Unless someone asks, we have no clue of the reason the owner added an extra axle on his Ford truck. Maybe it is for appearance, perhaps it’s to pull heavier loads.
Either way, there are plenty of these types of custom builds around, I have seen one in Florida a few years back that was not a 6×6 but rather a simple rear wheel drive.
Thus, I have trouble with the comment supposedly made by the uploader of the video clip where he states to have talked to the guy of the 6×6 before going up that ascent.
It is mind bending to see such comment made by a truck owner, at least he is driving one at the moment he took that clip.
The truck seem to be rear wheel drive as only the last rear axle have some slippage happening to the wheels. No spin occurs with the wheels in front of the last axle nor do the front wheels pull in any way. Thus, the driver either forgot he has a 6×6 and it is not engaged or he doesn’t have a 6×6 setup. Maybe he has a 6×6 setup and he does have the 6×6 engaged, but his system is broken. A broken transfer case and differential can create the symptom seen on the video clip. If the pass-through differential in front of the rear is broken it can drive the rear axle but not his own axle.
For those who care to know why that Ford truck could not go up, I made a little sketch.
Being only rear wheel driven, what happens here is that the last axle is being lifted due to the axle right in front of it creating leverage. The first frame and wheels setup show what happens when a truck with such setup tries to go up a hill. The last axle is shown stiff to show how far it would be from the road.
The second sketch of a frame and wheels represent accurately what you see on the video clip. Due to the suspension the last axle drops on the road, but since it is exerting a load only equal to the weight of the differential, suspension and wheels, it’s not enough grip.
I hope this information helps someone.
Oh! Before I end this, I want to jab at a fellow writer at Jalopnik, Mr. Tracy for a comment he made in his article titlted: Watch A Six-Wheeled Ford Super Duty Fail At Climbing A Slight Incline
Mr. Tracy, you said in your article the video you found demonstrating a 6×6 is almost certainly the exact same truck struggling to make it up the slight incline in Rhode Island, well it’s not. Apart from many other indications differentiating the two trucks, can’t you tell the difference between gasoline and Diesel engine?