Reply to chugwater crawlers:
You can get a parts manual and an operators manual from the Cat division that reprints old manuals.
When I checked they did not have a shop manual for a twenty two.
If you find a source for a shop manual let us know.
Have fun. This is a great hobby.
Caterpillar never produced a service manual (or Servicemans Reference Book as they are known) for the Twenty Two. The similarity between the Twenty and the Twenty Two was such, that it was deemed the Twenty SRB, would suffice for the Twenty Two.
You can acquire reprints of early publications from your Cat dealer .. here is the Cat website link to their publication list (click on "more" at bottom and then click on "Track Tractors") ..
Caterpillar Legendary Literature ..
http://www.cat.com/cda/layout?m=90800&x=7
The Twenty SRB is form number P1179B and it was first produced on 09/01/1931 ..
Track Tractors list of publications (BIG PDF file - 2.99MB and 30 pages) ..
http://www.cat.com/cda/files/268590/7/track_tractors.pdf