34,000lb rears

[Hay Dude]

Would you be comfortable with a tandem axle flatbed truck with 34,000lb rears?
Im used to 40,000lb rears being pretty much the “industry standard”.
As long as the rear tandems arent overloaded, I dont see a problem, but wondered if there were any inherent issues, problems? Axles snapping? Again, overloading wouldnt be an issue.
Never ran a set of “light tandems” like that.
BTW suspension is 40,000lb, but rears are 17K each, 34K total.

 

[Ferg52]

As long as the axle ratings/GVWR aren't exceeded, I don't really see an issue. The axles were rated as such for a reason. Only thing is they won't hold up as well as 40 or 46k rears.

 

[RickB]

Trans type and drive ratios have more to do with snapping axles and shelling out differentials than axle weight ratings so long as load limits are observed.

 

[RickB]

As long as the axle ratings/GVWR aren't exceeded, I don't really see an issue. The axles were rated as such for a reason. Only thing is they won't hold up as well as 40 or 46k rears.

Kind of contradictory. You might have meant 34k rears carrying 46k won't hold up as well as 46k rears carrying 46k.

 

[Ferg52]

Kind of contradictory. You might have meant 34k rears carrying 46k won't hold up as well as 46k rears carrying 46k.

Sometimes things make better sense in my head. Assuming the 34k rears are within their load rating and carrying the same weight as 46k rears (let's say, they both are carrying 25,000lbs), 34k rears will not last quite as long, because the heavier axles are built with heavier components/housings. Which, I suppose is irrelevant here.

Sorry, it's been a tiring day. My brain is ready for bed...

 

[Hay Dude]

Sometimes things make better sense in my head. Assuming the 34k rears are within their load rating and carrying the same weight as 46k rears (let's say, they both are carrying 25,000lbs), 34k rears will not last quite as long, because the heavier axles are built with heavier components/housings. Which, I suppose is irrelevant here.

Sorry, it's been a tiring day. My brain is ready for bed...

I know what you mean.
What I am driving at is this:
Will a set of 34,000lb rears wear out faster than a set of 40,000lb rears if both sets are operated within their limits and treated & driven the same way and properly operated?

I think not, but I’m trying to understand if 34Ks were susceptible to any greater level of failure than 40K’s. What I thought may be more vulnerable was locking rear action or power divider lock operation breaking something

 

[4570Man]

How much actual difference is there in the build construction?

 

[Hay Dude]

How much actual difference is there in the build construction?

Enough difference to rate each 17,000lb axle 3,000lbs less than a 20,000lb axle.
That’s all I know.
I would guess the axle shafts themselves are smaller in diameter, along with smaller bearings, hubs, seals, or ring & pinions, carriers, axle tubes, etc., but that’s guessing.

 

[BravoXray]

They shouldn't wear out any faster if not overloaded, the gearing is about the same. The axles and wheel bearings are smaller and will give you problems if continously overloaded.
In the 70s we ran a fleet of IHC F2000Ds with RA351 differentials and rarely had problems as long as they were not seriously overloaded or tried to pull heavy loads through soft material. Had a few snapped axles on trucks that got stuck and the drivers didn't dive up and get pulled out. Never broke a gear set though.
We also had some with Eaton 3 speed tandems too. Was basically two air shifted 2 speed rears in a tandem setup. Worked like a 3 speed auxiliary transmission. You could have both in low, front in high,rear in low, or both in high, power divider allowed the difference in ratios. Low ratio was 4.10 and high ratio was 3.55.

 

[4570Man]

Enough difference to rate each 17,000lb axle 3,000lbs less than a 20,000lb axle.
That’s all I know.
I would guess the axle shafts themselves are smaller in diameter, along with smaller bearings, hubs, seals, or ring & pinions, carriers, axle tubes, etc., but that’s guessing.

Or potentially they just rated them at 34 because that’s all they’re legal to run and it’s the same set of axels.