| 摘要 |
In the compact transmission of a hand-held reciprocating power saw, conversion of rotary to reciprocating motion is through a speed reducing bevel gear set (crown wheel and pinion) closely coupled by an eccentric drive pin in the crown wheel to a reciprocating saw blade carrier bar. A guide or bearing plate extending between the crown wheel and the saw blade carrier bar does double duty, guiding and supporting the saw blade carrier bar on one side and, on its opposite side, providing a thrust surface for the crown wheel. The crown wheel engages the guide plate through a thrust ring about equal in diameter to the diameter of the crown wheel. In this way, the shallow crown wheel may be positioned, supported and stabilized entirely by two simple bearings-a large diameter plain thrust bearing of essentially no radial capacity and a short radial bearing subject to virtually no bending or thrust loads. In an alternative embodiment the guide plate is eliminated and the reciprocating carrier bar receives the thrust load of the crown wheel.
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