M105A2C vacuum for brakes? Towing vehicle question too.

[Ruppster]

There is an M105A2C trailer coming up on GL and I've never seen one with the "C" at the end of the model number. So while reading the TM for it I see that the "C" means it has a vacuum connection for the braking system. Why was vacuum used instead of air pressure? Also, what vehicle would have been used to provide the vacuum, a gas powered M35?

I've also attached a picture of the data plate from it. Never heard of an M05 trailer either.

Thanks,
Ruppster
1985 M1009 Blazer

 

[juanprado]

Just curious if anyone here has a M105A2C and what exactly is the difference?

 

[steelandcanvas]

Got curious so I did a little search, seems they did have "vacuum brakes".

http://operatormanuals.tpub.com/TM-9-2330-213-14-P/TM-9-2330-213-14-P0022.htm

With the A2C designation, I was thinking a dropside 105?

 

[juanprado]

I guess I don't understand the difference in between vacuum brakes and air over / hydraulic ? On another site there are some pics but i don't see the difference?

 

[pitpawten]

Interesting that the data plate says only M05A2C (omitting the 1).

Is this standard, have to go look at mine now.

 

[Castle Bravo]

I guess I don't understand the difference in between vacuum brakes and air over / hydraulic ? On another site there are some pics but i don't see the difference?

Someone more knowledgeable than I can probably answer this better, but it seems like I remember there being some export G742 variant that had vacuum brakes. Perhaps the 105A2C is to paired with that vehicle?

 

[juanprado]

Well, I can say it now as the auction is over. There were a few USMC ones at Jacksonville on GP. The USMC part I don't think makes a difference. The pictures under the frame looked the same to me as M105A2.

There have been a few also on GL past history.

I know basic vacuum brakes on a car / truck that require a vacuum to the booster from the intake on a gas and an air pump for a Diesel but don't see how that applies to these trailers......

 

[rustystud]

There where early Military Vehicles (1950's) that used vacuum instead of air-pressure to apply the brake boosters and trailers. Some 6X4 trucks come to mind (Diamond REO) . I got this information from TM 9-8651 .

 

[juanprado]

These trailers looked modern with the dual wheel landing gear, metal bows and fiberglass sides with the later style swing tie downs in the back and the dual circuit brakes.

you can check out the pics at:
http://www.govplanet.com/for-sale/T...5&hitprm=k=m105a2c,md=M105A2C,sm=1&pnLink=yes

 

[rustystud]

These trailers looked modern with the dual wheel landing gear, metal bows and fiberglass sides with the later style swing tie downs in the back and the dual circuit brakes.

you can check out the pics at:
http://www.govplanet.com/for-sale/T...5&hitprm=k=m105a2c,md=M105A2C,sm=1&pnLink=yes

Your right, it looks like a 1980's models. Now that is strange to have vacuum brakes on such a modern trailer. I don't know of any truck since the early 1960's that uses vacuum braking. I'm talking about medium to large trucks here not modern pick-up trucks with vacuum boosters.

 

[FloridaAKM]

Oh joy, I won two of those trailers in the auction yesterday! I'll post what I find next week when I go to pick them up! They posted that they were air over hydraulic brakes like all the rest of the M105A2's are, some even had the air chamber broken off from forklift damage I surmise!

 

[juanprado]

Oh joy, I won two of those trailers in the auction yesterday! I'll post what I find next week when I go to pick them up! They posted that they were air over hydraulic brakes like all the rest of the M105A2's are, some even had the air chamber broken off from forklift damage I surmise!

Just check the data plate as only a few showed the M105A2C designation. The one I linked looked real nice and had a cover/bows in bed. I have a spare master cyl if you need it but no booster.

 

[MtnSnow]

The Original Poster's (posted in 2009) data plate shows a delivery date of 1953 made by Checker Motor Corp.

The trailer that Juan linked to sure looks to be a standard run of the mill M105a2 with the usual service & emergency air line connections.

 

[Wolfen]

The main difference between vacuum brakes and air. air over hydraulic/ and hydraulic brakes is, that you need vacuum to operate the brakes. This is not safe since if the engine stalls and you don't have a vacuum tank to supply vacuum, your brakes don't work. My dad, almost dumped a truck and trailer into a river when he was boarding a ferry, and the engine stalled. Personally, I would own a truck or trailer that had vacuum brakes. Just to be clear, I'm talking about vacuum operated brakes, not vacuum boost brakes.

 

[FloridaAKM]

The two I won had all the brake components intact from the pictures. There will be some other guys who go to pick up their trailers that look under them for the road inspection & wonder what happened here??

Just check the data plate as only a few showed the M105A2C designation. The one I linked looked real nice and had a cover/bows in bed. I have a spare master cyl if you need it but no booster.

 

[KaiserM109]

I give, what makes you think it is vacuum operated?

I looked at all the pictures and didn't see anything different from my 2 M105s and my MKT-85. I see the reserve tank and the relay valve attached to it. In fact, the wasp excluder is intact which means the new dealer has one on GL; GL usually tore up the relay valves with their fork lifts.

 

[Wolfen]

I never sais it was. I was saying, that if it wa, I would not buy it.

 

[FloridaAKM]

Monday is pickup day for one of mine, will let you guys know what I find out when there. If a unit with vacuum brakes is one of my pickups, it will be done with the Toyota truck as it has vacuum brakes ! The Deuce will pull the other one home using the air brakes unless the brakes won't release due to known problems with these trailers occasionally!