Vulcan Onshore Tip #28: Blind Piston Rings

Lower piston rings in the case of the Super Vulcan and the DGH series hammers, and upper piston rings in the case of Vulcan Pile Extractors, require a special installation technique. This special technique is necessitated by the fact that in these three product lines, the piston and the piston rings affixed thereto must enter the cylinder in which they function unaided by such devices as piston ring compressors or installers. Additionally it is impossible to visually check the piston ring as it enters its cylinder. The procedure is not unduly complicated if the following steps are carefully executed. The three illustrations below show the general method to be described in steps.

  1. Examine carefully the piston ring grooves for any burrs or dirt. Deburr if necessary and make sure the grooves are clean.
  2. Expand the piston rings and snap them into their respective grooves making sure that they rotate freely.
  3. Raise the end of the piston ring at the gap with a fine point screwdriver or other sharp instrument and place behind the ring a piece of water soluble paper (cigarette paper or toilet tissue is suitable for this purpose).
  4. Using a lead or bronze hammer, carefully tap the piston ring at the point of insertion of the paper into the groove where it will be wedged in place by the paper.
  5. Repeat this procedure with the other end of the piston ring and in the process or tapping the ring into the groove, be sure that the gap in thepiston ring is as nearly closed as possible.
  6. After the rings are so wedged into the grooves, the piston is now ready for installation in the unit.

Moisture in the steam or compressed air will soften the paper used to wedge the rings and they will expand to their normal operating position in a short period of time after the unit is laced in operation.

Note: more detailed information on piston ring dimensions and clearances can be found in the Guide to Pile Driving Equipment.

The recommendation of “cigarette paper” is an amusing anachronism, but the effects of use of that paper in its intended purpose turned out to be costly for Vulcan’s owning family.


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