(D)W5 Free Pendulum Clock

(D)W5 Free Pendulum ClockPerhaps the first advancement in mechanical horology in 100 years was introduced by Philip Woodward, British mathematician, radar engineer and horologist.

His W5 clock featured a mechanism in which a free pendulum is impulsed by a dropped weight timed by a slave pendulum. The rate of the slave pendulum is regulated by the rate of the free pendulum through a feedback mechanism. If it sounds complex, well, it is. But it provides one of the most fascinating and intricate timekeeping mechanisms anywhere.

Making it more precise

David Walter took Woodward’s concept to the next level with the (D)W5 Free Pendulum Clock. He added jeweled bearings, tungsten-carbide knife-edge suspension, barometric compensation on the pendulum bobs, and fused silica (quartz) pendulum rods. With a distinctive glass dial and spectacular skeletonized movement, and you end up with an extremely accurate timepiece that can’t fail to attract attention and admiration.

Philip Woodward, the original inventor, provided invaluable assistance to David during this clock’s development. In recognition of this, David kept Woodward’s W5 designation, adding the (D) to form his own initials as well.

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(D)W5 Free Pendulum Clock in Print

The prestigious magazine of the British Horological Institute, Horological Journal, published an extensive article on (D)W5. View PDF


  • Free pendulum technology gains accuracy by eliminating interference from traditional crutch mechanisms
  • Free and slave pendulums swing at a ratio of 30:21 to eliminate unwanted resonance
  • Fully jeweled – 64 jewels including the barrel and front center wheel pivots
  • Tungsten-carbide knife-edge suspensions in Invar blocks
  • Fused silica (quartz) pendulum rods with Invar fittings
  • Solid main movement back plate with skeletonized front plate
  • Glass seconds and main dials – etched with Breguet-style numbers
  • Heat-treated “blued” steel screws

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