# Wonder what R=A on a Clock Pendulum means? (#028)

Wonder what R=A on a Pendulum means?
There is some disagreement on the exact origin and language. Many believe that it originates from 18th century French and Vienna Clocks, and was later adapted by German Black Forest clockmakers.  For this reason you tend to see many 19th and 20th century German clocks using this style of pendulum.

R (Slow Down) = A (Speed Up) the Clock

R = Retarder, A = Avancer (French)

R = Rueckwarts, A = Aufwarts (German)

Adjusting the Pendulum. These pendulums have a nut to screw up or down. Bringing the Pendulum Bob (where the R=A is inscribed) down by unscrewing the nut (down and toward the R) slows down the clock. Screwing it up (toward the A) will speed up the clock. This is what you call “Regulating” the clock to keep accurate time.

In this illustration:
“Too Slow” means your clock falls behind in keeping time.  Therefore, you turn the nut to the right – towards “A” – which moves the pendulum bob up.   This shortens the length of the pendulum causing the oscillation (back and forth movement) to “speed up” and “regulate” the clock to keep better time.

“Too Fast” means your clock is running ahead of the actual time. Turning the nut to the left – toward the R – has the opposite effect of increasing the length of the pendulum, causing the oscillation and the clock to slow down.

Regulating a ClockKnow that a clock needs to be regulated when it’s not keeping proper time (running slow or fast).  “Regulating” a clock refers to adjustments made to the pendulum to effect the speed of the movement.  Know that there are many factors that contribute to your clocks speed: pendulum length, weight, material construction, temperature changes, and its hanging/sitting position.  You can find more information about regulating a clock at Bowers Clock and Watch Repair website.
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Happy Clockventure!