Delay on trailer brakes

[REEL ADDICTION]

I have a flat bed trailer when I hook it u to my tractor and drive it down the road when I apply the brakes it seems that the trailer brake 5 seconds later what could it be when I am hooked up to my lowboy this does not happen so we know its not the truck has to be with trailer. Also the brakes on trailer are good and they do release well. Could it be the main valve? Thanks for the help.

[David]

Did it do this before it got cold?

[REEL ADDICTION]

yes

[REEL ADDICTION]

i don't really use the trailer much spends more time parked than on the road

[hatcity]

Check adjustment first.

I like the trailer to catch first.

If adjustable, tighten then back off a quarter turn.

Pull arm to see stroke distance and set all trailer brakes the same

[David]

Might be a dirty or a bad quick release.

[rsb502]

Is this a spring brake trailer or an air over air? (Spring parking brakes or no) there is a different valve on an air over air brake system that will activate slowly when they get crusty inside. When were the brakes greased last? I know I'll catch hell for that one but I have this issue constantly with our backhoe trailers and 9 out of 10 times we can grease it and fix the issue the other 1 its the brake valve on am air over air. An air over air(no spring brake) will be slower to activate than a spring brake trailer due to relay valving on spring brakes it normally direct activation on a trailer.

[39 Baby Mack]

Is this a spring brake trailer or an air over air? (Spring parking brakes or no) there is a different valve on an air over air brake system that will activate slowly when they get crusty inside. When were the brakes greased last? I know I'll catch hell for that one but I have this issue constantly with our backhoe trailers and 9 out of 10 times we can grease it and fix the issue the other 1 its the brake valve on am air over air. An air over air(no spring brake) will be slower to activate than a spring brake trailer due to relay valving on spring brakes it normally direct activation on a trailer.

Are you sure about the direct activation of service brakes on a trailer without spring parking brakes?

A B&W RE-4 valve acts as a relay valve and an emergency valve---hence the name Relay Emergency valve.

Ron

[rsb502]

They didn't use a relay valve on any of my old trailers with spring brakes and I can't remember any of the trailers at Howard baer having them either, on air over air all the ones i have dealt with have the same valve.

[rsb502]

To better answer your question its the other way around, relay on air, not on spring.

[39 Baby Mack]

On all the old trailers I've ever dealt with

a trailer without spring brakes had a relay-emergency valve mounted to or fed by the tank on the trailer.

they had the emergency line and the service line going to this valve

coming out of this valve were delivery lines either two for a single axle or four for a tandem that feed the service chambers on the axle(s).

When in normal operating position the emergency line in the trailer constantly feeds the reservoir with air through the relay-emergency valve.

When a service application is made air going through the service line to the relay-emergency valve opens a valve in it and allows air to flow

from the reservoir to the chambers to make a brake application.

When in emergency position, when you put the tractor protection valve in park to drop the trailer, or in the case of an accidental separation air is cut off from the

emergency line and the relay-emergency valve then directs the air from the tank out to the brake chambers to lock them up.

That's what enables you to pull out from the trailer without it trying to follow you.

Or in the case of an accidental separation would lock the brakes on the trailer so it wouldn't be so wildly out of control.

The relay-emergency valves that I was used to dealing with on our old trailers were either B&W RE-4's or Sealco A-1000's.

The Sealco's looked like a flying saucer and acquired the nickname "Flying Saucer Valves"

Ron

[Freightrain]

So, you would have to air up the trailer to keep it in place to back under it again(I assume the tank would bleed down over time)? Or would you still be able to slip under without it moving? Inquiring minds........

