the earliest patent for a double-acting pin tumbler lock was granted to american physician abraham o stansbury in england in  but the modern version still in use today was invented by american linus yale sr in  this lock design used pins of varying lengths to prevent the lock from opening without the correct key in  linus yale jr was inspired by the original s pin-tumbler lock designed by his father thus inventing and patenting a smaller flat key with serrated edges as well as pins of varying lengths within the lock itself the same design of the pin-tumbler lock which still remains in use today the modern yale lock is essentially a more developed version of the egyptian lock