The Churchill I was the first production Churchill. It was built to traverse difficult terrain as the British assumed that the battlefields would break into mud, trenches, and obstacles created from prolonged battle.
The Churchill I and Churchill II were sold to the Soviet Union, they found the following defects that the British were already aware of:
In order to reduce the chance of the cast iron clutch socket cover, part Z.V.1/BB/44365, the engine RPM should never rise above 2000rpm. It is possible that some engines are limited below this number, but most are set at 2400rpm.
There were complications when starting the engine in the cold. The symptoms of this are: the engine cannot turn over at any rpm, and doesn't budge at a certain point when a start is attempted. If this happens, the engine must be thawed, and then started. This happens when a small amount of ice forms along the diameter of the cylinders, between the bottom of the piston and cylinder head.Water gathers in the engine from condensation in the exhaust system, and the condensate leaks through the open exhaust valve.
The fact that the engine has started cannot always be heard from the driver's seat. Be wary, and do not use the manual started when the engine has almost started, or is at least turning over. Make long pauses between start attempts in order to avoid damage to the starter gear and the flywheel crown. If the electric starter is faulty, there is no other way to start the engine other than towing the tank.
Since the engine of this tank has hydraulic plungers, it is especially important to drain and refill the oil, replace the filter elements, and clean the mesh filters, every 300mi (482km).
Certain difficulties were had with the cylinder head liners. To replace a damaged liner, the engine must be taken out of the hull. The cylinder head liner can also be replaced by using a special instrument, inserted into the two openings for spark plugs, to raise the cylinder head and replace the liner without removing the engine from the hull. Great care must be taken when replacing the cylinder head bolts, that the bolts are well tightened, and provide even pressure.
The cast iron cover, part Z.V.1/BB/44365, is not robust enough, and may crack. Cracks radiate out of the central opening of the cover, to the clutch lever slots. In order to prevent wounding of personnel and damage to the vehicle, the socket covers must be inspected often. If a crack is discovered, the vehicle must be taken off the road until a new socket cover is ready. Also, remember that when the clutch disks or case cover are changed independently, they should be carefully balanced before assembly.
The bolts of the clutch shaft with universal ball joints should be inspected regularly and tightened.
Gearbox and Steering
The 4-speed gearbox causes difficulty due to slipping of the third gear. When driving, be very careful, and fully engage every gear.
Some vehicles may be equipped with a limiter on the selected lever, to prevent engagement of a high gear. Due to the limit placed on the engine speed in section 1.1, the high gear limiter may be removed to compensate for the loss of speed.
The bolts in the clutch between the gearbox and final drives must be regularly inspected and thoroughly tightened.
Tracks, consisting of plates, must be calibrated in such a way that the plates engage the idler on both sides.
The bolts that attach the bogey carrier to the hull, and the bolts that attach the side armour, must be frequently inspected and tightened.
Rubber shock absorbers on each bogey, attached to the suspension carriers, need to be inspected often. Defective shock absorbers must be replaced immediately. If they are not replaced, then the bogey carrier may be damaged.
Difficulties in lubricating the road wheel axles with grease pumps, installed at the ends of the axles, may arise. The grease pumps consist of a double valve, and great care must be taken to ensure that sufficient amount of lubricant makes it to the axles to sufficiently lubricate the ball bearings.
The bogey carrier axle bolts should be frequently inspected and thoroughly tightened.
It is especially important to keep the hull under the engine and within the gearbox case clean and not covered in oil, gasoline, or water. This condition influences the performance greatly of the brakes, since the oil, gasoline, or water, may be easily caught into a stream of air from the engine fan, and end up in the right brake drum in the gearbox case.
To avoid having the track catch onto the rear tow loops, the rear loops must always be on the rear top eyes. When tow loops are used in the lower eyes, watch them to ensure that track links are not damaged.
The air that cools the radiators, passes through grilles on each side of the vehicle using a fan on a flywheel. The sucking action of the fan is enough to pull in dust, dirt particles, glass, leaves, etc., when driving off-road or on narrow roads. These foreign materials are deposited on the inner side of the radiator, lowering its effectiveness, and causing overheating or engine damage. The radiator must be inspected frequently, and foreign particles removed.
Turret Traverse Drive
When these tanks travel through a forest, it is important to make sure that the turret gun does not hit trees, or other obstacles while the vehicle moves. This causes serious damage to the turret traverse drive, since the friction clutch in the mechanism does not protect it when the tank travels at a speed of more than 6mph (10km/h)
When steering with the double differential, it is recommended to do so while the engine is at high rpm, avoiding doing so during contact with an obstacle or crossing of a steep grade, to avoid stalling the engine.
On soft terrain, there is a chance that the track will slip while driving, losing energy due to the action of the double differential, but immediate action of the brakes to the slipping track will allow the driver to prevent complete loss of energy and bogging down.
All of these peculiarities are characteristic of this special type of vehicle, and special attention must be paid to them while driving.