Vulcan Onshore Tip #72: Vari-Cycle II (306, 505, 506 & 508, 510, 512 Hammers)

The Vulcan Vari-Cycle II offers all the advantages and ease of use of the original Vari-Cycle with fewer parts and less maintenance.  When maintenance is required, it will be easier and less expensive.  The Vari-Cycle II uses the same principle as the original Vari-Cycle, except the trip shifting cylinder is built into the Open Steam Chest Head Bracket thus reducing the number of parts.  Air is supplied to the movable trip piston to move the trip into either the long stroke or short stroke position.  A detent holds the trip in position when the air supply is removed.  For the 306, 505 & 506 Hammers the Vari-Cycle II is P/N 13711.  For the 508, 510 & 512 Hammers the Vari-Cycle II is P/N 13730.  The Vari-Cycle II is designed to fit the above sizes of Hammers with a Traverse Trip or Vari-Cycle.  On your next new Hammer specify Vari-Cycle II or contact Vulcan to see if your Hammer can be converted.

Note: this was Vulcan’s last Onshore Tip, issued by the Tennessee Corporation. The history behind it, however, isn’t one of Vulcan’s happier adventures.

Vulcan patented the Vari-Cycle–especially important with concrete piles for energy variation–in December 1967. Eleven years later Conmaco patented essentially the device you see above. When Vulcan discovered this device (shortly after Conmaco’s patent publication) and that it infringed on the Vulcan patent, it demanded that Conmaco desist from infringement. Conmaco countered by offering a cross-licensing agreement, allowing Vulcan to make and sell Conmaco’s energy selector. Vulcan refused.

Conmaco did desist from infringement, but when Vulcan’s patent expired (1984) Conmaco was able to make their device without competition from Vulcan. By this time Vulcan began to market its 506 and 512 hammers, and the increased rebound loads from 5′ stroke driving gave the Vari-Cycle reliability problems on these hammers (the device in the larger hammers was more robust.) Adopting “Vari-Cycle II” would have solved this problem, but Vulcan was precluded from doing so until 1995, by which time Vulcan was headed towards merger.

This debacle was an illustration of a point made many years ago:

Agree with thine adversary quickly, while thou art in the way with him…(Matthew 5:25)


5 thoughts on “Vulcan Onshore Tip #72: Vari-Cycle II (306, 505, 506 & 508, 510, 512 Hammers)

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