WE CLAIM:
Claim 1. An air cylinder fluid circuit (10) comprising:
a switching valve (14);
an air supply source (16);
an exhaust port (18); and
a check valve (20);
wherein when the switching valve (14) is in a first position, a first cylinder chamber (32) communicates with the air supply source (16) while a second cylinder chamber (34) communicates with the exhaust port (18), and when the switching valve (14) is in a second position, the first cylinder chamber (32) communicates with the second cylinder chamber (34) via the check valve (20) while the first cylinder chamber (32) also communicates with the exhaust port (18); and
wherein a sonic conductance of a tube (40) connecting a cylinder port portion (36) of the first cylinder chamber (32) with the switching valve (14) is less than sonic conductances of the cylinder port portion (36) of the first cylinder chamber (32) and the switching valve (14).
Claim 2. The air cylinder fluid circuit (10) according to claim 1, wherein an adjustable throttle valve (22) is disposed between the switching valve (14) and the exhaust port (18) .
Claim 3. The air cylinder fluid circuit (10) according to claim 1, wherein an upstream side of the check valve (20)

is connected to a tube (42) branching off from the tube (40) connecting the cylinder port portion (36) of the first cylinder chamber (32) with the switching valve (14), and inner diameters of the tubes (40, 42) are smaller than inner diameters of a tube (48) connecting a downstream side of the check valve (20) with the switching valve (14) and a tube (44) connecting the switching valve (14) with a cylinder port portion (38) of the second cylinder chamber (34).
Claim 4. The air cylinder fluid circuit (10) according to claim 1, wherein an air tank (24) is disposed at a point on a tube (44) connecting the switching valve (14) with a cylinder port portion (38) of the second cylinder chamber (34) .