So many wheels, so little time: Breaking down a comprehensive Bendix wheel manual
Wheels, Brakes, & Struts
Many people are interested in landing gear components - I get questions about it all the time. This week I came across something interesting when uploading over 35 new Bendix wheel manuals to the AirCorps Library website. On the cover of almost every manual that I was processing, I noticed the same disclaimer: “This publication replaces in part T.O. 4W-1-31 (formerly AN 03-25BB-1) dated 20 May 1944.
What is AN 03-25BB-1?
Using the “Alphabetical Index of Technical Publications” (an invaluable resource) I was able to determine the title of AN 03-25BB-1 without having a copy of this manual on hand. We have several versions of the Alphabetical index, along with multiple versions of its counterpart, the “Numerical Index of Technical Publications”, both of which I use on a regular basis.
Long story short, the title of AN 03-25BB-1 is “Operation, Service, and Overhaul Instructions with Parts Catalog for Bendix Main, Nose, and Tail Wheels". This manual would have covered many different models of Bendix wheels, and I’m imagining it was pretty large.
TO 4W-1-31 & Subsequent Changes
As changes in the military Tech Order System evolved, the document number AN 03-25BB-1 would have been updated to TO 4W-1-31, and at that time would likely have contained the same information. The Air Force returned to the “TO” distinction (from AN) in the early 1950’s - read more about this change, and the tech order system by clicking here.
The big change clearly happened on 1-March-1955, when 4W-1-31 was broken apart into separate smaller documents. As time progressed, systems and components were becoming more and more complicated and it was natural that manuals were separated into more detailed sections that eventually became their own document with a unique document number.
A Manual For (Almost) Everything
Once 4W-1-31 was broken up, each supplement that was taken from it pertained to a specific model of Bendix wheel, whether it was a main, nose, or tail wheel. From the titles of these smaller supplements you will notice that Bendix wheels were distinguished by size and a roman numeral “type” distinction for each wheel, for example: Main Wheel 17:00-20 (type III), Nose Wheel 27 inch (Type I), Tail Wheel 10.5 x 4 (Type II), the list goes on and on.
Grouping Like Bendix Wheels Together
Another thing that I noticed when adding this group of manuals to the site was how the different types of Bendix wheels were grouped together by their new document number, after 4W-1-31 was broken up. For example, I noticed that all the documents with a “1” following the “4W” related to Bendix Main Wheels: TO 4W1-4-123 (for Main Wheel 26 x 6.6, Type VII) and TO 4W1-3-3 (for Main Wheel 30 x 5, Type II). Bendix tail wheel manuals were indicated by a “2”: TO 4W2-3-23 (Tail Wheel 10.5 x 4, Type II), while nose wheels were distinguished by a “3”: TO 4W3-6-43 (Nose Wheel 22 x 7.25-11.50, Type VI).
Bendix wheel information is just a small portion of the information we have relating to landing gear. We have almost 200 separate documents relating to all types of aircraft wheels, brakes, struts, and landing gear in general - browse here. Or maybe you just want to view and read full manuals without paying to download them? Become a member of AirCorps Library today for full access, just $9 per month or $75 per year!
