Tuesday, 6 June 2017

Cromwells in Normandy

"Remarks regarding the use of Cromwell tanks in Normandy

1. Exhaust fumes, exhaust system, sparkplug fouling

A. The tank's users discovered that the exhaust fumes of the tank gave away the tank's position in moist weather. 

In order to immediately prevent this from happening, a protective cap for the exhaust pipe was designed. It is easy to install and it's made from scrap metal and refuse. The latter is used as stuffing.
This cap has the following advantages:
  1. Exhaust fumes are spread beneath the horizon.
  2. The exhaust fumes are cooled by air, and their density decreases.
  3. Since it is easy to remove the cap, it's easy to replace the stuffing.
The use of the cap has the following drawbacks:
  1. Loss of full gun depression in the range from 5 o'clock to 7 o'clock.
  2. The protective cap is vulnerable to enemy fire and to damage when driving off-road.
B. Sparkplug fouling

Practice shows that even though the sparkplugs in the engine fouled on both sides, row "A", closer to the exhaust valve, is particularly prone to fouling. The exact figures in terms of miles or hours are unknown, but there were cases when a tank had to stop for 3 hours.

Another reason for breakdowns is the slow speed that the tanks must drive at along the roads.

The defects could be less frequent if drivers could be instructed to maintain high engine RPMs when idling or driving slowly. However, in practice, it is difficult to follow these instructions, since usually the drivers wear tight helmets, and it is very loud in the tank. It is difficult to keep track of the engine RPM. Users also insist that the first indicator of increasing RPMs for the driver is the activation of the regulator. They also say that the installation of a tachometer is very desirable. 

It proved impossible to remove an engine and check it in the field. Currently, investigation of all sparkplugs that proved defective is underway.

2. Design of the mudflaps

There are complaints about damage to the mudflaps, especially the front, from enemy fire, trees, etc. As a result, they are torn away from the tank. The shiny steel that is revealed along the entire side of the tank was easy for the enemy to see and could reveal its location.
A more robust design is proposed.

3. Delco-Remy charging device

The size of the charging device is insufficient, and it is difficult to keep tank batteries at full charge. In addition, the gasoline engine has many defects.

4. Driver's emergency hatch

Conclusions were made based on sets that were meant to be used in the field.
  1. Ball joint plate: up to 1/8" of metal must be removed.
  2. External ball joint: must have a cutout to remove the periscope.
  3. All other plates have to be cut down at both angles, and the attachment pins must be cut down by 1/8"-1/4" to fit to the hull plates.
  4. In some cases, up to 1" of metal has to be removed from the lower part of the rear plate of the turret to avoid fouling up the ball joints.
  5. If any set of plates is built for a certain tank they do not necessarily work with any other tank.
  6. It takes 4-12 hours to prepare the plates in field conditions.
5. 75 mm gun mantlet

There was a case of a direct hit to the BESA machinegun. The machinegun war thrown back into the radio, the gunner was killed. The shell passed through the mantlet and into the turret without damaging the turret at all.

6. Eccentric axle

A number of these axles was bent. Based on existing information, it was established that they were bent after the tanks drove through densely forested terrain.

7. Towing hooks

Both cases of tow hooks tearing off were investigated, and conclusions were made that the tear occurred on:
  • Non-swampy terrain
  • Even, not pitted, terrain
  • With clean tracks
  • While towing the tank in a straight line
A welded design of the towing brackets is being developed to increase robustness."


  1. How did a hit in the MG kill the gunner? I imagine it was the coax, which would have been on the loaders side if anything. Cant be the bow MG since that has no way of being tossed into the radio in the turret bustle.

    1. You got me digging on this one. The commander and gunner sit on the left of the Cromwell turret with the loader on the right. However, the Besa MG is mounted to the left of the main gun, which is unusual....normally the MG is on the same side as the loader. Besa's are belt-fed from the right. It's a little mysterious to me how it could be reloaded with the 75mm breech in the way.

      Nevertheless, with the MG on the same side as the gunner, you can see how he could have been killed by the hit described in the article.

  2. How is it possible that engine removal was impossible in the field? Engine removal is routine on any tank. The Cromwell appears to have a big, flat, easily-removed engine deck giving good access to the engine. ????

    1. An engine is among other things also heavy, so you need a crane to lift it out. I dont know how many ARVs the british had that could do that.

    2. Every tank battalion in the US Army had multiple small, truck-mounted cranes that could life out an engine. This is a routine part of maintenance. It is not credible that British units lacked similar equipment (indeed the most probable thing is that they had the very same trucks!). So, again, how is it possible that Cromwell engines could not be changed out in the field? No unit can be kept combat-ready if they can't do engine changes.