Lest you come away from my last posting thinking I am completely trapped in the past, I’ve invested a fair amount in new software during the past few years, and have been trying hard to learn to use it. My “inner curmudgeon” has good reasons for being skeptical of change, so I have to do some things by both the old method and the new before completely letting go.
Sometimes my reluctance is informed by my own ‘horror stories” — as described in the previous blog. Other times it is based upon stories told to me by someone else. Our trade has a long memory, and it is important for those promoting “new things” to understand why certain “prejudices” are widely held.
Let’s start with some market sectors still skeptical of surface-hardened gears. It may come as a shock to those who have never built a device with “soft gears,” but few American suppliers offered carburized gears until the early 1990s. Europe fully embraced “hard gears” more than two decades earlier, and they saw the oil patch in particular as a market ready for change during the 1980 oil boom.
The classic “horse head” pump-jack gearbox had evolved into a commodity product with “soft” lower-quality herringbone gears and standardized interface dimensions. Converting to “hard” gears offered weight and cost savings; the resulting prototypes were way different from the existing drives. Where a herringbone box was the size of an office desk, the carburized box was the size of a suitcase — almost comic with big shaft extensions sticking out both sides. The rating calculations said it would work, and brave customers quickly put them into service — but not for long.
The horse head pump applies an impact load to the same teeth every cycle. The old herringbone units had the same durability rating as the carburized models, but the strength ratings were 50% higher. Teeth started popping off the “hard” gears within weeks of installation, and old oilfield hands have never again trusted “hard” gears.
Once the carburized gearboxes were redesigned to equal the herringbone strength ratings, they lost their cost advantage and much of the weight reduction. They are great pump-jack gearboxes, but still have to overcome those negative attitudes.
I would never want to go back to through-hardened gears; the advantages of modern, carburized designs are just too great when operating conditions are properly analyzed. As President Reagan was fond of saying: “Trust, but verify.”