The first photo shows the rear with the access plate in place. Next the plate removed with a screw driver through an open access hole. The bolt secures the hole to fill the oil reservoir.
This photo shows how the lock was designed to be either a left or right handed bolt design. The two red and black arrows are arranged symmetrically to allow the components to mirrored around an imaginary line bisecting the case through the center. The white circles are exactly where threaded case plugs exist. These plugs are clearly seen in the prior two photos.
Busse Safe and Vault Co., hydraulic time lock, c. 1940. This unusual lock depended on the viscosity of an oil reservoir to control the timing of how long the lock would be on guard. The knob spindle has a pinion meshing with a toothed rack attached to a flange under the lock bolt. To activate the lock the user turned the knob counterclockwise. If the knob is rotated as far as one can, raising the bolt fully, it takes one hour for the bolt to fully retract. So this was a short term intra-day lock. The knob dial ring is missing as it would have been attached to the outside door surface. So it is unknown whether the knob had only one setting for the full deployment of one hour, or whether there were shorter time segments. My observation is that it has at most two settings of one-half to one hour. file 279
The name plate refers to the lock being "installed and set" by the Busse Safe and Vault Co. 308 N. Michigan Ave., Chicago, Illinois. It is unknown whether the lock was actually manufactured by Busse Safe and vault Co. or just marketed and serviced by that company.
The only other production hydraulic lock this author knows of is the Wooley from 1877.