20 Ton Trailer Air Brake Diagram

[OMB]

Hi,
I bought a used but not abused 1988 20 ton trailer last week that has had the air brake system neglected(understated)- parts missing and doesn't have spring brakes at all. I'm going to replace everything- cans, valves, lines, tank, etc.-looking for an air brake layout for the service and E brake but without ABS and an ECU.
Thanks in advance.

 

[nowing75]

Who makes it. I'm sure they will email you parts diagram. If it's a trail king let me know I have the books for it.

 

[OMB]

Custom Trailers which is not the current Custom Trailer Manufacturing, they went out of business about 12 years ago.

I'm sure they will email you parts diagram.

I contacted CTM and they had the courtesy to email a diagram but it is for the truck side, not trailer.

A Trail King diagram should work. I would imagine before ABS and ECUs there was one generic layout and I could figure it out but I'm going to take the easy way.

 

[heymccall]

Spring brakes weren't required by law, back then. My '95/'97 20 ton tag trailers don't have spring brakes.

 

[OMB]

Spring brakes weren't required by law, back then. My '95/'97 20 ton tag trailers don't have spring brakes.

You are correct. I don't know when the regs changed but my interpretation of the current FMCSA regs require E brakes on 2 axles on any trailer over 3,000 pounds (with exceptions). Quoted from FMCSA 393.43 Part C:
(d) Breakaway braking requirements for trailers. Every trailer required to be equipped with brakes shall have brakes which apply automatically and immediately upon breakaway from the towing vehicle. With the exception of trailers having three or more axles, all brakes with which the trailer is required to be equipped must be applied upon breakaway from the towing vehicle. The brakes must remain in the applied position for at least 15 minutes.

I'm not sure what things are grandfathered and what must be updated. A pre-1980 truck didn't have to have front brakes and that same truck isn't required to have front brakes now but older trailers seem to need maxi brakes even if they weren't originally built with them.
I'm doing the service and spring brakes but without the ABS & ECU.
Thanks to nowing75 for your help.

 

[525isx]

from sealco site --- http://www.sealcocvp.com/home/tech/pipe/sys/index.htm --- you don't need spring brakes,an emergency relay valve (instead of a standard relay ) will set up the brakes when disconnected, but spring brakes are nice.

525

 

[Birken Vogt]

Probably the simplest way to do spring brakes on a trailer that did not have them is to leave everything the way it was originally, just replace the cans with spring cans and plumb the spring chambers right to the reservoir.

This way, when parked, the emergency relay valve will apply air to the service chambers, until it leaks away, then the springs will gradually take over.