Abstract: A failure diagnosing device configured to diagnose failure of a swash plate pump includes: a history acquiring portion configured to acquire actual history data, the actual history data indicating a time-lapse change of the suction flow rate or suction pressure in a predetermined period of time; and a failure detecting portion configured to detect generation of an abnormality between a piston and a shoe based on the actual history data acquired by the history acquiring portion.

Abstract: A failure diagnosing device configured to diagnose failure of a swash plate pump includes: a history acquiring portion configured to acquire actual history data, the actual history data indicating a time-lapse change of the suction flow rate or suction pressure in a predetermined period of time; and a failure detecting portion configured to detect generation of an abnormality between a piston and a shoe based on the actual history data acquired by the history acquiring portion.

Abstract: A valve device of the present invention includes: a main valve body interposed between a first pressure chamber of a main passage and a second pressure chamber; and a pilot valve body provided in the second pressure chamber. A first pilot passage including a first restrictor extends from an outside of a housing or a primary passage to the second pressure chamber, and a second pilot passage including a second restrictor is formed at the main valve body. The pilot valve body is maintained at a first operation position by a pilot valve body biasing member and is caused to move to a second operation position by a valve body driving unit. When the pilot valve body is located at the second operation position, the main valve body is caused to move to an open position by a pressure difference between the first pressure chamber and the second pressure chamber.

Abstract: A valve device includes: a main valve element arranged so as to divide a valve element space of a housing into a first pressure chamber and a second pressure chamber; and a pilot valve element arranged in the second pressure chamber. A first pilot passage including a first restrictor extends from an outside of the housing or the primary passage to the second pressure chamber, and a second pilot passage including a second restrictor is formed at the main valve element. The pilot valve element is biased by a biasing member to close an upstream end of the second pilot passage. When electric power is supplied to a drive unit, the pilot valve element opens the upstream end of the second pilot passage. An excess flow prevention valve including a third restrictor is provided at the second pilot passage so as to be located downstream of the second restrictor.

Abstract: A valve device of the present invention includes: a main valve body interposed between a first pressure chamber of a main passage and a second pressure chamber; and a pilot valve body provided in the second pressure chamber. A first pilot passage including a first restrictor extends from an outside of a housing or a primary passage to the second pressure chamber, and a second pilot passage including a second restrictor is formed at the main valve body. The pilot valve body is maintained at a first operation position by a pilot valve body biasing member and is caused to move to a second operation position by a valve body driving unit. When the pilot valve body is located at the second operation position, the main valve body is caused to move to an open position by a pressure difference between the first pressure chamber and the second pressure chamber.