HMS Series
Motion Sensor
Vehicle positioning/motion sensor — confirms the vehicle is stationary and correctly positioned before a weighment is accepted.
Manufacturing
Built, installed & supported by HMT
Compliance support
Calibration & Legal Metrology guidance
System ready
Automation, ticketing & ERP integration
01Overview
Prevents a reading being captured while a vehicle is still moving or only partially on the deck — a common source of disputed weighments on a manually-operated bridge.
02How it works
Confirming stillness before the system trusts the number
A load cell reading taken while a vehicle is still rolling, braking, or only partially on the deck is not a valid weight — it's a snapshot of a moving, changing load. A motion sensor monitors the vehicle's position and stability on the deck and only allows the indicator or software to accept and record a weight reading once the vehicle has come to a genuine stop, fully positioned on the platform.
An interlock, not just a warning
The sensor doesn't merely flag a warning to the operator — it acts as an interlock in the weighment sequence, holding the system from finalizing or printing a ticket until the stability condition is met. That distinction matters: a warning can be ignored under pressure to keep traffic moving; an interlock physically prevents the invalid reading from being captured in the first place.
Why this matters more on unmanned sites
A trained operator watching the deck can usually judge by eye whether a vehicle is properly stopped before triggering a weighment manually. An unmanned or semi-automated site doesn't have that human judgment in the loop, so the motion sensor effectively replaces the operator's watchful eye with an automated check.
03Manufacturing & build quality
The sensor unit is built around a detection mechanism calibrated to distinguish a stationary, fully-positioned vehicle from one that's still moving or only partially on the deck, housed in a weatherproof enclosure suited to mounting near or on the weighbridge structure. Sensitivity and detection thresholds are set and tested against simulated vehicle approach and stopping scenarios during manufacturing, since a sensor that's too sensitive triggers false stability readings and one that's not sensitive enough delays valid weighments unnecessarily. The unit's output interface — typically a signal wired into the indicator or weighbridge software's interlock logic — is bench-tested before the sensor is dispatched.
04Problems it solves
Disputed readings from a still-rolling vehicle
A weight captured mid-motion doesn't reflect the vehicle's true static weight, and is one of the more common sources of disputed weighments on a manually operated bridge.
Partial-deck weighments
A vehicle only partially on the deck — front axles on, rear axles still off — produces a reading that understates the true total weight; the sensor prevents the system accepting a reading under those conditions.
Premature ticket printing
Without an interlock, a ticket can print based on a reading captured before the vehicle has settled, which then has to be manually voided and re-weighed — the sensor removes that rework.
Impatient drivers pulling away early
At busy sites, drivers under time pressure sometimes try to move off before the weighment is confirmed complete; the interlock keeps the system from recording a result until stability is genuinely confirmed.
05Why it matters
Every dispute over a weighbridge reading eventually comes down to one question: was that a valid, static reading, taken with the vehicle properly and fully positioned on the deck? A motion sensor is the piece of equipment that answers that question automatically, before a dispute ever has the chance to happen, and it's especially important as more sites move toward unmanned or lightly staffed operation, where there's no operator standing by to make that judgment call themselves.
06Salient features
- Detects vehicle motion/stability before weight capture
- Prevents partial-deck or in-motion readings
08Technical file
Need the full technical sheet?
Request drawings, model-specific details and project documentation from the HMT team. A downloadable product file will appear here once approved.
09Complete system
Plan beyond the deck.
A vehicle weighing point can combine the weighbridge with indicator, load cells, traffic management and H-Weigh software for an accountable end-to-end workflow.
08In the field
09Frequently asked
How sensitive is the detection, and can it be adjusted?
Detection sensitivity is set during commissioning to suit the site's typical vehicle speeds and deck length, balancing quick weighment turnaround against reliably rejecting in-motion readings — this is normally a one-time calibration task done alongside indicator setup.
Does it cause false triggers from wind, vibration, or nearby traffic?
It's calibrated specifically to distinguish genuine vehicle motion on the deck from ambient site vibration, but as with any sensor, mounting position and site-specific conditions are worth checking during commissioning to rule out false triggers.
Is it compatible with our existing indicator?
It's designed to interface with standard weighbridge indicators and software as an interlock signal — confirm your indicator or software supports an external interlock input before ordering.
Where does it need to be mounted?
Typically positioned to have a clear view of, or direct connection to, the deck or the vehicle's position on it, depending on the specific detection method — your installer will confirm the correct mounting position for your site layout.
Does weather affect its reliability?
The housing is weatherproof and built for continuous outdoor duty at a weighbridge site, the same operating environment the rest of the weighbridge electronics are designed for.
10Industries this serves
Ready to spec a motion sensor?
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