Argo HDI-True eight wheel drive?

[mightymaxIV]

Will someone please answer the following question? Is the Argo HDI with the Adamiral transmission true eight wheel drive. If I Jack this machine up on the right side leaving the left side on the ground and give the machine gas with no steering input will the machine pull off the jack or spin the wheels that are in the air? I need to know this! Argo says it's true eight wheel drive. I have been waiting for the 6x6 version of this machine. If it is not a true eight (or six wheel) drive I am no longer interested. Will an Argo dealer or some who knows the facts please answer this question so I can make an informed decision. I just want the real thing. Thanks Dan

[fixer2]

I also would like to know ,and Iam also waiting for a six wheel version.I need some thing to go into ungroomed snow thats deep in the woods i want to work the machine on the farm.Everybody shows picture of there 8wheeler not the six in really deep snow?why??

[pvisscher]

There is not a short answer to this one, so here is the long one. There is some confusion and misconception about this topic, much of this from marketing material generated from Argo competitors.
The best way to explain this is to compare these vehicles to farm tractors. A 4 wheel drive tractor pulling an implement is typically operated with the 4-wheel drive on and the differentials unlocked. This means that the right side tires and the left side tires develop equal torque but are free to spin at different speeds. The tractor is definitely operating in 4-wheel drive mode, as all 4 wheels are pulling. If the right side of the tractor runs over a patch of slimey mud, it is possible that the right side tires spin and the left side tires do nothing. The torque on each side is equal, but limited to the torque that the low-traction side can develop. The farmer taps the diff-lock button and carries on. Now, both right and left wheels of the tractor spin at the same speed, but the tractor will barely steer, so the diff lock is disengaged before the tractor needs to turn around.

On an Avenger or Frontier, the differential is unlocked. When driving straight, all 8 wheels are pulling, so the vehicle is certainly 8-wheel drive. If one side of the vehicle loses all of its traction, those wheels may spin while the other side does nothing. Torque on both sides is still equal, but limited to the torque that the slipping side can generate, so the side with traction may not develop enought torque to move the vehicle. The operator will typically feather the steering to slow down the spiinning side, thereby sending torque to the side with traction. This is mechanically simple and effective, but requires some driver skill and wastes power. However, the vehicle will NOT steer unexpectedly, a good thing in the land of lawsuits. A novice operator will simply get stuck, which is preferrable to unwanted direction change.

On a T-20 equipped machine, the operator can spin the right side and left side wheels at the same rate, with the same effect as locking the differential. However, this can only be done in a straight line. Should one side of the vehicle lose traction, the vehicle may steer in an unexpected manner, especially if pulling a heavy load or climbing a steep hill. (A skilled operator can react quickly and work around this.) A T-20 can ensure that all wheels are spinning, but only in a (hopefully) straight line. Any steering input will reduce or eliminate the drive to one side, effectively losing half of available traction. So, a Max is all-wheel drive, as long as it is driving straight. The main advantage of a T-20 is the potential for more efficient turning than a typical Argo, thereby avoiding the engine bog while turning.

The Admiral transmission combines the best traits from both systems. While driving in a straigh line, right and left side develop equal torque, in both high gear and low gear. If one side completely loses traction, the machine may stop as the one set of wheels spins. This ensure that no unexpected steering occurs. In high gear, the operator simply has to turn right OR left. In either case, torque is instantly redistributed to the side with traction. Regardless of the direction or force with which the operator steers, the side with traction will turn, thereby allowing the vehicle to extricate itself. The occurs because the transmission forces the inside wheels to spin at approximately 1/3 the rate of the outside wheels during hard steering, effectively locking the differential, but at a controlled ratio that allows for steering. This only occurs in high gear, and raises the efficiency of the vehicle while turning quite dramatically. While the machine will no longer do super sharp turns in high gear, the HDi is infinintely more trail friendly and is still able to turn sharper than UTV's.
In low gear, the inside wheels are forced to counter-rotate slightly in a turn. The rate at which they spin backwards is quite low (in an effort to increase efficiency and reduce heat build-up) but the effect is surprising. The slight counter-rotation keeps the tire treads from packing up, and actually cuts the turning radius in half (compared to the Avenger). Agility in extreme terrain is improved noticeably.

To sum up: if on a jack stand, it is possible to spin one side of the HDi freely, at least until the handlebar is moved. However, it was not designed to run on a stand, and it is much more fun in the forest, swamp, rocks, water, sand, etc.

[Roger S]

That was a great post, thank you. If we may pick your brain further.. you wrote

the transmission forces the inside wheels to spin at approximately 1/3 the rate of the outside wheels during hard steering

my question is, Is all steering that occurs in high range (light and hard/full), geared steering at the 1/3 rate?, or is there a varying rate of diff lock with steering input.

I guess when we get a diagram of the workings of the tranny, we can all get our brains around what is happening.

[mightymaxIV]

Very interesting, thank you for the information-the only way to truely see the results is by off road performance.

