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 Post subject: Brake shoe condeming limits?
PostPosted: Fri Feb 14, 2020 3:11 pm 

Joined: Mon Aug 23, 2004 9:37 pm
Posts: 274
Location: Niles Canyon Railway, near Sunol, CA
For cast-iron (steel back) and composition brake shoes - for tread brakes, not disk brakes:
1. What are the pass/fail specs for cracks and limits of wear?
2. What document has these specs?

Last night I skimmed thru the
Association of American Railroads
Code of Rules
Governing the condition of, and repairs to, freight and passenger cars
for the
Interchange of Traffic
Effective January 1, 1968

but couldn't find specs on brake shoe limits of wear and cracks.

Thanks in advance,
Doug Debs


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Fri Feb 14, 2020 4:00 pm 

Joined: Tue Dec 06, 2016 11:37 am
Posts: 18
Doug,
You want the Field Manual of the AAR Interchange Rules. Rule 12 covers cast and composite shoes.
My manual is the 1998 edition. I’ll see if I can post some pics (lunch time, on my phone).
Brian


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Fri Feb 14, 2020 4:40 pm 

Joined: Mon Aug 23, 2004 9:37 pm
Posts: 274
Location: Niles Canyon Railway, near Sunol, CA
Hello Brian:

Thank you! I just ordered a 1974 Field Manual of the AAR Interchange Rules from eBay ($5.99).

- Doug Debs


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Fri Feb 14, 2020 5:19 pm 

Joined: Wed Oct 13, 2004 12:56 am
Posts: 404
Location: Northern California
There are no fed. limits on brake shoe wear. There is no limit on cracks. Brake shoes are full of expanded metal so they will not fall apart if the cast iron cracks. The AAR wear limits on brake shoes are to get the brake shoe to the next inspection point without damaging the brake head and for billing reasons. In a controlled low mileage environment brake shoes can be worn right down to the brake head. What is really important is to ensure that piston travel does not get excessive.


Last edited by David Johnston on Sun Feb 16, 2020 12:36 am, edited 1 time in total.

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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Sat Feb 15, 2020 6:26 pm 

Joined: Tue Jul 06, 2010 1:57 am
Posts: 210
For what it's worth, back when I used to do car inspections, I was only ever taught about condemning limits on brake pads for disc brakes (3/8ths or 3/16ths, I can't recall off of the top of my head). When it came to brake shoes, I was taught there was no limit except the limit of usefulness. We were even encouraged to flip brake shoes that were wearing unevenly from top to bottom to make the most of the braking material.


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Sat Feb 15, 2020 8:50 pm 

Joined: Fri Apr 22, 2005 10:43 pm
Posts: 26
Anything less than 1/4 inch comes off at inbound inspection, as Dave said cracks don’t matter.


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Sat Feb 15, 2020 10:59 pm 

Joined: Thu Oct 03, 2019 2:31 pm
Posts: 15
It all comes down to how long do you think this shoe will last in the service its used in. when you are looking at the rim and the shoe is 1/2 inch. You have to consider that the tread is tapered. When we serviced locomotives if it was going to an outlying point you changed shoes because it was going to be out on the railroad for a while. And we would use the thinner shoes when we serviced local power. You haven't lived until you've dropped a cast iron shoe on your finger. Ran across locos that had an extra long cast iron shoe they were veeeeery heavy.


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Sun Feb 16, 2020 4:12 am 

Joined: Sun Aug 22, 2004 8:51 pm
Posts: 1769
Location: Southern California
When inspecting, be thorough.

I recall being on a multiple-day, overnight special train made up of a mix of private and Amtrak cars back in the '70s. During a return stop in Las Vegas one brake shoe was found to be almost or completely worn through to the brake head. Now this was also an over-riding brake shoe and when quickly observed with the brakes released the shoe showed no wear on the out edge. This sleeping car was in the middle of the train and for the overnight run to Los Angeles the brakes on the car were cutout. Now, I do not remember if this was a private car or an Amtrak car.

Another incident involves a heritage/museum special event -- a two-weekend "rail festival." During the day the crews on the multiple trains where changed several times. A brake test was made by each incoming crew. For most of these the brakeman had the brakes set and he walked the train checking that the brakes were applied; then they had the brakes released and returned to the rear of the train observing all the brakes were released.

Then we had a brakeman who was more diligent about doing the inspection; before having the brakes released he walked back to the rear of the four-car train. And there he found the brakes to have leaked off on the rear car. There was a leak in the 14" or 16" dia. brake cylinder of this heavyweight Pullman. We had the space to back up the train at this single end terminal and uncouple the car until the piston cup was replaced that evening (or the following week) after the event day.

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Brian Norden


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Sun Feb 16, 2020 1:06 pm 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1772
Location: Strasburg, PA
Zak Lybrand wrote:
For what it's worth, back when I used to do car inspections, I was only ever taught about condemning limits on brake pads for disc brakes (3/8ths or 3/16ths, I can't recall off of the top of my head). When it came to brake shoes, I was taught there was no limit except the limit of usefulness. We were even encouraged to flip brake shoes that were wearing unevenly from top to bottom to make the most of the braking material.
Yep, I've flipped shoes over, and swapped them side to side as needed if they weren't traking on the tread properly. Back in the '80's Huber Leath would pitch a fit if you replaced a brake shoe that you couldn't see through.

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"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."
C. S. Forester

Strasburg Rail Road Mechanical Department


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 Post subject: Re: Brake shoe condeming limits?
PostPosted: Sun Feb 16, 2020 8:37 pm 

Joined: Mon Aug 23, 2004 5:10 pm
Posts: 1049
We used to call those really worn brake shows "slippers!"


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