Reduction gearboxes in the Hub

Transmissions, Transfer Boxes, Axles, Drive Shafts
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Alex Roux
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Reduction gearboxes in the Hub

Post by Alex Roux » 19 Jul 2014 17:59

The latest Leisure wheels has Glyn's usual section in. This time on the need for unity in the 4x4 community

The issue also has an article on a pimped Amarok driven by Andre De Villiers.
This one sports reduction gearboxes housed in the wheel hubs.
I must be ignorant, but I have not seen or heard of this before.
Below is a picture from the magazine
ReductionGBoxinHub.JPG
ReductionGBoxinHub.JPG (512.75 KiB) Viewed 1778 times
This is the first time that I know of, of a way to improve clearance of the solid axles, other than larger tyres of course.

So after seeing this, I did some googling and found that Marks4wd in Australia seem to do this for Patrols!
http://www.marks4wd.com/mfk1750gq.html
Pity, I live in the wrong country and I do not have money either...

I have not found any commentary on this by users yet, such as the Patrol Oz Forum.
It inevitable makes the wheel track wider, but a big advantage must be the extra clearance of the solid axles, and no suspension complications from the lift either.
Does anyone else here know more on this?
ReductionGBoxinHub2.png
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Re: Reduction gearboxes in the Hub

Post by Tinus lotz » 20 Jul 2014 11:27

Alex piet has been looking at it for a long time .....he is back from holiday tonight lets wait to see wat he says...imho...will do it to a trail car no problem. ...but what about the 1000km to get there?????

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Re: Reduction gearboxes in the Hub

Post by Clem » 20 Jul 2014 13:35

Many military vehicles use them – at least some models (if not all) of the Unimog have them as well. I have my doubts as to their value on the average four-wheel-drive. I certainly would not be in a hurry to fit them on an overland vehicle. Something specialised for doing slow heavy work on extreme trails might be a different proposition though. For what it is worth, I am aware of one or two manufacturers out there for civilian use but I am not aware specifically of one made for the Patrol.

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Re: Reduction gearboxes in the Hub

Post by Peter Connan » 20 Jul 2014 15:09

As Clem said, many military vehicles use them. A few examples:
All Unimogs (and their derivatives such as our Buffel and Mamba), Samil 20, most of the Steyr products (Haflinger and Pinzgauer), the Volvo C30 series and some of the russians as well. Also the recent 6x6 Gelandewagen. A lot of tractors and other farming equipment also have them.

The Puchs are all independently-sprung swing-axle designs and the Mogs have torque-tube suspensions and the axles are mostly not ideal for conversions, but the Volvo C30 axles are very saught-after for conversions on Land Cruiser wagons (80 and 105 series).

Both the Pinzgauer and the Volvo C30 are very saught-after vehicles in Auz for overlanding use. The advantages are that they are great off-road, very reliable and the mini-bus-type layout gives excellent space utilization, but by our standards they are slow and underpowered (both vehicles have military-style top speeds of 90-100km/h).

In my limited overlanding experience, in an overlanding situation one mostly gets stuck by running out of ground clearance as one is usually driving on roads used by other vehicles, and as such an increase in ground clearance is beneficcial. However one seldom needs more than just a half-inch or so, that can be easily gained by just fitting one size larger tires, but this is not always the case.

The MArks axles seem very good, and I wish I had the money to buy a set. As far as disadvantages go, there are a couple: firstly, it does raise the vehicle a bit, so clearance in low garages etc comes into play. I understand it's about 100mm. In terms of stability though, the lift is more than offset by the increase in track, but this increase in track means that you struggle more on tight tracks, particularly as our cars are already among the widest. The other drawbacks are that they are a bit noisier (apparently no more than a set of muddies), that you need to run 17" wheels to clear the hardware, and then the big one: price and shipping.

Advantages are a real increase in ground clearance and a gear ratio better suited to larger tires (giving even more ground clearance) without changing suspension geometry and driveshaft angles, and by all accounts improved strength. Probably therefore they are better suited to a serious trail machine than to a general overlander, and the cost in Rand is going to be very hard to justify (if you are one of those people who have to justify money spent on your toys).
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Re: Reduction gearboxes in the Hub

Post by bogeyman » 20 Jul 2014 15:24

In addition to what Piet said above , bear in mind that this is a major drivetrain alteration.

Centre of gravity is much higher. The load carry and power transfer properties of the axles are altered and all this affects the drivability at speeds exceeding 60km/h/. This has road safety implications and possible insurance implications as well.

This mod is for vehicles intended for extreme offroad work and not for general everyday use.

Have you ever seen a happy Unimog on the N1?

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Re: Reduction gearboxes in the Hub

Post by Clem » 20 Jul 2014 17:56

Quite frankly, IMHO its a nice idea but if you NEED portal hubs where you are going, then you probably also need a different vehicle. Maybe a proper 4wd truck.

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Re: Reduction gearboxes in the Hub

Post by Alex Roux » 20 Jul 2014 17:57

Just another thing I thought of,

This is an extra gearbox per wheel
Will that not increase the resistance and hence reduce the power to wheels?
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Re: Reduction gearboxes in the Hub

Post by Peter Connan » 20 Jul 2014 19:45

Alex Roux wrote:Just another thing I thought of,

This is an extra gearbox per wheel
Will that not increase the resistance and hence reduce the power to wheels?
It will reduce power, but because of the gear ratios it will actually increase the torque at the wheels, depending on the ratio chosen.

They usually use straight-cut (or very nearly so) gears to reduce the power losses, but that's why they are noisy.
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Re: Reduction gearboxes in the Hub

Post by Alex Roux » 20 Jul 2014 22:16

Ahh, makes sense.
Thanks
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Re: Reduction gearboxes in the Hub

Post by Clem » 21 Jul 2014 05:51

Alex Roux wrote:Just another thing I thought of,

This is an extra gearbox per wheel
Will that not increase the resistance and hence reduce the power to wheels?
Yes. Do not expect to do any happy high-speed cruising. But on the other hand, as Peter has said, you will have loads of torque at low speed.

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