Lock washer

4x4M38 · Post by **4x4M38** » Mon Sep 11, 2017 8:14 am

120930 lock washer is described in the Ord 9 G740 as:

Washer, lock, S, phos finish, style No. 1, 0.67 OD,
3/8 in bolt size

120930 lock washer in the M38A1 parts diagram is listed as
an external tooth lock washer.

Are they the same washer or is the M38 style no. 1 a split
ring type?

These go on the D18 and I'm trying to figure out which
to install.

Thanks!

Post by **wesk** » Mon Sep 11, 2017 1:06 pm

If you convert that 120930 to it's FSN 5310-012-0930 and google it you get hits in other TM's and ORDs that still call it a lock washer with external teeth. Did you research the earlier serial number M38 lock washer just above it?

4x4M38 · Post by **4x4M38** » Mon Sep 11, 2017 3:05 pm

Hi Wes,
I did not look up the earlier M38 washer,
just assumed by the description it was a split
washer.

I need to do more of the FSN cross references.

It's a little tedious, as you point out the FSN numbers
did not come into use until post M38 production.

I can see where the ability to convert to the FSN provides an
opportunity for more clarity on a part description.

Thanks for the pointers.

kenperkins · Post by **kenperkins** » Mon Sep 11, 2017 5:32 pm

so,
I just took a look at 1952 TM9-1804B power train and body and it shows a part number of 7697469 which is the same as the 1951 ORD 9.
The 1955 ORD 9 shows the 120930 part number which I guess is a split lock washer after SN 56212.

Couldn't find any reference to a change in any ORD 7 or ORD 8

I would think your low SN would use the external teeth lock washer

Post by **wesk** » Mon Sep 11, 2017 6:58 pm

National Stock Number:
5310-00-012-0930

Federal Supply Class:
5310

National Item Identification Number:
000120930

Description:
WASHER,LOCK

Detail:
A washer which is usually round with a centrally located hole. Its edges and two bearing surfaces are so designed that applied pressure brings into play the spring tension and/or frictional locking principle which materially resists any tendency toward turning. It may be made of one or two pieces

Manufacturer Information:
120930 12204 DAIMLER CHRYSLER
120930 24617 GENERAL MOTORS CORP
120930 31007 NAVISTAR INTL CORP
120930 7X677 GENERAL MOTORS LLC DBA GENERAL MOTORS
4198004-16 05869 RAYTHEON COMPANY DBA RAYTHEON DIV IDS
7697469 19207 U S ARMY TANK AUTOMOTIVE COMMAND AMSTA-IM-MM
MILW6986TYPEB 81349 MILITARY SPECIFICATIONS PROMULGATED BY MILITARY DEPARTMENTS/AGENCIES UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
X2978DR 79410 LIBERTY VENTURES INTI LLC

Techincal Specification:
HARDNESS RATING 40.0 ROCKWELL C MINIMUM AND 50.0 ROCKWELL C MAXIMUM
HOLE DIAMETER 0.384 INCHES MINIMUM AND 0.398 INCHES MAXIMUM
MATERIAL DOCUMENT AND CLASSIFICATION FED STD 66 FED STD SINGLE MATERIAL RESPONSE OVERALL
MATERIAL THICKNESS 0.032 INCHES MINIMUM AND 0.040 INCHES MAXIMUM
MATERIAL STEEL OVERALL
OUTSIDE DIAMETER 0.670 INCHES MINIMUM AND 0.694 INCHES MAXIMUM
STYLE DESIGNATOR FLAT EXTERNAL TEETH
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION QQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
SURFACE TREATMENT CADMIUM OVERALL

4x4M38 · Post by **4x4M38** » Mon Sep 11, 2017 9:33 pm

That's a pretty amazing amount of information Wes.

Thanks.

Post by **wesk** » Mon Sep 11, 2017 9:41 pm

It only took less than one minute to find that info. Typed in the FSN from the ORD 9 in the google block and voila. Note that what it shows is both numbers are external teeth lock washers.

4x4M38 · Post by **4x4M38** » Tue Sep 12, 2017 5:34 am

Those must be some robust little buggers.

I just never thought looking at them that they'd
be as strong and effective as the split type.

I suspect they are much stronger than those guys we can get
in the plastic packages at the hardware store.

Post by **wesk** » Tue Sep 12, 2017 8:40 am

Hardware, just like tools, have their preferred applications.

The inner and outer toothed lock washers did very well in the old days when applied to the soft cast metals and soft steels. As the metals became much harder and the tensions much higher the split lock washer came aboard as the modern answer.

The toothed washer was also a favorite when electrical grounding was part of the equation.

Local hardware store versions are not necessarily weaker but they are usually not cadmium or phosphate coated for corrosion protection as is most of our specified hardware.

4x4M38 · Post by **4x4M38** » Tue Sep 12, 2017 6:13 pm

The ones I've bought would work firvekecteical
but don't seem as tough as these takeoffs.

They sure don't have that raised round boss around the hole.

RonD2 · Post by **RonD2** » Tue Sep 12, 2017 10:10 pm

Hey Brian. I discovered some time ago (not as long ago as Wes

) that the "NSN" (or preceding it, the FSN) systems seldom got rid of anything. Ever. You can still order a mule if you need one with a NSN (the 4 legged kind not the 4 wheeled kind). Our Uncle Sam still has stuff on shelf's that he doesn't even know is there until somebody asks for it. And he operates a system that if an item still has a NSN/FSN/MS number and he has a million but can't find any you can still ask for it and he'll go buy more! (Ok, maybe weapons and nukes excluded). And if something doesn't have a number they'll give it one and then go buy it! Most common things like lock washers have many numbers for the same one! A lifetime supply! Navigating the government supply system can be very confusing.

I happen to have some 3/8'ths internal-external lock washers under the military specification number MS45904-77, NSN 5310-00-953-8628. Cad plated, nice. Specs are at: http://www.parttarget.com/5310-00-953-8 ... 38628.html

And this outfit seems to have some in stock: http://www.tnjmurray.com/militaryvehicl ... A31BD70557

I've got some extra. Send me a PM if I can hook you up. That is, unless you're putting together a show queen? (I don't have any original NOS washers)

4x4M38 · Post by **4x4M38** » Wed Sep 13, 2017 6:43 am

Morning Ron,
Thanks for the offer. I have my takeoffs and other
than some wire brushing should work.

Re: government supply... reminds me of that scenes
at the end of the Indiana Jones movie where
that guy is wheeling a box into that infinite warehouse!!