The Stovebolt Site Forums The Parking Lot Big Bolts 42 1 1/2 ton two speed axle

Thanks for all the great info. When empty I just leave in high, no problem starting off. Usually take off in second gear.

Have halled a few loads and still have never had to use low range. These have been lighter loads, still stretching her legs a bit before putting her under a heavy load.

Haven't shifted the axle on the fly yet, guess a little nervous about tearing something up in the rearend. Will start playing with it soon at low speed.

Trying to treat a 2 speed axle gently can cause a variety of problems. Never, ever back off the throttle and then attempt to make an axle shift, up or down. With power applied, move the shift knob to the desired position, then lift off the gas or momentarily push the clutch pedal. This procedure allows the shift mechanism to "pre-load" and make a quick shift as soon as the load on the gears is released. This process works on both vacuum and electric shift types. If power is released first, it's likely that the rear end will go into a "false neutral" with a lot of gear grinding, and then slam into gear.

A driver trainee I was checking out did that with a Freightliner that had an Eaton 15 speed drivetrain. That one had two 2-speed electric shift axles that acted as a 3 speed unit, plus a 5 speed main box. The intermediate speed was obtained by shifting one axle to low and the other to high, and letting the inter-axle differential make up the speed difference. My guy backed off the power first, and then moved the splitter knob. The rig coasted about 50 feet and slammed into gear- - - - -shearing off a 2" diameter solid steel input shaft! Of course, we were close to max gross weight at the time, 78,000 pounds or so!
Jerry