Sherman differential covers

The M4 Sherman also had many variations in one of the parts that makes it easy to recognize to most of people: the differential cover.
There are two main types for this part :
-the early 3-piece differential cover, which is made of 3 cast parts bolted together
-the cast one-piece cover, which has two main variations : the rounded type and the sharp-nose type.

The differential cover

differential    differential

differential    differential

The differential cover is the piece of armor that protects the gearbox, the differential and the 2 final drives. The construction of the differential cover is very similar from an early model to a later one. It has 17 holes for bolts on the upper border, 11 holes on each side (8 vertical and 3 horizontal) and 20 holes on the lower border. Any model of differential cover can be adapted on any model of Sherman hull. 

3-pieces bolted differential covers

3-pieces differential    3-pieces differential

3-pieces differential

The 3-pieces differential cover, as seen on an early M4A4 (Serial number 4825), on an early M4A1, both with Direct Vision, and on a late M4A4 (Serial number 21048). The shape of the 3-pieces differential didn't change a lot between the first and last exemplars manufactured.
The main difference is the form of the upper border, along the bolt strip, which were initially protruding and exposed, but later better protected with the addition of a lip. Even if this model of differential cover had a great defect (it was not reliable and caused technical problems because it was not rigid enough), Chrysler used it on the M4A4s until the end of the production of this model.
Usually, the right-hand section of the differential carries the part number E4151, the center part carries the part number E1232 and the right-hand section carries the number E1231. A very early differential has been seen with part number D50993 to the left side, the number has been "drip welded".

1-piece cast differential covers

cast differential cover    cast differential cover

The 1-piece cast differential cover, as seen on an M4A2(75) with small hatches (part number E4186) and on an M4A3(75)W with large hatches (part number E8543). The shape of the 1-piece cast differential changed during its manufacture, the earlier version being more rounded, and the later version having a "sharp-nose" style. The upper border, along the bolt strip, also evolved, so that the bolts were better protected agains shells and explosive devices. The front towing lugs and the footsteps also evolved during the production (see below)

cast differential cover

The M4A3E2 tank, better known as "Sherman Jumbo", has a specific variant of the 1-piece cast differential cover.
The protection of the differential was
increased to 5 1/2 inches.

The upper bolt strip

bolt strip    bolt strip

bolt strip

bolt strip    bolt strip

The upper bolt strip evolved during the Sherman production. Earlier models have protruding bolts with no protection at all.
Later types have a protective lip to increase the protection of the bolts, and the last ones have a small depression to protect the boltheads.

The front tow lugs and foot steps

towing lug    towing lug

The front towing lugs, molded in the differential cover, evolved with it. These two pictures show the early model of towing lug seen on E4186 differential covers. The second picture also shows the shacke often used as a footstep.

towing lug

This photos shows an early cast footstep, as seen on an early E8543 differential cover installed on the M4A2 "Massaoua".
The period documents mention that the cast-in steps interfered with the crew's ability to work the quick release towing shackles, so they changed over to little welded on steps, as seen below (Joe DeMarco)

towing lug    towing lug

Two different models of welded footsteps, the last one seems to be a field addition, seen on the M4A3E2 "Jumbo" from the Brussels Tank Museum.