Medium Tank M3

The Medium Tank M3 was the main production version of the Medium Tank M3/ Grant/ Lee, and used a riveted hull and a Wright air-cooled radial engine. It was used in North Africa in 1942, but was then largely replaced by the M4 Sherman.

A number of changes were introduced on the M3 during its production run, mainly to deal with problems discovered in use.

Tests at the Aberdeen Proving Grounds revealed that carbon monoxide could build up inside the tank if both guns were fired with the hatches closed. Three new ventilators were added to the design to solve this problem - one on top of the turret next to the cupola, one on the left front hull roof and one on the right side of the hull roof.

The original M3 design used a Hycon hydraulic power boost on the steering system. In use this proved to be unreliable, and a modified Hycon system was introduced on 1 November. At the same time an alternative mechanical ling level steering system was developed, and was authorised for use on production tanks at the Detroit Tank Arsenal on 26 August 1941. In February 1942 the Ordnance Committee decided to use this more reliable system on all M3 production.

Changing Track on M3 Grant, North Africa,1942
Changing Track on M3 Grant, North Africa,1942

The Vertical Volute Spring Suspension used on the M3 had originally been developed for the Light Tank M2, and was then adopted for use on the Medium Tank M2, which was itself almost ten tons lighter than the M3. It soon became clear that the bogie assemblies weren't strong enough to cope with the extra weight, and a stronger version was designed. This had stronger volute springs, and moved the return rollers from the top of the bogie to a new bracket located just behind the top of the bogie. This modification only appeared on late production M3s.

Early production M3s had side doors on both sides of the hull, but these proved to be vulnerable to combat damage. During the production run of the M3 they were removed and replaced with an escape hatch in the right rear of the fighting compartment, behind the 75mm gun.

The height of the M3 was always a concern, and some US tanks were built with the cupola removed and the split hatch used on British Grant tanks installed instead.

As built both the 75mm and 37mm guns had exposed rotors to allow vertical movement. If these suffered minor battle damage they jammed, preventing the guns from moving. In order to protect them extra gun shields were installed to protect them.

Tests demonstrated problems keeping the periscope mounted telescopic sight properly aligned with the 75mm gun, and so during the production run a direct sight telescope was added on the left side of the 75mm gun mount.

In later production M3s one of the two hull machine guns was removed, and the machine gun port covered with a steel plug.

Production: 4,924
Hull Length: 222in with M2 gun, 241 with M3 gun
Hull Width: 107in
Height: 123in
Crew: 6 or 7
Weight: 61,500lb combat loaded
Engine: Wright Continental R975 EC2 9 cylinder air cooled
Hp: 340hp at 2,400rpm
Max Speed: 21mph sustained, 24mph max
Max Range: 120 miles cruising radius (roads)
Armament: 75mm Gun M2 or M3 in right front of hull; 37mm Gun M5 or M6 in turret; three .30in machine guns - one in turret cupola, one coaxial with 37mm gun, one in hull front






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How to cite this article: Rickard, J (16 June 2016), Medium Tank M3 ,

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