At what point is a double frame truck needed??

actually 5/16" rail is your standard rail bulk haulers drop down to a 1/4" rail 3/8" X 11.5 usual take about anything you would throw at it within reason the old double rail was 5/16 +1/4 there is some 3/8 +1/4 but a 1/2" steel rail is hella heavy duty

 

they use to take a 1/2" flat and weld under the bottom frame flange to stiffen it up some say it does as much as double railing. you mean like 5.02s, 5.73s and 6.34s?

 

Mines 11 5/8 frame height (3/8"). On the build sheet is has "Cross member, lift axle" & "Cross member, aux. trans". They are big "I" beam castings (not steel C) that run between the rails that bolt to 2 castings top & bottom of each that cover about 2' of the frame fore-aft. Hard to describe....

 

Mine are 10 1/2" X 1/4" double frame.

 

That setup is like my buddy's quick switch tractors. He's also got an 8-axle long logger that's double/triple frame- that thing is heavy for a day cab.

 

Mines a 240" 4 axle daycab I'm 24,000 empty.

 

All my dad's old tridrives were 3/8" single frame (tall rails), 69k rears, 6 way lockers, 18k front axle with dual steering boxes (required for extra assistance due to the heavy steer weight and wide base steer tires). My truck only has 1/4" x 10-1/8" frame. Its gonna be a single screw and probably run no more than 30-40k lbs gross once its up and running.

 

Dual range rears is what you want. Ours are 4.11 on the high side and work for most everything and 5.33 on the low side. Real nice for pulling passes when heavy. Almost like having another gear on the high side of the transmission. Sometimes it is even enough to keep you from having to drop to the low side on the transmission. We have three trucks with that setup.