All Wheel Drive ?

[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.

[Lang]

Mike K

I had a 1948 Landrover when I was a kid and the yellow knob lever had to be pushed down to get reverse in four wheel drive.

I joined the 11 Field Regiment CMF at 17 and when beginning my driver training course on Series 2 Landrovers rolled my eyes and pointed to my old Landrover in the car park when the instructor asked if I knew how to get it into four wheel drive. I was immediately branded as a smart arse when I looked down and saw all these strange levers poking through the floor.

Lang

[Grant Bowker]

Another vehicle that doesn't seem to fit the SAE classifications given above is the M135. Basically full time power to all wheels with an over-running clutch to the front axle that was locked automatically in reverse.

[Lang]

Grant is this not an "On Demand" system. It gives power when driven and lays idle when not? There are thousands of ways to achieve this result in the gearbox, transfer case, centre differential or front axle as in the M135

Lang

[Mike K]

Originally Posted by Lang

Mike K

I had a 1948 Landrover when I was a kid and the yellow knob lever had to be pushed down to get reverse in four wheel drive.


Lang

Lang

Your 1948 LR would have been a late 1950 model see here: Early land Rover chassis numbers begin with the model year eg 8 = 1948 0 = 1950 1 = 1951

https://www.aulro.com/afvb/attachmen...se-changes.pdf

There was a short production run where the later 1950 models had the free wheel system locked for reverse by a yellow knob control. Before the yellow knob, the 1948 to 50 models had a chain through the floor panel with a ring pull , rather like an old dunny chain !

[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.