Hmmwv is so unique. But I wonder why a few things

[Skrilex]

I heard recently that the reason hmmwv was built so wide was that in war times roads are made with tanks, and tanks are wide, and stuff that follows tanks has a better time if it’s wide like they are to match the tacks. Is this true?

Hmmwv is supplied without bumpers, yet when it’s time for a brush guard they seem to cover the entire hood with bars, which in my experience is the least likely place to take damage on the entire car when off road, why?

Why did they make them out of aluminum vs steel?

And why did they supply them with that gawd awful engine?

Dont tell me to read the TM. If you do I’ll know that you didn’t even read to the end of my post. I’ll never read the TMs. Mostly to spite those here that think they are a good read. Also because I don’t like naps.

 

[Dock Rocker]

I heard recently that the reason hmmwv was built so wide was that in war times roads are made with tanks, and tanks are wide, and stuff that follows tanks has a better time if it’s wide like they are to match the tacks. Is this true?

Hmmwv is supplied without bumpers, yet when it’s time for a brush guard they seem to cover the entire hood with bars, which in my experience is the least likely place to take damage on the entire car when off road, why?

Why did they make them out of aluminum vs steel?

And why did they supply them with that gawd awful engine?

Dont tell me to read the TM. If you do I’ll know that you didn’t even read to the end of my post. I’ll never read the TMs. Mostly to spite those here that think they are a good read. Also because I don’t like naps.

Don’t know about the width vs tank tracks but it sounds plausible.

The brush guard is to protect the cab and windshield against brush it wasn’t meant to be a bumper.

It would weigh as much as a tank if it were steel. That was to help with weight savings.

The 6.2 wasn’t that big of a dog in the early 80’s when the truck was designed.

You obviously aren’t big on maintenance and haven’t had any issues yet if you haven’t read the TM’s. It’s silly that people don’t read the literal instruction book because somebody hurt their feelings on the internet. That’s cutting your nose off to spite your face.




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[Awol]

I've heard the width is for the tank tracks. It makes sense to me.

The hood is fiberglass, and doesn't take to things hitting it very kindly. The brush guard keeps the hood and lights from getting whacked.

In this case, theres a few advantages of aluminum over steel. The truck is lighter, it wont rot, and due to its riveted construction, it's easy to replace damaged sections of the body.

The 6.2 is what it is. It's weak, makes no power, but is fairly reliable and extremely simple. Looking back on light truck diesel engine options, there wasn't much. Ford had the 6.9IDI, Dodge didn't have any real diesel option up until the 12v Cummins came out later down the line (unless you wanted a 6DR5 diesel).

 

[ken]

The 6.2 was designed for one thing. Fuel economy. They were also converting to a single fuel for all equipment so the 6.2 fit the bill. The 6.2 is also light weight compaired to other diesels. It will never be a 12V cummins but it was never intended to be. As long as it isn't over heated or over sped it is relilable. But then again that goes for any engine. I have one in a 82 GMC with well over 300K. So I know if maintained and treated well they can last. Running them at 220 deg + is just asking for trouble, for any older engine not just the 6.2. They are not as bad as you think. Keep it under 195 deg and never go over 3000 RPM and it will out last you.

 

[suzukovich]

The reason for the width, partly on how it was designed . To keep the height and center gravity low. The body was deigned with the frame, drivetrain and fuel tank contained in a tunnel, additionally this also provide protection for the componets. The use of the planetary gears simalar to the Mercedes Umog, this also combination keep the height of the vehicle down and increased the width to accommodate the driver and passengers. Otherwise as a traditional body on frame, it would of sat with a 5 inch lift and would be less stable platform to fire weapons from. The other requirement was the ability to fire the 50 cal without flipping over on its side. The MUTT or M151 could be flipped on its side when firing the 50.

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[GUNNUT in Iowa]

Not too sure about that "track width" thing.

An M-1 Abrams is 12' wide and a HMMWV is only 7' 1" wide. The tracks and/or wheels are pretty close to the outside of the vehicle.

Perhaps I am misunderstanding the point?

