Pressed Steel Car Company,
Inc. produced 1000 M4(75)s and 3700 M4A1(75)s from March, 1942 through December,
1943.
Production Order T-3017: 900 units: 550 M4A1, 350 M4: Serial Numbers 5 /
USA 3014761 through S/N 904 / USA 3015660
Production Order T-3163: 800 units: 477 M4A1, 323 M4: Serial Numbers
10660 / USA 3015661 through S/N 11459/ USA 3016460
Production Order T-3321: 400 units: 299 M4A1, 101 M4: Serial Number
13460 / USA 3016461 through S/N 13859 / USA 3016860
Production Order T-3605: 1600 units: 1374 M4A1, 226 M4: Serial Number
28005 / USA 3036535 through S/N 29604 / USA 3038134
Production Order T-4166: 1000 M4A1: Serial Number 36900 / USA 3069497
through S/N 37899 / USA 3070496
Some of the official documents
have it that specific Serial and Registration Number ranges were assigned to
distinguish M4s from M4A1s in the "mixed" Production Orders. In
counting heads, we have not found this to be the case. That is to say, it is
not possible to determine if a unit is an M4 or an M4A1 if all one has is the
Serial and/or Registration Number. An exception to this would be PSC's first
164 units, built from March through June, 1942. These were all M4A1s, and would
have been assigned Serial Numbers 5 through 168.
Despite US neutrality before
December 7, 1941, the British Government, which had been at war since September
1939, was permitted to contract with US firms for war materiel produced on a
strictly "Cash and Carry" basis. On October 25, 1940, the Pressed
Steel Car Company signed a 28.5 million dollar agreement with the British
Purchasing Commission for the production of 501 28 ton Medium Tanks. The design
which emerged in early 1941 was the M3 Medium. It was negotiated that the M3s
produced by PSC would incorporate a larger British designed turret as opposed
to the smaller turret of the original M3. The British labeled M3s with their
turrets "Grants," while M3s with the original turret configuration
were designated "Lees." The montage above documents the
rehabilitation and conversion of PSC's long abandoned Hegewisch Plant in
Chicago into a tank production facility. It is thought that the first PSC Grant
as shown in the lower left panel is now on display at the Tank Museum at
Bovington in the UK. The great drawback of the M3 was its sponson mounted main
gun. By the Fall of 1941, the Ordnance Department had produced a replacement
design which used the same mechanical components of the M3, but incorporated
the main gun in a rotating turret. The new M4 series, dubbed "Sherman"
by the British, entered production in early 1942, and completely replaced the
M3 series on the various assembly lines by the end of the year. The lower right
panel dates to the Spring of 1942, and shows M3 Grants on the right and M4A1
Shermans on the left.
In November 1941, the US
Government took over the Hegewisch plant from the British, and contracted with
Pressed Steel for the production of 900 Medium Tanks based on the recently
designed T6 (Sherman) pilot. All but 21 of the Shermans built by Pressed
Steel Car from 1942 through 1945 were powered by the 400 horsepower 9 cylinder
Wright Radial aircraft engine (most built under license by Continental Motors).
The photo above shows Serial Numbers 5 and 6, PSC's first and second units, on
the assembly line on February 18, 1942 (not 1941 as stamped at the top). These
and six others were accepted in March. PSC's first 164 units were cast hull
M4A1s. In July, the company took up production of the welded hull M4 model.
Government contracts were revised several times, and, all told, PSC produced
1000 M4(75)s and 3700 M4A1(75)s from March, 1942 through December, 1943. In
January 1944, the company switched over to production of the M4A1(76), and
built a total of 3426 units. The absolutely last Sherman made was an
M4A1(76)HVSS that rolled off the line at Pressed Steel in July, 1945.
