"Report on completion of experimental works on armoured vehicles from May 20th, 1941, to June 20th, 1941
Object 220 (KV-3 base)
As of June 20th, the tank traveled 1979 km in total, 584 km after reassembly. The 850 hp V-2SN engine #2(1193-03) installed on May 30th worked for 27 h. 21 m. During trials, the following defects were discovered:
- 3 sets of exhaust collectors burned up over the course of 284 km.
- 4 final drive ferodo ribbons burned up. Cause: improper installation and adjustment.
As of June 12th, the existing defects are:
- The second road wheel rim on the right cracked and is flaking.
- The rims of the 4th and 5th road wheels on the right were bent.
- The rims of all road wheels on the left were bent.
- The ignition fork is worn out by 2 mm.
- The rubber on road wheels 2, 3, 4, and 5 on the right, 5 on the left, is loose.
- The right final drive broke down. Upon disassembly, it was discovered that:
- The were destroyed: row ball bearings x2, roller bearings x1, conical ball bearings x1.
- The leading gear has worn down by 6 mm and shows signs of heat damage.
3 experimental road wheels with increased diameter rubber liner and washers were installed on the left (the rubber is compressed, the ribs of the washers rub against the tracks) and 3 production wheels with wire rings in the middle of the rubber disk were installed on the right. The dry air filters were removed and replaced with experimental Vortox oil filters which have a "mushroom" inside that prevents oil from being carried away into the cylinders. Exhaust collectors with compensators were installed on the engine.
Assembly of Object 220-II with 100 mm of armour began on June 7th. The following work was completed: final drives and torsion bar stoppers were installed. The gearbox, main clutch, side clutches were completed, but not installed. The tank will be ready no sooner than July 10-15th.
The tank traveled for 2237 km as of June 19th. 5 engines were replaced during the reported period (see attached table). The following defects were discovered during trials:
- Oil leak from the primary gearbox shaft grease retainer.
- Gearbox defects:
- Teeth from the 3rd and 4th gear and the conical gear from the main shaft were knocked off.
- The collar of the 2nd and 4th gear wore down by 4 mm.
- The 5th rubber shock absorber on the right and first on the left were destroyed.
- The paper fuel filters foul significantly and tear.
An experimental connection of the torsion bar with the suspension arm, hot installation (no grooves). Over 2000 km, no shift in diameter was observed. The gearbox with a casing from recycled aluminium worked for 1671 km without defects of the casing.
A new main clutch was designed, made in one assembly with the fan (with no dampener). It was installed on the tank. The levers and control rods for the main clutch are not ready. The latter are being moved to the right side of the tank, as it is the most free. The tank will be ready for trials by July 1st of this year.
As of June 20th, the hull and turret have not arrived at the factory. The gun from factory #92 is present. The plan for order #37061 is delayed on all counts. We must sound the alarm on this project. We don't know the pain points of this vehicle and if defects occur during mass production it will be more difficult to correct them.
The factory #92 representative received data on the Object relevant to the gun that will be installed in it.
Vortox air filters were tested on the tank. Trials showed that over 17 hours, the filters caught 8 kg of dust. The commission evaluated that the filter can work for 8-10 hours in highly dusty situations without cleaning. Vortox type air filters are now being installed on production vehicles.
The technical project is ready. A model is ready. The GABTU model commission will arrive at the factory on June 25th."