Recently acquired Gurney scale

This was made by the Gurney Scale Company in Hamilton, Ontario, Canada. Little else is known about it. It came from an industrial type building. The additional pans, pulley and cable system is a bit of a mystery. There is a square brass rod on the front that states place 4, 10, 50 or 100 items in the pan? I assume this is some way of determing quantities of an item without physically counting them. If any one has any additional information or an link to a manual I would be grateful.
Thanks in advance. hhbeam