| 摘要 |
The invention provides an air operated cleaning head (2) for a roof gutter. The head has a housing defining an airflow passage with an impeller located inside the passage. A gear arrangement connects the impeller to a drive shaft for a pair of driven wheels. Guide formations maintain the wheels in engagement along an outer rail (4) of a roof gutter (5). The guide formations are configured to straddle the rail with a counterbalance provided to maintain the head in balancing engagement on the rail. The counterbalance is an underslung air supply downpipe (3) extending pivotally from the head The guide formations (25.1, 25.2) are provided as a radial flange on the outside of the wheels and a radial spoke arrangement on the inside of the wheels. The spoke arrangement is freely rotatable on the wheel axles. The impeller (8) is supported in a dividing wall of the flow passage (7). Drive shaft switching means includes a flap valve (27) movable between seats on opposite sides of the dividing wall to reverse rotation of the impeller and thus also the wheels. The flap valve is secured to a pivot pin (35) with a lever extending from the pin away from the flap valve connected to the downpipe by a spring (38), whereby pivoting of the downpipe in one direction produces a bias on the flap valve in an opposite direction. |
