R-model brake lights issue

[Vladislav]

Finally attached the mud flaps to the light bars, got the protection film off them and connected wires.

Although got a trouble.

Brake lights fired up after pressing the pedal but didn't go off when released.

I had some challenge around parking knobs and so on and finally got the lights off taking off one of the wires on the service brake light switch on the firewall.

Today I took it apart, found nothing wrong but some patina. Cleaned up and put back.

Switched the ignition - lights were on (parking).

Made air pressure up and released parking knobs - lights went off - Ok.

Than applied service brakes several times.

They made all good but after 6-7 times the lights went steady.

I was surprized being shure the switch was good and after some thoughts disconnected the air line to it.

There was a good flow from it and the lights got off immediately.

I kept the line off for some while with no difference of the air pressure in it.

Then I sat in the cab and applied service brakes. The sound of air from the tube changed, got much harder than with the pedal released. But the there was still hard air flow from the pipe with brakes released.

So is it a problem with the foot valve?

Any suggestions on what to look over?

Vlad

[gearhead204]

Vlad check the trailer brake valve on the steering wheel shaft, is it partly applying also does it change if the park brakes are set or released? the mid 80's r mods. would turn on the brake lights if park brake is set and key is on.

[85snowdog]

Something else to check Vlad, I have had the plunger at the top of the treadle valve hang up a bit. If you take the pedal off, take the plunger out and clean & lubricate it. I have had that trouble myself in the snowplow, now its part of my regular maintenance . Just a thought.

[BC Mack]

Vlad...

what 85snowdog said... and check the pivot pin on the pedal, you should be able to rotate the roller freely.

very common for these parts to seize after being parked in a damp climate, I doubt if the piston in the footvalve is sticking but it is possible..

BC Mack

[Vladislav]

Thank you for the advices guys.

Gearhead - the lights are indeed on when in parking and the key is on although they get off when the knobs released. If the service brake switch is disconnected of wires or the air line. That trolley valve handle on the steering column I didn't check moving, will try.

Good point about the top of the threadle valve. I got it half stuck after this past winter (and almost stuck on the second R I haven't started much longer). I applied WD-40 on them both, had to turn the plunger around with pliers and put some engine oil on. After some movements it looked well. About the same with the pin and the roller.

Now looks like I need to pay attention to it again.

I will

[Vladislav]

Glad to let you know I'm a happy guy having such a nice support crue

The trolley valve handle was half applied.

I got my son invovlved into wire connecting to give him some minimum practice.

After he has done with the indicators I sent him into the cab to switch them for the test.

So looks like he made a bit much for that.

I just never had the idea that trolley valve can do anything when red knob isn't applied.

Moved and greased the threadle valve top by the way

[85snowdog]

Glad to hear you got your problem solved. I am also happy your son is getting his hands dirty working on your R.

On a different note, I noticed your air cleaner has been redone, I am sure it met the same fate as a lot of Canadian R model air cleaners, Rotted out behind the lower

strap.

Is the air cleaner new, or did you rebuild it? And the air cleaner bracket, is it chrome plated ?

Keith

[gearhead204]

Vlad please don't send payment in rubbles nobody here where I live can do the conversion! a six pack will do just fine lol.

[Vladislav]

Vlad please don't send payment in rubbles nobody here where I live can do the conversion! a six pack will do just fine lol.

Don't worry about that. A couple of years back Farmer52 determined all payments from Russia to do in Vodka

By the word, do you still have access to those ex UPS MH's?

I need some stuff for the my one but just use to keep this question outta my brains

[Vladislav]

Glad to hear you got your problem solved. I am also happy your son is getting his hands dirty working on your R.

On a different note, I noticed your air cleaner has been redone, I am sure it met the same fate as a lot of Canadian R model air cleaners, Rotted out behind the lower

strap.

Is the air cleaner new, or did you rebuild it? And the air cleaner bracket, is it chrome plated ?

Keith

That air cleaner is one of the parts wich are on this truck fully restored.

I had two of them on two trucks so I took the better one.

Had to drill off the weld to take out the pipe to attach air horse because of rust in between. Sand blasted every thing separately than welded back. Had to weld some rusty spots. Brang to the paint shop where they primered it and put some overpaintable liquid seal onto every seam.

Than painted it the future truck color.

