The idea of using gravity force to drive various mechanisms has been applied for a long time. A characteristic application of this principle in time measuring devices is gravity application in pendulum and weights clocks. A weight lifted at a certain level is easy to be used as an energy source. A device could be arranged similar to the drum in lifting equipment where the rotation of the drum caused by a rope wound on it is used [16].
Using linear reading scales is quite unusual for most time measuring devices but could be preferable in certain cases. It would be easier to install limiting units on a linear reading scale. This is the case for such measuring devices used for various processes or for laboratories. If the rotary motion of the shaft of a vertically mounted drum of a drum hoist (lifting device, crane, etc.) is used to drive a vertical screw then this screw could directly move an indicating hand on a linear scale by means of a nut on it sliding along linear guides.
The arrangement for a time measuring device comprising a linear scale is beginning to shape up although we still had the same difficulties. It would be better if we could find a suitable regulator. The weight suspended on the rope wound around the drum would not be moving uniformly once released but would accelerate. We remembered the holdback effect of the adopted hydraulic brake [16]. This brake is more efficient than a similar one involving air resistance. When the weight slowly moves down the force induced in the rope and the torque on the drum would be constant. Once the resisting moment caused by the hydraulic brake is made equal to the one resulting from the weight acting on the drum the rotation speed would be constant. Thus the time reading scale is dissectioned in equal intervals.
It would be necessary to introduce a certain gear drive to get higher rotation speed of the hydraulic brake rotor. This represents a shaft with pots mounted on it rotating in a liquid containing vessel (water, machine oil, etc.) [16].
We finally made the arrangement installing a lifting and dropping screw on the hydraulic brake vessel. This allowed the vanes on the rotor of the hydraulic brake to be more or less immersed in the liquid thus changing the value of the resisting moment. In this way an adjustment of the hydraulic regulator could be achieved. A pulley is installed (half a pulley block) to shorten the vertical stroke of the weight and ensure sufficient duration of device operation.