Sometimes you can, sometimes not.
A warded lock and a lever lock may use the same keyhole. There are even warded lever locks.
You can usually identify a disc-tumbler lock (not a disc detainer) lock by looking in the keyway and seeing the flat disc tumblers. But an Ingersoll lock can look like a disc tumbler if you look inside the keyway.
Most pin tumblers you can identify by looking in the keyway and seeing the pins. But the Kwikset Smartkey looks like a pin tumbler if you are only looking in the keyway. Those can be spotted by the rectangular slot next to the keyway. But just because there is a rectangular slot next to the keyway does not mean it is a SmartKey. U-Change has a rectangular slot next to the keyway, too. And it is a pin tumbler lock.
Disc detainer locks are fairly easy to identify.
Tubular locks are easy. But some things that look like tubular locks, or at least similar, can be something else entirely.
There are so many exceptions with locks. That is what fascinates me - there is always something new to see/find/add to your collection. Some of the different things are new, some are old. Lever locks may have the levers that need the key turned to operate, and some lever locks may need the key only to be pushed in to operate.
The first pin tumbler padlocks were push-key operated, too. The Yale PKPT (Push Key Pin Tumbler) padlock. (Made a key for another one of them today). With those you do not use a tension wrench because the plug is part of the shackle and must be pushed far enough in with the key for the shackle to be lifted before it can be turned. Use a tension wrench, and all you will do is bend the wrench and damage the keyway.
It really comes down to experience. If you hang around here and read enough posts, you will learn a lot.
Graham Pulford's book,
High Security Mechanical Locks, is an outstanding resource. The best book resource I have seen so far. But strong word of caution - it will be a taunting toy catalog. I want one of these! Ooh, one of those, too! Gotta have that one! Some are very hard to find, and some are rather expensive. He is even a member here!
This site is the best online resource you will find for lock information. Use the search button!
Gordon
Just when you finally think you have learned it all, that is when you learn that you don't know anything yet.
