Today we present a document from the Medical Research Laboratory at Fort Knox from 1952 on ‘Tank Crew Problems.” This report examines issues reported by tank crews concerning ergonomic issues of US tanks, primarily the M4 Sherman series. The report is divided in five different sections, one for each crew position. This is not a very long report, totaling about 23 pages. We have reprinted some of the specific crew complaints below, they should prove rather interesting to anyone looking for information on what it was like to be a Sherman or M26/M46 tank crewman (these were copy-pasted from the PDF, so there might be some typos.) Special thanks to forum member LeuCeaMia over at SH for pointing this document out. A PDF of the full report can be downloaded here.
Problems of the Commander
1. When operating the tank radio it is necessary to hold the spring-loaded switch on the BC606 control with one hand while holding * the microphone to the lips with the button depressed with the other hand. While going cross-country in rough terrain, my tank was taken under fire by enemy troops. In attempting to radio to other tanks in my platoon, I was unable to hold on securely and operate the radio, too. The tank came off a rice paddy and I was severely shaken up and fell to the turret floor.
2. I was acting as a tank. commander on an M-4 tank with a 76-mm gun. We were firing on the range in October 1951. Each time the gun was fired the back blast not only carried a great amount of concussion back into my face, but also hot gases. The most objectionable feature of the back blast was the small particles of metal rotating band that were blown back with great force which lodged metal particles in both my face and hands. Even though binoculars were used, one particle lodged in my nose about 1/4 inch from my eye. Another officer actually had a particle blown into his eye and was hospitalized for about two months. This officer was sent to specialists who were unable to remove the particle and it may eventually lead to the loss of his eye. The combination of the flash, concussion, and flying metal from the rotating band make it difficult for the tank commander to accurately spot the hit of the round in order to make adjustments in the fire on the target. If goggles are used, it makes it almost impossible to use the binoculars which are necessary.
3. When firing, as tank commander, the 76 or 90-mm tank, I always have a lot of trouble with the back blast hitting me in the face and spoiling my sensing. The vision block in the turret ring is “not large enough to get a good forward view. This is on the M4 and the M46.
4. This incident occurred on a tank comber course at Fort Hood. Everyone was buttoned up except the tank commander. On this run, it was his job to spot targets and either fire on them with his 50-cal. or give the gunner the firing orders over the interphone system. As he was firing on a target with the 50-cal., another U: target appeared that required the use of the 76-mm gun. The tank commander had to stop firing the machine gun in order to press the to-talk switch on his chest set so that he could communicate with the gunner. The machine gun had to go out of action temporarily because it can not be effectively fired with one hand. The loader couldn’t take over because he had to be ready to do his loading job. Because the intercom system required the use of the hands, the fire power of the tank was considerably lessened for short period of time.
5. While a tank commander during a range problem, we were required to drive our M-24 tanks and fire all guns. The first thing to happen was that I lost communications with my driver. His shift lever had caught in the cordage and pulled the plug jacks from the control box. On the same problem, the loader, in turning around with the cordage on the wrong side of his body; pulled his plugs. The result was momentary confusion and loss of time. This same thing has happened with every member of my crew and with me time after time.
6. I have been in an M4E8 tank which mounted the 50-cal. machine gun on a pedestal mount at a time when the column in which I was riding was suddenly attacked by low-flying enemy aircraft. As tank commander, I found it impossible to take the plane under fire,, due to the length of time required for the tank commander to crawl out of the turret, mount the back deck, and fire. Even if there were time, the tank commander would be placing himself in the most exposed position possible for the very doubtful advantage of firing a 50-cal. m, g. at a high-speed aircraft. I notice that new tanks, i.e., the M41, include the pedestal mount for the 50-cal., thus making the gun almost entirely useless.
7. About Z December 1950 in Korea, tank commander of an M-4 tank, caught his foot between turret and traversing basket, crushing foot. Tank commander was standing in normal position on grenade box just to the rear of the tank gunner. His rignt foot was pointed out at a right angle which allowed his foot to be caught between the rotating turret and the hull. This is a frequent accident on the M-4 tank, most cases being less serious than the above, however, still painful.
8. On various occasions, I have noticed that, in my opinion, the tank commander’s seat in the M-46 tank causes a slight degree of discomfort and irritation to the tank commander when traveling with the tube in the travel-lock position. If the seat is raised high enough for the tank commander to observe properly, there is no room for his legs and knees due to the proximity of the rear of the turret and its various compartments. If the seat is on the down position and folded back, the tank commander cannot see due to the great depth of the fighting compartment. The various notches which regulate the height of the seat are ot very little consequence with your turret reversed. The guard for the 90-mm gun prevents the tank commander from turning sideways to the right.
