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3 line brake chambers

PostPosted: Tue Mar 12, 2019 3:12 pm
by V8Brockway361TL
Was wondering how many people have come across 3 line brake chambers in the past. Definitely White trucks ( 60s era) had these and i think some early Brockway's did. When releasing the parking brakes it also required a minimum of a 90 pound application on the foot pedal to release the brakes. If you did not do the foot application you could feel the brakes dragging. Never had any experience with them other than a driver. But looked like there were 3 air lines going to the chambers. In my own mind thought the 90 pound application helped to push parking brake side back. Stan probably has had experience with these. Thanks Frank

Re: 3 line brake chambers

PostPosted: Tue Mar 12, 2019 8:43 pm
by Huskiedrive2
Well Frank, I'm sorry. In 43 years of messing with these trucks I've never heard of a 3 line brake chamber. You mentioned applying the service brake to assist in releasing the park brake. That would require a service air line which as we know is one of the two lines on current production chambers. I can't get my head around what the third line could be, unless in might possibly be an exhaust line if the quick release valve were built into the chamber. Single action chambers and piggyback chambers with a parking brake function have looked pretty much the same since the '40's. Single action first of course and then piggyback in the '60's. I you find any information, please share what you find.

Re: 3 line brake chambers

PostPosted: Wed Mar 13, 2019 7:31 pm
by V8Brockway361TL
Without a doubt there was instructions near the traditional looking parking brake button telling you to make the minimum 90 pound application. Of course I tried it without doing it to see what would happen and you could feel you didn't have a 100% release. Then I would step on it and unit rolled free. I almost 100% sure there was 3 lines going to chambers but never had the opportunity to get underneath. Our White's had them and I thought a couple of our 60 era Brockways had them. Thanks Stan

Re: 3 line brake chambers

PostPosted: Wed Mar 13, 2019 9:20 pm
by fuller10b1120
this brake systemis the dd3 system found on most bus
es I cant type i know the system 207 512 0039 aimenyt