This article explains how to correctly position the Smart Trac on different types of rotating assets. It's intended for technicians and engineers responsible for installing sensors in the field.
Sensor position directly affects the quality of vibration data collected and, consequently, the accuracy of the Insights generated by the platform. A poorly positioned sensor can produce inaccurate readings, false alerts, or fail to detect real issues on the asset.
Before you start
Before positioning the Smart Trac, make sure that:
You've read the Smart Trac mounting guide. Positioning and mounting are separate steps — this article only covers where to place the sensor, not how to attach it.
The asset is identified and you know its type (electric motor, centrifugal pump, gearbox, etc.).
You have physical access to the recommended monitoring points (near the bearings).
The Smart Receiver is already installed and within range, or you know where it will be installed.
Important: If you position the sensor before mounting it, validate the position one last time before final attachment. Repositioning a sensor that has already been mounted can damage the asset's surface or the sensor's base.
General positioning principles
Before reviewing the specific cases by asset type, understand the two rules that apply to any installation.
1. Align the sensor with the asset's X, Y, and Z axes
The Smart Trac has three internal axes (X, Y, and Z) that must be aligned with the asset's directions:
Axial direction: parallel to the machine's rotation shaft.
Radial direction (vertical): perpendicular to the shaft, pointing upward.
Horizontal direction: perpendicular to the shaft, on the horizontal plane.
The practical rule: at least one of the sensor's axes must be aligned with the asset's axial direction. Ideally, the other two axes are aligned with the radial and horizontal directions.
2. Keep the sensor's identification visible
When choosing which side of the sensor to attach to the asset, position it so that the identification label (with the Smart Trac's name and code) remains visible after mounting. This makes future maintenance, replacements, and audits easier.
Sensor's axis assessment
There are 3 references for aligning the sensor's axes in relation to the asset's axis. Any of them is valid, as long as one of the sensor's axes is aligned with the asset's axial direction (indicated by the green dashed line in the diagrams).
Reference 1
The sensor is mounted on the side of the bearing, near the asset's shaft. Depending on the sensor's rotation, either the Y or X axis aligns with the axial direction.
Variation A — Y axis aligned with axial direction: the sensor is mounted so that the Y axis points outward, in the same direction as the asset's shaft.
Variation B — X axis aligned with axial direction: same physical position, but with the sensor rotated 90° so the X axis aligns with the axial direction.
Reference 2
The sensor is mounted on the end of the asset's shaft, with the Z axis pointing in the axial direction. The two variations show possible orientations of the X and Y axes.
Variation A — Z axial, Y vertical, X horizontal.
Variation B — Z axial, X vertical, Y horizontal.
In both variations, the Z axis is the one aligned with the axial direction.
Reference 3
The sensor is mounted on top of the bearing. Depending on the sensor's rotation, either the Y or X axis aligns with the axial direction.
Variation A — Y axis aligned with axial direction: the sensor is mounted on top, with the Y axis pointing in the direction of the asset's shaft.
Variation B — X axis aligned with axial direction: same top position, with the sensor rotated so the X axis aligns with the axial direction.
💡 Tip: Whenever possible, choose the reference that allows you to mount the sensor on a flat surface near the bearing. Irregular surfaces compromise both mounting quality and reading accuracy.
Positioning by asset type
The Smart Trac monitors over 30 types of rotating assets. The most common cases are listed below. If your asset isn't listed, follow the general principles above and use the most similar asset as a reference.
💡 Tip: When in doubt about a specific asset, contact the Customer Success team before installation. Repositioning sensors after mounting takes time and can damage surfaces.
Electric motor
Axis orientation: mount the sensor with the Z axis in the equipment's vertical direction. The X and Y axes should be aligned with the horizontal and axial directions, respectively.
If you can't align the Z axis with the radial direction, mount the sensor so that at least two axes are aligned with the vertical and horizontal directions.
Monitoring points: monitor two points near the bearings:
Drive End (DE) — the side where the motor connects to the driven equipment.
Non-Drive End (NDE) — the opposite side, usually where the motor's cooling fan is located.
These positions provide higher sensitivity for fault detection because they improve the transmission of vibrations from the motor to the sensor.
Parallel-shaft gearbox
Monitoring points: install one sensor per shaft, as close as possible to the corresponding bearings.
Monitor both the input shaft and the output shaft.
For each additional reduction stage, install an additional sensor near the bearings of the corresponding intermediate shaft.
This setup allows you to detect faults associated with each stage of the system separately, instead of just identifying that "something is wrong" with the gearbox as a whole.
Centrifugal pump
Monitoring points: there are two main points.
Drive End (DE): mount the sensor as close as possible to the bearing housing. This provides higher sensitivity to vibrations.
Area near the blades: a critical point for detecting cavitation, impeller wear, and bearing-related issues.
