Vulcan Offshore Tip #8: Vari-Cycle Hammers

Vulcan Vari-Cycle (Stroke Control) is available for all Vulcan Single Acting Hammers having a cylinder which has as an integrally cast pad part thereof the necessary mounting pads for installation of the Vari-Cycle equipment. Shown in the table below are the first Serial Number and date of those hammers (by size) having Vari-Cycle factory installed or mounting pads for field retrofit.

Hammer Size Serial Numbers and Date
Onshore Hammers Offshore Hammers
#1 See Note 1
06 See Note 2
08 GB-8095/10-27-72
010 GB-8100/11-2-72
014 FI-6250/5-13-69
016 FI-6515/12-19-69 FH-5500/2-1-68
020 FG-5190/12-19-69 FH-5530/2-15-68
030 FH-5645/4-19-68
040 FG-5330/12-8-67
340 GC-8245/2-12-73
540 GD-8800/5-22-74
060 FH-5555/6-15-68
360 GD-9025/7-19-74
560 GC-8445/7-18-73
3100 GE-9450/6-11-75

All Hammers having Serial Numbers subsequent to those above are configured as to accommodate Vari-Cycle.

Note 1 — The following Size #1 Hammers are equipped with mounting pads for Vari-Cycle:

GC-8455/GC-8555/GC-8595/GC-8715/GC-8765

Vari-Cycle mounting pads on this size Hammer were discontinued 8-23-74.

Note 2 — The following Size 06 Hammers are equipped with mounting pads for Vari-Cycle:

GD-8750/GD-8740/GD-8825/GD-8605/GC-8605/GC-8685

Van-Cycle mounting pads on this size Hammer were discontinued 7-24-74

Note: This tip obviously does not cover the hammers later than the mid-1970’s, especially the onshore 5′ stroke hammers. Their situation is complicated; you can contact us to ask questions about this. All of the Vulcan 5100, 5110, 5150 and 6300 hammers can accommodate Vari-Cycle and indeed virtually all offshore hammers from the 1970’s onward were either equipped with Vari-Cycle or Traverse Trip.  Below are some photos of the Vari-Cycle mechanism.

020-vari-cycle
The Vulcan Vari-Cycle, again for the 020 offshore hammer. This works by shifting the movable trip (the trip with the arc slot) between two different cut-off wedges, which in turn varies the stroke. Variable stroke is essential for concrete piles to control tensile stresses. For offshore hammers, it is not so critical, which led to the use of “manual” overrides such as the traverse trip.
trip-shifting-cylinder
A photographic “exploded view” of the Vari-Cycle. It uses the “old” Vulcan part numbering system, which was used until the early 1970’s. Many parts still get ordered using that system.
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