It’s quite slow and annoying to unlock a regular rotational combination lock.
Also, it’s easy to overshoot your target number and have to enter the combination all over again.
There are alternative types of locks, but few of them have the same form factor as the ubiquitous rotating-dial combination lock.
Fig. 1: This combination lock is straightforward but annoying to unlock, usually requiring you spin the dial around completely at least 3 or 4 times.
So if you want to secure a locker with a faster and less annoying lock (and you don’t want to carry a key), what can you do?
Answer: we can design a lock where the combination is actually a series of motions on the shackle, rather than on the dial of the lock.
A normal lock only has two positions for the shackle: open and closed.
But this new lock could have a series of notches on the shackle to allow the person unlocking it to precisely enter a combination, as seen in Figure 2.
Fig. 2: A person unlocking this type of lock will just appear to be angrily fumbling with it, but they’re actually inputting the code: for example, “up one notch, up one notch, down one notch, up two notches.”
(The dial remains, but it’s just a decoy.)
PROS: Works as a drop-in replacement for any existing combination lock.
CONS: Might cost more? But otherwise, none.