Help Identifying Large Iron Lever Lock

[timof5stars]

In the same box of locks that help my S&G 826A, I found the following lock:

It has a very unusual keyway and key. It also has a small iron spike at the end of the chain. What is that for?

The only markings on the lock are written on the drop/dusty cover but I can't make them out. I thought someone more experienced tham myself might recognize this. Here is the best image I could get. As you'll see, it is quite faded:

There is also writing at the tip of the drop/dust cover - looks like it begins with the letter "V". Not sure this is even English:

The back is unremarkable with the exception of two brass strips that are flush through the back plate of the lock - apparently it is part of the internal mechanism.:

The lock is in the unlocked position and the shackle freely rotates on its hinge:

The key fits the keyway and partially rotates. But the mechanism does not move when a small amount of pressure is applied. I was afraid any additional pressure might damage the lock so I discontinued my attempt to engage the locking mechanism.

Does anyone know what we're looking at here?

Thanks