Paper roll tachograph

Tachograph charts and thermal paper rolls are recording materials for analogue and digital tachographs respectively. They allow driving activities, speed and distance to be checked, but serve different purposes: analogue charts record directly via styli, while digital tachographs store data electronically and print it on request. Incorrect paper, an unsuitable speed scale or damaged recording layers can result in illegible records, even when the unit itself is working correctly.

Always identify parts using the vehicle's chassis number. Visual comparison or selection by model name alone is never sufficient. Also check the make, model number and approval number of the tachograph actually fitted: on older vehicles, the original unit may have been replaced. The engine variant does not determine the choice of paper; the recording unit and its approved recording materials are the deciding factors.

This applies, for example, to cab installations in MAN TGL with C or LX cabs, MAN TGX with XLX or XXL cabs and Mercedes Actros with Lang StreamSpace or Lang GigaSpace. The cab designation alone tells you nothing about the consumables required. Identifying the unit is also essential for buses and tachograph-equipped vans, such as Mercedes Sprinter and MAN TGE.

• Analogue tachograph charts: check the diameter, centre hole, recording duration, speed scale and any engine speed recording function. A scale up to 125 km/h is not interchangeable with a scale up to 140 km/h if the unit's approval does not permit this. The approved tachograph types must match the markings on the chart.
• Thermal tachograph paper rolls: check the paper width, maximum roll diameter, roll length, core design and specified winding direction. Use paper approved for the unit concerned; generic till rolls are not an equivalent alternative.

For both types, paper thickness, dimensional stability and surface quality are functional parameters. For thermal paper, heat sensitivity and the print's resistance to light, moisture and heat are also important. Follow the manufacturer's dimensional tolerances and storage conditions.

1. Identify the recording problem. Check whether data is missing from the digital memory or only from the printout. A faulty printer or an empty roll does not automatically mean that the electronic record is missing.
2. Inspect the material. Look for water marks, distorted roll edges, creases, discolouration and scratches in the chart coating. Measure the paper width and roll diameter with a vernier calliper without compressing the paper; compare these with the unit's specifications.
3. Check the paper feed. Fit the roll according to the loading diagram and close the printer drawer fully. A blank printout can result from the thermal layer facing the wrong way. Misaligned paper or an oversized roll will cause jams.
4. Carry out a comparison test. With the vehicle stationary, make a test printout using a new, approved roll. Persistent longitudinal streaks may indicate dirt or defects on the thermal print head; clean it only in accordance with the manufacturer's procedure.

Interrupted or displaced traces on analogue charts may indicate damaged coating, insufficient clamping or problems with the styli and drive mechanism. If the fault persists with a correct new chart, have the unit inspected by an approved tachograph workshop. Do not break any seals or adjust any recording mechanisms.

On tachographs equipped with a Kitas sensor, this motion sensor on the gearbox supplies signals for recording speed and distance. Faults in the sensor, wiring or pairing with the tachograph cannot be resolved by fitting a new chart or paper roll. The correct Kitas version depends on the vehicle and the generation of tachograph fitted; select it using the chassis number and unit details. Have diagnosis, replacement and the required pairing and calibration carried out by an approved tachograph workshop.

Replace damp, distorted or discoloured rolls completely. Store spare materials in a dry place, in their original packaging and out of direct sunlight; a hot dashboard accelerates the deterioration of thermal paper. Avoid contact between printouts and solvents or plastic sleeves containing plasticisers. After replacement, check legibility, printing across the full line width and even paper feed. Keep sufficient compatible spare materials on board and retain records in accordance with the applicable legal requirements.