As this meshes with a gear but slightly larger in diameter, a slow speed of the drill chuck is possible.
The back gears are put in and the drill chuck is revolved slowly.
A very convenient form of drill chuck for small drills is shown in Fig. 1072.
However, if much drilling is done, then round shank twist drills to fit the drill chuck will work better.
The slow speed is obtained by shifting the clutch so that the top bevel pinion drives the drill chuck.
This holder is simply a drill chuck fitted with a special shank.