[rsb502]

Freightrain, Baby Mack is correct on the air over air trailers brakes only work with air in the trailer reservoir, once the trailer tanks leak off the brakes are gone till you charge the system again. As you charge the system the brakes first set then release it takes longer for them to release to move the trailer than a spring brake trailer that t's and both charges the tank and releases the spring brakes since you have to charge the tank first to release the park brakes. The valves are a pain as they get older and I actually had a to wait a week to get one for an old Heil dump trailer I had a few years back everyone was out of stock. Freightrain the air over air brakes actually work very similarly to your namesake (freight train) brakes, on a train you have one train line that goes from the fron to the bak it charges the tanks on all cars in the train to 90psi then holds 90, as you make a brake set in the locomotive you are actually releasing air from the trainline and the pressure drop allows air from the reservoir on the cars to route to the brake chamber and set the brakes, the more you release the harder the set. If you have ever heard a locomotive set the brakes it lets air bleed off thru a valve under the engineers side of the cab, bad thing about train brakes once you drop the trainline too far by using the brakes too much you lose your brakes until you re charge the trainline releasing the brakes till you get back to 90psi. This has caused several runaways on hills over the years out west, the engineer makes a brake set, then another, then another not paying attention to his air usage and runs the train out, then all you have is locomotive brakes and dynamic brakes, which is a whole nother monster (I work for CSX, roadway equipment mechanic).

[39 Baby Mack]

Larry

They would leak down over time, some would hold longer than others.

I've backed under ones that have sat a week and wouldn't move and others that were parked the night before and started to roll off.

We used to have folding landing gear on these old trailers with honest to God steel wheels on them (no adjustment up and down)

in this case you used wooden blocks under the dolly wheels to adjust the height when you unhooked the trailer.

I always preferred using the term unhook rather than drop because that used to happen once in awhile!

I can remember backing in under these old trailers and seeing the trailer start to move.

Now when that happened the proper thing to do was to (STOP!) and hook the air lines to the trailer and charge the brakes then continue back

until the fifth wheel latched---makes sense right?

Well that meant you had to get out and hook the lines to the trailer, which sometimes were a little short depending on how far you got under the trailer

before it started to roll or find some more lumber to block the wheels on the trailer.

Another game you could play was "see if you can catch the trailer" this was played by quickly dumping the clutch while in reverse and hopefully hook the

trailer before it rolled off the blocks.

If it rolled off the blocks before it hooked it would then be to low to get under it without more lumber and a couple of bottle jacks to pick the trailer up!

Dumb game to play but I was guilty of it too!!!

Most times it worked but when it didn't it made you feel like a real asshole. How much time did you save from being lazy and not hooking the air lines up?

Ron

[rsb502]

Larry

They would leak down over time, some would hold longer than others.

I've backed under ones that have sat a week and wouldn't move and others that were parked the night before and started to roll off.

We used to have folding landing gear on these old trailers with honest to God steel wheels on them (no adjustment up and down)

in this case you used wooden blocks under the dolly wheels to adjust the height when you unhooked the trailer.

I always preferred using the term unhook rather than drop because that used to happen once in awhile!

I can remember backing in under these old trailers and seeing the trailer start to move.

Now when that happened the proper thing to do was to (STOP!) and hook the air lines to the trailer and charge the brakes then continue back

until the fifth wheel latched---makes sense right?

Well that meant you had to get out and hook the lines to the trailer, which sometimes were a little short depending on how far you got under the trailer

before it started to roll or find some more lumber to block the wheels on the trailer.

Another game you could play was "see if can catch the trailer" this was played by quickly dumping the clutch while in reverse and hopefully hook the

trailer before it rolled off the blocks.

If it rolled off the blocks before it hooked it would then be to low to get under it without more lumber and a couple of bottle jacks to pick the trailer up!

Dumb game to play but I was guilty of it too!!!

Most times it worked but when it didn't it made you feel like a real asshole. How much time did you save from being lazy and not hooking the air lines up?

Ron

Ha, I pushed that old Heil dump trailer back one day and it went about 50yds down into the back yard, with neighbors watching it was pretty embarassing!

