The dunnage airbag inflation circuit of this invention includes a pilot
valve that is controlled by a pressure sensing line in communication with
the dunnage bag, and an arrangement of other valves to allow the dunnage
bag to inflate up to a certain preset pressure. The pressure sensing line
controls pilot air to various valves and ultimately to the main pilot
valve allowing airflow to the dunnage bag until the dunnage bag reaches a
certain preset pressure. The inflation circuit also includes (i) a safety
pressure valve to stop airflow to the dunnage bag if for some reason the
dunnage bag continues to be inflated past the preset pressure, and (ii) a
stop valve that allows an operator to manually override the pressure
valve and stop the airflow to the dunnage bag.