1wonton Posted October 4, 2016 Share Posted October 4, 2016 Adding spring brakes to my old trailer. Have service brakes only now, what components do I need? Have relay valve on truck (B75 Mack) for truck spring brake: do I need another relay valve on trailer, or what? Simple diagram for a simple man, please. Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/ Share on other sites More sharing options...
Popular Post BGarofalo Posted October 5, 2016 Popular Post Share Posted October 5, 2016 Easiest way to convert is get yourself a full function valve like a Haldex KN28601. Valve threads into tank and provides all functions thus eliminating additional valves. Service and park hose go from valve to each chamber and 2 air lines run from the front of trailer to valve. Very straight forward conversion. I have a customer with old 70's era tankers that we converted over to spring brakes with this method. 3 Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-347857 Share on other sites More sharing options...
1wonton Posted October 8, 2016 Author Share Posted October 8, 2016 10/4, thank you, I'll check it out. Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348170 Share on other sites More sharing options...
thomastractorsvc Posted October 11, 2016 Share Posted October 11, 2016 You should also add another air tank. I restored a low boy trailer last year and posted about it. search my name and you will find it. 1 Quote Robert"I reject your reality and substitute my own." Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348390 Share on other sites More sharing options...
ranchhopper Posted October 11, 2016 Share Posted October 11, 2016 I just added spring brakes to both axles on the rear of the superliner now I have a bit of air coming out of the quick release valves when the brakes are released. Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348416 Share on other sites More sharing options...
Popular Post alex g Posted October 11, 2016 Popular Post Share Posted October 11, 2016 Your quick release valve could be faulty or you have a faulty brake chamber leaking air back thru system Sent from my SM-G386W using Tapatalk 3 Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348437 Share on other sites More sharing options...
ranchhopper Posted October 11, 2016 Share Posted October 11, 2016 8 hours ago, alex g said: Your quick release valve could be faulty or you have a faulty brake chamber leaking air back thru system Sent from my SM-G386W using Tapatalk Its coming out both quick release valves I figure there may be a bad diaphram or something wrong with one of the chambers. Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348470 Share on other sites More sharing options...
alex g Posted October 12, 2016 Share Posted October 12, 2016 Sounds like you may have something plumbed wrong. Sent from my SM-G386W using Tapatalk Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348473 Share on other sites More sharing options...
ranchhopper Posted October 12, 2016 Share Posted October 12, 2016 15 minutes ago, alex g said: Sounds like you may have something plumbed wrong. Sent from my SM-G386W using Tapatalk I run the lines like they were run when I got the truck it only had spring brakes on the rear axle used the same line and split it with a T they had a distribution valve the spring brakes and service brakes came out of Which I eliminated because I ran the service brakes from a single valve instead of splitting it with one valve per axle. Quote Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348477 Share on other sites More sharing options...
j hancock Posted October 12, 2016 Share Posted October 12, 2016 Here is a link to a Bendix brake book and there are several diagrams that may help. http://www.suspensionspecialists.com/techinfo/Bendix_Brake_Handbook_2009.pdf 1 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/47152-spring-brakes/#findComment-348519 Share on other sites More sharing options...
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