Daewoo Solar 300LC-V, Manual

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S0707270K
Page 8 Swing Motor (Toshiba MFC200)
When piston (50) is moving like as mentioned above, spring (49) force is increased from low force to
high force, cushion relief operation is actuated at low pressure first, then it is increased to the rated
pressure after a few moments have passed. By this slowly increasing pressure, the shock loading of
the motor decreases when starting or stopping.
Bypass Valve Operation (Bypass Valve Section Drawing)
When stopping the upper structure (after moving it by operating the control valve), it tries to continue
turning by inertia force. The hydraulic motor starts to operate like a pump, and brake pressure is generated
at one of the ports. If for example it is port (A), as this brake pressure oil flows through orifice (a3 and a2)
into the rear chamber of check (64) on side (A), the side (A) check (64) pushes the side (B) check (64) to
the left. until it contacts seat (62) on side (A). This action closes the bypass passage, while reducing speed
of the upper structure.
After the upper structure is stopped, but it is reversed by brake pressure, the pressure of side (B)
increases, and the side (B) check (64) tries to push on side (A) check (64), but the oil of rear chamber of
check (64) discharges slowly by opening the oil regulating valve consisting of side (A) poppet (65) and
spring (66). Now the side (B) check (64) moves slowly, allowing pressurized oil to flow through orifice (b1)
into center chamber, and bypasses through orifice (a1) to the side (A) port.
After the side (B) check (64), moves to a position where the bypass passage is closed by being
compressed against seat (62) on side (B). Like this, by generating process of reverse pressure of side (B)
port, pressure oil flow is not stopped and reversing is prevented by bypassing this pressure to side (A) port.
Figure 3