| 摘要 |
An accessory transmission conversion mechanism of the type disclosed in the U.S. Pat. No. 4,177,539, to Elting, for causing the lance tube of a long retracting soot blower to oscillate about its longitudinal axis, is provided with a lost motion driving connection between the yoke driving gear and the crank of the Scotch yoke which generates the oscillating motion. A holding portion on the gear permits locking out such lost motion when desired. When lost motion is present, the blowing path is automatically changed when the blower reverses. When locked out, the blowing pattern is changed so that the jet traces the same path in each direction of movement.
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