The vaccuum to the stack is cut off for the reroll function or for fast 
forward depending on which player unit you have.  Most Schumann pianos 
had either a Schuman player stack or a Standard player mechanism.  The 
latter had a "S" monogramed in the pedal pads.  When the transmission is 
put into reverse, a valve is activated by various means to close off the 
suction going to the stack, and the tempo/governor function is disabled 
so that all the vaccuum goes to the motor.  This is sometimes done 
totally by levers, rods and such.  Other players mechanisms have a 
pneumatic response handling all this.  If you have a valve on the tranny 
that you don't know what it does, this connects to the governor, and the 
cancel valve via a "Y" connector.  Let me know how else I can help.  Lar

--¶
--- Larry Fisher RPT, Portland Metro's Authority on PianoDisc Systems
        For more information call (360) 256-2999 in Vancouver, Wa.
                      or email larryf@pacifier.com