I have a Dover composite traction it is a bank of their elevators. Elevators 1 and 3 are no issues only on elevator 2 . only when homing to a floor the unit will not respond to the hall or car calls unless the CST relay then doors open and will take calls again both from hall and car until it homes again. when this happens the FT timmer comes on and stays on.

I do not have a print in front of me, but what I remember is CS pulls in with the second slowdown and drops out when the door times out. If CS stays energized it will create a Failure timer. So whatever is not letting CS drop is causing the problem. It was commonly called a CS lockup in this area of the country. A lot of the time as I recall it could be caused by a hooked hoistway door. Good Luck.

You have to look and see what causes FT (failure timer) to pull in. When you pull in the CS relay to open the doors, something happened that didn't allow the doors to open, (no UC problem at lobby) and therefore FT timed in and that takes the car out of service. You were saying CST and that sounds like the circuit we used to get out of a CS lockup. CS lockup usually occurred when approaching a floor, not at the floor. But a FT can only happen at the floor. Sounds like there is also a zoning problem, since FT coming in should allow the next zone car to respond.

Buildup on hangar track at the lobby could let the door sag back and hang the lock.

Anyone have Dover composite electrical schematics that you would share? Thanks