Matt Toms postulated that the comb was part of some release system for quick jettisoning of a towed trailer. Kurt Laughlin, always willing to tackle a Sherman riddle, reasoned that the comb could have been a device for securing the end of a release cable, strap, or sheathed cord that was used to release the trailer hitch from inside the tank, and set out to research this further.

Photo courtesy of Kurt Laughlin

Kurt visited the Aberdeen Proving Ground museum "holding pen". The comb on the M3A5 is pictured left. It shows an overall view with the classic comb, but with a small square fitting in line with it at the top of the differential housing. This is actually a square tube with a cross bar and small wheel or pulley inside. Note that the differential housing bolt is missing behind the fitting, and is open into the tank interior. On the M3, there was no readily accessible hole to feed the cable into the interior, so a differential housing bolt was omitted. The pulley was likely added to make it easier to pull the cable over the sharp corner of the hole.

Also, he noted that Jim Mesko's US Self-Propelled Guns in Action shows a M7 pulling an ammo trailer on page 13: "There is a cord or cable running out of the casement opening below the gun, over the differential housing, and possibly under the hull ... to the trailer hitch? The photo on page 16 shows some sort of cord or cable looped between the left (field-installed) step on the differential housing, behind the step, and down the front of the differential housing."

Not yet convinced, Kurt did some more research and after checking TM 9-791 for the Armored Trailer M8 found it is obvious that the release line went up over the rear deck to the cupola. So thanks to Kurt's efforts we can dismiss the possibility that the comb was part of a release system for quick jettisoning of a towed trailer.

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