"Evaluation of reliability of the MkIV and its mobility data
- The English heavy tank MkIV has insufficient reliability of some components and is a vehicle with an unfinished design, not ready for production.
- The MkIV tank crosses slopes poorly, as it loses its tracks at a 20 degree angle. This angle is too small. It is still possible for the tracks to slip off at angles less than 20 degrees.
- The fuel expenditure is reasonable on all road types.
- The hull is abnormally long compared to its width and height. The front of the hull is located low, between two high-rising tracks, covered by large mudflaps. This reduces visibility for the driver and hull gunner. Observation periscopes installed near the driver and gunner to little to improve visibility. When the gun is facing forward, the barrel does not clear the mudflaps. This leads to the mudflaps breaking off when hit by the shockwave from a shot.
- The observation devices installed in the turret provide satisfactory vision. Identical devices have been found in the model 1939 Polish Vickers tank.
- The tank engine is very modern, of the car and tractor type. The engine uses a minimal amount of deficit metals and is suitable for mass production. However, the engine of the MkIV is an unfinished design, and its reliability is doubtful. The toughness of cylinder block heads is also in doubt, as they are relatively short compared to their width (the engine has valves on the side). If the toughness is insufficient, the head will warp, causing it to punch though the layer between the head and cylinder block. If not noticed in time, this will cause cylinders to break down prematurely. When using the MkIV tank, water levels in the engine must be observed carefully. If water levels start dropping, the cause must be found immediately.
- In the tank's transmission, the turning mechanism, placed in one assembly with the mechanical gearbox, deserves attention. The turning mechanism lets the tank turn in place, lets it turn easily, and retain good maneuverability for a heavy tank on the move.
- The hydraulic servos reduce the efforts required to operate the tank.
- The suspension is insufficiently robust for a 40-ton tank. As trials showed, welding seams rupture, and inner road wheels fly off the bogeys, followed by outer road wheels along with the axles, the bogey balancers start rubbing on the track, and quickly break. The flanges of the road wheels are placed immediately next to the track links, which causes friction, and wears down both the track and wheel. The wheels heat up during motion, and friction with the track increases. The track pins have insufficient robustness, and break.
- The English heavy tank MkIV "Churchill" has sufficient armament, protection, and maneuverability to be capable of fighting German tanks effectively.
- Currently, the MkIV is an unfinished and unpolished design. When used in the army, the MkIV will require frequent repairs and replacement of parts and components.
- Several elements of the tank (turning mechanism in the same assembly as the gearbox, etc) are original, and can be recommended for use in domestic vehicles."