[liflod]

So it works like Cletrac steering in high gear?

Also, I read somewhere there are no external disc brakes on the HDI?

[pvisscher]

In high gear, the tightest turn will be achieved at the 3:1 wheel ratio. Like an Avenger, it is still possible to slip the steering brake disk to achieve a larger turning radius. The major difference (compared to an Avenger) is a massive increase in efficiency in this particular situation. Whereas a simpler braked skid steer may require 20 hp to perform a sweeping turn at higher speed, the same turn will only require about 8 hp in the HDi. This is particularly noticable when trail running or doing simple steering corrections at high speed, where the HDi doesn't slow down at all.

Concerning the brake disks, there are still steering disks on the HDi, as well as a set of dedicated hydraulic stopping disks. Separating the steering and stopping functions adds considerably to safety and control. It would have been possible to use internal brake disks or brake bands, but the issues concerning oil contamination and serviceability dictated external disks. A set of pads on the HDi last almost forever and take less than 30 minutes to swap; sure beats dissassembling a transmission!

[AussieMax]

I have to disagree with some of the statements above. Firstly, the differential steering Argo has used for ever does produce unexpected turns. For example, when you are in high gear and you try to turn gently to follow a slight curve in a trail, while jerking away on the brake if you over do it the thing will shoot off sideways sending you off the trail. Another time would be when you go over the brow of a steep hill. Right at the point where the machine is pivoting on the centre axles, they have a tendancy to swing around as the diff passes all its torque to the easiest side. I've driven both Argos and T20 fitted machines, and can't say that when in a bog that a T20 has ever produced a dangerous swing in direction because one side lost traction, I thing that is a bit of an exageration! Wet brakes/clutches don't really produce oil contamination problems either, otherwise devices like the auto transmission in you car would be high maintenance items. Wet bands that last for 20 years sure beat overheating dry discs.
The theory behind a triple differential transmission is good in terms of efficient steering etc, but my problem is with the complexity, extra moving parts and added cost of such a unit. The T20 is a simple and effective, lightweight, relatively low maintenance unit that has proven durability. They are not perfect, and do require some skill, but I think the ability for the operator to control the speed of each side independantly is a good feature.
Just my thoughts

[mightymaxIV]

I hate to ask this really dumb question but here goes-Should I look forward to a 6x6 with the Admiral transmission? I absolutely hate the way the current frontier steers and robs power when you steer it!

[smog]

is there a problem with your MAX IV ? I have an Argo 8x8 with the older transmission and IF I ever find a good cheap Max IV for sale upstate NY, VT or NH, I will drive down from Canada to pick-it up then sell the argo.

[pvisscher]

AussieMax: Disagree away, not a problem. My point concerning unwanted steering was that the old style Argo transmission will not steer unexpectedly when the operator is not steering. Turning response when the operator intends to steer is more dependent on operator skill, and this applies to virtually all skid-steer systems. Concerning oil contamination and wet clutches/brakes: this is highly dependent on load and power as well as duty cycle (as it applies to steering). The smaller Max seems to do fine with a single speed transmission such as the T20, but a heavily loaded Argo 8-wheeler will overload it.
A lot of this thread is based on theory; real-world performance is much harder to quantify as the off-road environment is extremely varied and unpredictable. Different machines, different operator, different conditions, different results. Solution? Multi-brand group rides, and lots of them! I would suggest at least twice weekly for the next year or so. It is a tough burden to bear, but it is in the name of science.

As for MightMaxIV: it is not a dumb question. (That is all I will say.)

[Roger S]

I think you guys are both right. Older Argo steering can be touchy, for a novice iin a six wheeler pulling hard on the sticks. And being unexperienced with a t20, I found it to whip around changing directions in a mudhole as it found traction. Neither is a problem for a driver with experience.

Wet clutches/bands.. if built heavy enough they'd last forever, otherwise you have the problem of delicate bands and drums. If a driver abuses them, it's a lot more $ to fix than a set of brake pads.

[mightymaxIV]

Smog, love my MaxIV but love the Argo Frontier, like the ground clearance, low range and 25" tires, but hate the way it steers. Would love to have one with the admiral transmission and ability to counter rotate in low range, that would be very usefull in the woods and mud holes with logs and roots. Without the adimral it's a no deal!

[AussieMax]

It seems to me that the new admiral still requires the driver to react to send drive to the side that is slipping. I think the best system for true 8 or 6 wheel drive is hydrostatic. There is no power transfer at all from side to side, and it is infinitely variable forward or reverse. It provides total control over speed and power to each side as you want it, and almost no maintenance. There are disadvantages of course, (extra weight/heat) but you can't have the cake and eat it too. All of these systems work, I guess it depends on preference and budget.
The admiral seems to have corrected the issue of torque loss on turns, but if you drive it into a mudhole and one side spins, do you have to brake that side to keep moving like the old Argos?

[Roger S]

the operator simply has to turn right OR left