Above provides a right rear
view of the first PSC M4A1, Serial Number 5, USA 3014761. A small number of
early Pressed Steel and Lima Locomotive M4A1s were assembled with the M3 style
"pepperpot" exhaust and muffler setup. We've asterisked the
"pepperpots" on both the Grant and Sherman in the photo. Field
reports from users of the M3 Medium noted that the original exhaust system
created a dangerous heat build up on the engine deck, which, in some cases,
melted the leather straps holding the pioneer tools. The Ordnance Department
developed a solution that replaced the pepperpots with center mounted exhausts
pipes that directed the hot gasses down and away from the tank. An unfortunate
consequence of the new configuration was that, in order to make room for the
exhaust setup, the M3's interior mounted air cleaner was replaced with two
externally mounted cleaners that were very vulnerable to combat damage. In any
case, the Ordnance Department directed that all M4A1s not built with the new
standard M4/M4A1 exhaust and air cleaner configuration would have it
retrofitted before issue.
The first PSC M4A1, Serial
Number 5, USA 3014761 was not officially accepted until March, 1942, but it was
shipped to Ft. Knox, Kentucky for evaluation on February 27. The Signal Corps
photo above is part of a series taken shortly thereafter touting the "new
M4 medium tank," and noting its superiority to the M3 design. The
"completely streamlined... all cast body" is contrasted with the M3's
riveted hull. The limited traverse of the M3's sponson mounted 75mm main gun is
compared to the gun's relocation to the center
in a fully rotating turret. At
this point, the original short barreled M2 gun seen in the February
photo, was
replaced with the standard M3 75mm, and the M34 rotor shield (1) was
added. It is thought that 10 or so of PSC's first M4A1s had
turrets equipped with the rotor sight (2). On March 5, 1942, the
Military Characteristics of the M4
series were revised to eliminate the two fixed machine guns. We suspect
that
only the first unit actually had the fixed MGs factory installed. The
number of
hulls in the production pipeline that had had the fixed MG holes
machined out
up to that point is unknown. The holes were ordered to be plugged and filled in
by welding. A cable clamp (3) was installed on both the front and rear of the
first few units. The front clamp was soon eliminated, and the cable was
attached to the left front towing shackle. Serial Numbers 5 and 6 were built
without head light guards. On these units, the head light plugs (4) simply
swung free on their retaining chains. Two standard headlights are seen
installed. The lights shown in a previous photo are "hooded." On
early M4A1s, detachable "blackout hoods" were provided for the
driving lights. Later, a special purpose blackout head light was provided for
the driver. When not in use, the head lights were stored inside, and the holes
were sealed with the plugs.
Click on photo for more details
A number of the first PSC
M4A1s were shipped to the Armored Force at Ft. Knox as soon as they came off
the assembly line. The photo above shows a pair parading past the Brown Hotel
in Louisville, Kentucky on Army Day, April 4, 1942. The tank in the foreground
is PSC's first unit, while the one in the background is their sixth, Serial
Number 10, USA 3014766. Note that Number 10 "still" has the pepperpot
exhaust, but is "now" installed with the head lamp guards. Serial
Number 5, USA 3014761 can be seen with the driver's hatch lifting handle in the
"first position," mounted towards the rear and on an angle, while SN
10 has the handle mounted in the "standard" position. Oddly, many subsequent
PSC M4s and M4A1s are seen with the handles in the first position. Counting
heads suggest that the standard position was fully adopted in August, 1942. An
anomaly seen exclusively on PSC M4s and M4A1s is the riveted lower hull. The
military characteristics of the M4 series only authorized "fabrication by
welding" of the lower hull. Our "head count" suggests that
Pressed Steel Car began production with, and continued to use riveted lower
hulls until around May, 1943. We have found no explanation for this exception,
but it may be that PSC was tasked with using up the remaining supply of M3
Medium riveted lower hulls once production was terminated. Company
correspondence mentions that the interior protruding rivets of "our
special lower hull" necessitated a slight divergence in the standard
arrangement of the Sherman's internal stowage.