All Wheel Drive ?

[Mike Cecil]

Thanks Lang, that is interesting.

That seems to confirm that, thus far, MH were the 'original' users of the term 'All Wheel Drive' on both their placarding on the scuttle of Fords equipped with the MH drive system, and in their handbooks and technical data. Attached is an MH technical manual which is dated January 1939, and uses the term both on the front cover and throughout the text.

This website seems to provide a reasonable differentiation between the two systems in terms of current usage, but on reading the MH manual, it seems they (ie MH) used it in a different sense: a conventional system which would cover both their 4x4 and 6x6 applications.

https://www.digitaltrends.com/cars/w...l-wheel-drive/


Mike

[Lang]

Thanks Mike.

My comments above about Studebaker seem to indicate two bob each way with the expression "all wheel drive 6x6".

Maybe "all wheel drive" was not any type of official designation but just a simple use of the English language at the time like "flat bed" or "cab over engine" which simply accurately described a feature and was not any sort of marketing catch phrase. MH produced both 4x4 and 6x6 and the phrase covered both systems.

I think the motoring journalist in your link is trying too hard. They are all 4x4, four wheel drive or all wheel drive - what about "part time four wheel drive" and "full time four wheel drive"? The only difference is how they get the power to the wheels and there are so many combinations and system mixes. I am certain AWD and Four Wheel Drive are purely marketing terms that have come to mean generally a description for sporty cars and soft-roaders or a description for off-roaders. Any attempt to claim they are two entirely different animals is BS.

Lang

[Mike Cecil]

Yep, you are spot on I think, Lang.

Mike

[jack neville]

I wonder how many 4x4 or 6x6 vehicles produced by various countries were full time all wheel drive. Most have a transfer case to disconnect the front drive. Could this have something to do with MH AWD claim.
The later Ford Marmon Herrington gun tractors were fitted with a ‘compensator’ transfer case to eliminate windup in the driveline. A primitive centre diff.
For an Australian built vehicle to have full time AWD was quite unusual I’m thinking.

[Lang]

Jack

I will check but I think both FWD and Nash were full time four wheel drive back in WW1. Aren't the WW2 (if not forever) FWD trucks full time four wheel drive?


Well, we had to have some rules somewhere! This puts the kybosh on motoring writers flights of fancy about different systems - they are all "All Wheel Drive" - this also includes one we have not mentioned IWD (Individual Wheel Drive ie hydraulic or electric motors on each wheel such as Tesla)

SAE Recommended Practices
Per the SAE International standard J1952, AWD is the preferred term for all the systems described. The standard subdivides AWD systems into three categories

Part-Time AWD systems require driver intervention to couple and decouple the secondary axle from the primarily driven axle and these systems do not have a center differential (or similar device). The definition notes that part-time systems may have a low range.

Full-Time AWD systems drive both front and rear axles at all times via a center (inter-axle) differential. The torque split of that differential may be fixed or variable depending on the type of center differential. This system can be used on any surface at any speed. The definition does not address inclusion or exclusion of a low range gear.

On-Demand AWD systems drive the secondary axle via an active or passive coupling device or "by an independently powered drive system". The standard notes that in some cases the secondary drive system may also provide the primary vehicle propulsion. An example is a hybrid AWD vehicle where the primary axle is driven by a internal combustion engine and secondary axle is driven by an electric motor. When the internal combustion engine is shut off the secondary, electrically driven axle is the only driven axle. On-demand systems function primarily with only one powered axle until torque is required by the second axle. At that point either a passive or active coupling sends torque to the secondary axle.

In addition to the above primary classifications the J1952 standard notes secondary classifications resulting in a total of eight system designations:

Part-Time Non Synchro System
Part-Time Synchro System
Full-Time Fixed Torque System
Full-Time Variable Torque Passive System
Full-Time Variable Torque Active System
On-Demand Synchro Variable Torque Passive System
On-Demand Synchro Variable Torque Active System
On-Demand Independently Powered Variable Torque Active System
Lang

[Mike Cecil]

I think the White M3A1 Scout Car 4x4 was full time FWD?

The MH compensator system in the transfer case that you mention, Jack, appears to have been standard on MH conversions - it is included in the January 1939 manual I have (front cover in a previous post). The Aust Dingo Scout Car also included it, and it is referred to in the handbook for that vehicle.

I'm pretty sure the FWD Model B of WW1 was selectable 4x2 or 4x4 with a high-low range selection as well. A cab lever engaged the front drive shaft into the transfer case: been a while since I had a good look at one, though, so the memory may have failed!

Mike

[lynx42]

Originally Posted by Mike Cecil

I think the White M3A1 Scout Car 4x4 was full time FWD?

The MH compensator system in the transfer case that you mention, Jack, appears to have been standard on MH conversions - it is included in the January 1939 manual I have (front cover in a previous post). The Aust Dingo Scout Car also included it, and it is referred to in the handbook for that vehicle.

I'm pretty sure the FWD Model B of WW1 was selectable 4x2 or 4x4 with a high-low range selection as well. A cab lever engaged the front drive shaft into the transfer case: been a while since I had a good look at one, though, so the memory may have failed!

Mike

Yes Mike, the M3A1 White Scout Car is in constant 4 wheel drive. The strain on the drive is colossal. I have backed into my garage and jacked up a wheel and unwound 3 or 4 inched of twist out of the drive.

