Chicago Safe & Lock, Co., Chicago, Illinois - 2 movements - Gem model

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This model is a bit later in the production run from the one illustrated below. The main differences being in the finish of the twin platform escapements. These have a nickel-plated, wavy machined damascene finish and a plain nickel plated case, whereas the one below has a plain brass finish for the escapement platforms and a diamond pattern on the case very much like those found on the later Consolidated model cases and was probably a discarded case from that company, see explanation with example below.

Gem model, 1885. 4 5/8"w x 3"h x 2 1/4"d, Case #65, movement pair #629. file 290



On March 19, 1885 the Chicago Safe & Lock Company introduced their first time lock and was located at 209-217 South Canal Street in Chicago (currently the site of a high rise building, Chicago is this author's home town) . The first order from the E. Howard Company was for one-hundred units numbered from 500 to 600. This company had recently acquired the services of Henry Gross who was a key employee and inventor at the Hall safe & Lock Company. His patents, especially that of February 8, 1876 formed the basis for that company's line of time locks. Gross left Hall over disputes over patent royalty payments. Later that year on December 11th Chicago Safe & Lock Company placed an order with E. Howard for twenty new dials that bore the marking Gem Time Lock Co., Gross Patents, Chicago, Ills. Thanks to this change, possibly an attempt to avoid lawsuits, this lock is known as the Gem time lock. This author has seen a few other examples of this lock but none have this designation on the dial.

The two movement Gem time lock is very similar to Gross's two earlier time locks from his previous employer. The front and back movement plates and mainspring barrel are nearly identical, and although the gears and and platform escapements are the same size they are not interchangeable. A new feature introduced in this design was the single arbor that winds both movements simultaneously.(1) This was to avoid the mistake of winding one movement to a different time than the other or worse, as stated in Gross's patent, the operator only winding one movement thus exposing the time lock to the very real event of a lockout if that one movement should fail. But an essential reason, not mentioned, is the fact that the plate makes it impossible to set the second movement independently to the same time as the left movement since it has no dial or dial hand! This single winding arbor feature would next appear in Yale's line of Model A through E time locks in 1887. The obvious difference between the Gem model and those by Hall is the rotating plate substituting for a second dial on the right. On that plate Gross also included a version of his Infallible Chronometric Attachment™, a popular option on Hall and Consolidated time locks. This feature allowed the operator to set the time lock but introduce a delay before the lock would go 'on guard' allowing the safe to be used until a time later in the day, usually a few hours basically allowing him to preset the lock. Since gross had assigned the original patent that covered this device, he had to come up with a new way of accomplishing the same task, and while this example works, it is not as elegant a design as his original. There is also an inner open sector that contains a movable stud. That stud is what engages the release lever below and puts the lock 'off guard'. Under normal operating conditions the stud is set to zero. In this way the lock will go off guard when the dial pointer on the left hand dial goes to zero. However, if one accidentally over winds the lock say by three or four hours up to twenty four hours, then the operator can use the winding key to loosen the stud and slide it to four, re-secure the stud and it will then contact the release lever four hours earlier. When the lock goes off guard and the movements stop due to the pin contacting the release lever and stopping power from the springs, the result will be that the pointer on the dial will come to a stop at four hours on the dial. This warns the operator that the stud is moved off zero and onto four and to put it back to zero before normal set up, that is winding in the correct number of hours. This author's guess is that given the fact the plate was necessary for the redesigned chronometric attachment, it was a simple matter to include this overwind feature. Gross's original chronometric attachment could operate over a normal dial and so Hall's locks featured dual dials rather than a single dial paired with a rotating plate. Those locks, however, did not include an over wind feature. As with the single arbor winding both movements simultaneously, this feature would not appear until Yale's series of Model A through E time locks. It makes sense that this rollback feature appeared on the time locks that have a common winding arbor. With independent movements, if one realized the mistake before winding the second movement, the second one could be wound to the right time and the safe would open at the correct time. The reason that a rollback feature was not widely adopted is for security. Suppose there is a safe in a jewelry store to which several people have the combination. The owner wants to lock up for the weekend and so sets the time lock to go on guard at 5:00 PM on Saturday to open at 9:00 AM Monday. So he dials in 40 hours (apparently everyone worked on Saturdays since the locks during this period generally only went up to 48 hours! But what if another employee while out of the eyesight of the owner uses the roll back feature to chop 24 hours off the duration the time lock will be on guard. Then all the employee needs to do is arrive 16 hours later at 9:00 AM on Sunday and clean out the safe. The only other instance of a rollback feature I have seen besides the Gem and Yale time locks was in some models of modern Swiss-made movements of the 1970's and later.

Interestingly, E. Howard's production records reveal that Chicago Safe & Lock ordered only seventy cases with their first order of one-hundred movements. The earliest Gem locks are thought to be assembled in unmarked cases discarded by Hall Safe & Lock. This example is probably one of those as the case has the diamond damascene pattern seen on their other locks. Chicago Safe & Lock placed another order of one-hundred Gem time locks numbered from 601-700 on May 31, 1888. Of the two hundred made, six surviving examples of the Gem time lock are known today but given the original number produced there are certainly more.(1)

Gem model, 1885. 4 5/8"w x 3"h x 2 1/4"d, Case #9, movement pair #588. file 187

These are the three front cover drawings of the Henry Gross patent #315,612, April 14, 1885 covering the design of this lock.


The lock as received was undamaged, but had probably not been serviced in fifty to maybe nearly one-hundred years. So the oil last used was long dried out. The video below shows the process of re-oiling all of the pivots. This is a short-cut method of servicing an otherwise fairly clean and operational time lock allowing one to use it occasionally for display purposes. This also avoids the possibility of damage when an old movement is taken down to its individual components, especially in the areas of the escapement and its pallet and roller jewels and balance wheel hair spring. Replacement parts are non-existent. A true strip and clean overhaul would be necessary if the lock were to be returned to service, an unlikely event for a rare one-hundred-thirty-two year old artifact.


The first two photos below are from the Harry Miller Collection, Nicholasville, Kentucky. That collection had three of these locks, two of which are shown below. The first one is number 576, very close to this example at 588. It too looks like it was put into a Hall case as the door decoration was the same as used on their time locks. The second photo shows a plain case with a serial number from the second order as it is in the 650 range (last digit is covered by the dial hand). It has a bevel glass insert, but it is unknown if this is original or a replacement. It appears that the second order all had these plain cases. A fourth example is in the Mossman Collection at the General Society of Mechanics and tradesmen in Manhattan, last photo. It also is from the 500 series (570 or so, again last digit is hidden) and so has a case that appears to be more refined and perhaps also mounted into a Hall case.



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(1) American Genius Nineteenth Century Bank Locks and Time Locks, David & John Erroll, pp. 224.