The bearing that's about to fail doesn't announce itself. It starts as a slightly elevated vibration reading at the Drive End in the radial direction — 3.8 mm/s where 2.5 was the baseline six months ago. Then, two months later, it's 5.2 mm/s with a temperature rise at the 90-minute reading. Then it's 7.4 mm/s and suddenly you're scheduling an emergency replacement during a production run rather than a planned shutdown window. The difference between those two scenarios is whether you had a trending dataset or just the last reading.
Three-Axis Vibration at Three Measurement Points
Drive End a, Drive End b, Drive End c capture the three-axis vibration signature at the Drive End bearing — axial, radial horizontal, and radial vertical. Each axis responds differently to different failure modes. Radial readings that are elevated while axial remains normal typically indicate misalignment between the motor and driven load. Axial vibration that's increasing independently of the radial axes suggests a loose component or impending thrust bearing failure. A uniform increase across all three axes indicates imbalance — either the rotor itself or the load it's driving.
Motor Body d, Motor Body e are the mid-body readings that capture structural looseness and frame resonance issues that don't show up clearly at the bearing measurement points. A motor body that's vibrating more than the bearing housings suggests a mounting problem — loose feet, soft foot, inadequate base rigidity — rather than an internal bearing or rotor issue.
Non Drive Motor f, Non Drive Motor g, Non Drive Motor h close the three-point measurement scheme. Non-drive end bearing failures are common in direct-drive applications where the NDE bearing carries the residual magnetic pull from the rotor — the unbalanced magnetic pull (UMP) that creates a constant radial load even in a nominally balanced system. NDE readings that are elevated relative to baseline on a motor that shows normal DE vibration is a specific signature that points directly at NDE bearing wear.
All nine readings together create a vibration signature for the motor at this inspection. Compared against the previous signature and the one before that, the pattern of change identifies which failure mode is developing before the magnitude has reached the alarm threshold.
Sequential Thermal Profiling
DE 30 min, DE 60 min, DE 90 min at the Drive End, Motor Body 30 min, Motor Body 60 min, Motor Body 90 min, and the same three intervals at the NDE capture the thermal rise curve rather than a single temperature snapshot.
A bearing at normal temperature when cold that rises 12°C in 30 minutes and plateaus at 15°C over 90 minutes is operating in thermal equilibrium. The same bearing that rises 18°C in 30 minutes and continues rising to 28°C at 90 minutes is not in equilibrium — it's generating more heat than it can dissipate, which indicates a lubrication issue, an overloaded bearing, or the early stages of mechanical failure. A single temperature reading at any one of those three timepoints doesn't tell you which scenario you're in. The three-interval curve does.
Motor body temperature that's rising faster than bearing temperature indicates a ventilation problem — blocked cooling fins, failed cooling fan, inadequate ambient airflow in the motor enclosure. The relative rates across measurement points, not the absolute values, are the diagnostic signal.
Motor and Location with Date & Time complete the record with the asset identity and inspection timestamp. On a site with 40 motors across multiple locations, the combination of these three fields is what makes a vibration reading interpretable — the same magnitude reading means something very different on a 37kW centrifugal pump motor and an 11kW conveyor drive motor.