The Dingo has the M-H 'J' series transfer case with a compensating gear which you have to engage to select 4 wheel drive reverse.

Of course, we all know that the Ferret, Saracen and Saladin also have all wheel drive at all times with just the diff to help compensate.

Regards Rick.

[Mike K]

Early Land Rovers have a weird system up until 1951 . There is a free wheel clutch on the front transfer case drive to the front axle. Basically the vehicle is in 4X4 mode permanently but the clutch only engages and provides drive under certain conditions ie when accelerating under load in muddy off road driving. Its great in theory but as with many of these drawing board ideas they found out it had major drawbacks. Driving up/down steep hills you would lose the 4x4 effect just when you needed it . Driving in reverse, you pulled a ring in the floor and doing this would lock the clutch in drive but this lead to other problems if you left the clutch locked . They ditched the whole idea and changed over the tried and proven conventional methods

[Lang]

The humble 4x4 started in France when manufacture Latil began making front wheel drive vehicles and then making the natural shift to 4x4s before the turn of the century. The first 4x4s were tractors and gun tractors.

1900 – 1910
A lot happened during this time frame – the first battery powered vehicle is brought out with a battery powering each wheel. This was later expanded to a petrol engine driving a dynamo and electric motors to power the wheels but it was too expensive and didn’t take off.

The Spyker was built, making the first full-time four wheel drive car to be created. Caldwell Vale 4x4 trucks were created by Felix and Norman Caldwell, introducing trucks with four wheel drive and four wheel steering.

1911 – 1920
The Four Wheel Drive Auto Co (FWD) was launched and started selling 4x4 vehicles. During World War One there was a huge increase in the amount of four wheel drive, all-terrain vehicles being manufactured. Jeffery Quad started producing 4x4 trucks, the Big Lizzie was launched in 1915 and the first Oshkosh four wheel drive truck was made.

[maple_leaf_eh]

Two of three plated vehicles at my house have some form of selectable front and rear wheel drive.

The angular green one has a four-speed transmission and a lever to engage the front axle from the transfer case. A previous green occupant of the covered shelter went further to have a three-speed transmission, a two-speed transfer case, and selectable front axle drive. I would term these vehicles as Four-Wheel Drive or FWD. (Never mind the complicating concept of non-locking differentials.)

The shiny silver one reserved for the Residential Sergeant Major, normally is front wheel drive, also abbreviated as FWD for some. It also has a rear axle driveline that may be engaged for slippery or uncertain traction. [I, of course am forbidden to leave the hard surface roads to do any sort of true loose surface performance testing.] The corporate descendant of Henry Ford's organization refers to this capability variously as 'all-wheel drive', in lower case, and in company literature as 'Front-wheel drive and All-Wheel drive', in mixed case.

The only distinction that I can draw between the green vehicles is their second axle is deliberately engaged, while the shiny one has some sort of wizzardly magic crystals that decide when to play and when to simply watch the action. That and marketing puffery.

[jack neville]

I wonder how many 4x4 or 6x6 vehicles produced by various countries were full time all wheel drive. Most have a transfer case to disconnect the front drive. Could this have something to do with MH AWD claim.
The later Ford Marmon Herrington gun tractors were fitted with a ‘compensator’ transfer case to eliminate windup in the driveline. A primitive centre diff.
For an Australian built vehicle to have full time AWD was quite unusual I’m thinking.

[Grant Bowker]

Going back to the M135, all of the SAE terms:
On-Demand Synchro Variable Torque Passive System
On-Demand Synchro Variable Torque Active System
On-Demand Independently Powered Variable Torque Active System
seem awfully fancy compared to a system that was of the same vintage as the early LandRover described above (only slightly fancier in being linked to the reverse shift position, the truck had an automatic transmission as well to simplify driving). The variable torque of the M135 is basically binary, either engaged or not.
It would seem that the SAE J1952 standard was first published 1991,(well after the M135 and LandRover were designed) https://www.sae.org/standards/content/j1952_199101/ and to be a bit picky is only intended to apply to light trucks up to class 3 which seems to top out at 14000 pounds GVW. https://en.wikipedia.org/wiki/Truck_classification It isn't clear if this is the same class 3 definition SAE is using.
I could facetiously claim the 4wd system on my F350 is also "on demand" - when I demand power to the front wheels by moving the floor mounted shift lever, power is delivered.

I wasn't trying to tell anyone they were wrong, only to suggest that are a large variety of systems that can't all be neatly pigeon holed.

[Lang]

Grant

I was not suggesting you are wrong just that the SAE main descriptions are general names for the only three possibilities to achieve all wheel drive. Even then one could argue "on demand" is really a part time system. How they are arrived at is only limited by the imagination of the engineers and how complicated and expensive the manufacturers are willing to pursue development of the weird and wonderful.

I think the 3 general descriptions (part time, full time and on-demand) cover everything possible but the sub-list of methods and designs to achieve one of those 3 results will go on expanding forever.

It is still hard to pigeon hole a design. What about a vehicle that normally runs 90% rear and 10% front - got to be full time. But if it has sensors that detect rear wheel slip and feeds power to the front axle until there is a 50/50 sharing it has got to be on demand? And if you can turn the four wheel drive off completely it has to be part time?

Lang

[Lang]

Mike K

Thanks for the Landrover info.

Lang