4x2 with double tires versus 6x4

Buba

A total creep
Which configuration is better for a truck expected to drive on "not very good roads":
- 4x2 with double tires in back (rear wheel drive, of course)
- 6x4 with single tires in back (rear wheel drive, of course)

I am talking about 1935-45 timeframe.
 

Atarlost

Well-known member
If 6x4 means that two axles have motive power then that. It's harder to get all the drive wheels stuck in the mud that way. I'm not sure what benefit that has over 4x4 with double tires in the rear, though. Indeed, having any unpowered axle probably makes it worse.
 

Buba

A total creep
Yes, 6x4 means two powered axles.
In this case - In the back, close to one another, under the cargo platform.
An example:
800px-Kfz70.jpg


For off road a 4x4 with single tires is better than either :)
 

Megadeath

Well-known member
Yes, 6x4 means two powered axles.
In this case - In the back, close to one another, under the cargo platform.
An example:

For off road a 4x4 with single tires is better than either :)
Surely it makes sense to split the power front and back? I'm an idiot in such things, but wouldn't that give you greatest advantage in difficult terrain?
 

LordsFire

Internet Wizard
Surely it makes sense to split the power front and back? I'm an idiot in such things, but wouldn't that give you greatest advantage in difficult terrain?

Mechanically, pushing takes less effort than pulling, so you can get more speed performance out of rear-wheel drive.

If you're in the boundary area between 'solid' and 'too soft to drive on at all' splitting your motive force up between the different wheels can be very useful. I spent many years in my childhood going 'dune bashing' in dune sea style deserts, and 4WD and/or slightly lower tire pressure can make a hell of a difference.

However, with the amount of weight you put in military trucks, moving through mud and soft sand just isn't in the picture in the first place. If it's supposed to move all terrain, you get something tracked out there to do that. I don't know if anyone still uses half-tracks, but in-between situations is what that was designed for, and equipment doctrine is what determines whether you're planning on trying at all.
 

Atarlost

Well-known member
However, with the amount of weight you put in military trucks, moving through mud and soft sand just isn't in the picture in the first place. If it's supposed to move all terrain, you get something tracked out there to do that. I don't know if anyone still uses half-tracks, but in-between situations is what that was designed for, and equipment doctrine is what determines whether you're planning on trying at all.

The US Army used 4x4s in the Pancho Villa expedition and liked them enough to order fifteen thousand for WWI. These were rated for 3 tons off road or 5 tons on road so were pretty substantial. (The FWD Model B 3 ton truck).

In WWII a lot of the CMP variants were 4x4s as well with the C60X a 6x6 and the F60H a 6x4 with power on the front and middle axles (which is what I'd assume from a 6x4 as driving two axles right next to each other is most of the complexity for almost none of the benefit). The Morris C8 Field Artillery Tractor was a British 4x4. America's GMC CCKW 2.5 ton truck was a 6x6.

The USMC's current MTVR is a 6x6 7 ton truck. The army's M939 5 ton truck is a 6x6. The Mercedes-Benz UNIMOG series (1948-present) is a 4x4. So unlike halftracks, multi-axle drive transmissions on military trucks weren't a flash in the pan that was demonstrated to be impractical during wartime.

There's a move to 6x6s, but real military planners that have studied real wars with real trucks believe there is real merit in the more complicated multi-axle drive trains. The historical verdict is in. Any theory that doesn't mesh with practice is wrong.

The move to 6x6s in modern military trucks suggests that the third axle adds something that double tires on the rear axle doesn't, so there may be some benefit to front and middle 4x6 over 4x4 with double tires on the rear axle, but if you're driving on not very good roads in the 1935-1945 period you'll regret not having multiple widely separated drive axles. Because good roads means paved roads. Not very good roads doesn't. Look at pictures of WWII trucks in the field and you see a lot of packed dirt or mud that is presumably packed dirt in the dry season.
 

Marduk

Well-known member
Moderator
Staff Member
However, with the amount of weight you put in military trucks, moving through mud and soft sand just isn't in the picture in the first place. If it's supposed to move all terrain, you get something tracked out there to do that. I don't know if anyone still uses half-tracks, but in-between situations is what that was designed for, and equipment doctrine is what determines whether you're planning on trying at all.
They absolutely do. Of course that's where the difference between good military trucks and pro drivers and merely mediocre trucks with random dude drivers comes out the most. Naturally the recommended payloads for offroad are reduced at least by half, and naturally trucks are expected to be in good shape for this (sorry Russians, no rotten chinesium tires). You are kinda sorta right until about 70's, as back then most armies still bothered with tracked supply vehicles to attend mechanized formations (like MT-LB, or supply variant M113), but with advances in modern automotive technologies, there are trucks that can absolutely do it. You can also notice it in the massive proliferation of 6x6 and 8x8 armored vehicles, sometimes even made on the same chassis as trucks. Notably some countries with particularly wide remote areas with poor infrastructure, sometimes also not kind to heavy tracked vehicles, are completely or almost completely based on wheeled vehicles now.
Which configuration is better for a truck expected to drive on "not very good roads":
- 4x2 with double tires in back (rear wheel drive, of course)
- 6x4 with single tires in back (rear wheel drive, of course)

I am talking about 1935-45 timeframe.
Off-road? You can't go wrong with more axles, and you absolutely can't go wrong with more powered axles.

If you are interested in the topic, there is also a game, Snowrunner, that explores the whole idea of wheeled vehicles of all more and less exotic sorts driving offroad in detail, with decent physics simulation.
 

Zachowon

The Army Life for me! The POG life for me!
Founder
The US Army used 4x4s in the Pancho Villa expedition and liked them enough to order fifteen thousand for WWI. These were rated for 3 tons off road or 5 tons on road so were pretty substantial. (The FWD Model B 3 ton truck).

In WWII a lot of the CMP variants were 4x4s as well with the C60X a 6x6 and the F60H a 6x4 with power on the front and middle axles (which is what I'd assume from a 6x4 as driving two axles right next to each other is most of the complexity for almost none of the benefit). The Morris C8 Field Artillery Tractor was a British 4x4. America's GMC CCKW 2.5 ton truck was a 6x6.

The USMC's current MTVR is a 6x6 7 ton truck. The army's M939 5 ton truck is a 6x6. The Mercedes-Benz UNIMOG series (1948-present) is a 4x4. So unlike halftracks, multi-axle drive transmissions on military trucks weren't a flash in the pan that was demonstrated to be impractical during wartime.

There's a move to 6x6s, but real military planners that have studied real wars with real trucks believe there is real merit in the more complicated multi-axle drive trains. The historical verdict is in. Any theory that doesn't mesh with practice is wrong.

The move to 6x6s in modern military trucks suggests that the third axle adds something that double tires on the rear axle doesn't, so there may be some benefit to front and middle 4x6 over 4x4 with double tires on the rear axle, but if you're driving on not very good roads in the 1935-1945 period you'll regret not having multiple widely separated drive axles. Because good roads means paved roads. Not very good roads doesn't. Look at pictures of WWII trucks in the field and you see a lot of packed dirt or mud that is presumably packed dirt in the dry season.
We don't use the m939 anymore. We the the FMTV, or Family of Medium Tactical Vehicles.

We use 4x4 and 6x6 in that family eith our heaviest vehicle being 8x8
 

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