Why calibration matters
A brake tester is a measuring instrument. Its readings decide whether a vehicle passes, so the force it displays has to match the force actually applied. Over time, mechanical wear, temperature changes, knocks and electronic drift can move that relationship. Calibration checks the measuring chain against reference equipment and corrects it where it has moved.
What the engineer does
- Pre-checks. The engineer confirms the machine is mechanically fit to be calibrated: rollers turning cleanly, sensors secure, no faults logged. Calibrating a machine with a mechanical problem just records a wrong answer precisely.
- Reference setup. UKAS-accredited and traceable reference equipment is fitted to apply known loads to each measuring side.
- As-found readings. Readings are taken across the measuring range before any adjustment, so you have a record of how far the machine had drifted.
- Adjustment. Where readings fall outside tolerance, the machine is adjusted to BM's procedure and re-checked.
- As-left readings. A final set of readings confirms the machine is within tolerance.
- Certificate. You receive a calibration certificate as a PDF, and a paper copy is provided straight away for your records.
DVSA requirements
Calibration applies to all schemes. If your brake tester is used for statutory testing, follow the current DVSA requirements that apply to your site.
Keep your certificate safe
The certificate is your evidence the machine was in tolerance. Keep it where you can produce it for an inspection or audit. Every BM calibration certificate carries the machine's serial number (starting SR0), which is also the quickest way for us to look up your unit when you book.
When to call between calibrations
Don't wait for the next due date if you see warning signs:
- readings that look high or low compared with what you'd expect for a familiar vehicle
- a zero that won't settle or wanders with the machine idle
- side-to-side imbalance that appears on every vehicle
- any knock to the roller set, sensor or cabling, or work in the pit
- replacement of a load cell, sensor or measuring board
Any of these can mean the calibration no longer holds. A check visit is quicker than explaining questionable results later.
Booking calibration
We can calibrate as a standalone visit or alongside servicing, which we usually recommend so mechanical issues are dealt with first. Calibration is included in the new 12-month BM Brake Testers service contract from V-Tech, available on a quote-only basis.