No it’s not specifically for heavy haulage. The Leylands, M.A.N’s to name two had them for normal haulage work. That’s not to say they weren’t used for heavy stuff.
The direction of rotation isn’t reversed. The diff is normal except for having lighter half shafts. I’ve posted some pic’s further back for b kings benefit ( who incidentally we haven’t heard of for a while), have a close look at them and the description with the first one. They’re not complicated, just need studying.
Bluey Circles:
Carryfast:
There are numerous different final drive ratio options available to customer choice.But the inconvenient point for Bking is that they all reduce the gearing from the gearbox output to the wheels.The main advantage of hub reduction being that it provides a significant gear reduction between the diff output side and the wheels.Thereby reducing torque loadings accordingly in that component chain to provide equivalent torque at the wheels.is this not heavy haul stuff ? I don’t think I have ever even seen one let alone work on one. Can imagine them being pretty uneffficiet fuel wise and very noisey, just more stuff to bugger up … and if it is like some sort of sun and planet set up? would that not make it run backwards, or is it clvererer than that?, if not, so where do they reverse the direction of drive … in the diff ? maybe a rear facing crown, or is that a stupid idea.
Not just heavy haul older Dafs used to have them and most Terberg tugs have them you can spot them by the hub filling more of the wheel. Yes, they are epicylic but pretty tried and tested design. It’s on wiki under portal axles which is what a similar design is used to raise axle clearance on 4x4s.
peterm:
No it’s not specifically for heavy haulage. The Leylands, M.A.N’s to name two had them for normal haulage work. That’s not to say they weren’t used for heavy stuff.
They were certainly used as standard fit on even the 16 tonner Clydesdale.While the principle obviously makes even more sense as weights and therefore torque inputs increase.
Hub reduction does have more parasitic losses, pretty obvious really considering the extra gears, but it not only multiplies torque, it also reduces shock loads on the driveline, useful in both heavy haul and off road work, so it’s a worthwhile trade off.
Mercedes only went to single reduction on the revised first generation Actros, which was around 1998. They do whine a little, none more than the Leyland Roadtrain.
On the subject of torque, I remember reading a “did you know” type article about the torque produced by an engine, although 1500lbs/ft sounds a lot, it’s actually not much more than the force a man can produce with a four foot extension bar on a socket, only around ten times as much, I know it’s not scientifically correct, but to put torque into layman’s terms, a man with a four foot bar should be able to propel 4.4tons up a hill at the same pace as a 44ton lorry with 1500lbs/ft of torque, but as you can figure out, it would be impossible, unless that four foot bar was hooked up to a block and tackle, or several to be more accurate, with the equivalent torque multiplication as a gearbox and differential provides the man could easily get that 4.4tons up the hill.
some back of the ■■■ packet calculations of how much torque is being delivered to wheels to propel truck. lets work this out from the energy being consumed.
if at a steady 56 mph on flat ground you’re getting 10mpg
this would be burning diesel at a rate of 7.1ml per second
energy in diesel is 9241 kcal (calories) per litre
so at 56mph would be using 65 calories per second (kcal)
1 kcal (calorie) per second is 4200 watts
so truck is using 274,430 watts of energy
lets assume “Tank to Wheel” efficiency of 22%
so power delivered to wheel = 60,375watts or 81 horse power (at drive wheel not flywheel)
at 56mph wheel spinning at 426rpm
so torque needed at drive wheel would be in region of a continuous 960 lb foot
(which is pretty much about double how tight the lug nuts should be!)
newmercman:
On the subject of torque, I remember reading a “did you know” type article about the torque produced by an engine, although 1500lbs/ft sounds a lot, it’s actually not much
^ That’s the bit which Bking obviously missed. 
Wow! I’m really impressed, it takes me a month of Sundays to do these sorts of calculations. It takes a further month of Sundays to even look up the correct formulae for working it all out. Even then transposing it to make X the subject in the slightly more complicated ones gives me brain fade.
Can I have your ■■■ packet please? 
peterm:
Let’s see if i can help our resident ex spurt out with these reduction Hubs now I’ve sorted meself out with posting pictures.2
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Brilliant post there preterm. I remember that geartrain assembly from my younger days… overdrive boxes… Laycock de Normaville, later, GKN Laycock. "D’ type and ‘J’ type. ( two o/d ratios ).
When the average boy racer was going 1100 / 1300 Mk 1 Escorts, mine was a GLS Hunter, 1725cc, Holbay head & twin 45 d c o e Web c’arbs, ( & the o / d box ) of course… o/d on, less torque… better not confuse him eh 
newmercman:
Hub reduction does have more parasitic losses, pretty obvious really considering the extra gears, but it not only multiplies torque, it also reduces shock loads on the driveline, useful in both heavy haul and off road work, so it’s a worthwhile trade off.Mercedes only went to single reduction on the revised first generation Actros, which was around 1998. They do whine a little, none more than the Leyland Roadtrain.
