"Disadvantages of wide tracks?" Topic

I've just been looking at the parts to the 1/76 Airfix Tiger 1 (from 1961) and the much newer Cromwell. The former's tracks scale out very accurately (in width anyway, and that's about all you can say for them) to the correct 72cm. The Cromwell's in contrast are painfully thin.

This made me wonder. The Cromwell was much lighter than the Tiger, of course, but it was similar in weight to a T34, which had much wider tracks. The advantages of wide tracks over skinny ones from a ground pressure perspective are obvious, so why were these not universally adopted? Were there disadvantages to having wide tracks?

I don't mean logistical disadvantages such as the Tiger's making it so wide it didn't fit standard railcars. I am just thinking in actual intended use. Were there situations in which wide tracks were a handicap, that explain why late war designs like the Cromwell and Comet didn't have them?

I think the main reason for wider tracks was the expected terrain they were to operate on. The Russians expected to operate in areas with soft terrain or snow for much of the year, whilst the British were designed to operate in Western Europe in firmer terrain, so wider tracks were not expected to be needed. This was modified later by the addition of track extensions to some tanks.

I would think that wider tracks would make it easier to throw a track in sharp turns. And maybe be harder to repair because they are heavier.

Note the use of words "think" and "maybe".

I would think that narrower track had more left/right flexibility as the pin(left to right) length is shorter. A narrower track is also easier to move due to less inertia and would therefore need less strength in the drive train. . These are just engineering "thoughts", as i have only driven tanks few times and never engineered one!

I remember the US had grousers to widen their tracks. The problem was that in towns they were broken off by street curbs.

I suspect that British railway loading gauge also played a role in the maximum width of a British built tank. Several British tanks were around the 9'6" width mark, with tracks of 14" width. Making the tracks much wider might mean making the hull narrower to compensate. That would compromise the turret ring size and therefore restrict the size of gun that could be carried etc., etc.

As noted wider tracks generally give an AFV better capabilities crossing "softer" ground, etc., … E.g. Snow Shoes, it spreads the wearer's weight out a bit, etc. Making it "easier" to walk across snow.

I would think that wider tracks would make it easier to throw a track in sharp turns. And maybe be harder to repair because they are heavier.

Yes and no … "Good Track Drivers" don't normally take "sharp turns"/pivot steer at higher speeds or climbing up a grade, broken terrain, etc. To risk breaking or throwing a track. But sometimes you may have no choice.

A narrower track may be easier to repair if only for each track block is lighter. More easy to "manhandle", etc. But good crews know how to fix their "Iron Monster". And there are usually some direct support maint. assets around too. That could help if need be. But are not always …

Any crew who had to replace track blocks sometimes all of them as they may have reached their max useable life span. I.e. the pads/shoes/links are wore to the point of you will probably break/throw a track, etc.. That they have to be replaced. Just like a car tire. Replace/repair track is generally a lot of work.

Regardless, it is a task that has to be done, so they don't break at the "wrong" time, etc. But is very labor intensive. Like a lot of things with AFVs.

I remember the US had grousers to widen their tracks. The problem was that in towns they were broken off by street curbs.

In some cases it depends on how and with what a road is constructed, that type of damage may/is going to happen regardless. I've seen what M88 Heavy Tracked Recovery Vehicles do to a small village road in the ROK. "Crunched" it like peanut brittle. And of course one M88 broke a track. The crews had to dig under the M88 to repair the track and get it mounted. With the help of the other M88 … Took over 24 hrs. …

I would think that narrower track had more left/right flexibility as the pin(left to right) length is shorter. A narrower track is also easier to move due to less inertia and would therefore need less strength in the drive train. . These are just engineering "thoughts", as i have only driven tanks few times and never engineered one!

That is probably true in some cases based on the overall design and weight of the AFV, etc. But as we saw sometimes in e.g. early WWII, many smaller thinner tracks may not be as survivable when crossing over rough terrain, etc. And even moving at a higher speed on a road you could throw/break a track.

Hopefully the designers/engineers have taken those sort of things into account. And the AFV has been thoroughly tested. But even then happens. E.g. IIRC, the early US M1 MBT had to have "ring" added to the drive sprocket as in certain situations the track could be thrown off the sprocket. But the design flaw was rapidly "fixed" with that modification.

Great thread! Very interesting and informative.

Wider tracks can also pick up more crud and transfer it to the inside surface where it can make the track come off the road wheels even when travelling in a straight line – one of the reasons for the 'mud chutes' on Inter War tanks was that this had been noted back in WW1, wider tracks just made the problem worse.

And you can bog a T-34, specially if you don't know what you are doing.

