Anyone know more on 6X6 class 8 truck?

Sugest Dana TC with air control

really I used to drive 6x6 trucks and they are not speedy (over 50 mph they vibrate), fuel milage is low becouse they use "slow" axels, truck is too heavy (usually double frame rails ore welded with thik steel bars, like KRAZ).

Imo, for off road operations I'd choose 8x8 ore 6x6 cabover with daycab.

 

it is not all. for terrain pusher lift axel is better. when you rise front trailer axel more load on trucktor to assist tracktion

 

A lot of newer all wheel drive trucks dont have a transfer case at all. The drive shaft to the front drive axle runs from the power divider on the front rear. When the power divider is locked the front drive axle is also engauged. Buy doing away with the transfer case it saves a lot of weight. Drive line vibration is also less because the front drive shaft is almost flat how ever they are long and may need a carrier bearing. Axle gearing is usually low and the transmissions need a low low (8LL, 9LL, or an 18 speed) because of a lack of low range in the transfer case. Some trucks do have transfer cases. Some are single speed with no low range. They only engauge or dis engauge the front axle. Other have low range just like a pick up truck transfer case. Most with low range only use a basic 9 or 10 speed. Trucks with automatic transmissions also use transfer cases with low range. Transfer case manufactures are Eaton Fuller, Dana Spicer, Rockwell(Meritore) and Napco. (Their may be others) New trucks are all air shift with a simple switch on the dash. Some old truck Ive seen had a lever and shift linkage (Mack and Oshkosh). FWD had a 3 speed transfer case. It had high and low range like most others but also had an over drive that was and air switch on the main trans shifter and was used like a splitter. The main trans was a direct drive 5 speed. The od was split just like todays super 10 and made for a 10 speed od. Front drive axles are made buy Dana/Spicer, Meritore, Marmon Harrington, and ZF. You might notice most all wheel drive class 8 trucks have super single tires. Axle raitings are usually 21k, 22k, or 23k. Most have a standard "open" differential but I have seen a concrete mixer with an air locker.

 

Marmon-Harrington does many conversions.

 

There is a whole list of companies that do the conversions.

Fabco also makes front axles in addition to MH

Rockwell and MH also make transfer cases.

My truck has a MH MT-17 front axle 4.82 ratio, Rockwell 44K rears with Detroit Lockers 4.88 ratio, a Rockwell MR-226 two speed transfer case, air engaged with manual high low. The transmission is an Allison MT-643

The truck cruises at 58 mph at 2500 rpm, this seems to be it's sweet spot and the mileage varies from 7 to 9 mpg. There is no noticeable vibration even though I am running cross tread tires on the front axle.

 

yep, I saw this style too, but really it adds too long DS from rear to front with two support bearings. If no automatic hubs this DS is the sourse of vibrations. That's why I'm sceptic about use these trucks on highway

 

cant see reason why not to use transfer case this is much better design and not that heavy lets say vg1600 is 290kg or 250kg in one speed version

vg2000 is 330kg

having no transfer case means more strain to driveline components



if you are interesting in to save weight try to look at hydrodrive , MAN have it since 2005 , it is available in US via poclain hydraulics , in many applications it would be enough ....it almost have no drawback except some oil leak

 

also we consider here that it is best to avoid front wheel drive unless if it is really necessary, when truck with front wheel drive get in age( 10years) it become at least twice more expensive to maintain than truck with only rear drive.... this is "bottomless hole" ( i mean whatever you repair it is never end it is always something wrong )

really necessary means that there is just too much mud and heavy terrain which would damage rear wheel drive truck over longer period



trucks with front wheel drive usually need 5L/100km more (about 1mpg less)