摘要 |
To prevent powder caused by wear of brushes from entering a contact chamber, a first stationary contact is electrically connected to a battery and a second stationary contact is connected to positive brushes, wherein a contact bracket is provided to hold the first stationary contact, and a contact chamber cover is provided to interpose and hold the second stationary contact between the contact chamber cover and the contact bracket so that the contact chamber can be kept in an airtight state.
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