Daewoo Solar 300LC-V, Manual

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S0707270K
Page 6 Swing Motor (Toshiba MFC200)
crowd dump speed is reduced. If trench mode is turned "OFF" - diminishing the size of the opening through
the swing priority valve - arm speed increases as slew rate falls off.
Connected through the e-EPOS controller, the switch of the trench mode changes the voltage of the
electronic signal sent to the solenoid valve.
When the trench mode is engaged, an engaged voltage signal to the solenoid valve shifts the "swing
priority" spool valve to increase oil flow through the swing motor. With trench mode "OFF," voltage is
disengaged while current flow is reduced, shifting the spool in the priority valve for increased oil flow to the
boom/arm side of the circuit.
Make-up Valve Operation
Unlike those designs for hydraulic swing motor application which incorporate a separate, external
counterbalance valve, the problem of motor rotational speed overtaking or surpassing oil flow rate at the
motor’s supply-side inlet is answered with pressure-control valving that is incorporated in the motor casing.
1. Half brake condition (Condition that relief valve (45) does not operate)
When reducing swing speed by half after rapidly accelerating the upper structure, and supply oil from
pump to port (A) is suddenly reduced, a supply oil demand is still present due to inertia of the upper
structure. This causes pressure (c) to turn into negative pressure, since the motor starts to act like a
pump. Since the motor is now acting as a pump, make-up oil is needed to supply oil in (c).
However, if pressure at port (B) is lower than the operating pressure of relief valve (45), the supply oil
from port (A) to (c) flows through port (B) and flows out to the control valve. so that needed oil at (c) is
insufficient with the only oil coming from the control valve (control valve is half lever position so that oil
quantity from pump is controlled.).
To prevent the insufficient supply of oil, a make-up check valve (36) is installed.
2. When brake operates (Condition that relief valve (45) operates)
When the control lever is set to neutral by rapid operation at condition of (1), the supply oil from pump
to port (A) is zero, but the upper structure will continue to turn due the force of inertia. When this
happens, relief valve (45) in port (B) opens, and oil flows through relief valve oil passages (g) and (h),
pushing make-up check (36) in port (A) off its seat. Oil is then supplied to oil passages (b) and (c).
This is still not enough oil as needed to make up for the oil that leaks through the motor case drain. To
protect the motor, make-up check (36) opens, allowing oil from the make-up port to supply the
additional oil, preventing cavitation in passages (b) and (c).
IMPORTANT
The trench mode setting only has a noticeable effect if both functions are used at the same time,
when the right and the left joysticks are each engaged simultaneously, to control swing and
boom/arm functions.