9. During a period of training a group of men in our own battalion on gunnery and actual firing of the 76-mm gun on the M-4 Tank, and also a period of firing on the 90-mm gun on the M-46, I found a lot of difficulty in having the men who were tank commanders use the Vane Sight. In practically all cases when the men were questioned on the use of the Vane Sight for proper deflection to get the gunner close to target in deflection, they came up with the same complaint, that the location of the sight made it difficult to use, especially when it was necessary to “button up”. There was such a very restricted space there and an uncomfortable position you had to get into to use the sight to an advantage, So they merely looked at the tube and decided it was pointed close enough in the direction of the target without squirming down to a position where you could sight with the Vane Sight. But this did not give them the effectiveness that could be obtained if the sight could be used easily.
Problems of the Gunner
1. Tank Range, Fort Knox, Summer Camp, Summer of 1950. A man’s arm has just been broken, his nose is bleeding, and his mess kit, which was strapped to his side is now all bent in – Why? The gunner fired the gun and the loader wasn’t ready or hadn’t given up. Between the noise and confusion, gunner trying to pay attention to what he is doing and also listening to the Tank Commander’s commands, he finds it hard to remember the loader, much less remember whether he has given up or not, to signify he is ready. This happens many times; because the loader’s “up” is not a satisfactory signal.
2. It seems that because the bottom for the 76-mm gun and that of the 30-cal gun are so close together, the 76-mm was fired by mistake while the driver and boy did not have their heads in. I almost caused both of these to lose their hearing, along with endangering the life of the loader. If he had not been out of the way of the recoil, I don’t think he would have liked it.
3. When tank commander uses his power-traverse control handle (on M-4 tank), it causes the gunner’s power traverse control handle to exert a crushing force on the gunner’s right knee. Perhaps this has happened to me because I have long legs (height 6’31’), and have difficulty in finding a position for my right knee while I am in the gunner’s seat.
4. Azimuth indicator is in an awkward place on all tanks. It would increase the efficiency of the gunner in my estimation if the indicator was placed just beneath the sight and tilted toward the gunner like the speedometer on a car. It would save wear and tear on the instrument in this manner, also.
5. 1 saw a man squeeze his foot between a portion of the moving turret in the M-4 and the stationary portion of the hull. He was the gunner of an M-4A3 Medium Tank, and the turret was in power traverse. Unbeknownst to this man, his foot protruded beyond the ring and when he traversed the turret, his foot was badly crushed between the turret ring and the hull support.
6. Turret traversing lock on M4A3E8 and several other tanks is located behind the gunner, making him twist around in seat and lose leverage because of awkward position when releasing lock. For cure of both above complaints, I suggest relocating traversing lock where it is easily.visible and can be reached and unlocked with ease. Probably best position would be in front of gunner where he can pull directly back on lock thus, with maximum leverage.
7. This is not an instance of particular time, but the result of a series of experiences. The gunner’s position on any tank is, naturally, cramped and full of hydraulic lines, wheels, gears, and dial boxes, all of which are metal and extremely uncomfortable to be bounced against. It has been my unhappy experience to find that even a gentle cross-country run in a tank can throw the knees and legs of the gunner against these various metal obstructions sufficiently hard to cause crippling bruises and cuts.
Problems of the Loader
1. I was acting loader on the firing range at Fort Knox ior M4A3E8 tanks. The type of tank has no bearing on the instance because the result would be the same in any of our present models. We had sent a round on-the-way and the breech was open awaiting a new round. Being the loader, I quickly got another round from the ready rack and placed it in the chamber and rammed it home, The gunner had absentmindedly, or accidentally, put his foot on the foot firing switch before I said, “Up”. Therefore, the firing of the round was almost immediate and the recoil from the gun barely grazed my right arm. No injury was received, but a broken or shattered arm could have been the unlucky result.
2. During tank firing training in an M4A3E8, mounting a 76- mm gun, I found that if I observed all the safety rules for loading my legs would begin to cramp, due to the unnatural position, after 10-15 minutes. Since I am a normally proportioned individual of average size, I am sure others must have the same trouble, and for this reason, I believe the loader must be given more room in future tank design.
3. Loader’s fighting area is too small in M-46 tank. The ready racks in the M-46 are located in a position that hampers the rapid loading of the gun. Anyone but a very small man with gorilla like physique, is extremely uncomfortable.
4. At Camp Irwin, California, last August, while working in M46 tanks, I had my loader drop a round on the primer while taking it right out of the ready rack. It was hot and his hands were wet is the reason he couldn’t hold it, but I think the main reason is the ready rack itself. The rim at the bottom makes you lift the shell straight up before you can get your hand on the base to handle it.
Problems of the Driver
1. When driving the M4A3 or M4Al medium tank while buttoned up, once your eyes become accustomed to the light by looking through the periscope, it is extremely difficult to read any of the gauges on the instrument panel. Since it is necessary that you do glance at these gauges occasionally, and in order to do so you have to wait a few seconds for your eyes to become readjusted to the darkness, I believe that if a brighter instrument panel light were installed it would allow you to read the panel without those few seconds delay.
