Hydraulic control system for a washing machine

Claim 1

A dishwashing machine comprising a tank defining a chamber having rack means therein for receiving articles to be cleaned, a water supply line extending to said tank, first and second fill valves within said water supply line, said first fill valve being located upstream of said second fill valve relative to the flow of water within said supply line, means including a motor for circulating water within said chamber, means including a drain line for removing water from said chamber, a normally closed drain valve within said drain line, water pressure actuated means for operating said drain valve, means defining a water passageway connecting said pressure-actuated means to said water supply line between said first and second fill valves for controlling the operation of said drain valve in response to selected operation of said fill valves, timer means for actuating said motor and said fill valves according to a predetermined program, said drain valve being open when said first fill valve is open and said second fill valve is closed, said drain valve being closed when both said fill valves are either open or closed or when said first fill valve is closed and said second fill valve is open, and control means separate from said timer means for at least momentarily opening said second fill valve when said first fill valve is closed to assure a release of water pressure within said passageway when both said fill valves are closed.