Help with tow hitch plunger

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Jon
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Re: Help with tow hitch plunger

Post by Jon » Tue Mar 13, 2012 1:26 am

Absolutely nothing mate, just want this cleared up as it may be another "TM - SNL Mistake" listing it as a 20NF, is it a "socket head cap", or as listed a "set screw"
I'm not into egos, and I don't need to belay the fact I have 45 years of experience with engineering, I just want to know what's correct.
The hdls.......headless ?
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Re: Help with tow hitch plunger

Post by Joe Gopan » Tue Mar 13, 2012 4:20 am

I don't now why I should be raked over the coals , I did not make the error.
Set screws have many ways to be described,some are formal some are generic.I don't have a clue where my Mechanical Engineers Handbook is stashed it has been 30 years since I have needed it. The definition in it may be more correct. Ego? not really, just trying to help out on some simple terminology that I happen to have some background in. I am very familiar with threaded fasteners as I operated a structural testing laborarory among other job descriptions for a number of years while employed for the government, fasteners, welding, and structural fabrication was my responsibility, and what is is wrong with that?
Check out the TM10, and SNL parts manuals from 1942 throughout the life of the MBT/M-100 and look at the number of descriptions for the set screw installed in the casting, there are many, and many more in the industry.
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Re: Help with tow hitch plunger

Post by Bill H. » Tue Mar 13, 2012 8:05 am

The set screw on my Gemco T1 was 1/4 X 3/4 20 wich is course thread. My M416 uses the same thread. :?
Bill H.

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1952 Dunbar Kapple M100
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Re: Help with tow hitch plunger

Post by Chuck Lutz » Tue Mar 13, 2012 8:59 am

OK...while the G529 manual says 1/4-20NF-3/4......if you go to the Willys MBT TM 10-1230 or the Bantam TM 10-1281 you will find the following:

62 x 2....53035 Set Screw 1/4"-20 x 3/4" headless G.M. No. 102379

So it is a set screw (headless) and it is a 1/4"-20 COARSE THREAD and it is 3/4" long. the G529 is WRONG.
Chuck Lutz

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Bill H.
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Re: Help with tow hitch plunger

Post by Bill H. » Tue Mar 13, 2012 9:04 am

IIRC we ran across this 10 years ago or so. :|
Bill H.

"Each shall seek his own kind, in other words, a bird may love a fish but where would they build a home together?" Tevye, Fiddler on the Roof

1952 Dunbar Kapple M100
1953 Willys M38A1
1962 AMC M422A1
1965 Stevens M416B1 X 2
1967 Kaiser M715

2 Timothy 3:1-5

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Re: Help with tow hitch plunger

Post by Joe Gopan » Tue Mar 13, 2012 9:22 am

It is all about terminology and familiarity with the 1/4 Ton trailer. The Army practiced "commonality" and many parts were shared thru the production period of the MBT/BT3/M-100. It will be noted that the ORD 7-8 SNL G-529 dated December 1951 lists the subject set screw asORD Part No. 102379 BOLT, set, hdls,rd-pt, S, 1/4-20NC-3 X 3/4".
I have seen this particular item installed OEM in both a Socket (Allen) and Slotted type set screw on the countless number of trailers I have serviced and the hundred or so Draw Bar Castings I have sold.
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Jon
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Re: Help with tow hitch plunger

Post by Jon » Tue Mar 13, 2012 10:49 am

Chuck Lutz wrote:OK...while the G529 manual says 1/4-20NF-3/4......if you go to the Willys MBT TM 10-1230 or the Bantam TM 10-1281 you will find the following:

62 x 2....53035 Set Screw 1/4"-20 x 3/4" headless G.M. No. 102379

So it is a set screw (headless) and it is a 1/4"-20 COARSE THREAD and it is 3/4" long. the G529 is WRONG.
Thanks Chuck, I knew we'd get to the truth of the matter.

JR
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Re: Help with tow hitch plunger

Post by Joe Gopan » Tue Mar 13, 2012 11:40 am

Not all SNL G-529 Catalogs are wrong, the 1951 dated one is correct along with the Part Numbers it lists, what is the date of the SNL Chuck is quoting from?
Unless the screw is broken off flush inside, it will be quite obvious to anyone examining the threads whether it is NC or NF.
Last edited by Joe Gopan on Tue Mar 13, 2012 11:43 am, edited 1 time in total.
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HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
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Jon
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Re: Help with tow hitch plunger

Post by Jon » Tue Mar 13, 2012 11:42 am

25th July 1945
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Re: Help with tow hitch plunger

Post by Dale Jordan » Tue Mar 13, 2012 11:49 am

I'm lost on this one , any photos ? so is it a hex head , round head slot or flat head slot or grub srcew ? Dale
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Re: Help with tow hitch plunger

Post by Joe Gopan » Tue Mar 13, 2012 11:53 am

And it is also listed in error as NF in the copy of ORD 7-8-9 G-529 Change 2 Dated 25 August 1944 Luca sent me.
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HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
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Re: Help with tow hitch plunger

Post by Joe Gopan » Tue Mar 13, 2012 11:57 am

It is a 1/4" NC X 3/4" round point, headless set screw, it screws into the hole as far as it can go.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
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Re: Help with tow hitch plunger

Post by Bill H. » Tue Mar 13, 2012 12:00 pm

I think you will find there are more than a few that are a slotted round head also.
Bill H.

"Each shall seek his own kind, in other words, a bird may love a fish but where would they build a home together?" Tevye, Fiddler on the Roof

1952 Dunbar Kapple M100
1953 Willys M38A1
1962 AMC M422A1
1965 Stevens M416B1 X 2
1967 Kaiser M715

2 Timothy 3:1-5

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Jon
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Re: Help with tow hitch plunger

Post by Jon » Tue Mar 13, 2012 12:17 pm

Dale Jordan wrote:I'm lost on this one , any photos ? so is it a hex head , round head slot or flat head slot or grub srcew ? Dale
Check your email Dale.
Jon Rogers
AUSTRALIA


http://jeepdraw.com JeepDraw Home Page & Drawings
Parts Colours Page http://jeepdraw.com/PART_COLOURS.htm
1944 GPW195611 20531384 ACM-2 17781
1942 MBT 19433W

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Re: Help with tow hitch plunger

Post by Chuck Lutz » Tue Mar 13, 2012 1:22 pm

While you might find an Allen head set screw, a Star set screw, a hex head, a round headed/slotted screw, a Phillips screw or a wooden dowel in there to keep the plunger from travelling further to the right of the trailer.....the Willys and Bantam TMs are rather specific on what the FACTORY installed and whatever "replacements" or substitutions or what Pvt. Partz jammed in there when he lost the 1/4"-20 x 3/4" SET SCREW WITH ALLEN WRENCH SOCKET is due to Army-Know-How or changes or mistakes in LATER printings of the GOVERNMENT manual rather than the manual created by the MANUFACTURERS of those trailers.

Given that there an AWFUL lot of M100 style Drawbar Brackets installed on G529 trailers....perhaps someone who HAS an M100 DBB can check the thread pitch and even see if it is an Allen socket set screw in there! Perhaps the M100 trailers used a 14"-20NF x 3/4" screw of an undertermined design?

And....to be fair...if someone with a Willys or Bantam Drawbar Bracket (with correct part numbers on it) can check the thread pitch and report if they found an Allen socket set screw in there or not...that would be helpful also!
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
Bantam T3-C 1947


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