| 摘要 |
A pneumatic impact power tool has a tool body with a bit-receiving axial bore in its end surface. A cap is threaded on the end of the tool body and has an end wall spaced from the end surface to define a cavity and a lobed opening in the cavity matably receiving a like-lobed bit shank, the cavity being dimensioned to accommodate the lobes. Spring-biased balls project into the cavity from radial bores in the end cap to engage the shank lobes and bias them to a rotational position non-aligned with the opening lobes to inhibit removal. The cavity is dimensioned to afford a slight axial clearance to accommodate axial movement of the lobes. A cover on the end cap is recessed to receive the bias springs, retaining both the springs and the cover in place. The end cap has a annular channel communicating with an exhaust passage in the tool body and four exhaust ports in the end wall.
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