M931a1 pulling civi trailer

[Hank Elrod]

I just purchased a m931a1 for use on a farm. I am new at this so please have patience with me. My question is if I pull a civi trailer can I lock the air brakes on the trailer when the truck is shut down? It is important for me to be able to safely lock all axles as I want to push big square bales on a flat bed with a big tractor and I want to make sure that I don't push my new prize down a steep hill while I am loading bales out of the field. Thanks in advance for your help.

 

[wreckerman893]

Since there are no air valves on the dash like in a commercial vehicle there are two ways you can do it. One, bleed the air off by fanning the brake pedal until the pressure drops enough for the trailer brakes to lock automatically or disconnect the air lines and the trailer brakes will lock once air is off them.

 

[m16ty]

Some older trailers don't have spring brakes and will roll away if the air leaks off. I don't recall the year spring brakes were mandatory but I've got a 1994 Trail King trailer without spring brakes and a 2000 Talbert with spring brakes.

If you want the trailer brakes to lock and stay locked, make sure you have spring brakes. It wouldn't be that big of deal to add them to a older trailer if needed.

 

[quickfarms]

Spring brakes were supposed to have been installed on trailers starting in 1978

 

[m16ty]

Spring brakes were supposed to have been installed on trailers starting in 1978

You may be right on that but I've got a 1994 Trail King trailer that my Dad bought new in 1994 that doesn't have spring brakes. I've also got a 1982 Trail King trailer that doesn't have spring brakes.

Here's a pic of the '94.

 

[Derrickl112]

Since there are no air valves on the dash

the m939 series DO have trailer supply valves.

 

[FireFighterHill]

The other concern ive seen mentioned with using the M931 to pull civi trailers in the height of the 5th wheel hitch on the tractor. This is especially true on A1's with super singles. An m931 with the articulating hitch and super singles is much higher than a normal semi.

 

[goldneagle]

You can always trade your Super Singles to someone that has 11.00-20's. Also you can get a civilian 5th wheel and swap it out with the one on the M931 if it is too tall.

 

[doghead]

I disconnect my air line to set the brakes on my tagalong trailer, when loading.

 

[wreckerman893]

the m939 series DO have trailer supply valves.

Really? Please post pics of yours. My M927 has a "Spring Brake Override" button but not yellow and red air supply valves like you see on a M915/916/920 or commercial vehicle. The OP was talking about an M931 which (if I remember correctly) do not have the yellow and red valves. When I drove them you turned on the air valves when you coupled to the trailer using valves located on the rear of the tractor.

 

[Derrickl112]

Really? Please post pics of yours. My M927 has a "Spring Brake Override" button but not yellow and red air supply valves like you see on a M915/916/920 or commercial vehicle. The OP was talking about an M931 which (if I remember correctly) do not have the yellow and red valves. When I drove them you turned on the air valves when you coupled to the trailer using valves located on the rear of the tractor.

The m931/932 tractors have a trailer supply valve for pulling semi trailers. The tag trailer glad hands operate with the use of a dash valve.

The trailer supply valve is located under the emergency engine stop pull lever.

 

[Sephirothq]

those 14.00 x 20 tires are going to be a problem with hitting your landing gear of your trailer. It might look ok if you are straight but as soon as you make any type of sharp turn you will be tearing up your tires.

 

[Hank Elrod]

Thank You, so I guess i to need to find a military flat bed then if I want to keep my tires. I am not worried about my trailer running uphill but i do not want to ruin my new tires. I am correct is assuming that military trailers do NOT have spring loaded brakes?

 

[Derrickl112]

I have an m871 for sale. It has S cam air brakes

 

[quickfarms]

I have an m871 for sale. It has S cam air brakes

Spring brakes are available on both s cam and wedge brakes.

I have an ex military trailer that has s cam non spring brakes

 

[Hank Elrod]

Do all military trailers have adequate clearance between the kingpin and landing gear so that one could use the super singles on all military trailers? Also, does anyone know what the minimum measurement would be from kingpin to landing gear to use super singles? Would removing and reattaching the landing gear on the trailer be an option? ......sorry for my ignorance, we currently have all big straight trucks and this is our first venture with tractor trailers......our hope was to use this tractor to pull loads of grain (looking for a shorty dump trailer as well) and hay (shorty flat bed) out of the fields to the home farm and liquid fertilizer to the fields from the home farm via a short van trailer with tanks inside. Very little hauling with this rig would be on-road miles. Our goal is to eliminate some single purpose straight trucks and use a common tractor to pull everything.

 

[av8or]

The m931/932 tractors have a trailer supply valve for pulling semi trailers. The tag trailer glad hands operate with the use of a dash valve.

The trailer supply valve is located under the emergency engine stop pull lever.

My m932A1 also has the valve pictured. It was also converted to S Cam brakes by military. None of the rest of the M939 series trucks I have, have the valve.

 

[ichudov]

My M927 has trailer air supply connectors on the back, but does not seem to have a "tractor protection valve".

Do you think that if I found a good trailer with airbrakes, I could use it with airbrakes using M927 as a tractor?

(the M931A2 that I have, is a true semi tractor with a trailer protection valve)

 

[M813rc]

Double post

 

[M813rc]

Do all military trailers have adequate clearance between the kingpin and landing gear so that one could use the super singles on all military trailers?

Definitely not! A lot of trailers will not clear, some will just squeak by.

An example is my M128 behind the M931A2. To clear the rear tires on turns, I have to flip the landing gear pads vertically behind the gear legs and strap them there, then I'm fine. If I don't flip them up, they WILL hit the tire tread.
Not all trailers have pads that will flip back, so its not always an option.

I have watched a buddy tow his M146 behind an M931A2, he will occasionally strum the landing gear if the road bumps and the turn are right. Some other times, I don't think I could slip a piece of paper in there! He usually tows it with his M915, not issues there.

The M270? I could ride a bicycle between the 931 rear tires and the landing gear on that one!

Others can chime in, but it seems to me that if the trailer has 9.00 tires stock, or a single axle, you will have problems with the super-single tractors. Military trailers that come with 11.00 tires stock will probably work, but some may be too close.

Cheers

PS - added a picture that shows what I mean by strap the pad vertically behind the leg. The picture also shows what happens to a pad when it catches the lugs on the tire. It wasn't immediately obvious that it was too close, until I turned into a parking lot driveway.