Bently Nevada 330101-00-28-10-02-00 3300 XL 8 mm Proximity Probe

• Radial Vibration: Take radial vibration for example—basically you’re watching how the shaft moves inside a sleeve bearing. Under normal conditions, it stays within a stable range. But once there’s imbalance, misalignment, or the bearing starts acting up, the trend changes quite obviously. Experienced engineers can usually spot something off just by looking at the curve.
• Shaft Centerline Position: Some people overlook this at the beginning, but it’s actually quite useful. In simple terms, you’re tracking where the shaft “sits” over time. If it slowly shifts, that usually points to bearing wear or changes in the oil film. It’s not something that trips an alarm immediately, more like an early warning sign.

• Axial (Thrust) Position: Axial (thrust) position is one you really have to keep a close eye on, especially in turbines. If the shaft moves too far forward or backward, there’s a real risk of rotor and stator contact, which is a serious failure. That’s why this signal is often tied directly into the ESD system—once it exceeds the limit, the machine shuts down. No debate there.
• Differential Expansion: This usually comes into play during startup and shutdown. The rotor and casing heat up at different rates, so they expand differently. If you don’t monitor it, you might run into problems like rubbing or even seizure. So during these phases, operators tend to watch this parameter closely to make sure it stays within an acceptable range.

• Keyphasor® Signal:
• basically detects a “once-per-turn” mark on the shaft (a notch, pin, something physical). Every rotation gives you one pulse.
• This pulse acts like a reference point. With it, you can line up vibration data, calculate phase angles, and get accurate RPM.
• Without this, data is still there, but kind of “floating”—fine for basic monitoring, not great for detailed analysis. Most engineers will want this in place if they’re doing serious diagnostics.

These setups are usually not for small or non-critical equipment—more for machines where downtime is a big deal:

• Turbomachinery: Steam, gas, hydro turbines… all running fast, under heavy load. If something goes wrong, costs add up quickly, so monitoring is pretty much standard.
• Compressors: Both centrifugal and reciprocating types. In industries like oil & gas, compressors are often key to the whole process. If they stop, production usually stops too—so people don’t take chances here.
• High-Duty Pumps: We’re talking big, continuous-duty units, not small utility pumps. Over time, small issues like vibration or misalignment can build up, so having monitoring in place just helps avoid bigger problems later.