 

[suzukovich]

Now I will cover the 6.2. The 6.2 was pretty much the only option. The Army in the contract requirements was a diesel engine. The 6.2 was already in use in the M1008/09 CUCV. So it was the logical choice as parts were readily available in the Army supply system. Fuel, although the 6.2 was designed for diesel the Army was converting to JP8 with the fielding of the M1 Abrams Tank. JP8 burns hotter then diesel and would kill any seals in the older diesel engines especially in the injector pumps. The NG and Army reserve units were the only ones burning diesel in the Humvees as for the most part received on the economy vs from HEMTT fuelers in the Motor pools or FARPs. The current diesel fuel is low sulfer unlike # 2 diesel. It burns hotter and is similar to JP8. With #2 the 6.2 ran cooler.

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[suzukovich]

Not too sure about that "track width" thing.

An M-1 Abrams is 12' wide and a HMMWV is only 7' 1" wide. The tracks and/or wheels are pretty close to the outside of the vehicle.

Perhaps I am misunderstanding the point?

Read my post. Width had nothing to do with the M1 Abrams.

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[Skrilex]

Hmm interesting about the track width. So how wide is the inside hump that the Abrahms leaves? Probably at least 7’ huh?

I guess that makes sense about the 6.2 being only thing available although I have to imagine there was some sort of applicable alternative engine designs at the time no? It’s too bad they missed the mark by such a small margin with that engine. It seems like if it were made just 5% tougher/better/heavier that it would’ve been a total winner in all applications.

 

[Skrilex]

I believe aluminum was chosen for weight but it’s still an interesting choice because when you actually weigh the differences between a steel body car and aluminum you find that you dont save that much weight. In the humvee I’d guesss the savings at less than 200 lbs. but, that’s 200lbs of other stuff you can strap on so it all counts.

 

[suzukovich]

Hmm interesting about the track width. So how wide is the inside hump that the Abrahms leaves? Probably at least 7’ huh?

I guess that makes sense about the 6.2 being only thing available although I have to imagine there was some sort of applicable alternative engine designs at the time no? It’s too bad they missed the mark by such a small margin with that engine. It seems like if it were made just 5% tougher/better/heavier that it would’ve been a total winner in all applications.

My many years in the Army. I constantly would prove that the Humvee could go anywhere the Abrams went and in addition thru terrain the Abrams couldn't. For you Marines out there. Without the fording kit


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[dilvoy]

Width is the way it is because the engine, trans, t case and diffs are all above the level of the bottom of the frame for protection so with the mil standard generator being used, there was a wide area needed, even with placing the engine in very crooked, then you need a place for a person on each side of the vehicle and ofcourse the width of the big tires needed to be considered. It is still about a foot narrower than a dually!

 

[GUNNUT in Iowa]

Read my post. Width had nothing to do with the M1 Abrams.

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I did read your post. Neither you or I said anything about the width having to do with the M1 Abrams. I was responding to the OPs original statement - "I heard recently that the reason hmmwv was built so wide was that in war times roads are made with tanks, and tanks are wide, and stuff that follows tanks has a better time if it’s wide like they are to match the tacks. Is this true?"

Sorry for the confusion.

I still contend the width of the HMMWV has nothing to do with the width of the M1 Abrams (or any other tank). I drove the HMMWV a bunch during my 25 years in the Army - never even got close to a running tank.

I do believe some vehicles might be designed with other vehicles in mind. Will the end product fit inside this particular aircraft? - and - Can we fit it or this many on a rail car?, for instance. Not so much Will it drive down the road that a tank drove down?

As was previously stated, it is my experience HMMWVs weren't necessarily designed with driving down roads as a prime consideration. We spent much time driving our HMMWVs off the road.

The only time we even considered tanks was when there was a possibility we might get run over by one.

I do have experience with that possibility - in an M151, which is a whole different story. M-60s (yes, more than one) sure look big coming at you in the early morning while you are driving on the road. I still don't know why they weren't on the tank trail.

 

[suzukovich]

I did read your post. Neither you or I said anything about the width having to do with the M1 Abrams. I was responding to the OPs original statement - "I heard recently that the reason hmmwv was built so wide was that in war times roads are made with tanks, and tanks are wide, and stuff that follows tanks has a better time if it’s wide like they are to match the tacks. Is this true?"

