Tachograph Calibration, Sealing and Inspection: The Operator's Duties

A tachograph is legal measuring equipment, and like a weighbridge or a fuel pump it only counts if it is calibrated. DVSA’s guidance on operators’ responsibilities makes calibration, sealing and inspection an operator duty, with fixed cycles and specific triggers, and it is one of the easiest compliance areas to audit and one of the most embarrassing to fail.

The basic requirement

All tachographs used for recording drivers’ hours, whether analogue, digital or smart, must be properly installed, calibrated and sealed. The work can only be done by a vehicle manufacturer or an approved tachograph calibration centre. An installation plaque must be fixed to or near the tachograph, and calibration centres issue a certificate showing the details of any inspection they carry out.

Operators must make sure these requirements are met before a new or used vehicle goes into service. Buying a second-hand truck without checking the tachograph plaque is buying unknown risk: if the unit is out of calibration or the seals are broken, the records it produces are compromised from day one, and they are your records.

The cycles

The intervals differ by tachograph generation:

• Analogue tachographs: inspected every 2 years and recalibrated every 6 years.
• Digital and smart tachographs: recalibrated every 2 years.

For digital and smart units, recalibration is also required outside the cycle when certain events occur:

• after any repair to the tachograph;
• if the vehicle registration number changes;
• if the unit’s UTC clock is out by more than 20 minutes;
• after any alteration to the circumference of the tyres or the characteristic coefficient of the vehicle.

That last trigger is the one fleets miss. A change of tyre size alters the relationship between wheel rotation and distance, which is exactly what the tachograph measures. Tyre policy is a tachograph compliance issue, not just a cost decision.

Inspection and recalibration dates appear on the installation plaque and are updated by the calibration centre. Your maintenance planner should carry those dates like MOT dates, because they have the same character: miss them and the vehicle should not be working.

Seals are evidence

Sealing is what makes a tachograph installation trustworthy. Broken or missing seals suggest interference, and the law treats them accordingly. GB legislation does provide a defence where a seal is broken if the breaking was unavoidable, the seal could not be immediately repaired, and everything else about the assimilated or AETR rules was being complied with, but you never want to be relying on a defence. A driver who spots a broken seal should report it like any other defect, and the repair should be treated as urgent.

When the tachograph breaks down

Breakdowns have their own rules under the assimilated and AETR regime:

• The tachograph must be repaired as soon as possible.
• If the vehicle cannot return to its base within a week, the repair must be carried out en route.
• The driver keeps a manual record meanwhile. GB legislation protects driver and operator from conviction where the vehicle was on its way to a place of repair, or repair was not immediately practicable and the driver was keeping a proper manual record.

For digital and smart tachographs there is a data protection step too: ask the repair centre to download any data held on the unit. If that is not possible, the centre should issue a certificate of undownloadability, which the operator must keep for at least 12 months. That certificate is your evidence that missing data is missing for a legitimate reason.

Calibration sits inside the wider data duties

A calibrated unit is the start of the data chain, not the end. The same operator responsibilities guidance requires vehicle unit downloads at least every 90 calendar days and driver card downloads at least every 28 calendar days, with production of records to enforcement officers for 12 months. A perfectly calibrated tachograph feeding a download regime full of holes is still a compliance failure; the calibration cycle, the download cycle and the record retention duty work as one system.

Building it into fleet admin

• Record calibration and inspection due dates per vehicle in the maintenance planner, with alerts well ahead.
• Check the plaque and certificates when acquiring any used vehicle.
• Flag tyre size changes to whoever owns tachograph compliance before the wheels go on.
• Train drivers to report clock drift, seal damage and unit faults as defects, with the same status as a brake warning light.
• File certificates of undownloadability with the same care as the data itself.

Tachograph calibration is unglamorous, scheduled, bureaucratic, and absolutely foundational: every drivers’ hours defence you will ever make rests on the accuracy of the box behind the dashboard.

Sources

• Drivers’ hours and tachographs: goods vehicles, section 5, responsibilities of vehicle operators (GOV.UK)
• Drivers’ hours and tachographs: goods vehicles (GOV.UK)