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A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. [1] The device usually displays the revolutions per minute (RPM) on a calibrated analogue dial, but digital displays are increasingly common.
Uhlhorn was an engineer, mechanic and inventor, who invented in 1817 the first mechanical tachometer. [1] [2] Between 1817 and 1830 he was inventor of the Presse Monétaire (level coin press known as Uhlhorn Press) which bears his name. [3]
The first wristwatches were made in the 16th century. Elizabeth I of England had made an inventory in 1572 of the watches she acquired, all of which were considered to be part of her jewellery collection. [174] The first pocketwatches were inaccurate, as their size precluded them from having sufficiently well-made moving parts. [175]
Tachymeter scale on a Citizen watch bezel. A tachymeter (pronounced / t æ ˈ k ɪ m ə t ər /) is a scale sometimes inscribed around the rim of an analog watch with a chronograph.It can be used to conveniently compute the frequency in inverse-hours of an event of a known second-defined period, such as speed (distance over hours) based on travel time (distance over speed), or measure distance ...
Sometimes inventions are invented by several inventors around the same time, or may be invented in an impractical form many years before another inventor improves the invention into a more practical form. Where there is ambiguity, the date of the first known working version of the invention is used here.
Wild brand subtense bar. Another device used in tacheometry to measure distance between the measuring station and a desired point is the subtense bar. [2] This is a rigid rod, usually of a material insensitive to change in temperature such as invar, of fixed length (typically 2 metres (6.6 ft)).
At these times, the clock runs slower. Depending on the type of flight, tach time can be 10–20% less than Hobbs time. Many organizations, such as flying clubs, charge by tach time so as to differentiate themselves from fixed-base operators as 10–20% less time recorded makes it 10–20% cheaper to fly (if the hourly rate is the same). In the ...
The analogue tachograph head uses styli to trace lines on a wax coated paper disc that rotates throughout the day, where one rotation encompasses a 24-hour period. If the disc is left in the head over 24 hours, a second trace will be written onto the first, and so on until the disc is removed.