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M870A1 Acquisition Thread

Castle Bravo

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Did you notice the droop on the gooseneck of the A1? I guess it was that one that the GL guy inspected for write up on and just copied it for the other three. "pivot pins oval" etc.
I did not. Its hard to tell from the snow and odd angles. I didn't even see the mention of the oval pivot pins. Interesting. My gooseneck droops a good 12" or more when it is not on the trailer.

Not sure which one gets used more, 3 1/2" for the 916 or 2" for the 931....
I 'spose that chock blocks, binders, chains and prybar (not for A1'a though) are not technically listed as Bii in the TM, just "Operators Controls and Indicators"[2-2]. Probably never see any of them on any that come out!
I guess that the Bii "Truck wrench" and " ..handle" are pretty standard for wheel changing.

Do you know if the 931 and the 916 have different fifthwheel heights? The later LoadKing 403LF trailers (civi version) have a "shim" that is used to change the height of the gooseneck for different tractors - like an optional stop block that goes in the parallel linkage. Would be a nice mod if you have both Kingpins as it already has 12 and 24v lights.....
Yeah, the 931 and 916 have different 5th wheel heights.

M915 50" height 2" kingpin
M931/M818/M52 57" height 2" kingpin
M931A1/A2 60" height 2" kingpin
M916/M920/M1070 64" 3-1/2" kingpin
M123 and M26 tractors are also 3-1/2" kingpins, and I presume a similar height to the other 3-1/2" kingpin tractors. I know the M123 had different fifth wheel heights (E1? A1? Not sure...)

The "official" tractor for the M870 or M870A1 should be the M920. The 920's GVWR and GCWR fit the 870's numbers correctly. I don't think the 2" kingpin for these trailers is a usual military item. The 5 ton tractor doesn't have a rear winch and really doesn't have the ratings to utilize an 870. I think it would have to be a 14R20 equipped tractor (931A1 or A2) to have a chance of functioning correctly. Maybe a 931 with 11R20 tires wouldn't drag the front of the trailer on the ground, but it would probably have trouble going over a speed bump.

I know a guy with a M870/403LF that made a new "pin hole" lower than the stock one to make it work with a M52A1 (!) Seen here, about 20 seconds in - https://youtu.be/OdoM603D0VU?t=20s
 

agazza2

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Excellent fabrication work by M35A2-AZ on these outriggers. You will definitely be glad you had them made up now instead of actually when you need them. Thanks for all your help yesterday Matt and expertise removing the winch/components.
 

zebedee

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M870 x 4 auction Augusta ME, May '15 (CLOSED)

I did not. Its hard to tell from the snow and odd angles. I didn't even see the mention of the oval pivot pins. Interesting. My gooseneck droops a good 12" or more when it is not on the trailer.

Noticeable when you throw on a couple of perspective lines and the "horizon".

A1 sag at ME.jpg

Same quote on all four....

[h=4]Description:[/h]M870 Semi Trailer, Low Bed, 40 ton, Construction Equipment Transporter. 13 tires, 10.00 x R15. Lock and hinge pin holes oblong on gooseneck platform and hinge plate, hinge plate steel decking rusted and cracked, cross member welds cracked - trailer bed & gooseneck platform. Trailer not road worthy unless fixed. Mutilation not required & no title documents will be provided. Buyer loads, No GL/Guard Assistance Available.
 

Castle Bravo

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Noticeable when you throw on a couple of perspective lines and the "horizon".

View attachment 558906

Same quote on all four....

Description:

M870 Semi Trailer, Low Bed, 40 ton, Construction Equipment Transporter. 13 tires, 10.00 x R15. Lock and hinge pin holes oblong on gooseneck platform and hinge plate, hinge plate steel decking rusted and cracked, cross member welds cracked - trailer bed & gooseneck platform. Trailer not road worthy unless fixed. Mutilation not required & no title documents will be provided. Buyer loads, No GL/Guard Assistance Available.
Interesting, yeah.

Here are some photos of my trailer off the tractor and on. You can see the amount the trailer droops when its not on the tractor.

When the trailer is unloaded and you come to a stop, the trailer seems to slow down quicker than the tractor does, so you "extend" all the slack in it. When you let your foot off the brake to move it to the throttle, gravity takes over and you feel a push from the trailer. It almost feels like how surge brakes feel.

Presumably, you could remove the gooseneck pins, set the trailer brakes, and pull the tractor forward to "stretch" the trailer out a bit.
 

Attachments

Castle Bravo

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That paint job is looking real good.

What's with the hatch at the center rear of the trailer, that some tool storage or something?
Its a storage box/tiedown box/tool box/whatever box. It was added by the previous owner. It is very handy.
 

Castle Bravo

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A couple of photos -
m870a1-76.jpg

This is the interior of the rear electrical junction box.

m870a1-75.jpg

These are the wood deck hold down clamps. Several people on here were interested to see what they look like. I like them in that you do not have to drill any holes into the trailer to hold the deck down.
 

zebedee

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Last edited:

Castle Bravo

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CB - I just came across this TM ( loading a Cat D8K on to an M870 ), it doesn't appear to be complete (fig 1, 2, 4, 5 & 6 are missing), but it's worth a look..


http://www.combatindex.com/store/tech_man/Sample/Const_Dozer/TM_55-2410-234-14.pdf


It's interesting how they suggest running the tie down chains through the trailer hinge gap!


EDIT - Found full TM;

http://www.liberatedmanuals.com/TM-55-2410-234-14.pdf

... but the pics are cr@p.
I think I have that TM, but I never noticed the tiedown arrangement before. That is interesting. There does look to be a large enough gap on the M870A1 as well to put a 1/2" chain through there.

One of the things that is a positive about the 870A0's open wheel wells is the ability to run chains around the open struts between the axles.
 

zebedee

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One of the things that is a positive about the 870A0's open wheel wells is the ability to run chains around the open struts between the axles.
I noticed that too - a little crude though, running chains over bodywork edges rather than dedicated "D" rings etc. "MIND THE PAINT". You would have thought that the build specs for the trailer would have catered for all the expected loads!
I do however consider the covered wheels of the A1 (& +) are the bigger win. I think if I end up with an A0 rather than A1, I'd probably still make that a necessary mod, along with Marine ramps and a rear locker like you did (I already have a 7/8 inch snatch block for unloading which will drop right in there)....
 
Last edited:

NDT

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Lovin' those delineator plates, look perfect there and talk about safety upgrade on a hard to see trailer!
 
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