Unloader valve having bypass valving means

An unloader valve, for use in combination with (a) a fluid-working machine, such as an air compressor or the like, and (b) a supply of fluid at excursive pressures, said unloader valve having bypass valving means, comprising:

• a substantially hollow body having at least a pair of spaced-apart openings formed therein;
• a first of said openings defining porting means for admitting fluid into said body;
• the other of said openings defining porting means for admitting fluid from said body into a fluid-working machine;
• means within said body operative for throttling conduct of fluid from said first opening to said other opening;
• said body having wall means for confining, therewithin, said throttling means;
• said wall means comprising a wall having a given passageway, formed therethrough, with ports in which a first of said ports opens into said body for fluid communication thereof with said other opening in shunting bypass of said throttling means, and a second of said ports opens externally of said body for fluid communication thereof with a supply of fluid at excursive pressures;
• said ports defining opposite ends of said passageway;
• and
• valving means, interfaced with at least one of said first and second ports, operative, in response to given, predetermined, pilot fuid pressures addressed thereto, for opening and closing said one port to fluid conduct therethrough;
• wherein
• said wall has a third port formed therein, which opens onto said valving means, for introducing therethrough and addressing to said valving means operative, pilot fluid pressures from a supply of fluid at excursive pressures.