Automatic transmission fluid changer apparatus

A transmission fluid changer system for tapping into a downstream component of an automatic transmission operative to pump transmission fluid and also tapping into an upstream transmission component for removing used transmission fluid from said downstream component to a drain tank while supplying pressurized fluid from a supply tank to said upstream component, said system comprising:

• a housing;
• a fluid control circuit mounted in said housing, including a drain tube for connection on one end to said drain tank and formed on its opposite end with a downstream drain end, and a supply tube for connection on one end with said supply tank and formed on its opposite end with an upstream supply end;
• a drain hose connected at one end to said drain end of said drain tube and including on its opposite end a connector for connection with said downstream component;
• a supply hose connected at one end to said supply end of said supply tube and including on its opposite end a connector for connecting to said upstream component;
• a return line in fluid communication on one end with said supply tube and having an opposite end for connection with said supply tank;
• and
• a flow control apparatus including a pressure responsive valve device for directing flow between said supply tube and said return line to maintain a predetermined pressure in said supply tube.

A transmission fluid changer system for tapping into a downstream component of an automatic transmission operative to pump transmission fluid at a predetermined rate and also into an upstream transmission component for removing used transmission fluid from said downstream component to a drain tank while supplying pressurized fluid from a supply tank to said upstream component, said system comprising:

• a housing;
• a fluid control circuit mounted in said housing, including a drain tube for connection on one end to said drain tank and formed on its opposite end with a downstream drain end, said fluid control circuit further including a supply tube for connection on one end with said supply tank and formed on its opposite end with an upstream supply end;
• a drain hose connected at one end to said drain end of said drain tube and including on its opposite end a connector for connection with said downstream component;
• a drain control valve for controlling flow through said drain tube;
• a supply hose connected at one end to said supply end of said supply tube and including on its opposite end a connector for connecting to said upstream component;
• and
• a flow control valve on said housing for controlling the rate of flow through said supply tube at a rate substantially equal to said predetermined rate.

A method of introducing clean transmission fluid from a supply tank under pressure to an upstream transmission component upstream of an automatic transmission pump while removing fluid from a downstream transmission component downstream of the pump, including the following steps:

• selecting a transmission fluid changer apparatus of the type having a housing encasing respective supply and drain tubes having respective inlet ends and outlet ends, respective supply and drain hoses connected with said supply outlet end and said drain inlet end, respectively, and including on the free ends of the respective supply and drain hoses connectors for connecting with the respective said upstream and downstream transmission components and a first flow control valve for controlling flow in said supply tube;
• uncoupling said upstream and downstream transmission components to leave a respective transmission fluid inlet and outlet accessible for respectively adding clean and removing used transmission fluid;
• connecting the respective said supply and drain connectors with the respective said transmission fluid inlet and outlet;
• operating said transmission pump to flow transmission fluid at a predetermined rate from said transmission through said drain hose to said drain tank, while simultaneously flowing pressurized clean transmission fluid through said supply hose to said upstream component;
• and
• adjusting said first flow control valve to establish a flow rate through said supply hose substantially equal to said predetermined flow rate to thereby flow fluid into said transmission at substantially the same rate said transmission pumps used fluid from said transmission.