The Vulcan Pile Extractor was the last major design by James N. Warrington (U.S. Patent 1,736,104) to enter production, which it did in 1928.
The extractor uses a simple, valveless design where the ram is thrown upward by the incoming steam or air. It strikes an anvil located in the top of the machine. The impact force is transmitted through the side bars to the cross pin and onward to the connecting links.
Although it could in principle be used to extract any pile, Vulcan pile extractors were primarily used with sheet piling, as this type of piling is very common in temporary works. An example of this is shown at the right. The main method of connecting the extractor with the piles was through the two bolts that passed through the connecting links and the corresponding holes in the sheet piling, which the sheet pile supplier would commonly drill or burn in the sheeting.
In some cases the holes could be avoided by the use of Heppenstal tongs, which are similar in principle to the grips seen on impact-vibration hammers. Vulcan also developed and patented its own pile grips as well.
Vulcan’s main competitor was the MKT “E” series, which were very similar in construction. In the 1960’s Vulcan also marketed the Nilens series of extractors, which featured a cable wrap system for transmitting the impact along with a Heppenstal type grip.
Impact extractors represented the best way of removing sheet piles until the 1970’s, when the vibratory drivers took over the job. However, for smaller jobs where there were few sheets, or jobs where the sheets were embedded in very hard soil or the interlocks rusted or beaten together, the impact extractor remains a useful tool for removing sheet piles after their job is done.