I think the decision on narrow versus wide tracks was more financial than anything else: You can build more tank for less if the tracks are smaller. Because the western allies didn't run in to the Rasputitsa (sp?) they didn't consider it worth the extra cost and weight to put on wider tracks. And of course, as soon as they faced severely muddy or snowy conditions they made adjustments.

"I remember the US had grousers to widen their tracks."

Think you are mixing this up with duckbill extensions. The US tanks did have grousers which were mounted on tracks to increase traction especially on ice and snow but these were steel bars and did not increase the width measurably though there were some sets made which did:
link

Duckbill extensions were used to increase traction in soft terrain such as mud:

I'd be genuinely surprised if the assumed terrain or cost were a major factor in western nations' track design. Not saying it wasn't so, but just that it would be surprising.

After all, pre-war British tanks were designed to fight where? I don't know, but they did fight in both NWE and the desert (I disregard those that served in Asia, because initially none did and later they were mainly US types). Either both locales were foreseen and the same skinny tracks were ideal in very different conditions, or only one was foreseen, the tanks weren't ideal, but nevertheless the same cheery assumption that the tracks only needed to work in one theatre was carried over into later models.

I guess cost is always a factor, but how much of the cost of a tank was wider tracks? I know unlikely parts can be expensive – 25% of the cost of a Spitfire was the propeller, apparently – but tracks strike me as pretty uncomplicated.

A narrower track is also easier to move due to less inertia and would therefore need less strength in the drive train.

A narrow track has less inertia than a wider track, because it has less mass per track link. But it also has less rolling resistance than a wider track.

These combine to mean that it takes less force to get a given amount of movement with a narrow track.

It is a balancing act, between the HP and torque you can deliver to your drive sprockets, the speed and/or acceleration you want to achieve with that HP and torque, and the type of terrain you want to be able to move over.

The T-34 is often described as having a "Christie" suspension. But Christie was adamant on using a very narrow track to maximize automotive performance. Look at a Soviet BT or a British A13 to see just how narrow the tracks were on tanks that were only slightly removed from Christie's design work.

Use narrow tracks, and when you are on hard flat surfaces you will move faster, using less fuel, and causing less wear on the drive components, than you would if you used wide tracks. This simple engineering truth affected many inter-war designs. On the other hand, use narrow tracks and no amount of efficiency in your drive train will matter when you belly your tank on a plowed field. This simple operational truth drove most post-war designs.

Or so I have read. Only tank I have ever "broken track" on was a Panther, and I did precious little of that, and as a volunteer I could take a rest, get a drink or walk away any time I wanted. Even with all that ability to back my pansy-@ss out whenever I felt the need, those big wide links made for some HEAVY work!

-Mark
(aka: Mk 1)

I'd be genuinely surprised if the assumed terrain or cost were a major factor in western nations' track design. Not saying it wasn't so, but just that it would be surprising.

Remember tracked vehicles were designed to go cross-country. As they are much better at it than wheeled, generally. Moving along a road no matter what the size of your track you will move "faster". Faster being relative to the vehicle we are talking about, e.g. a T34 vs. a Tiger II.

As I have said before no matter how fast you are moving if caught out in the open. You can't out run a high or low velocity main gun/AT round.

tracks strike me as pretty uncomplicated.

Generally they are but they still have a number of moving parts. Which if some of those parts "fail" you'll probably have to repair/replace some track.

It is a balancing act,

Yes it is … Power to weight ratio is critical. More armor and a bigger gun will make your AFV/MBT heavier. But to be useful it still must be mobile. As mobility and firepower are what modern mobile combined arms warfare is all about. It just took some armies in WWII a little longer to understand that.

Then thru out the war, it was in many cases a race to get
"bigger" "better" AFVs on the battlefield. To defeat your enemy(s). Which was not always the case when the Germans invaded Poland and France at the beginning of the war. The Germans understood combined arm with the Blitzkrieg, etc. Most of the other armies were fighting the last war. In the beginning at least.

And in the long run as the war went on … quantity beat quality, in many cases. There was more to it than that. But for this discussion it has a little relevance, IMO …

On the other hand, use narrow tracks and no amount of efficiency in your drive train will matter when you belly your tank on a plowed field.

It's like we used to say about 4 wheel drive. Does not mean you won't get stuck … it will just take twice as long.

No matter what size the track a good crew who knows how to use, maintain and repair their vehicle makes a big difference. However, as always … happens …

those big wide links made for some HEAVY work!

Indeed and it is not only on a Panther …

A poor tank driver is also a potential threat to track integrity.

B

Very true … And the TC has to be very good as well … But again happens. One of the best things to make a tank crew "better" is training & experience …