Tube drivers on the Circle, Hammersmith and City and District lines on the London Underground last week showed how workers have the power to put safety over managers' wishes.
They refused to move trains on the three lines on Thursday of last week.
Drivers of the 1972 'C' stock trains on the three lines had refused to put them in service after managers failed to respond to serious safety concerns over emergency braking systems.
A fault found in several trains potentially allowed emergency brakes to be released and the train to continue motoring without the driver having to reset the system. Workers raised their concerns on Tuesday.
Services returned to normal following checks on braking systems and emergency discussions between safety reps, London Underground Limited (LUL) and the failed Metronet consortium.
Bob Crow, the RMT rail workers' union general secretary, said, 'An emergency meeting with safety reps finally took place this morning, and LUL reported that the entire 'C' stock fleet was tested overnight.
'Our safety reps have satisfied themselves that the tests had been carried out correctly, a briefing note on the problem is being issued by LUL to all train operators, and the company has apologised in writing to the driver who first raised the problem.
'It is regrettable that managers only took our members' safety concerns seriously after they took decisive steps to ensure their own and their passengers' safety.'