Simple observations regarding gearbox repairs can help you discover what is wrong with your power transmission equipment. Here are some tips to troubleshooting certain mechanical transmission product problems.
Power transmission equipment provides a rotary motion and torque between equipment and a primary mover. If there is a problem in the support, maintenance, loading, alignment or installation of a mechanical power transmission product, this can lead to gearbox repairs. In addition, distress to gearbox equipment can be caused by missing components, such as gears and shafts. All of these issues can cause a mechanical power transmission product to run less efficiently. To keep your gearbox equipment running smoothly, plan for preventive maintenance, lubrication and regular visual inspections.
Misalignment of gears often causes gear tooth fracture or surface distress. Using AGMA ratings to guide you, ensure that there are no abnormal elastic deflections in the supporting structure of power transmission equipment, thereby reducing the risk of gear tooth damage.
Gear Failure Classifications
There are four main classifications of failures regarding gearbox repairs: plastic flow, pitting or surface fatigue, breakage and wear. A visual inspection of the gearbox will show you the differences.
Plastic flow wear. Plastic flow wear creates a depression on the contact area of a gear tooth, or gives its ends a fin-like appearance. This wear generally occurs with soft gear materials in gearbox equipment. To prevent plastic flow wear decrease contact stress, use harder surface and sub-surface materials and increase the spacing accuracy between the teeth.
Pitting and surface fatigue. Repeated surface or sub-surface stresses can cause surface fatigue in power transmission equipment. A high amount of stress being placed on the surface of a gear tooth causes pitting. In a mechanical power transmission product, pitting can happen quickly and occurs mainly through-hardened gearing. While some pitting is normal, reduce its occurrence by minimizing speed and load weights when breaking in gears, and use a quality lubricant.
Breakage. Breakage is the most significant failure in regards to gearbox repairs. Breakage occurs in power transmission equipment when the stresses exceed the endurance of a gear’s tooth. This occurs at areas of distress on a shaft, the more tensile side of a tooth, or the tooth root fillet. Prevent breakage by controlling torque, installing resilient couplings, using lubricants and reducing the amount of bending stress and transient loads on a mechanical power transmission product.
Spalling. In gearbox repairs terminology, spalling is when a large area of surface material breaks away from a gear tooth. Spalling looks like overlapping or interconnected pits in one location, or like longitudinal cracks on a tooth’s surface. Spalling is usually caused by insufficient core hardness/case depth, high-contact stress, too high of a load and improper heat treatment.
Wear on power transmission equipment. It shouldn’t be a surprise that moderate to heavy wear of an industrial gearbox impairs performance, causing cracks in gear teeth, changing its shape and can result in breakage. Proper maintenance of the machinery will reduce the effect of wear – conduct regular lube changes, use a quality lubricant and filter present contaminates.