The shell of the chuck has patent information stamped on the smooth bend.  The base of the chuck holds jaws in machined grooves.

It is a simple and effective construction.

The Friction Roll

Millers Falls catalog for 1903 describes this part of the drill in one sentence - "It has cut gears and adjustable friction roll to prevent gears from springing out of engagement." 

The function of the Friction Roll is to control the main gear and single pinion gear in proper alignment and ensure smooth rotation.

There are three parts to this device:  a cylinder with machined off-set shaft, a flanged roller wheel mounted on the shaft, and a locking screw to hold the cylinder in the mounting bracket.

When installed, the wheel rides on the shaft and by lightly touching the rim of the gear, it controls the thrust that tends to push the teeth of the pinion and the gear out of engagement.  The gap between the roller and gear's rim is adjusted by turning the shaft cylinder. 

Since the shaft is not in the center of the cylinder, it will move the wheel further or closer to the gear's rim.  The locking screw is used to do just that - lock the position of the cylinder in the desired place after adjustment of the gap is achieved.