Brake problems disrupt ScotRail's new trains on Edinburgh-Glasgow line
The train operator admitted it was the latest of a series of similar problems to have hit the class 385 electric trains since last month.
It is understood the latest incident happened near Winchburgh on the main Edinburgh-Glasgow line at lunchtime, when the brakes did not work properly.
The Japanese-designed Hitachi train was taken out of service, but others in the fleet are still operating.
A rail source said of a previous incident last month: “The train almost overshot Falkirk High, due to ‘very poor brakes’ after investigation by Hitachi.
“In the rear three carriages, a computer isolated all the brakes for no apparent reason, so only the front four carriages were braking.”
ScotRail chief operating officer Angus Thom said: “The brand new Hitachi class 385 electric trains have been operating well since their introduction in July.
‘A technical fault has been identified on one of the trains today which Hitachi is now investigating.
“We are sorry to any customers whose journey was disrupted as a result of this.”
A ScotRail spokesman added: “The train in question today is heading to [Edinburgh depot] Craigentinny for testing.
“It caused some delays and cancellations earlier in the day.
“The remaining 385s are still currently in service.
“There were a small number of cancellations in September caused by the fault.
“All trains have normal braking and secondary braking to keep people safe.”