Electric hand drill with switch in hand grip - has rotation reversing switch behind hand grip switch determining motor rotation direction in any hand grip switch position

摘要

The hand grip switch has two ON positions and is connected by two electric lines to an electronic control unit, incorporated in the drill housing and used for speed change. The speed can be manually set by a potentiometer included in the grip and its starting contact is connected to the drive motor in the switch first ON position. In the second switch ON position, the motor is conductively connected to the potentiometer setting. The switch has its input connected to a feed voltage source, while a rotation reversing switch is series-connected behind this switch. This direction switch determines directly the drive motor sense of rotation in both ON positions of the switch. In the first ON position it enables via a switching contact the change-over of the drive motor in the other direction.