tachograph
noun [ C ]
uk/ˈtækəɡrɑːf/ us/ˈtækəɡræf/ TRANSPORT
an electronic machine in a vehicle such as a truck that records speed, distance travelled, and stopping periods, and that is used to check that the driver is obeying rules about the number of hours they can work in a particular period:
His tachograph limits the maximum hours he can work.
Lorry drivers travelling from channel ports often take their first `tachograph stop' in Northamptonshire.