and hold back the bottom edges of mail pieces behind the separating fingers creating a temporary gap timing belts 98 aid in the process pushing the bottom of the stack 80 forward as fingers 100 are lifted by cam 68 to create the temporary separation in stack 80 as jogger 40 advances a set of fingers 74 rise up into the temporary gap sliding into stack 80 without lifting mail pieces out of the stack after fingers 74 have engaged the stack cam 68 lowers separating fingers 100 releasing the stack and allowing it to continue to advance while as illustrated and described separating fingers 100 are driven with cam 68 the fingers could be actuated with a cylinder solenoid or a similar device controlled by a timer or sensor detecting a finger 74 moving into position to be inserted into the stack as best illustrated in fig3 upper sprockets 44 and 46 are positioned in a horizontal plane above lower sprockets 48 and 50 and positioned closer together than lower sprockets 48 and 50 this sprocket arrangement requires chains 42 to travel around lower sprocket 50 reversing direction before traveling up and over sprocket 46 simultaneously roller guide pins 78 traveling in guide grooves 84 orient brackets 70 as the brackets are carried by chains 42 around sprocket 50 as will be appreciated by reference to fig3 and 6 in conjunction as chains 42 travel around sprocket 50 guide roller pins 78 traveling through guide grooves 84 cause the fingers 74 to move from a downwardly pointing orientation in the return segment 60 of path 52 to an upwardly pointing orientation in the sloped loading end 54 of path 52 thus as shown fingers 74 are oriented vertically before engaging stack 80 further because the fingers 74.