Note that the Class 150 dmu features a 2 stage transmission with a torque convertor.  The transition to lockout occurs at approximately 45 mph when accelerating and falls out of lockout at around 35 mph when decelerating.  Efficiency is low in the non-lockout stage especially if full throttle is used from a standing start. Later operating instructions dictated that only notch 2 should initially be used to avoid overheating the torque convertor.  The unit has a design speed of 75 mph although the te curves extend to 80 mph. Higher speeds in favorable conditions have been observed with a balancing speed of 83 mph on level track.. This is unlikely to be achieved with the degree of monitoring now in place.