From the Illinois Railway Museum Blog, January 11, 2011

http://www2.irm.org/blogs/

Perhaps one of the biggest news items concerns Chicago Surface Lines 3142, a true workhorse of our summer Museum operations. Since its initial restoration that car puts on a lot of miles and we were well aware of the impending shortage of replacement cast iron brake shoes. For two years this has been in the process, with many hundreds of hours invested in the shop and by members at home. Remember that brake shoes are CONSUMED in operations and this is not normally covered by restoration funds. In this case the tab could well run to $8,000, or we face the possibility of the car not operating this entire season.

Our efforts to date have come to several dead ends for a variety of reasons, not the least of which is the disappearance of small foundries suited to make these specialty castings in small quantities. But we made a lot of progress this week. Lorne Tweed has taught himself to use AUTOCAD and created a file for the brakeshoe pattern. This was converted to a stereo lithography file and a plastic prototype was created using a 3D printing process in nearby Crystal Lake.

With this tangible sample in hand it was fitted to the car, and needed adjustments were defined. The next steps will be to furnish this prototype to a foundry who will use modern laser tracing to mill a new pattern for the shoes and get them cast. HERE'S HOPING - - -

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While Maine is significant distance away from Illinois, and I'm sure that standard gauge trolley brake shoes are much different in size and shape than two foot gauge brake shoes - we use a local foundry for our brake shoe (and other casting) needs. Auburn Stove Foundry in Auburn, ME.

Would it be possible to fabricate a brake head that would accept an off the shelf composite shoe?

dave

Possibly, but that wouldn't be a historically correct restoration, would it?

Jeff

You just cannot make a change like that. Cast Iron shoes have a different coefficient of friction than the composite shoe. You would have to make changes elsewhere in the brake system and/or its rigging.

There are low friction composite shoes available, which are direct replacements for cast iron brake shoes. No changes in cylinder pressures or sizes, or leverage ratios are needed, just remove the old cast iron and apply the low friction comp shoe. Much lighter than their cast iron equivalents (think lower shipping costs), they are typically a bright yellow color to distinguish them from their high friction composite counterparts. I have heard some roads are now using them on their steam locomotives.

Mike Tillger