Gearboxes are extremely tough. They’re built to withstand harsh conditions and extreme loads. Oftentimes, we are so habituated to consistent gearbox performance that we may not notice clues of impending difficulties. In our work of gearbox repair, we notice certain problems that are common across industries and arise time and time again. To provide insight into how to prevent these complications from occurring in the first place, we present the top five gearbox maintenance issues, along with their causes.
Top Five Gearbox Maintenance and Performance Issues
Misalignment.
Misalignment is the most common reason for gearbox repair. Signs of misalignment include premature gear pitting, bearing pitting, and ultimately, failure. There are many causes of misalignment, from set-up error to deflection under load, to thermal expansion. Incorrect gearbox selection is another classic reason for misalignment.
Incorrect/Low Lubrication.
Just as the human body can’t survive long without blood, gearboxes cannot long avoid failure without lubrication. Combined, lubrication and contamination account for about a quarter of gearbox failures. Applying the wrong type of lubricant, failing to monitor lubricant contamination, and lack of lubrication are all causes for lubrication issues. Additionally, even small lubrication leaks can add up to large problems, as any decrease in lube will leave the gearbox open to overheating and failure.
Bearings Problems.
About half of all gearbox failings can be traced to the bearings. Rolling bearings are common in small and medium gearboxes; plain bearings are more common in larger sizes. Rolling bearings are sensitive to misalignment, debris, contamination, shock, and vibration. Contaminants can collect in the bottom of the gearbox, wearing out lower bearings. Incorrect alignment, such as using a vertically designed gearbox in a horizontal application, can also wreck bearings.
Thermal Instability.
Also known as thermal runaway, thermal instability happens when there is a significant temperature difference between the shaft and the housing. In this instance, a positive feedback loop is set up where the bearings lose clearance and grow pre-loaded, exacerbating thermal problems. High speed shafts are prone to thermal instability, especially when operating in cold ambient temperatures. Rapid acceleration, external heat going into the shaft, and hollow shafts are common factors leading to thermal instability.
Torsional & Lateral Vibration.
As machining torques and speeds rise, the likelihood of resonant vibrations increase as well. Side-to-side and twisting vibrations can be multiplied through resonant vibration. Over time such vibration can cause fatigue cracks, increased gear wear, excessive noise, shaft failure, and other problems. Resonance analysis is no easy task for gearboxes; systems engineers require manufacturer data for calculations. Mounting mechanisms and support structure rigidity also contribute to resonance.
It’s rarely easy to figure out why a gearbox failed, and how the system must be altered to prevent similar failures in the future. Our expert gearbox repair technicians can provide in-depth expertise in these subjects. We can repair any gearbox issue, and we can typically get it done in 24-48 hours. With repair, you’ll accrue significant savings over purchasing a new gearbox. Plus, our repairs are guaranteed with a one-year warranty. Collectively, we have more than a century of experience in repairing Falk, Dodge, Farrell, Hansen, and other gearbox brands. Call us today to learn more about your options for repairing gearboxes through Mar-Dustrial.
Posted under Machinery Maintenance on Tuesday, July 28th, 2015