On the subject of torque, I remember reading a “did you know” type article about the torque produced by an engine, although 1500lbs/ft sounds a lot, it’s actually not much more than the force a man can produce with a four foot extension bar on a socket, only around ten times as much, I know it’s not scientifically correct, but to put torque into layman’s terms, a man with a four foot bar should be able to propel 4.4tons up a hill at the same pace as a 44ton lorry with 1500lbs/ft of torque, but as you can figure out, it would be impossible, unless that four foot bar was hooked up to a block and tackle, or several to be more accurate, with the equivalent torque multiplication as a gearbox and differential provides the man could easily get that 4.4tons up the hill.
I think someone needs to understand exactly what is meant by “torque”, “force” and “power”. Then he might not be inclined to post drivel about a bloke with a 4ft bar being able to propel heavy weights at the same speed as a lorry…
And not forgetting the source of all this ’ torque ’ ; the power unit and the diesel it burns over a greater number of crankshaft degrees. Hence a flatter torque curve.
A narrower rev range requiring more g/box ratios. 12 - 16.
Now it’s all auto box technology, the electronics seems to tell the driver who’s boss…
We’re still banging our heads against walls while falling in to the troll trap. Roll on the next school holidays when we’ll hear from him/her again.
Simon. We had a 4 cyl’ 1.9 Holden Commodore for a while, with all the anti pollution crap on it. Gutless, heavy on juice and generally a pain. I blocked a few pipes, disconnected the ‘air pump’ and threw the carby away, replacing it with a twin choke Weber. It was never gonna be a racer, but what a bloody difference. It felt like double the power and half the fuel consumption. Shows what even a little bit of breathing improvement makes. I’m sure it only had about 20 ft.Ib’s of torque* before my simple mod’s.
Roymondo:
newmercman:
Hub reduction does have more parasitic losses, pretty obvious really considering the extra gears, but it not only multiplies torque, it also reduces shock loads on the driveline, useful in both heavy haul and off road work, so it’s a worthwhile trade off.Mercedes only went to single reduction on the revised first generation Actros, which was around 1998. They do whine a little, none more than the Leyland Roadtrain.
On the subject of torque, I remember reading a “did you know” type article about the torque produced by an engine, although 1500lbs/ft sounds a lot, it’s actually not much more than the force a man can produce with a four foot extension bar on a socket, only around ten times as much, I know it’s not scientifically correct, but to put torque into layman’s terms, a man with a four foot bar should be able to propel 4.4tons up a hill at the same pace as a 44ton lorry with 1500lbs/ft of torque, but as you can figure out, it would be impossible, unless that four foot bar was hooked up to a block and tackle, or several to be more accurate, with the equivalent torque multiplication as a gearbox and differential provides the man could easily get that 4.4tons up the hill.
I think someone needs to understand exactly what is meant by “torque”, “force” and “power”. Then he might not be inclined to post drivel about a bloke with a 4ft bar being able to propel heavy weights at the same speed as a lorry…
None taken…
Nowhere do I mention speed. I said quite correctly that a man with a 4ft bar can produce 150lbs/ft of torque and that using a block and tackle with the same torque multiplication as the gearing on a lorry with 1500lbs/ft the man with the 4ft bar would be able to propel 1/10th of the weight up the same gradient.
That my pedigree chum, is physics, plain and simple.
You’re welcome…
newmercman:
None taken…
the man with the 4ft bar would be able to propel 1/10th of the weight up the same gradient.That my pedigree chum, is physics, plain and simple.
You’re welcome…
Although some say AEC’s engineers advised the film makers in this case. 
peterm:
We’re still banging our heads against walls while falling in to the troll trap.Simon. We had a 4 cyl’ 1.9 Holden Commodore for a while, with all the anti pollution crap on it. Gutless, heavy on juice and generally a pain. I blocked a few pipes, disconnected the ‘air pump’ and threw the carby away, replacing it with a twin choke Weber. It was never gonna be a racer, but what a bloody difference. It felt like double the power and half the fuel consumption. Shows what even a little bit of breathing improvement makes. I’m sure it only had about 20 ft.Ib’s of torque* before my simple mod’s.
- I’ll explain that again later for benny hill’s… sorry kings benefit.
Holden. I was trying to remember what Aussies GM’s version of it was. I can sleep easy now
newmercman:
newmercman:
a man with a four foot bar should be able to propel 4.4tons up a hill at the same pace …Nowhere do I mention speed.
Er, I won’t mention it to Roymondo if you don’t Mercman
Hahaha FAIL!!!
So drivel is a pretty accurate description then…
newmercman:
Hahaha FAIL!!!So drivel is a pretty accurate description then…
I wouldn’t go that far. Pure typo. Our policiticians take us to war on typos
I know what you mean and it’s correct in my opinion. “Give me a lever long enough and I’ll move the earth” etc.
No I made a balls up, to do what I said in the first post the man would need to spin the bar at 1400rpm (as an example) and that ain’t happening. I have given myself a sound thrashing as punishment for my error.
Can you tell me where I can buy one of your super engines where I get more power out than the engine put out.?
Bking:
Can you tell me where I can buy one of your super engines where I get more power out than the engine put out.?
Where not getting ‘more power out’ we’re trading ‘speed’ for ‘torque’.It’s just that in the case of hub reduction that trade is taking place at the hub thereby reducing torque loading in the driveline especially that between the diff output side and the wheels.