The Jones mechanical Tachometer...one of the last maximum hand tachometers still around...part 2, calibration info from the factory....

As mentioned in the previous post on Jones  tachometers this second post contains the calibration instruction for the Jones centrifugal mechanical tachometer and completes the information I have on them.
They differ from the Smiths centrifugal speedometer and tachometer in the method of calibration and is more precise as a result. The Smiths instrument had a dial scale which was not linear whereas the Jones is linear. This meant the Smiths instrument had a series of different dial scales available as part of the calibration method, some seven different dial for their 60mph speedo for example...I will do a post on the Smiths centrifugal/governor speedometer in a future post...
Service Instructions for the Jones Motrola 5100-5200 series speedometer and tachometer..