Hahl Pneumatic Master Clock

This Blog follows my restoration of a Hahl Pneumatic Master Clock.

If you have a Hahl clock or parts for a Hahl clock please email me at stotlarj@gmail.com.

Hahl made Pneumatic master clocks that in turn ran slave clocks throughout schools, factories, office buildings, etc.

The clock compresses or expands one or two bellows every minute. This change in pressure would cause all slave clocks to advance one minute.

This particular clock came from the Mentor High School in Mentor, Ohio.

This clock would have operated the slave clocks in the school and it would have also operated the bells for class periods. The bell program unit is the cylindrical unit below the clock.

I obtained it locally from a lady who has owned it for years. it was in very bad shape when I picked it up.

Clicking on pictures will enlarge them.

Video of Hahl Pneumatic Master Clock in Action

Finished at last

I finally wrapped up my clock project. Today I put the restored movement in the case and ran new cable for the weights. It is keeping perfect time.

Picture shows weights, pendulum and bell relays. Each weight is 70 pounds. The brass tube on the left side of the clock contained a glass vial that was filled with glycerine and red dye. This was a visual check to see if you had an air leak in the system.

Cylinder below clock mechanism is the device to program when the school bells would ring