2-40
2. DESCRIPTION OF FUNCTION AND OPERATION
SWASH PLATE MOTOR
The cylinder block incorporates nine pistons. The end face of the cylinder block is in contact with the
valve plate having two woodruff ports B and C (distributing valve to change over between high and
low pressure).
Principle of generation torque
When high pressure oil (Pressure P) is introduced to the B port, the inclined surface is pushed by a
force of "F = P
Ý
A, A : Piston sectional area" per piston and the piston receives a reaction force
from the inclined surface. The piston that is restricted in the moving direction by the cylinder block
due to the reaction force generates a rotating force. The total of rotating force by the reaction force
of the high pressure side pistons works on the cylinder block. The generated rotating force is
transmitted as a torque to the shaft via the spline to turn the shaft.
On the other hand, if the high pressure oil is introduced to the C port, the opposite rotation is
caused.
The output torque and the revolution are calculated as follows :
Output torque (T)
P
Ý
D
Ý
i
Ýɽ
m
Ýɽ
G
T =
2
ÝӕÝ
100
Revolution (N)
Q
Ý
1000
Ýɽ
v
N =
D
Ý
i
D : Displacement (cm
3
/rev)
P : Effective drive pressure (MPa)
Q : Inflow (L /min)
ɽ
m : Mechanical efficiency (motor) (%
Ý
10
-2
)
ɽ
v : Volumetric efficiency (motor) (%
Ý
10
-2
)
i : Speed ratio of reduction gear
ɽ
G : Efficiency of reduction gear (%
Ý
10
-2
)
1
1
)
Â
Â
X
X
High pressure oil "B"
Low pressure oil "C"
View X-X of valve plate(Outline)
R35Z72SM02