Silly,
If a pistol gripper was utilized in suck a fashion, the stop ring would still be the final limit in which the piston can travel when electrical or mechanical devises fail.
Solidstate,
When was the unit installed?
Has the unit been modernized?
How old is the jack assembly?
How Is the controller and car station being changed to eliminate the 6th?
If they truly wish to eliminate the 6th floor, the system should be modernized to reflect such a change. If the unit is to be modernized and the jack assembly isn't being replaced, then I agree a sleeve is a great solution to shorten the travel of the piston.
If they don't wish to modernize the unit, why not just disconnect the car and hall calls for the 6th floor at the controller?
