Hi all

We have sewer pipe that allows a downstairs pump to send effluent etc back to street level, where this pipe goes under our road level deck there is a flexible rubber joiner that allows a plastic 60mm pipe to go into a 70mm pipe. 

The issue is that the pipe vibrates when the pump is sending the waster back up and the vibration eventually after many months the rubber reducer wiggles loose (despite metal bands) or more recently developed a fine spilt. I have replaced it already once in 20 years.

You can see the setup here 

I now wonder whether this setup is typical or was a workaround to allow a smaller pipe to join a larger pipe, why wasn't a cemented joiner used?

Thoughts welcome