June 14, 2022
The last stronghold for herringbones was — and remains — the venerable oil field pumpjack gearbox. Although known by a variety of other names, nothing says “oil field” to the average gear guy or gal than this ubiquitous suction rod pump with a crossbeam that goes up-and-down with huge counterweights. One of the largest facilities that produced these devices is a little over a mile from my home in Oil City, Pennsylvania. The Oilwell Services plant in the Siverly neighborhood employed 1,500 people — until its closure in 1987 and a move to Texas that still has economic impact on this region. My only visit to this town prior to house hunting was a sales call to that plant in 1979. Oil was booming in 1979, and since we had many herringbone machines it was a great idea to look for orders from one of the largest producers of pumpjacks in the country. That rocking motion characteristic of these machines puts peak load on the same spot during every cycle and herringbones, even when made out of ductile iron, had been surviving under that abuse for decades. Around that time carburized and hardened gears with ground flanks were taking over industrial gearboxes because of their more compact size. A noted German gear maker promised big cost savings by applying modern technology to this ancient product sector. Their gearbox typically weighed less than a third of what the ductile iron herringbone incumbent did. Only they did not appreciate that damn impact load. The latest and greatest gear technology suffered broken teeth within weeks of entering service. There are in fact grandchildren of the oilfield engineers who lived through that debacle who are distrustful of carburized gears to this day. A very old pumpjack has been installed outside our city hall as a memorial to the region’s history. It was restored from pieces found in the junkpile in Hasson Park, across the street from my house. Somehow that junk pile escaped notice during the WWII scrap drives and the restored mechanism will serve as a testimony of clever use of primitive technology.