Sorry for the confusion.

I still contend the width of the HMMWV has nothing to do with the width of the M1 Abrams (or any other tank). I drove the HMMWV a bunch during my 25 years in the Army - never even got close to a running tank.

I do believe some vehicles might be designed with other vehicles in mind. Will the end product fit inside this particular aircraft? - and - Can we fit it or this many on a rail car?, for instance. Not so much Will it drive down the road that a tank drove down?

As was previously stated, it is my experience HMMWVs weren't necessarily designed with driving down roads as a prime consideration. We spent much time driving our HMMWVs off the road.

The only time we even considered tanks was when there was a possibility we might get run over by one.

I do have experience with that possibility - in an M151, which is a whole different story. M-60s (yes, more than one) sure look big coming at you in the early morning while you are driving on the road. I still don't know why they weren't on the tank trail.

Yes the requirement to be transported in a C130 or the C141 was part of the design specifications laid out in the contract. In both aircraft height is limited to 110 inches and 88 inches wide.

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[SCSG-G4]

Way back when the HMMWV was proposed (IE., before the contracts were signed), one of the 'reasons' was that the jeep/mutt left a narrower track than the trucks and an observant enemy could learn a lot of useful information by the number of jeep/mutt tracks in off-road areas. As in what type of unit came through. The HMMWV was designed with the same footprint width as the cargo trucks to help obscure that type of information. Not that it was perfect by any means, but it generally meant that only the last vehicle or two could be made out clearly, and all the rest of the tracks were difficult to decipher.

 

[riderdan]

I believe aluminum was chosen for weight but it’s still an interesting choice because when you actually weigh the differences between a steel body car and aluminum you find that you dont save that much weight. In the humvee I’d guesss the savings at less than 200 lbs. but, that’s 200lbs of other stuff you can strap on so it all counts.

Every pound counts when you're airlifting/slinging/parachute dropping equipment. As I recall the original HMMWV was pretty near the sling weight limit of the original Blackhawks (7000 lb HMMWV vs 8000lbs external load capacity of the UH60). In addition, I suspect some construction contract decisions are influenced by the "coolness" factor and in the late 70s/early 80s an aluminum bodied truck must have seemed pretty high speed.

 

[dohabandit]

The tactical trailer for the HMMWV has wheelbase set to match so it won't have issues bouncing around the wheel ruts.
I have an original brush guard and it is solid steel. Not aluminum.

 

[suzukovich]

The tactical trailer for the HMMWV has wheelbase set to match so it won't have issues bouncing around the wheel ruts.
I have an original brush guard and it is solid steel. Not aluminum.

Until the 1101 and 2 went into production M101 trailers we refurbished with Humvee tires and rims, new axle with increased width and height. Became the M101A3. I have towed both and actually prefer the 101A3. I have even pulled a M105 and a Water Buffalo with a Humvee.

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[snowtrac nome]

First the brush guard was an option units put on, ours in the 80's were fielded with out them. There was one built by louverine, and another one built out of angle iron that were first put to gather off drawings at 3rd shop and later were contracted out, the louverine guards are the one you want they were heavy and did a good job. the hmmwv sits the way it does for a low silloett and to maintain that and keep the powertrain above the frame the powertrain must sit between the operator and tc. I remember reading some place overall width couldn't exceed 88 inches to allow for passing through Europeon rr tunnels. As for aluminum why not its light wont rust out and is extremely rigid also non magnetic.

 

[dohabandit]

I have a turtle mfg corp M101A3. It has a split axle that raises the center to the same height as the HMMWV. The wheels also seem to be a little bit wider than the fenders.
It does use the same bolt pattern for the wheels/hubs as the HMMWV. I don't have the nicer goodyear MT tires on there, but have thought about taking a split rim and mounting some spare tires that I have to make it match the truck.

I have pulled two trailers behind the HMMWV. The M101A3 with the same wheelbase runs much better in the sand than a narrower trailer where it ends up wildly running from side to side from time to time.

I suspect my brush guard is the old angle iron version. It has sides that are cut at 45 degree angles like a stop sign.
I ran it through some brush and can confirm it works well! heh.