| 摘要 |
<p>A manual tool suitable for driving nails into concrete or the like comprises an axially extended tube and a ram mounted for reciprocal movement therein, the ram having a handle at one end thereof. The diameter of the ram along its length is substantially less tan that of the bore of the tube. The end of the ram remote from the handle is provided with a low friction means to space the ram from the walls of the tube. Typically the low friction spacing means comprises a plurality of ball bearings located respectively in a plurality of recesses formed in the radial surface of the ram.</p> |
