The first track types used for the U.S. medium tank series consisted
of a steel frame with flat rubber moulded blocks. The steel frame carried
two rubber bushed pins.
During the Spring of 1942 the Japanese advance cut off sources of natural rubber in the Far East. Since each set of tracks (incl. spares) required 1,734 pounds of rubber, and synthetic rubber being a poor substitute, several designs of steel tracks were made. On these the full rubber block was replaced by steel treads riveted or welded to the link frames. Later, tracks with a combination of steel treads and moulded rubber tops were manufactured. Besides the early flat treads, parallel steel bars and steel or rubber chevrons were introduced to give a better grip on certain types of soil.
During 1942/1943 Canada designed and tested a track type consisting of single pin cast steel links, doing away entirely with the double rubber bushed pin type design. Aptly named Canadian Dry Pin or C.D.P., this track type looked a lot like German tank tracks. It did not not use valuable rubber and they proved both cheaper to make and lighter than the U.S. type steel links. C.D.P. tracks were fitted to Canadian-built Sherman related AFVs.
The double rubber bushed pin track came in two basic types: 16" wide
with 1-1/8" pins and 16-9/16" wide (or 16-1/2", sources differ) with 1-1/4"
pins. There was one type of 16-9/16" wide track, the T37, which had 1.44"
All medium tanks and related AFVs with VVSS used 79 (or 78) links per track, except for the M3A4, M4A4 and M4A6 which used 83 links per track since they had longer hulls.
An example of how track types superseded each other is documented for the Ram. The Ram Tank II Illustrated Parts List says the first 1,157 Ram tanks (built from 12-'41 to 01-'43) were originally fitted with Rubber Standard (WE210) track, even though early examples can be seen fitted with T41 track. The following 792 (built from 02-'43 to mid '43) were fitted with T54E1 track. T49 and A.S.F.(T37) were supplied as spares only. However, in use any Ram could be seen fitted with other track types as well.
The two tables linked below list the known track types and their characteristics.
Note: pictures of track links will follow in due time when I have good
pictures for all types. Also see my Wanted
section at the bottom of this page.
With the introduction of the HVSS system the track was altered. The
outside guide horns on the end connectors were replaced by a single inside
guide horn. First, a single dry pin cast steel link was produced, but this
was replaced by inside guide, double rubber bushed track designs. These
came in full rubber and steel/rubber combinations.
All AFVs with HVSS used 79 (or 78) links per track, except for the M40 155-mm GMC and the M43 8-inch HMC (which had longer hulls).
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