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WSM Minor Change II Service Engineering Section
2. Background and meaning of start-point setting
1) The purpose of this setting is to keep the knob's operating force of starting the attachment
(thumb cylinder) constant whether the engine runs idle or at maximum speed.
2) The proportional control valve's start-point is activated when you have slowly moved the knob
to start the attachment that is connected with the service port circuit.
3) The knob's action point is referred to in some different factors: knob's movement, output volt-
age, controller's output PWM current, proportional control valve's hydraulic pressure, pilot sec-
ondary pressure of service port main control valve, and hydraulic pressure of attachment
(thumb cylinder, for example).
4) The start-point setting works as follows. When a component of the service port system line has
been replaced, the component with its slightly different individual behavior pattern may deli-
cately affect the line's final output. To compensate such deviation, the initial setting (star-point
setting) must be entered in the controller.
5) The following factors are important in affecting the start-point.
6) These factors are therefore considered for the start-point setting.
(1) Oil temperature
(2) Engine rpm
(3) Proportional control valve
(4) Main control valve, service port section
(5) Service port load fluctuations
(1) Oil temperature
o
50 qC
(2) Engine rpm
o
Idling, Maximum
(3) Proportional control valve
o
At each replacement
(4) Main control valve,
service port section
o
At each replacement
(5) Service port load fluctuations
o
Basically it is preferable to make the setting for
each attachment. If it does not feel unusual,
however, it can be up to the user's judgment.
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