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WSM Minor Change II Service Engineering Section

f. S/P valve start point setting

1. Performance characteristics profile: Knob shift amount vs Output current

1) A dead zone is provided to keep the thumb intact in neutral. Some margins are also given to

start the thumb at each end.

2) The right-end, neutral, and left-end settings of the knob are presupposed to be in memory.

3) The profile is flexibly modifiable even for maximum engine rpm and idling speed. When the

engine runs at middle speed, for example, the average is determined from the idling map and

maximum map and finally outputted.

4) Suppose that the thumb starts moving at the current of 500 mA. The knob's operating map must

begin with 450 mA because it is necessary to provide an inching zone and give better feeling.

5) At the 500mA level, however, there could be fluctuations due to the control valve, proportional

control valve, hoses and other factors. The meter keeps the initial map and performs as well,

but the inching zone might be longer or shorter depending on the machine.

6) The starting point setting is made to cope with such problem. In the setting mode, the meter

shows the current gradually higher from 450 mA. When the thumb starts moving, the operator is

supposed to press and release the button twice for releasing and grasping of the thumb. The

meter memorizes the then setting.

The following correction is made for control.

Address 48:

Release R Deviation

Address 49:

Grasp L Deviation

Proportional control valve BProportional control valve A

Right end

Left end

Neutral

Knob

950 mA

450 mA

Current