Sargent & Greenleaf 831B dissassembly pictures

[dosman]

So anyway the story is that my father has been through a high number of burglaries over the past several years at his rural country home. He recently lost a brand new riding lawn mower and was asking me for some advice on good locks for his shed so I started hunting around. While resistance to manipulation was a high priority, protection from brute-force was my primary concern. Eventually I found a surplus dealer on Ebay selling the retired Sargent&Greenleaf 831B padlocks. After further research I decided this was about the best that my money could buy. So anyway, he was rather pleased to receive this for his birthday. It turned out to be a near-mint lock that appears to have never been used (Evident by the inspection sticker still on the bottom). I took the opportunity to disassemble it and take some photo’s before I presented it to him.

I didn’t take a precise measurement but I am guessing it weighs about 4-5lbs. The body is cast steel and there are only 5 parts not counting sub-assemblies, I didn’t see much that could go wrong. It’s obviously resistant to shims and the 6-pin Medeco core is “good enough” for me. Coins are US quarter and Euro 50 cent.

Front View
(Well, ok it's actually the back of the lock but you can't see the shackle from the front)


Disassembled
Notice the hole in the right side of the body




Bottom
The strange shaped of the key hole is used to prevent a normal key from turning backwards for disassembly. Also I believe this is (or was) a restricted keyway only availble to the Fed, someone else might be able to provide more info.


Lock
The Medeco core and a shot of the keys. The normal key is on top, the control key is bottom.


The only different between the control key and the regular key is the shoulder. The odd looking key hole interacts with the shoulder to prevent a normal key from turning backwards for disassembly and maintenance. I have more photo's also, at some point I plan to put a site up with pictures from my meager but growing collection.

Thanks.

[devildog]

Those are EXCELLENT locks, and that one does look to be in excellent condition. Anything by Medeco is excellent, but that one in particular is a beast of a lock AND it has a high-security Medeco core in it

I would've just gotten him an AM700 as he probably just needs something resistant to forced entry as opposed to something truely high security, but oh well, if I could afford it I'd probably have Medecos (or Abloy Protecs) installed on my parents house along with a bunch of other physical security improvements, even though they probably don't really 'need' it.

hmmm...didn't TOOOL or somebody put out a paper specifically on this lock that had a bunch of info. in it?? Anyone know about that?

[dosman]

I found some various sources of info on this lock from .mil and .gov sites, below is some text I copied down. While this doc was more about the 833, it does indicate that the 831B is still qualified for military use until it needs service. I might add that I paid $70 w/shipping for this one, although I've heard of surplus dealers selling them for as little as $10-15.

Although several padlocks have been approved by the Department of Defense (DoD) as high security padlocks, only the Sargent and Greenleaf (S&G) Model 833C meets the requirements of MIL-P-43607G, the current military specification for high security padlocks.

High security padlocks are mandated by DoD to secure arms, ammunition and explosives, and chemical and special weapons. Critical assets such as these require the highest level of physical protection available. It is important that padlocks used to secure storage structures meet the most current requirements. The 833C is the only padlock available that provides the required resistance to forced entry. The keyway used in the 833C is restricted to DoD and is protected by patent and Federal law. Continued use of the LK1200 and 831B in high security applications is approved until service is required. At that time, they must be replaced with the S&G 833C. No attempt should be made to repair, cannibalize, or assemble locks from parts. Mixing locks from unmatched locks alters performance and risks exposure to compromise. The S&G 833C is available from the Defense Supply Center Philadelphia (DSCP). DoD users can order as follows:

NSN 5340-01-217-5068, Padlock; Standard Unit Price $198.95
NSN 5340-01-323-1087, Replacement Cylinder (with two operator keys and one control key)

Contractors can order:
NSN 5340-01-449-4346, Padlock; Standard Unit Price $170.41
NSN 5340-01-449-4349, Replacement Cylinder (with two operator keys and one control key)

For more information, contact Kim Nguyen at (215) 737-xxxx, DSN xxx-xxxx or by Email: knguyen@xxxx.xxx.mil

For Navy activities, these padlocks are also available from the Naval Surface Weapons Center (NSWC), Crane, Ind. For information, contact NSWC Crane, Defense Locking Systems Branch at (812) 854-xxxx, DSN xxx-xxxx. Only One High Security Padlock Meets Requirements

Obligatory quote: "There can be only one"

[n2oah]

Nice breakdown. At least "Gay Powers" didn't inspect your S&G padlock. I had a 8077 with that inspector.

[n2oah]

Ah, I forgot to add that I am putting one of these on my locker, although the policy states "all other locks will be cut off". I'd like to see them cut an 831B.

[devildog]

Anything with a hardened boron-alloy shackle will generally defeat boltcutters, so anything by American would work, I'd use an American 700...or maybe that 748 I've got, that would be funny.

Any lock other than what exactly?

[n2oah]

Other than the master lock combo padlocks issued by the school.
I have an 8077 laying around that I could use.

[mrdan]

I had one of those lock when I got out of the ARMY. Got it from the armory. Given by the guy in the armory. I ended up giving it away years ago.

[dmux]

we have that lock on our arms room


they key says medico on it and it is like a 10 pin lock with about half angled cuts (biaxial)

[devildog]

Ok, I've got one of those and I've got a control key for it and would like to disassemble it, but I'm lacking the disassembly instructions for it and I'm not exactly clear on what you've done there; can someone help--how do you disassemble an 831B?

[Omikron]

Very nice find!

I'll have to keep an eye out for one like that myself!

[dosman]

I would be happy to explain. The control key turns backwards from a normal key and pops the square piece out of the side. In fact, if you hold it so that your hand doesn't cover the square cutout on the side and quickly turn the control key it will usually pop out a little on it's own. Sometimes it takes some jiggling though.

After that slides out it exposes the inside of the lock and the "shackle restrictor" can then be dropped out of the top along with the core. I always enjoy seeing designs so simple work so effectively, this lock only has 5 pieces.

[lockpickroy]

have you tryed picking it ? I bought 2 on E-bay i should get them in a week or so .

[Lucky1406]

Well, I just bought one of these locks, But I'm not sure how long it will be before I can pick it. I've been reading about medeco locks, and cant wait to try and pick one, but the only ones that I've been able to play with have had sidebars. Too hard for me right now. My problem is that with some of the locks that I have right now, they are all in the advanced forms, and I cant get the info on how to pick them yet. But my three months are comming up soon, maybe I'll get lucky and be allowed passage into the great and powerfull OZ(also known as the advanced forms) hehe,
NIck

[Bud Wiser]

Hey DD, isn't that exactly the same lock I bought from you on ebay a while ago? btw, were you able to pick it?