Control for timber board stacker - uses booms responding to retainers controlled by difference paths in air gaps depending on board stack width

摘要

The board stacker operation is based on finding the difference between the total stack width and gap-less width. The result is used to control booms by retainers which are moved horizontally by this difference value and then retracted at the same time as the booms pull back over the total width. The difference path for the retainers is found by a bank of limit switches spaced at the front edge of the stack on batten which adjusts on stand to suit the total width. The retainers have power and difference path cylinders rigidly joined at the pistons so that the difference piston sides can be bridged by variable chokes whose upstream magnetic valves respond to the limit switches.