Hitachi W 6VB2, Technical And Service Manual, Page: 11 / 25

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7-6. Variable-Speed Switch
This switch is equipped with a variable speed control circuit. Through the control circuit, the speed can be
controlled up to 75 % of maximum speed according to the degree at which the switch is depressed.
A disadvantage of this system is that if the bit becomes locked resulting in stoppage of the motor, the speed
control circuit may be burnt out. In such a case, the switch should be released immediately or turned OFF. To
avoid damage to the switch circuit, the customer should be advised to increase driving speed gradually until the
screw is driven approximately halfway into the workpiece, then depress the trigger to obtain optimum speed.
Fig. 4
Switch characteristics (Approximately shown converted into the linear line)
Maximum speed change point
Trigger stroke
speed
8. PRECAUTIONS IN DISASSEMBLY AND REASSEMBLY
The [BOLD] numbers in the descriptions below correspond to the item numbers in the Parts List and the exploded
assembly diagram.
8-1. Disassembly
A. Disassembly of the parts within the handle
(1) Removal of the Handle Cover
Loosen the three Tapping Screws D4 x 20 [31], and remove the Handle Cover [29].
(2) Removal of the Carbon Brushes
With a small flat-blade screwdriver, lift up on the Brush Holder [36], and pull it out slightly.
Next, pull out the terminal portion which connects the two Carbon Brushes [35] and the lead wires from the
Speed Control Switch [32]. When pulling the terminal, it is best to push the Carbon Brushes fully into the
Brush Holder.
(3) Removal of the Cord
Loosen the two Tapping Screws D4 x 16 [44] which retain the Cord Clip [45], and remove the Cord [48]
together with the Cord Armor [46].
B. Removal of the armature and stator
(1) Removal of the Armature
Remove the three Tapping Screws D4 x 40 [9] from the Gear Cover Ass'y [10], and remove the Inner
Cover Ass'y [23] from the Housing [29]. The Armature [25] can then be taken out.
(2) Removal of the Stator
First, remove the Fan Guide [26] from the inside of the Housing.
Then, loosen the two Tapping Screws D4 x 50 [27], and lightly tap the end surface of the Housing [29] with
a wooden hammer to loosen and remove the Stator [28].
100 %
75 %
0