HI:
Thanks for your answer. I guess this is where I am getting confused  you say that changing shaft diameter will not affect torque 
This is what I dont understand  on the last pulley if I had a 1" shaft sticking out you are saying that this 1" shaft will pull with the same force as a 10" shaft ??
sO SAY THE 1" SHAFT CAN PULL 7500# ARE YOU SAYING A 10" SHAFT COULD PULL 7500#?
SAY THE RPM OF THE SHAFT IS 1OO
THE 1" SHAFT WOULD THEN PULL IN A 7500 # LOG 314" IN ONE MINUTE
WHILE A TEN INCH SHAFT PULLING 7500# WOULD PULL THE LOG IN 3140 INCHES IN ONE MINUTE
IT SEEM TO ME THAT THE FORCE WOULD BE MUCH LESS WITH THE TEN INCH SHAFT THEN THE ONE INCH SHAFT ?? aM i USING THE TERM TORQUE WRONG ??
ps THE 300 FT LB IS JUST A hypothetical
