US Post office lock

[somenewguy]

This is not my auction, but I have seen these type of locks before and I am not sure what they are for:

http://www.ebay.com/itm/Steel-US-Mail-Lock-Without-Key-USPS-Post-Office-Padlock-/131123722802

Also seen here, about halfway down the page: http://www.antique-padlocks.com/postal_us_a-z.htm

Can anyone say exactly what these are for and how they are used? I have an idea but I have not been able to confirm it.

[confusion]

It appears to be a warded lock
my guess is turning the key will push up some kind of latch unlocking the door

I could be entirely wrong though

http://en.wikipedia.org/wiki/Warded_lock

[somenewguy]

I assume the lock mechanism is fairly simple, like a handcuff lock (though perhaps there are extra wards or other complications). What I am wondering is how it was used in the post office and for what? For example, to lock up mail sacks of registered mail?

[Squelchtone]

I assume the lock mechanism is fairly simple, like a handcuff lock (though perhaps there are extra wards or other complications). What I am wondering is how it was used in the post office and for what? For example, to lock up mail sacks of registered mail?

yes, for registered mail.

[Raymond]

These locks were used to lock a rope clinching device on large bags of mail. The rope was pulled tight to close the top of the bag, the metal clamp was closed and the lock secured the clamp. It has several levers and locks by simply pushing onto the bar.

[somenewguy]

Thanks to all for the responses, sounds like my guess was spot-on. It looks like (from the auctions on ebay) that these are not too valuable. I found a couple for sale pretty cheap.

Are they keys universal (i.e one key opens all of the locks, like handcuffs)? I have one of these locks but without a key. I have not tried to manipulate or cut open the lock to investigate.

[torontosafecracker]

http://www.google.com.br/patents/US1103015

maybe that'll help with the key question. I've never seen one before today. Cool stuff.

[phoneman85]

I have one of these with a handmade key. I bought it at a swap meet and the seller had made a key out of solid brass stock. Pics of locks with keys seem to have a key with cuts identical to mine, so I'd assume they are universal. very neat little locks, you lock them by pushing them onto something like a hasp or ring.

[MacGnG1]

yes there is only one key for the LA mailbag padlocks.