3MAA01Z
B
F
F
F
F2
F2
F2
F
F1
F2
D
C
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SLEW MOTOR
Hydraulic motor
The cylinder block (1) is constructed with the pistons (2),
and its end surface comes in contact with the valve plate
(3) containing two half-moon-shaped ports B and C. The
cylinder block (1) rotates freely and is connected to the
drive shaft (4) via the spline. On the other hand, the swash
plate (5) is fixed to the housing.
When the high-pressure oil is led to the port B, the pistons
(2) push the swash plate (5) with the force F per piston.
F = P x A P: Pressure A: Piston sectional area
The force F used to push the swash plate (5) by the pistons
(2) is divided into two: the force F1 that pushes the plate
and the force F2 that rotates the cylinder block (1). The total
sum of the components in the direction of rotation of the
high-pressure side piston generates a rotational force in the
cylinder block (1), and via the spline, the torque is transmit-
ted
to the shaft (4), turning it. Conversely, if high-pressure
oil is introduced to the port C, the rotation is the reverse of
the above.
Relief valve
This relief valve is equipped with shockless function and
works in two stages.
The 1st stage
When the relieving operation starts, the pressure P1 in the
chamber B is kept low, while the pressure P in the chamber
M becomes high due to the oil flowed into it.
At this time, there are two forces acting on the poppet (10):
the force F which moves the poppet (10) to the left, the
force (F1) which pushes seat against the right side. Since F
= P x A, F1 = P1 x A1, P > P1 and A > A1, the poppet (10)
is moved to the left by this force “F-F1”, and the pressure
is released from the chamber M through the passage in the
supply side. That is, during the time piston (11) is moving to
its stroke end, the relief valve operates at low pressure.
The 2nd stage
When the piston (11) reaches the stroke end, the pressure
in the chamber B increases and becomes equal to that of
the chamber M. At this time, the force moving the poppet
(10) to the left side becomes “P = P1” and thereby “A-A1”.
This allows the relief valve to operate at the specified set
pressure.
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