Reading time: 1,000 words, 2.5 to 4 minutes
To understand the difference between 4 X 4 and All-Wheel Drive, you first need to understand that ordinary Two Wheel Drive is actually ONE wheel drive – whichever wheel has the least traction gets most of the power and this causes the vehicle to spin-out in slippery conditions. Solutions that mitigate this such as No-Spin differential or Limited Slip diffs are expensive options.
4 X 4 is just a Two Wheel Drive in the front and one in the back. Thus whichever wheel has the least traction still gets most of the power and the vehicle spins out just like a Two Wheel Drive. A lot of 4 X 4 drivers fail to understand this and consequently they’re overconfident and think they’re invincible. Four Wheel Drive works well at slow speeds in difficult terrain like mud or snow but they’re dangerous at highspeed in slippery conditions.
All-Wheel Drive (AWD) uses No-Spin diffs and a computer controlled transfer case in the middle that adjusts power between front and rear axles. That’s why AWD is expensive. All four wheels may spin (unless equipped with Traction Control) but the wheels spin at different rates that adjusts power to all 4 wheels according to traction and this helps keep the vehicle under control.
The video link below teaches at least two things:
1) Slow down in slippery conditions regardless what type of drive you have.
2) 4 X 4 drivers think they have better control than Two Wheel Drive. They don’t!
Notice when the 4 X 4 driver loses control in the video below, the spin-out becomes worse. It’s unlikely the driver lived long enough to learn the lesson because there’s very little left of the vehicle when both vehicles collided at highway speed. Seat belt and airbags would have done little good.
Notice too, the 4 X 4 practically disintegrates upon collision with the 18-wheeler. They’re both travelling at highway speed so their combined speed is well over 100 MPH (180 KPH). Read about the danger of pick-up trucks below.
Warning: the video below is graphic!!! However, don’t feel guilty if you watch it several times. There’s much to be learned from this video. To see the video CLICK HERE
The Danger of Pick-Up Trucks
Pick-up trucks aka ½ ton or ¾ ton trucks are much more dangerous than most people realize. When the U.S Federal Motor Vehicle Safety Standards were enacted in the 1960’s and later adopted by other countries, 97% of vehicles on the road were passenger cars and only 3% were pick-ups and vans. Half a century ago, most pick-ups and vans were considered “tradesman vehicles”. They were driven short distances and rarely on highway speeds at high speed so increased safety standards were not applied to them.
However, today half of all new vehicles sold are pick-ups and safety standards that apply to passenger cars still do NOT apply to pick-ups. Auto manufacturers make little profit on cars but hey make a huge profit on over-priced pick-ups, many of which are 4 X 4s.
These increased car safety standards include door impact rails, crumple zones and roll-over protected passenger compartments. It also includes various side impact protection and other safety systems.
Most pick-ups lack these safety features. Although, pick-ups are designed to look tough; the operative word is ‘look’ and looks are merely appearances. I saw photos of a collision between a pick-up and an Oldsmobile Delta 88. The passenger side of the pick-up looked like it had been opened with a giant can-opener. The entire side was ripped open from the front fender to the rear tail-gate and the unfortunate passenger lost her right foot. The Oldsmobile had a slightly dented front fender and was still driveable.
I’ve seen videos of various makes of pick-ups that were tested by dropping them upside down onto the cab. The cabs were completely crushed to the level of the hood and box. On roll-overs, drivers and passengers in pick-ups have little protection. And, because 4 X 4’s have higher ground clearance they are more apt to roll than cars.
Several other factors need to be considered. Pick-ups have a very light rear. When a light rear-end vehicle starts to spin, it is very difficult to regain control and a driver is apt to over-correct i.e. over-steer. Often this sends the pick-up into oncoming traffic as shown in the video above.
A word of warning to those pick-up drivers who haul a ‘counterweight’ in their box for increased traction in slippery winter driving conditions: if the added weight is not firmly secured, in a front end collision it could torpedo through the box and into the cab. Even bolted through the floor of the box may be insufficient to secure a heavy weight.
The same applies to loads covering the rear cab window. I once saw the remains of a pick-up involved in a front-end collision. It had been hauling firewood. The cab was full of firewood and the inside of the front windshield was completely covered with blood. I doubt the occupants survived.
Another thing is GVW; the pick-up’s rated Gross Vehicle Weight affects how much weight a pick-up can carry. GVW is rated for a bare truck with no options. The more factory or after-market options a truck has, the more it weighs and the less weight it can safely carry.
British Columbia did a safely blitz on pick-ups. Those carrying loads were weighed on highway weigh scales. Some had to remove most of their load to be within the vehicle’s GVW. Often, only a single layer of firewood weighing less than 200 pounds (100KG) achieved maximum GVW. A so-called half-ton or 1,000 pounds (453 KG) carrying capacity has been reduced by more than 80%.
And, remember the heavier the load a pick-up carries the more it raises the center of gravity on a vehicle that already has a high center of gravity. A further height increase in the center of gravity increases the risk of roll-over in a vehicle that is NOT designed to roll over safely in the first place.
March 28, 2012
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