Fluid control apparatus

A fluid control apparatus, comprising:

• an actuator, having a first fluid chamber (6a) and a second fluid chamber (6b);
• a flow directional control valve (5);
• a pilot valve means (1) which is operated by a pilot pressure from a fluid supply source (3);
• first supply and return passages (33, 36) which communicate said first fluid chamber (6a) with said flow direction control valve (5), an intermediate portion of said first supply and return passages being formed in said pilot valve means (1);
• a second supply and return passage (34) which communicates said second fluid chamber (6b) with said flow directional control valve (5);
• a first intermediate passage (35) and a second intermediate passage (37) which communicate said pilot valve means (1) with said flow directional control valve (5);
• and
• a fluid supply passage (31) and a fluid exhaust passage (32) which are communicated with said pilot valve means (1),
• said flow directional control valve (5) selectively communicating one of said first intermediate passage (35) and said second intermediate passage (37) with said first supply and return passages (33, 36) and the other of said first intermediate passage (35) and said second intermediate passage (37) with said second supply and return passage (34);
• said pilot valve means (1) including
• a check valve means (23) which is disposed in said intermediate portion of said first supply and return passages (33, 36) and which prevents flow from said first fluid chamber (6a);
• a first valve means (14, 16, 16e) which permits fluid flow between said fluid supply passage (31) and said first intermediate passage (35) when said fluid supply passage (31) is supplied with fluid from said fluid supply source (3) and which stops fluid flow between said fluid supply passage (31) and said first intermediate passage (35) when said fluid supply passage (31) is not supplied with fluid from said fluid supply source (3);
• a second valve means (2e, 2f, 16) which permits fluid flow between said fluid exhaust passage (32) and said second intermediate passage (37) when said fluid supply passage (31) is supplied with fluid from said fluid supply source (3) and which stops fluid flow between said fluid exhaust passage (32) and said second intermediate passage (37) when said fluid supply passage (31) is not supplied with fluid from said fluid supply source (3);
• a third valve means (2e, 2b, 16) which stops fluid flow between said second intermediate passage (37) and said intermediate portion of said first supply and return passages (33, 36) when said fluid supply passage (31) is supplied with fluid from said fluid supply source (3) and which permits fluid flow between said second intermediate passage (37) and said intermediate portion of said first supply and return passages (33, 36) when said fluid supply passage (31) is not supplied with fluid from said fluid supply source (3);
• and
• a pusher means which pushes said check valve means (23) so as to permit fluid flow from said fluid chamber (6a) when said fluid supply passage (31) is supplied from fluid from said fluid supply source (3).