How are most semi transmissions lubricated?

Transmission case has gear oil in it. Oil is flung around by the turning gears. Driveshaft is disconnected from the rear axle so the transmission is not damaged during towing. When the driveshaft is disconnected in this way, the transmission gears do not move.

 

Correct. Splash only. ALWAYS disconnect the driveshaft when towing. Remember, the engine and transmission are hooked together.

 

Dont know about that. The accepted practice is to unhook the driveshaft from the rear axle.

 

Allot of towing companies just pull one axle out and put cardboard over the hole.
With a tube out, I'll spin the spider gears instead of the driveshaft as it's the least resistance.

 

There actually is a pump in most transmissioms, driven off one countershaft. Usually supplies the cooler circuit and the return oil gets routed to critical areas. Ultimately the goal when towing a truck is to prevent the transmission from being turned with the engine off so it doesn't fail due to lack of lubrication.

 

if they can't tow from the back then they are pulling the shaft, I would never let a tow truck driver pull my axle.

I work with a guy who flat towed his rig a week after a motor rebuild. he now has a new new rebuilt motor and tranny, everything heated up so bad it melted.

 

As a tower with over 20 years in the field, and a diesel mechanic, it is preferred to pull the driveshaft but some pressed in u-joints are difficult to remove or there is driveshaft damage so it is acceptable to pull axles. DO NOT let the tower pull only one axle, this will cause the differential spider gear to overheat and damage your differential, pull ALL 4 axles or the driveshaft.

The axles in a heavy duty truck are full floaters, so there is no chance of damaging anything by pulling them, just be sure they put a real axle cap on it not just some old piece of cardboard or rag stuffed in the hole. Granted, on some differentials you have to lock in the locker or you may drop the pin which will cause damage, but generally speaking it is just as safe, if not safer to pull the axles. When pulling the driveshaft the tower has to be sure to "unload" the tension or they could be seriously hurt, plus if it is a timed shaft they could mess up the timing if they pull it all the way out from the truck, I recommend just disconnecting the shaft from the front differential and tying it to the frame rail with a strong strap or mechanic wire. It is also imperative to use new strap and bolt kit when reinstalling, the straps and bolts stretch and are one time use only. This is why as a tower I will not reinstall a driveline, ever, not going to take the liability for it.