Installing in Vibrating Environments: 25 g Resistance Is a Property of the Body — Anti-Loosening Comes Down to Workmanship

When a sensor fails under strong vibration, the body almost never gives way first — the installation loosens first. The Germanjet Series 13 mobile hydraulics offers 25 g vibration resistance and 100 g shock resistance on the body, and reaches IP69K, so it is suited to construction machinery, mobile hydraulics and other severe applications. Bracket bolts backing off, a magnet carriage shifting, and fatigue fracture at the cable root, however, can only be solved by installation workmanship. This article covers anti-loosening, vibration isolation and inspection methods under vibrating conditions. For the product-specification background, see IP protection ratings; for the installation overview, see installation and commissioning in practice.

Keep the figures apart: Series 13 is 25 g vibration / 100 g shock. Most profile and in-cylinder types are 15 g / 100 g to IEC 68-2-6 / 68-2-27 — do not write 25 g across the whole range.

Be clear what "25 g vibration / 100 g shock" actually means

These two figures are the body's withstand capability under specified test conditions: vibration resistance addresses continuous cyclic vibration; shock resistance addresses short-duration high-amplitude acceleration (for example reversing impacts or drop impacts). They guarantee that the sensor is not damaged and can continue to work; they do not guarantee that the reading is unaffected under vibration — mechanical vibration itself produces a real displacement of the position magnet relative to the rod, so a fluctuating reading is "measuring correctly", not "measuring inaccurately".

The first step in a vibrating application is therefore to distinguish: is the reading fluctuation a real displacement (the machine is vibrating), or a measurement abnormality (installation or electrical)? The method is to observe the machine state and the reading waveform together. If the fluctuation frequency matches the machine vibration frequency and the amplitude is reasonable, it is a true reflection and should be filtered on the controller, not by adjusting the sensor.

Anti-loosening: three layers, applied in order

The alignment mark costs almost nothing, yet it turns "has it loosened?" from a judgement question into an observation. It is strongly recommended on the magnet bracket, the sensor flange and the connector.

Position magnet and carriage: the links most likely to fail under vibration

Vibration lets the position magnet creep relative to the measured part, which appears as zero drifting with time (see tracking down reading errors). Three handling points:

• Magnet fastening must have a mechanical anti-rotation / anti-back-off measure; friction alone is not enough;
• The external-type carriage coupling should retain floating freedom but must not be sloppy — float is to relieve radial constraint; slop produces impact in the clearance under vibration. The two are different; practice is in external installation;
• Re-measure the magnet mounting reference dimensions on a schedule and compare with the as-installed record. That is far earlier than waiting for the reading to go wrong. For how to record dimensions, see five magnet installation pitfalls.

Cable and connector: high-incidence sites of vibration fatigue

Vibration destroys cable by fatigue: the connector root, the edge of a fixing point and a bend are loaded repeatedly. First the screen strands break (noise immunity falls for no obvious reason), then the cores break (intermittent no-output). Protection points:

• Place the first fixing point close to the connector so that vibration stress is not transmitted into the connector root;
• Keep a suitable spacing between fixing points so that long unsupported lengths do not whip;
• Use energy-chain or dedicated flex-rated cable for cable that travels with a moving part; do not make do with ordinary cable;
• For connector selection and seal maintenance, see M12 connector selection and seal maintenance.

The troubleshooting idea for intermittent faults is "test while vibrating": with the machine running, tap or flex each section of cable lightly and watch whether the reading responds. The break region can be located quickly. Related criteria are in the signal-jump troubleshooting flow and no-output troubleshooting.

Vibration-isolated mounting: when it is needed, and when it must not be used

Fitting vibration pads between the sensor and the vibration source can reduce the vibration level transmitted to the body, but an external sensor must not have vibration pads added casually — isolation means allowing relative displacement, and once the sensor mounting datum can move relative to the machine, the measured displacement includes the pad deflection. The workable approach is to isolate further upstream (between the whole machine and its foundation), not between the sensor and the machine. A cylinder-integrated type does not have this contradiction, because the rod is rigidly connected to the cylinder.

On the selection side: for mobile hydraulics, construction machinery and other strong-vibration applications, prefer the Series 13 mobile hydraulics; on stationary machines where vibration comes mainly from reversing impact, consider a cylinder-integrated solution (Series 16 cylinder-integrated, Series 17 hydraulic-cylinder integrated), because the mechanical chain is shortest and the number of joints that can loosen is smallest. For industry scenes, see construction-machinery cylinder position solutions.