a way that preserves as much clearance as possible between the rigging and the top of the rail.

Kelly, on that 60% figure, is that number spread out amongst however many shoes are on the locomotive? In my case, with a 93,000 lb. locomotive, 60% would be 55,800 lbs. and spread out amongst four shoes would be 13,950 lbs. force per shoe, or 27,900 lbs. if I have to stay with just two shoes.
Author:  Dave [ Mon Jan 12, 2015 7:31 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
Might be worth knowing that we're running at walking speed on a couple hundred feet of track hauling a few ingot buggies. I think we can make do with much less than would be necessary for non industrial operation.

dave
Author:  Kelly Anderson [ Tue Jan 13, 2015 9:56 am ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
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Author:  Rick Rowlands [ Mon Nov 23, 2015 9:24 am ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
I'm back working on the idea of the steam brake for the 58, and am looking for a steam jam brake valve. I am sure there must be a few laying around off of locomotives that steam brakes were removed from, so if you know where one might be I would be interested. Also might be interested in a steam brake cylinder if the right size.
Author:  dinwitty [ Mon Nov 23, 2015 10:55 am ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
...or ask one of these 7 1/2" gauge folks to build a brake valve..

with friction bearings on engine and cars they may not roll far at the slow speed
Author:  QJdriver [ Mon Nov 23, 2015 4:23 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
If you're not hauling passengers, try doing it the way it was really done. Open your cylinder cocks, reverse that sucker, and give it a shot of steam. You'd be surprised how good that works, they even weighed cars that way at Westfield Sugar Estate. Those engines would have had steam or air brakes if they were needed for the service they performed.

No parking brake, either, I take it ???
Author:  Lincoln Penn [ Mon Nov 23, 2015 5:02 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
Rick:

Kelly's advice is sound.

If you do go with composition shoes, black or yellow, you will need different brake heads,
as heads for iron shoes will not accept composition shoes and vice-versa. This is because of the differences in pressures.

On the good side, you won't have to give a thought to where to find replacement shoes.
There are millions of them out there and more being manufactured every day.

You most likely would be able to find a steam brake valve on some industrial 0-4-0T or 0-6-0T in a park someplace.
Author:  Jennie K [ Mon Nov 23, 2015 9:26 pm ]
Post subject:  Re: Locomotive Brake Shoe Force on Wheel
You may want to take a trip up to Sandusky, Cedar Point's roster of locomotives are still fitted with steam jam brakes. Their #4 is a Porter and you could see in person how it was done.
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