Time-control circuit for pneumatically operable devices

A timing control arrangement for a pneumatically operable tool for tightening and securing a loop of plastic strapping about a package, comprising:

• a source of fluid at a predetermined line pressure;
• a first manually-operable, normally-closed valve interposed between said tool and said source of fluid at said predetermined line pressure;
• a first conduit fluidically connecting said first manually-operable, normally-closed valve and said source of fluid at said predetermined line pressure;
• a second pressure-operable, normally-open three-way valve operably mounted within said first conduit between said first valve and said source of fluid at said predetermined line pressure, wherein said second valve has a pressure-actuator operable at a predetermined line pressure to close said second valve and interrupt said fluid flow from said fluid source to said first valve;
• a third manually-operable, normally-closed three-way valve having an upstream end and a downstream end;
• a reservoir having a predetermined volume;
• an adjustable means for adjustably controlling the rate of fluid flow;
• a second conduit fluidically connecting said source of fluid at said predetermined line pressure and said upstream end of said third valve;
• a third conduit fluidically connecting said downstream end of said third valve and said adjustable fluid flow means;
• a fourth conduit fluidically connecting said adjustable fluid flow means and said reservoir;
• and
• a fifth conduit fluidically connecting said fourth conduit and said second valve pressure actuator,
• said adjustable fluid flow controlling means being operable to control said rate of fluid flow to said reservoir and said fifth conduit so as to actuate said second valve pressure-actuator at said predetermined line pressure when said third manually-operable normally-closed valve is opened and thereby close said second normally-open valve so as to terminate fluid flow to said tool at a predetermined time even when said first manually-operable normally-closed valve is opened.

A timing control arrangement for providing an adjustable and predeterminable operating period of time within a pneumatically operable device in order to control an operative cycle of said device, comprising:

• a first conduit fluidically connecting said device and a source of fluid at a predetermined line pressure;
• a first manually-operable, normally-closed, three-way valve wherein said valve has an open position to which said valve is movable from a normally closed position;
• a second conduit fluidically connecting said source of fluid at said predetermined line pressure and said first manually-operable, normally-closed valve;
• an adjustable flow rate control valve for adjustably controlling the rate of fluid flow;
• a third conduit fluidically connecting said first manually-operable, normally-closed, three-way valve and said adjustable flow rate control valve;
• a fluid reservoir;
• a fourth conduit fluidically connecting said adjustable flow-rate control valve and said fluid reservoir;
• and
• a second line-pressure actuable, normally-open, three-way valve mounted within said first conduit between said source of fluid and said pneumatically-operable device for normally providing fluid communication through said second valve when said second valve is normally disposed at a normally-open reference position, and wherein said second valve has a pressure-operable actuator fluidically coupled to said fourth conduit such that said second valve is operable by said predetermined line pressure within said fourth conduit so as to be movable from said normally-open reference position to a closed position so as to block fluid flow to said device at a predetermined time after manual actuation of said first normally-closed, three-way valve to an open position.