The images on previous page show how No. 2A drill evolved from No. 2 model.  The frame was actually identical in the design and all working elements and surfaces were the same.  However, one major change was introduced in the production process - the casting methodology.  Here is a comparison of three different frames:

But this was not all...

Construction Elements of 1938 release

The 1938 release of No. 2 hand drill was a complete breakaway from previous design.  All No. 2 drills produced between 1895 and 1938 were equipped with one pinion and a friction roll, counteracting pinion action. 

Friction roll on No. 2 - 1921

One pinion on No. 2 - 1921

  With the 1938 model designers completely changed the design of main gear/pinion assembly.  The friction roll was abandoned and second pinion was introduced.

1938 edition with two pinions.

However, in 1938 design one element of main gear/pinion assembly was carried forward from previous models - the ball bearings.  The number of balls in the bearing varied. 

In early models there were seven balls, reduced to five in later models, including 1938 release.  Two races were standard on all models until introduction of No. 2A model.