"American Embassy in Moscow, Military Mission
January 13th, 1944
To the Tank Directorate
M4A2 Medium Tank
For your information, we attach the aforementioned list of difficulties encountered by our personnel with M4A2 tanks of the latest type. We also send you methods of resolving these issues.
- Turrets of many tanks are poorly fitted, therefore turning them in order to fire on the move is difficult. This usually happens due to incorrect installation of the turret ring and due to incorrectly assembled liners of the traverse mechanism. There should be a liner between the mount of the case and the turret wall. The thickness is chosen such that the space between the gear teeth is minimal, 0.002"
- Most radiators in M4A2 tanks leak due to poor design of the radiator mount which causes excessive vibrations of the radiator during movement. Several instances of leaking radiators were observed on brand new tanks. This definitely happened due to an oversight at the factory. Measures are being taken to prevent this.If a leak is detected in a radiator in an accessible place then it can be sealed. If the leak is inside the radiator then it is easier to replace the radiator core then attempt to repair it.In your case it is recommended to order spare radiator cores in addition to the regular set of parts.
- Defects have been found in the road wheel bearings caused by the use of a new neoprene grease seal, which turned out to be unreliable. If a neoprene seal is installed then dirt can get through and enter the ball bearing, which is quickly destroyed as a result.In addition, the seal can be torn off by the pressure of the grease gun and increase the possibility of dirt entering the ball bearing.It is recommended to install grease seals of the old type produces from leather. There are fewer defects with road wheels that use roller bearings than those that use ball bearings. This likely happens due to the difficulty of installing the ball bearings correctly.It is necessary to carefully track the condition of the neoprene grease seals so that they are tightly packed and no gap is seen.
- Cases of breaking of the volute spring mounts often occur. This happens if the plug freezes to the swing arm pin. In this case the plugs should be wiped clean and covered in antifreeze. The spring mounts have been reinforced as a preventative measure.The drive sprocket crowns often loosen from their proper place. It is necessary to carefully watch for the bolts loosening. If replacing bolts, use new one with brass nuts.
- Final drives produced by companies other than Fisher Body Division of General Motors it is necessary to inspect the differential brake drum for deep scoring caused by instruments. Do not drain the oil during the inspection. If the drums are poorly finished it is necessary to remove them and polish them thoroughly. If the grooves are too deep then it might not be possible to repair the damage.
- The clutch bolts should be frequently inspected. Defects due to poor seating of the clutch bolts have been observed.
- The turret ring groove collects water, which starts to mix with the grease. If the turret is hard to turn by hand then it should be removed and the turret ring cleaned.
- Even though larger air cleaners are being installed now, oil from the cleaners might start leaking into the engine after 10 hours of work in dusty conditions . The cleaners need to be carefully inspected. The frequency depends on how hard the engine is pushed.
- Tanks equipped with exhaust cowls (to reduce dust) are vulnerable to .50 cal machineguns. The cowls should be removed before battle.
We hope that this information is useful to your tankers that work on M4A2 tanks.
John Deane
Major General of the American Army
Head of the American Military Mission"