Bank Vault Time Lock Collection

The purpose of a bank vault time lock is to keep the vault door locked until the timer runs down. When the timer runs down a bolt is released and the door may be opened, or more often, the right  combination had to be dialed and then the door opened. While the time lock is running, even the right combination would not be enough to open the door. This was very important, since before the introduction of the timer in 1874, there was the nasty problem of bank robbers kidnapping the bank president or cashier; marching him down to the bank at night and forcing him to open the door. (There were no central alarm systems back then).

The very early time locks had a combination bypass which could override the time lock. This "secret" combination was known only to the time lock company and was not to be disclosed to bank personnel. This seems a bit odd today, after all there's a risk of someone from the time lock company robbing the vault,  but there was some fear that if the time lock failed, the vault door would have to be forced off (which is true). Most time locks had two or more movements to provide redundancy in the event of one timer failing, any one timer winding down to completion would allow the door to be properly opened. Soon after the introduction of the first time lock to be installed on a vault door in 1874, they proved to be quite reliable (not to mention the peace of mind to bank personnel once the bad guys learned that they could not open the door) and were widely accepted to this day.

Much of the information I have learned in this field has been generously given by Dr. John Erroll, curator of the John M. Mossman collection at the General Society of Mechanics and Tradesmen of New York. He and his son, David, have recently published a definitive book on this subject titled American Genius Nineteenth-Century Bank Locks and Time Locks, as well as articles by David Christianson and James W. Gibbs. 1