The coroner, Richard Sturt, told the inquest in Dover that the limiter was supposed to restrict the coach's speed to under 70mph, but the vehicle's tachograph showed it had been travelling at 78mph. The anti-lock braking systems on the coach were also faulty, he added.
Mr Sturt was outlining evidence to the jury at the inquest into the 10 deaths. The coach crashed in wet weather on the M2 near Faversham in Kent last November. The tourists were on trips to Canterbury and Leeds Castle as part of a package holiday.
Mr Sturt told the jury: 'You will hear from witnesses who say they saw the coach driving at 70mph. However the coach tachograph shows a top speed of 78mph. Both the anti-lock brake systems at the front of the coach were faulty, and so was the warning light.'
He added that the vehicle was only fitted with single-glazed windows.
Mr Sturt said the coach driver, Leslie Golds, 54, was 'one of the most experienced drivers' employed by the Travellers Coach Company of Hounslow, west London. But he had exceeded his driving hours and the night before the crash had just four and three-quarter hours' sleep. It was Mr Golds' first time behind the wheel of that particular vehicle after a last- minute switch, he told the jury.
Mr Golds, of Hoddesdon in Hertfordshire, died of crush injuries and a ruptured liver after the coach hit a van driven by Robert Marshall, of Thamesmead, south- east London. The coach slewed off the motorway and tumbled down an embankment.
The victims included Harry Faull, 65, a high school principal, and his wife, Carolyn, a teacher, from Dearborn, Michigan, both of whom died from crush injuries. Two sisters, Deborah Becnell, a lawyer, from Lafeyette, Louisiana, and Frances Hubbard, 52, a housewife, from Houston, Texas, died from crush fractures to the skull, rupture of the heart and asphyxia from crush injuries to the chest. They had taken the trip with another sister and their mother, both of whom survived.
Mr Sturt said 40 witnesses would be called during the five- day inquest, including survivors. The hearing was adjourned to today. Technical evidence is expected to be heard tomorrow.