2. I suggest that improvements be made on the periscope in the M24 tank, as well as in other tanks. I believe that the periscope should have a larger picture opening so that while crossing hilly country, there wouldn’t be so many blind spots while coming out of a deep ditch or going over the peak of a hill. At present, the periscope cannot be moved without taking a hand off of the steering laterals. If it could be moved, possibly with the head or by the inertia of the tank itself, I believe it would be a big help to safety and better maneuvering.
3. I suggest that they change the steering in the M4A3 tank, Because you need two hands to steer and you start up a grade, you have to shift gear and it’s hard to steer the tank at the same time. There should be a way of steering the tank with one hand and shifting gears with the other.
4. When I was learning to drive an M4 tank, the motor would have a tendency to be sluggish. After a few moments of looking into the matter, I found that my knee had hit the magneto switch and had knocked it onto only one bank when the motor should be running on both banks. A person has a tendency to let their leg relax on the clutch pedal and a person’s knee will always hit the magneto switch. This still happens to me all of the time, even though I try not to do so.
5. In my limited experience in taking turns now and then driving a tank (mainly M4A3EB), I have found it difficult at times to stop a tank in an emergency or slow it down in a hurry while going down a hill or over rough terrain. The difficulty is in not having a spot to plant your foot while driving, and to brace yourself to pull back on the steering laterals. In order to pull them back sufficiently while going down hill, I have had to stand up and brace myself against the front of the hatch and apply backward pressure to the laterals This makes it extremely harder to have to be jumping up and down in that manner. Also, at times, I have conked myself on the chin or elsewhere rather hard if I hit a sudden bump or obstacle while in this position.
6. I am a tank commander ofa M4A3E8 tank, and I am constantly having trouble with my driver’ s skinning their hands while shifting gears. When you try to shift from fourth into fifth gear, if you hold the lever as you should, your knuckles will strike the transmission housing as you place it in gear.
Problems Common to Tankers
1. On at least a dozen different occasions while on field problems with my platoon, I have found an excessive delay on the part of my men in reporting on enemy position which they have spotted, or a malfunction of their tank which has just been noticed, and such matters requiring immediate radio or inter-communications, for the simple reason that the men cannot be made to wear their lip microphone for periods in excess of one hour. They say that after that length of time, the microphones become so irritating that they have to take them off. I have found this to be especially true in hot weather when perspiring is excessive.
2. It is necessary for me to wear glasses all the time. I have a reasonably bad astigmatism. Without my glasses, it is difficult for me to make out the instruments and readings on the tanks. With the present type of goggles (full vision with rubber edges and plastic lens), it is impossible for me to wear my glasses under them. With the glasses under the goggles, the goggles don’t fit tight to my face; they exert pressure on my nose over the glasses and other parts, which makes it painful and irritating to wear; if the occasion arises to remove the goggles quickly, the rubber lips inside and the flexibility of them (they collapse and catch the glasses) pull your glasses off with them.
3. For 12 months, I was a member of a tank battalion in Korea. One of the most bothersome pieces of equipment I used in the tank was the earphones. It was necessary to wear the earphones for long periods at a time – 6 to 15 hours each day. The small nipple inside the phone protruded into the ear, causing great discomfort after a few hours of operation. If the earphones had these nipples removed, reception was decreased considerably and the roar of tank engine made reception without the nipple protruding into the ear practically nil. Consequently, radio reception after a few hours of operation became increasingly poor because men would not keep their earphones on their heads. Tank or crash helmets, with earphones built in, did not help much because reception was about the same as if the nipples had been removed from the standard earphones.
4. During basic training, the company was firing the 75-mm tank gun at moving targets. Each man was to fire 5 rounds. After a few rounds, the tank was filled with fumes from the gun, and this state of affairs considerably interfered with the loader and the gunner’s operations. The tank hatches were open and some of the fumes escaped this way; but in combat, this would not be an ideal method to get rid of the fumes.
5. The M4E8 tank hatch on the driver and bog compartment I believe is a hazardous implement. That is it is not securely enough latched and may be jarred loose while the tank is in motion thus moving around and smashing the driver in the head. I saw this happen and the results were front teeth knocked out and a large gash in the base of the skull.
6. When climbing on tanks – especially when wet – I have seen men slip on the wet steel and take a nasty fall due to the inability to get a foothold and a handhold at the same time. There used to be on a few M 24s a foot rung to step up on, but I have not seen them lately.
7. Every time one operates in a tank as any member of the crew, the M-19 field jacket is both cold and clumsy. It prevents a big man such as myself from getting in and out quickly. Also is annoying, because it catches on all the things sticking out in the tank turret. The end of the sleeve next to the wrist catches on everything. The skirt below the waist cord is another thing that catches on everything.
8. In the closeness of any type tank, bulky clothing can be very much in the way, and sometimes dangerous. In most cases, the fatigue clothes are ill-fitting, have bulky pockets, and by the time a man has on enough clothes to keep warm, he can’t move inside the tank, at a speed to be sufficient.