To provide a gear pump which can reduce a loss torque during an operation.
The gear pump of an inscribed gear pump includes first, second housings 1, 2 having a pump chamber 3 communicating with an intake port 3a and a discharge port 3b, a drive gear 4 rotatably driven in the pump chamber 3, and a driven gear 5 engaged with the drive gear 4 in the pump chamber 3 and rotatably driven by the drive gear 4. This inscribed gear pump sucks an operating oil from the intake port 3a between tooth faces formed of the drive gear 4 and the driven gear 5, and discharges the operating oil from between the tooth faces to the discharge port 3b. The first housing 1 has a housing body 1a, and a movable part 1b movable to the housing body 1a. Thus, the pump chamber 3 is expandable so that the intake port 3a and the discharge port 3b are short-circuited.
TAKAGI HIDEJI
ITO ATSUSHI
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