Bearing block
Axis orientation: mount the sensor with the Z axis in the equipment's vertical direction. The X and Y axes should be aligned with the horizontal and axial directions, respectively.
Alternative configuration: it's also acceptable to mount the sensor with the Z axis aligned with the shaft supported by the bearing. In this case, prioritize the bearing's load zone.
Important: For large bearings (those supporting shafts with diameters greater than 50 cm / ~20 in), vertical mounting is not recommended. In these cases, mount the sensor with the Z axis pointing toward the center of the shaft, within the load zone.
Planetary gearbox
Position the sensors at rigid structural points that transmit machine vibrations effectively. The main monitoring points are:
Input shaft: mount the sensor on the bearing, positioned radially to the shaft.
Planetary stages: mount the sensor on the outer ring of each stage, or on adjacent points that offer sufficient rigidity.
Output shaft: mounting the sensor on the output shaft bearing is also a valid option, especially for monitoring the final stage of the gearbox.
Screw or lobe compressor
Monitoring points: monitor both shafts, installing sensors at the Drive End (DE) and the Non-Drive End (NDE).
Mount the sensors at structurally rigid points, near the bearings. This ensures accurate transmission of the vibrations generated by the compressor's operation.
Bevel and worm gearbox
Monitoring points: install one sensor per shaft, as close as possible to the corresponding bearings.
Monitor both the input and output shafts of each stage. This setup allows you to detect:
Gear wear.
Misalignments.
Bearing issues.
Reciprocating pump
Monitoring points: mount the sensors as close as possible to the shaft bearings, preferably at the Drive End (DE) or the Non-Drive End (NDE).
These points correspond to the most structurally rigid regions of the machine, allowing vibrations to be transmitted to the sensor more efficiently.
Screw or lobe blower
Monitoring points: monitor both shafts, with sensors at the Drive End (DE) and the Non-Drive End (NDE).
Mount at rigid points near the bearings to ensure sensitivity in fault detection.
Liquid ring vacuum pump
Monitoring points: mount the sensors near the shaft bearings, preferably at the Drive End (DE) or the Non-Drive End (NDE).
These areas are the most structurally rigid, which improves the transmission of vibrations to the sensor and increases the accuracy of fault detection.
Gear pump
Monitoring points: install one sensor per shaft, as close as possible to the corresponding bearings, preferably at the Drive End (DE) or the Non-Drive End (NDE).
These points represent the most rigid regions of the pump and ensure accurate readings.
Quick reference table
Asset type | Number of sensors | Main points |
Electric motor | 2 | DE and NDE |
Parallel-shaft gearbox | 1 per shaft (minimum 2) | Bearings of input, intermediate, and output shafts |
Centrifugal pump | 2 | DE and area near the blades |
Bearing block | 1 | Load zone |
Planetary gearbox | 3+ | Input shaft, planetary stages, and output shaft |
Screw / lobe compressor | 2 | DE and NDE of both shafts |
Bevel / worm gearbox | 1 per shaft | Bearings of input and output of each stage |
Reciprocating pump | 2 | DE and NDE |
Screw / lobe blower | 2 | DE and NDE of both shafts |
Liquid ring vacuum pump | 2 | DE and NDE |
Gear pump | 1 per shaft | DE and NDE of bearings |
Smart Receiver positioning
The Smart Receiver's position directly affects the performance of the sensors connected to it. Follow these rules:
Ensure access to power. The Smart Receiver requires an external power source. Don't choose a location without a nearby outlet or connection point.
Don't install inside metal electrical panels. Metal blocks the signal between the receiver and the sensors.
Respect the 100-device limit per receiver. This number may be lower depending on your plant's topology (walls, distance, interference).
For the complete receiver installation walkthrough, see the Smart Receiver Installation Guide.
Common issues
Symptom: The Insights generated seem inaccurate or inconsistent after installation.
Likely cause: sensor is poorly positioned, with no axis aligned to the asset's axial direction.
Solution: check the orientation of the X, Y, and Z axes in relation to the asset. Reposition the sensor following the principles in this article.
Symptom: The sensor isn't communicating with the Smart Receiver.
Likely cause: the Smart Receiver is installed inside a metal panel or too far from the sensor.
Solution: reposition the receiver outside of metal panels and within range, based on your plant's topology.
Symptom: I can't identify the Drive End (DE) and the Non-Drive End (NDE) on my asset.
Likely cause: the asset doesn't have clear visual identification, or it's an atypical piece of equipment.
Solution: the Drive End is the side where the motor connects to the driven equipment (via coupling, pulley, or belt). The Non-Drive End is the opposite side, usually where the cooling fan is located on motors. If you're still unsure, contact the Customer Success team.
If the issue persists after following the steps above, contact Tractian support.