I Am Just Curious To Ask A Few Technical Truck Questions.

So here's another question for the old-timers. How would the turning radius on a new, lightweight model tractor with it's setback axles compare to the old cabovers? It seems fairly close to me or at least a very nice happy medium.

My brother drove a cabover in the 90's and marvels at how much smoother and quieter my truck is and the perks that make the job so much easier these days. I'd love to be able to tell him my truck can turn just as tight as his did also.

Even in Top Gun, one of the pilots, Hollywood?, told Maverick that he was low on gas in his F-14 Tomcat jet when he was guiding Cougar back to the ship.

He's a fighter pilot. He's super cool. He was slingin around cool phrases.

You were talking about 'gas mileage' in a big rig. You're not a fighter pilot. That's not cool, that just sounds like a nerdy 4 wheeler talking to a big rig driver.

If you talk about 'gas mileage' to 100 truckers, 95 of em are gonna laugh at ya, the other five are just gonna stand there starin' at ya like you're a weirdo.

So say 'gas' if you want, but Bud's saving you some grief.

It's a job, and I do not want anything to make it more difficult or more time consuming.

Sooooooooo much this. Every time I see one of those clowns pull in somewhere with one of those super stretched out frames (99 times out of 100 pulling a spread behind it), I cringe so hard. And every time it takes him at least 3 times longer to get backed into a hole...if he can get it there at all. Sure, it looks pretty sitting still or going down the road, but in real-world practicality it's just a big shiny turd with the turning radius of a WWII era battleship. I'll take my Cascadia over any of those trucks any day.

Even in Top Gun, one of the pilots, Hollywood?, told Maverick that he was low on gas in his F-14 Tomcat jet when he was guiding Cougar back to the ship.

He's a fighter pilot. He's super cool. He was slingin around cool phrases.

You were talking about 'gas mileage' in a big rig. You're not a fighter pilot. That's not cool, that just sounds like a nerdy 4 wheeler talking to a big rig driver.

If you talk about 'gas mileage' to 100 truckers, 95 of em are gonna laugh at ya, the other five are just gonna stand there starin' at ya like you're a weirdo.

So say 'gas' if you want, but Bud's saving you some grief.

Yep, and the 'wtf' smiley was not directed at you, but at my stupid gas joke lol.

It's a job, and I do not want anything to make it more difficult or more time consuming.

Sooooooooo much this. Every time I see one of those clowns pull in somewhere with one of those super stretched out frames (99 times out of 100 pulling a spread behind it), I cringe so hard. And every time it takes him at least 3 times longer to get backed into a hole...if he can get it there at all. Sure, it looks pretty sitting still or going down the road, but in real-world practicality it's just a big shiny turd with the turning radius of a WWII era battleship. I'll take my Cascadia over any of those trucks any day.

You forgot that it is a spread axle Reefer !!!!

What is the point of a spread axle Reefer is beyond me.

Patrick wrote:

You forgot that it is a spread axle Reefer !!!!

What is the point of a spread axle Reefer is beyond me.

Other than they look cool? ...same reason you have it on a flatbed.

In many states (not sure which ones) a minimum 10'1" axle-spread on the trailer will allow for a 40k load on the rear axles as long as the total does not exceed 80k. This is also something common in Canada, "split or spread", although not sure why. Hopefully the heavy-haul and flatbed experts, OS, Pat, Dragon and Bud can offer up something of substance on this.

Patrick wrote:

You forgot that it is a spread axle Reefer !!!!

What is the point of a spread axle Reefer is beyond me.

Other than they look cool? ...same reason you have it on a flatbed.

In many states (not sure which ones) a minimum 10'1" axle-spread on the trailer will allow for a 40k load on the rear axles as long as the total does not exceed 80k. This is also something common in Canada, "split or spread", although not sure why. Hopefully the heavy-haul and flatbed experts, OS, Pat, Dragon and Bud can offer up something of substance on this.

I don't know if I'm an expert, but I have thought about the spread axle quite a bit. What's great about it is that you don't have to worry quite so much about where the heavy stuff on a flatbed load is, as long as you put it toward the back.

After weighing a few loads when I first went solo, I rarely checked axle weights when I was pulling a flatbed. It was usually when I had coils of different sizes on a stepdeck when I had to have the axles together for some state's kingpin law.

For the most part, I knew if gross was 80k or less, I was good on all axles, since my steers were always right around 12k. That left 68k for drives and rear axles. If the center of mass was at or slightly to the rear of the center of the trailer, my drives couldn't be more than 34k, and it would be pretty hard to get more than 40k onto the rear with such a load. I never worried that one of those axles would be over 20k, since that too is pretty hard to do with any kind of uniform load. It was also pretty rare to have a load where my gross was over 78k, so that always left wiggle room too.

When I did see axle weights, I would be over 34k fairly often on the rear. I didn't like to drive too unbalanced if I could avoid it, but a difference of a couple of tons wasn't too noticeable. Some places weren't so skilled at balancing the load, though. (I'm looking at you, steel place in Texas that took forever to load and then put 39.5k on the rear axles.)

So, for the most part, the folks loading flatbed trailers knew they could go a little heavier on the rear, and that's how they would load it if they weren't certain what the drives would end up weighing. When they load stuff that is easy to move around (like pallets of shingles or bunks of lumber or stacks of drywall), generally they start loading from the center of the trailer. The middle marker light is usually (but not always!) dead center of a 48' trailer, so they would center there or a foot behind it. When it's stuff that spans the length of the trailer, like steel beams or rebar or utility poles, they still try to center it front to back, but again err on the side of putting more weight on the rear.

My theory, then, is that the reason for spread axles is to make it easier to get a load balanced "close enough" without worrying too much about the details. And I think they're most popular on flatbeds since it's so much easier to move stuff around from front to back on an open deck than it is inside a box.

But that's just a theory. I'm willing to be corrected.

By the way, this whole axle weight thing is another reason to love smooth-bore tankers. If you have 12k on the steers because your fifth wheel is in the right spot, and even if you're right at 80k, you're not going to be over 34k on the drives or the rear tandems once the stuff stops sloshing around.

I understand the reasoning on a flatbed. My point is why on a reefer. If a flatbed needs reworked for whatever reason it is a fairly accessible process. In a giant refrigerated box, you would have to drag everything out. I rather be able to slide the tandems and call it a day.

Patrick replied:

I understand the reasoning on a flatbed. My point is why on a reefer. If a flatbed needs reworked for whatever reason it is a fairly accessible process. In a giant refrigerated box, you would have to drag everything out. I rather be able to slide the tandems and call it a day.

There are a lot of good technical articles on this. I've read many of them and here is what I've come away with:

There is a far greater amount of nose weight on a reefer due to the appliance (inside and outside) and a fuel tank filled to capacity. The theory is if you limit the weight towards the nose and load a greater amount of the mass closer to the end of the trailer, there is a much lower chance of being overweight on the drives and also exceeding 20k per trailer axle on a ten foot spread. There are loads where this actually makes sense; like bagged seed corn. Single pallets are loaded in the center, double after the first 3-4 so more weight is towards the rear. Seed corn is notorious for blowing out the trailer sides, so it's preferred to keep much of it off the wall and staggering pallet placement.

There are also a few states that will allow 86,000 pounds gross using this configuration. Haven't checked which ones but guessing upper Midwest and north west.

The other theme that seems to be repeated, less weight on the tractor equates to less wear and tear.

With that said, I'll stick with my sliding tandems!!!