Roll stop and operating method of the same

A pneumatically operated roll stop of controllable speed for stopping a roll, said roll stop comprising:

• a frame having a pivotal joint;
• a stop arm having a first end and a distal end, said first end being operatively connected to said pivotal joint, said distal end provided for making contact with said roll to be stopped;
• a pneumatic cylinder comprising a cylinder unit having first and second end defining a cavity therein and a piston axially aligned in said cylinder separating first and second working chambers and a piston rod operatively connected to said piston axially extending outward from said cavity at said first end of said cylinder unit, wherein one of said rod and said second end is operatively engaged with said frame and the other of said rod and said second end is operatively engaged to said stop arm;
• a control valve;
• first passage means for pneumatically connecting said first working chamber to said control valve;
• second passage means for pneumatically connecting said second working chamber to said control valve;
• a pulsed valve pneumatically connected to said first passage means;
• and
• control means for opening and closing said control valve and for modulating the opening and closing of said pulsed valve for pneumatically controlling said first and second working chambers for regulating the movement of said stop arm to stop the roll.