Adding Tractor Protection Valve to M818

I want to add a tractor protection valve to my M818. I searched and have not come up with anything on the subject. I think jwaller installed one in his M818 but I didn't find anything written up about it.

I know how the red valve would control the trailer air through the tractor protection valve. I would like to also have a parking brake for the tractor while it is running.

So I have 2 questions.

1. Tractor parking brakes?

I know the M818 doesn't have air brakes so there will not be a parking spring brake for the tractor. Would hooking up a valve that supplies air to the service brake tow system connection on the front of the M818 apply the tractor brakes and effectively act as a parking brake as long as the air system is pressurized?

2. Type of tractor protection valves:

I realize there are different control valves for the different tractor protection valves. I'm just looking for information on what has been used before if a member has made this modification.

Ray

I know I put up a post about it. lemme search for it somehow. might have been on the old site.

I put in a tracotr protection valve and a air actuated parking brake. IE red and yellow knobs. I did it for the sole intention of trying to get the 818 to pass an airbrake inspection test and for different reasons I never could get it done but the valves work and do their job as intended.

I added a trailer supply valve to my M818. Sold it before I added a tractor protection valve though. After you have the trailer supply valve, the protection valve is very easy to add. See my writeup in http://www.steelsoldiers.com/5-ton-...-question.html?highlight=trailer+supply+valve

By the way, the valve and trailer brakes work great and it's MUCH more user friendly than the stock set-up. I realize that you were asking about tractor parking brakes, but it sounded like you were concerned about the trailer too so I added my 2 cents. I don't know for sure, but it seems to me that air tractor parking brakes would not be too practical. Air pressure wise, all the 800 series trucks I have seen leak down pretty quickly. Second problem is that in my experience, if the hydraulic brakes are not perfect, the fluid eventually leaks past the seals-i.e., if you stand on the brakes of any car for very long, the pedal creeps to the floor. As small as the master cylinder is with as many wheel cylinders as there are on an M800, I would think the air pack cylinder would bottom out pretty quickly.

Huh, I guess I just assumed that all M818s had the tractor protection valve.... Why don't they? When did these valves fall out of favor and why?

....The M275 tractor I'm trying to buy has one on the steering column....

Jon

JDToumanian said:

Huh, I guess I just assumed that all M818s had the tractor protection valve.... Why don't they? When did these valves fall out of favor and why?

....The M275 tractor I'm trying to buy has one on the steering column....

Jon

Click to expand...

that is NOT a TPV, but a hand trailer brake control
the early m series did not have a tpv,--- the m35, m54, 809
I was thinking of using a disk on the read axle rear flange, with spring pull offs and a spring pot, no air on , air off, because the parking brake on the 5ts suck, especially the heavier ones

jwaller said:

I know I put up a post about it. lemme search for it somehow. might have been on the old site.

I put in a tracotr protection valve and a air actuated parking brake. IE red and yellow knobs. I did it for the sole intention of trying to get the 818 to pass an airbrake inspection test and for different reasons I never could get it done but the valves work and do their job as intended.

Click to expand...

It would be great if you can find the post jwaller. It sounds like you did exactly what I want to do. I think I know what to do; it's just easier to ask before reinventing the wheel.

Autocar, the primary purpose of the mod is to have a tractor protection valve. Thanks for your link. Having a trailer leak and loosing all the tractor air is not something I'm going to let happen if I can avoid it. The idea of a tractor parking brake is more for convenience while the engine is running. It certainly is not a real parking brake, since when the air goes away it does too.

Tow4 said:

It would be great if you can find the post jwaller. It sounds like you did exactly what I want to do. I think I know what to do; it's just easier to ask before reinventing the wheel.

Autocar, the primary purpose of the mod is to have a tractor protection valve. Thanks for your link. Having a trailer leak and loosing all the tractor air is not something I'm going to let happen if I can avoid it. The idea of a tractor parking brake is more for convenience while the engine is running. It certainly is not a real parking brake, since when the air goes away it does too.

Click to expand...

not if set up as NO AIR it SETS, NEEDS air to release, that could be set up on the existing pb

Thanks for the info Ron, I was mixed up.... I read about tractor protection valves and understand now.

So the 2.5 ton trucks and 800 series and older 5-tons do not have this TPV? These trucks have air-hydraulic brakes, is a TPV really necessary?

Jon

Tow4 said:

Autocar, the primary purpose of the mod is to have a tractor protection valve.

Click to expand...

I figured it would be easy to add, but you need the trailer valve first. You would cut into the service brake line and splice in the TPV, then connect the control port of the TPV to the emergency line downstream of the trailer valve. If there was a break in the emergency line, the trailer valve would pop which would shut off emergency air to the trailer and at the same time shut off the TPV so application of the tractor brakes would not supply air to the service line. Remember that the TPV protects the tractor only in the event there is problem with the trailer or its connection lines-it doesn't prevent air loss in the tractor if the problem occurs in the tractor air system(unless something happens in the trailer emergency line downstream of the trailer valve).

basically what I did was intercept the air supply line that goes to the trailer and run it to the valve in the cab, then from it to the place where it originally went. that way you can now leave the valve on the catwalk open all the time.

The parking brake valve works awesome as a means of holding the truck during winching orerations and is much simpler than the electric setup the wreckers have. These old trucks do leak down very quickly so it´s not a means of parking brake that would hold for more than 5min with the truck shut off.

for that one all I did was T into the line that goes to the front of the truck during towing operations. supply that line with air and you have a pakring brake.

which line on the front, driver side or passenger side

jwaller said:

basically what I did was intercept the air supply line that goes to the trailer and run it to the valve in the cab, then from it to the place where it originally went. that way you can now leave the valve on the catwalk open all the time.

The parking brake valve works awesome as a means of holding the truck during winching orerations and is much simpler than the electric setup the wreckers have. These old trucks do leak down very quickly so it´s not a means of parking brake that would hold for more than 5min with the truck shut off.

for that one all I did was T into the line that goes to the front of the truck during towing operations. supply that line with air and you have a pakring brake.

Click to expand...

That's what I was planning to do for the TPV jwaller. Thanks for confirmation that the service line on the front will act as a parking brake when supplied with air.

73m819, you use the service (blue) on the front. I don't remember which side.

Thanks to everyone for all the help.

Ray