Case crush and tooth fracture on a helical pinion is the kind of damage that demands engineering analysis before anyone starts cutting replacement gears.

Most gearbox repair follows a familiar sequence. A unit shows up damaged, the shop measures what’s worn, makes replacement parts, reassembles, and ships it back. Scott Franks, P.E., spent decades inside that world at Lufkin Industries and came to believe it wasn’t enough. In 2015, Franks and his partner, Albert Stokley, opened Luftex Gears in Lufkin, TX. They built the company around a structured four-pillar service model—Inspect, Analyze, Advise, and Produce—that put engineering analysis ahead of production. A gearbox that arrived at Luftex didn’t go straight to the shop floor. It went through engineering first. “Our time at Lufkin Industries is where we learned the value of customer relations through inspecting, analyzing, advising, and producing to ultimately complete the repair,” Franks says. What pushed them to go independent was the 2013 GE acquisition of Lufkin Industries. “The GE philosophy towards customer relations didn’t align with ours, so we decided to provide an alternative choice to customers who value involvement through Luftex.” Luftex had no OEM product line and no installed base. Everything depended on the expertise of its people. During those startup years, Franks took seven days off in five years. Operators became CNC technicians. Managers and engineers doubled as ground crews and janitors. Everyone learned to drive a fork truck. Inspection in Two Modes Luftex’s inspection work splits into in-plant evaluation of running equipment and shop analysis of failed units. In-plant inspections look for signs of proper lubrication supply, acceptable contact across tooth flanks, and any evidence of metal distress. Scheduled periodic inspections add a trending layer: has the contact pattern shifted? Has noise increased? Have bearing clearances changed?

“If caught early enough, mitigation processes can be successfully implemented,” Franks says. When a failed unit arrives at the facility, inspection starts with what Franks calls a “30,000-foot evaluation,” associating major damage with probable causes. Then the unit goes through an engineering analysis to verify the design against AGMA or ISO standards before root cause work begins. For gearboxes that arrive without original documentation—common in older steel, mining, and sugar operations—reverse engineering starts in conversation with the customer, not at the measurement table. “The name plate on the gearbox doesn’t affect how the components react when in operation,” Franks says. “What’s important is how a gearbox reacts to the conditions it sees while running at the required service load, speeds, and operating environment.” The analysis may lead to recommended changes in bearing design, gear geometry, or lubrication—well beyond like-for-like replacement. “There are numerous facilities with gear cutting machines that can offer to manufacture a gear but with little ability to analyze the validity of a design,” Franks says. “It is this service that Luftex can provide that many companies offering gear or gearbox repair cannot support.” Adding a Pillar: Educate During the startup years, Luftex operated under four pillars but didn’t have the bandwidth to formalize training as a service. The 2019 acquisition by Sumitomo Drive Technologies changed that. Sumitomo absorbed the administrative overhead and freed Luftex’s people to focus on production, continuous improvement, and formal customer education. Today, Luftex hosts several two-day gear schools each year and offers customized on-site training. The curriculum starts with the foundation—checking that it’s solid, flat, free of burrs, and making full contact with the bottom of the gearbox housing. From there, it moves to verifying proper alignment between mating rotating elements to ensure load distribution, coupling setup (different methods for different gear designs), and unit startup checks covering lube pumps, oil flow, temperatures, and recommended inspection and documentation frequency. Franks describes attendees having “ah ha” moments when a discussion topic connects to a recurring problem back at their plant—root causes that turn out to be alignment issues, foundation problems, or lubrication regimes that were wrong from the start. “A company’s culture has a tremendous effect on how open the communications are between a supplier and owner when trying to establish what caused a failure,” Franks says. “Sumitomo intends to engage customers who value an honest relationship that leads to a partnership that benefits both parties.” Analyze, Advise, and the Honesty Question Having Sumitomo behind Luftex gives the analysis stage a depth most independent shops can’t match. Franks describes cases where a customer installed a competitor’s gearbox and immediately had reliability issues. Luftex’s analysis revealed the units were originally undersized for the application and the original housing wasn’t large enough to make the necessary modifications required for a reliable design. In extreme cases like this, the only fix is a properly rated Sumitomo OEM replacement. The advise stage is where that analytical depth pays off in practice. Luftex presents options with the strengths and weaknesses of each: a temporary repair that buys time while a permanent solution is planned, a long-term repair with investment in spare critical components, or a new unit if repair costs exceed replacement. Sometimes a repair wins even when a new unit is cheaper, because delivery lead times on new equipment may not fit the customer’s downtime window. “Sumitomo Drive Technologies has the means to offer multiple options to a customer and help them decide what best fits their needs,” Franks says.