Speed controller for electrically driven tool - has wedge blocks moved by fitting tool onto spindle acting against centrifugal switch carrier

摘要

The speed controller for a motor (1) driving a tool includes a two section control block (13) mounted on the spindle (8) of the motor. When a tool is fitted onto the spindle, projections passing through openings (22) in a bearing plate (3) slide the outer section of the block inwards. This has a sloping face which is pushed inside the sloping inner face of the inner section of the block, and has a lug projecting from it, which fits into a hole (17) in the inner section. This inner section has an outer sloping outer face which is forced against the sloping inner faces (15) of two bodies (11) mounted on a plate forming a centrifugal governer. These two bodies are mounted on leaf springs and carry electrical contacts which are held against counter contacts on opposing bodies (12) on the plates. Centrifugal force causes the contacts to open, the counter contacts having springs behind them.