The straps were a different story. I bought 304 SS strips, formed them and polished. Drilled the old straps off the brackets. Sand blasted brackets and primered them. Than welded new straps to the brackets and after that painted the body color having the straps masked. Bought SS nuts and put everything together.

All that took about 3 calendar months.

[85snowdog]

Looks great! Thanks for the pics Vlad.

[doubleclutchinweasel]

Glad to let you know I'm a happy guy having such a nice support crue

The trolley valve handle was half applied.

I got my son invovlved into wire connecting to give him some minimum practice.

After he has done with the indicators I sent him into the cab to switch them for the test.

So looks like he made a bit much for that.

I just never had the idea that trolley valve can do anything when red knob isn't applied.

Moved and greased the threadle valve top by the way

Yep. Trolley valve will operate brake light switch. Air just shouldn't go out to trailer unless red valve is in.

Dad taught me to tap the trolley valve from time to time, just to be sure it was not applied. Still do it to this day!

[Vladislav]

There must be some special brake lines arrangement to allow the trolley valve bring pressure into the brake switch line, and if I understand correct, to the truck's chambers, but don't activate them

Thanks you for the advice, I will remember your dad from time to time

[doubleclutchinweasel]

There must be some special brake lines arrangement to allow the trolley valve bring pressure into the brake switch line, and if I understand correct, to the truck's chambers, but don't activate them

Thanks you for the advice, I will remember your dad from time to time

Vlad,

There is a "double-check" valve on the treadle valve, with the air-operated brake light switch in it (see picture). Whenever air is delivered, either by the tradle valve or the trolley valve, this switch is made. I had to replace mine last year, because air was leakiing out of the switch portion when the brakes were applied. And, yes...that is a mirror under the treadle valve. I was reading the numbers off the treadle valve!

The double-check valve allows air to be ported to the line which feeds the tractor protection valve (and ultimately the trailer service line) whenever EITHER the treadle valve OR trolley valve is actuated, and closes off the other valve so the air does not escape. This double-check valve is why air goes to the trailer brakes whenever either valve is activated, but the trolley valve does not apply the tractor brakes.

So, air will definitely be delivered to the supply side of the tractor protection (TP) valve whenever the trolley valve is actuated. But, if the trailer supply valve (the red one) is not pushed in, the TP valve will be closed, and the air cannot go out the delivery side.

Whenever the red valve is pushed in, air is sent to the "emergency" side of the TP valve, and out to charge the trailer air system. This air pressure also causes the TP valve spool to shift, opening the "service" side porting as well. This allows the air flow from either the treadle or trolley valve through the TP valve, and out to the trailer service line. If the red valve is pulled out, or if it pops out on its own, due to a drop in air pressure, the TP valve automatically closes off the service brake side as well, so applying brakes does not cause air to go to the trailer brakes. This keeps you from losing your service brake air if you...for example...lost your trailer!

Incidentally, I just replaced the TP-3 valve on my R611 this evening (see other picture)!

Does that make it clear as mud?!

[doubleclutchinweasel]

Here is a Bendix TP-3 valve cutaway. It shows how the valve spool is designed. Air on the "top" causes the service side (bottom) to open. If there is no air on the top side, the spring causes the service side to be closed off automatically.

[Vladislav]

Wow, all that makes sence.

I unerstood the general princip (and i's important!) although it looks like your truck has slightly different design than my one of 1988.

I think it must have the same basic components such as a double-check and TP valves. But the brake light switch is not attached to the threadle or any other vavle. It is located on the firewall and attached to the plastic air line. That line is blindsideed (doesn't go to any other point excepting the switch) so I think it just starts from the same point as on your truck the switch is fitted in. Or something like that.

By the time I don't work over my brake system but will do (at least I'm going to). Everything about air is ruined due to wide repairs using steel wire or screw clamps. Russian KamAZ rear chambers have their place and some of them are pretty leaking. Air ride bags aren't far from the brakes.

I remember the list of "done" when you offered your R for sale. Should say you was doing it the right way. I mean repairs.

Thanks again for a care about my light green beast. I don't have a manual for an R or any newer Mack (newer then 60's), that's why I have my knowlede limitated

[doubleclutchinweasel]

Sorry. I thought yours was older. But, yes...the principal is the same.

[Vladislav]

It just looks rough. And in many points is...