Vibration is one of the earliest signs that something in a drive train has changed. It can come from the gearbox itself, from the motor or coupling, or from the driven machine and its foundation. Because vibration also damages bearings and seals over time, finding its source early usually costs less than repairing what it causes.
This guide supports an initial root-cause assessment on an installed industrial gearbox. Formal vibration analysis by a qualified specialist may still be needed.
How gearbox vibration shows up
It may be felt on the housing, heard as a hum or rumble that changes with speed, seen as movement of mounting feet or guards, or noticed as loosening fasteners. Vibration that appears only under load, only at a certain speed, or only after warm-up gives useful clues.
Likely causes to check, from outside in
Foundation and mounting
Loose or stretched bolts, a flexible base frame, missing shims or a soft foot allow the housing to move. Check these first because they are common and simple to correct.
Coupling and alignment
Misalignment between motor, gearbox and driven shaft, or a worn coupling element, produces vibration linked to shaft speed. It also loads bearings and seals.
Driven machine
Unbalanced fans, damaged pulleys, material build-up on rotating parts or process surges can transmit vibration back into the gearbox.
Bearings and gears inside the gearbox
Bearing wear or damage, and gear tooth wear, usually produce vibration with a characteristic noise and may be accompanied by heat or particles in the oil. See the bearing damage guide for these signs.
How to judge it on site
Record when the vibration occurs and whether it changes with speed or load. With the machine isolated, check mounting bolts, shims and coupling condition, and look for fretting marks. After correcting external causes, run under controlled conditions and compare. If vibration remains, check oil condition and bearing temperature, and arrange a formal measurement.
When the gearbox itself needs attention
Consider inspection or replacement when vibration persists after mounting and alignment are corrected, when it is accompanied by abnormal noise, heat or metal particles, or when bearing damage is confirmed. Send the nameplate, a description of the installation and your observations for a replacement review.
Related: gearbox bearing damage · unusual gearbox noise · Send your nameplate
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