[39 Baby Mack]

Freightrain, Baby Mack is correct on the air over air trailers brakes only work with air in the trailer reservoir, once the trailer tanks leak off the brakes are gone till you charge the system again. As you charge the system the brakes first set then release it takes longer for them to release to move the trailer than a spring brake trailer that t's and both charges the tank and releases the spring brakes since you have to charge the tank first to release the park brakes. The valves are a pain as they get older and I actually had a to wait a week to get one for an old Heil dump trailer I had a few years back everyone was out of stock. Freightrain the air over air brakes actually work very similarly to your namesake (freight train) brakes, on a train you have one train line that goes from the fron to the bak it charges the tanks on all cars in the train to 90psi then holds 90, as you make a brake set in the locomotive you are actually releasing air from the trainline and the pressure drop allows air from the reservoir on the cars to route to the brake chamber and set the brakes, the more you release the harder the set. If you have ever heard a locomotive set the brakes it lets air bleed off thru a valve under the engineers side of the cab, bad thing about train brakes once you drop the trainline too far by using the brakes too much you lose your brakes until you re charge the trainline releasing the brakes till you get back to 90psi. This has caused several runaways on hills over the years out west, the engineer makes a brake set, then another, then another not paying attention to his air usage and runs the train out, then all you have is locomotive brakes and dynamic brakes, which is a whole nother monster (I work for CSX, roadway equipment mechanic).

Sorry to disagree but they don't work like train brakes.

On a train, like you said, you make a brake pipe reduction in the train line to make a brake application.

This makes the valve on the car send air from the reservoir to the brakes on the car. ( I think they used to call it a triple valve?)

That's the only way it can work-- there is only one brake line through the train.

On a tractor and trailer there are two-- the emergency line feeds the trailer reservoir and keeps the brakes released.

The service line is basically a signal line and triggers the relay-emergency valve on older trailers without spring brakes or the relay valve(s) on trailers with spring brakes

to actuate the brakes.

Ron

[39 Baby Mack]

Ha, I pushed that old Heil dump trailer back one day and it went about 50yds down into the back yard, with neighbors watching it was pretty embarassing!

I hear you!

Been there done that!

Very embarrassing!

Ron

[rsb502]

Yep still a triple valve, it was a loose reference about the charging system. The newer electronic train brakes NS, Amtrak and others are testing have a steady 90psi trainline and an electrical connection on each loco and car. The whole train has to be equipped the same, an electronically controlled brake valve that is actuated by an electrical signal from the locomotive thru the train. I don't think it will catch on since older cars don't work with the system, it would be cost prohibitive to run only certain cars in certain trains, NS actually ordered whole unit coal trains with the system to try it out.

[rsb502]

WOW! I just realized how far off subject we went here, oops!

[39 Baby Mack]

WOW! I just realized how far off subject we went here, oops!

I'll say, but to bring it back to trucks again there was talk about them doing that on trucks too.

Saying it would take less time for an electrical impulse to reach the rear of the trailer than it does for the air to get back there.

Same old shit people trying to fix things that aren't broken!!!

Ron

[Freightrain]

Isn't that was a relay valve is for? Making it react quicker? Put a large volume out to a valve , then use a small amount to control it.

I grasp the concept of how the brakes work(on train and trucks) for the most part. I still marvel at how accurately these valves work back and forth.

I remember back in the early days of the steel wheel dolleys on trucks, some even had flat pads that the wheels dropped through. That is how I can tell if a trailer is really old. I have also seen the automatic dollys work.

[39 Baby Mack]

Larry

The reason for the idea of the electric signal is it would take the place of air signal to the relay valve.

The electric signal could travel to the rear of the trailer to work the relay valve quicker than the air signal does now.

Ron

[rsb502]

Yeah, in a train it decreases stopping distance by a few hundred feet depending on speed and weight and application time by 20-40 seconds at the rear of a 7500'+ train. Another big plus is they eliminate broken knuckles due to slack action when braking, which eliminates stopping in emergency on the mainline holding up traffic.

[REEL ADDICTION]

i will check the trailer is a 2000 great dane flat bed

[39 Baby Mack]

The flat bed is a 2000 Great Dane-----ABS brakes.

What year is the lowboy?

Ron