Abstract: A plunger pump system including a plunger pump, and a shuttle valve connected to the plunger pump having a valve body reciprocally fitted in a hollow portion formed in a valve casing to divide the hollow portion into a liquid supply side chamber and a liquid discharge side chamber. The shuttle valve has a liquid supply hole which provides communication between a liquid supply line and the liquid supply side chamber and which is closed by a first end surface of the valve body when the delivery pressure of the liquid is higher than the supply pressure of the liquid. A first connecting hole provides communication between the pump liquid supply hole and the liquid supply side chamber. A liquid discharge hole provides communication between a liquid discharge line and the liquid discharge side chamber and is closed by a second end surface of the valve body when the supply pressure of the liquid is higher than the delivery pressure of the liquid.

Abstract: A plunger pump system including a plunger pump, and a shuttle valve connected to the plunger pump having a valve body reciprocally fitted in a hollow portion formed in a valve casing to divide the hollow portion into a liquid supply side chamber and a liquid discharge side chamber. The shuttle valve has a liquid supply hole which provides communication between a liquid supply line and the liquid supply side chamber and which is closed by a first end surface of the valve body when the delivery pressure of the liquid is higher than the supply pressure of the liquid. A first connecting hole provides communication between the pump liquid supply hole and the liquid supply side chamber. A liquid discharge hole provides communication between a liquid discharge line and the liquid discharge side chamber and is closed by a second end surface of the valve body when the supply pressure of the liquid is higher than the delivery pressure of the liquid.

Abstract: In a plunger pump having a pump chamber delimited by a cylinder and a plunger reciprocating in the cylinder, and a first seal member provided between an inner surface of the cylinder and an outer surface of a plunger to prevent a liquid in the pump chamber from leaking to the outside, the inner surface of the cylinder and the outer surface of the plunger are out of sliding contact with each other, and a second seal member is interposed between the first seal member and the pump chamber. During a suction stroke, the second seal member is in sliding contact with the outer surface of the plunger to prevent dust, which is produced as the result of wear, from flowing to the pump chamber from the first seal member side. During a discharge stroke, a minute gap is formed between the second seal member and the outer surface of the plunger.