At TORONTO TRANSIT COMMISSION Meeting on February 18, 2009 a report was generated that concluded that potentially all subway car motor housings could eventually develop cracks and fail in fatigue. Although the city immediately removes, from service all motors with cracked lugs.
With old equipment like this it is good to see the city staff use some good technology to thwart the problem, see below.
From the report…
To safely allow T1 cars to continue in service until replacement of the motor housings, TTC Engineering worked with a specialist in Non Destructive Testing (NDT) techniques to develop a method of inspecting the motor lugs on the train and identifying lugs with a crack initiation.
This method utilizes an eddy current non destructive test technique. Since originally finding the broken lug, NDT specialists are being used and will continue to be used to inspect the entire T1 fleet every 90 days until new housings are installed. Cracks develop slowly, allowing for detection while they remain small and pose no risk of failure. Any motor with an indication of a crack is immediately removed from service.
Initially, Engineering Staff tried to design a safety restraint under the motor to prevent it from dropping to track level if the motor lugs failed. After determining that an effective restraint could not be developed (May 2008), it was decided that the motor castings would require replacement. Following discussions with the OEM, it was agreed that they would supply redesigned castings. An acceptable redesign was completed, and in September of 2008 a mutually agreeable production schedule was established, followed by a review of labour required to complete the project. However at the time that this course of action had been determined, the 2009 TTC workforce had already been established, and the relevant