When did the description 4WD become 4x4, and why?
--
L\'escargot.
|
It's always been used in off-roading circles, because the system is more precise.
4 X 2 = 4 wheels, 2 driven
4 X 4 = 4 wheels, 4 driven
6X 6 = 6 wheels, 6 driven
6 X 4 = 6 wheels, 4 driven
6 X 2 = 6 wheels, 2 driven
etc.
It's also useful to describe the particular transmission mode being used at any moment - eg one axle disconnected, or free-wheeling hubs disengaged. So a 4 X 4 would normally be driven on the road in 4 X 2 mode to save wear on the front tyres.
|
|
Surely only one wheel is actually driven in 4x2 thats why it is possible to get a land rover stuck when the two nearside wheels are stuck even thought the other two are on hard stand.
|
Surely only one wheel is actually driven in 4x2 thats why it is possible to get a land rover stuck when the two nearside wheels are stuck even thought the other two are on hard stand.
Both are driven its just that the nature of differentials lets one slip. In fact the same could be argued in 4x4 mode - its possible in a 4x4 with a centre differential (not all have one) to spin just one wheel despite being in '4x4' mode.
Limited slip diffs can help to some extent but the real answer is to lock the diff - ie. force both output shafts to turn at the same speed. Depending on the 4x4 you can lock the centre and/or rear diffs (and in rare cases the front too).
|
>> but the real answer is to lock the diff - ie. force both output shafts to turn at the same speed. >>
Or, as on my 1949 Ferguson, use the individual wheel brake to stop the wheel that is spinning and transfer all the power to the one that has grip.
The same effect can be a useful dodge in an ordinary car, if the handbrake acts on the driven wheels. Partially applying the handbrake puts a load on both wheels, so tending to restrain the wheel that is spinning.
|
|
|
|
It's always been used in off-roading circles ...........
The manufacturers (and off-roading farmers and the military etc) called them 4WD vehicles long before the general public started buying "4x4" Chelsea tractors.
--
L\'escargot.
|
I'm sure both terminologies have been in use for ages. The military of course have always had an interest in 6 wheeled vehicles, which are better described by the X useage. They also have/had trailers with driven wheels too, powered via the PTO on the back of the LandRover or lorry.
There was an interesting project in an offroading mag some years ago to build an 8X8. It was based on two LandRover chassis welded on top of each other, but offset so that the wheels were evenly spaced. It had front and back steering, linked but with the rear lockable, and the two sets of transmissions were linked by an additional transfer box.
|
I'm sure both terminologies have been in use for ages.
In terms of my lifetime, 4x4 is a relatively recent description.
--
L\'escargot.
|
In terms of my lifetime, 4x4 is a relatively recent description. --
The eariest references I can find are:
1898 - Latil (France) began making front wheel drive units, and then 4 X 4
1940 - first Jeep described as "a general purpose, personnel, or cargo carrier especially adaptable for reconnaissance or command, and designated as ΒΌ-ton 4x4 Truck". That was in the publicity brochure to celebrate its famous drive up the Capitol steps.
4WD seems to have come in the 70s.
|
|
|
|
4x4 is an off roader (i.e. Range Rover)
4x2 is an off roader with only two driven wheels (i.e. X-Trail)
4WD is a car with 4 driven wheels (i.e. X-Type, Quattro, Impreza etc)
2WD is a normal 2 wheel drive car further defined by being FWD or RWD
|
4x4 is an off roader (i.e. Range Rover) 4x2 is an off roader with only two driven wheels (i.e. X-Trail) 4WD is a car with 4 driven wheels (i.e. X-Type, Quattro, Impreza etc) 2WD is a normal 2 wheel drive car further defined by being FWD or RWD
The Mercedes-Benz G6 of 1933 (the kind Hitler used to ride around in) was 4WD although it had 6 wheels. ie it was really a 6 X 4. The rearmost wheels were powered, not the front. Some Range-Rover based ambulances have been built as 6 X 4 but with power to the front and one of the rear pair.
|
|
And the Brough Superior was 3x2. Rear had two tyres:) Other oddities include the Megola rotary engined FWD machine (1921 -25) and the more recent Yamaha 2wd (and maybe others for motocross purposes!)
|
|
A slightly eccentric lorry layout was 6x2 with the twin axle at the front - designated - IIRC - twin steer or Chinese six (the Chinese six bit is ever so slightly smutty)
|
|
And of course all children are aware of the shortcomings of 3 X 1 tricycles on wet grass.
|
|
Of course there is also AWD, that's what it says on the side of my Forester ;)
|
|
|
|
Saw a New York Fire Service ladder truck on the Tv the other day - 6 wheel cab unit with front 4 steering and driven then an articulated body carrying the ladders then a separate control cab with an operator in it steering the rear tender unit from the back to enable it to get around tight corners in Manhattan.
By my reckoning it was a 10x4 with 6 wheel steering!
|
|
|
I vaguely remembered some 6x2 cars appearing in Formula 1 in the 70s. A quick Google confirmed that I wasn't imagining it:
www.f1nutter.co.uk/tech/6wheels.php
|
|
|
