White Twinscrew?

[rmgill]

What is a White Twin screw? Two separate drive shafts to each rear axle?

http://www.armyjeeps.net/Armor/saracen_6x6_apc.htm

 

[mangus580]

2 Drive axles? Is my opinion

 

[No.2Diesel]

Maybe it refers to the truck's engine having both a supercharger & turbocharger. Thats my guess.

 

[mangus580]

You might be on to something there.

http://en.wikipedia.org/wiki/Twin-screw_type_supercharger

 

[Elwenil]

I have also heard the term used with truck transmissions.

 

[Boatcarpenter]

I think it is just truckers' lingo for a tandem drive axle tractor. Single axle tractors are just known as single screw.
BC

 

[jasonjc]

2 drive axles

 

[Autocar]

It refers to the tandem axles. Twin screw means there are two rear axles and they are both driving(powered) axles as opposed to having only a single rear axle or tandems with one driving axle and one tag(unpowered like a trailer) axle. Is this truck and trailer rig for sale?

 

[No.2Diesel]

I stand Corrected:

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The 'Twin-Screw' Tandem


What we've described above is a single-drive axle. A tandem-drive axle comprises two single-drive axles linked by a short drive shaft. Because the tandem has two sets of gears, it is often called a "twin screw." It's also called a "live tandem" because both axles drive. (A tandem using one live and one "dead," nondriving axle is called a "tag tandem" if the dead axle is behind the live one; and a pusher tandem if the dead axle is ahead of the driving axle.)

Attached to the forward of the two driving axles in a twin-screw tandem is an interaxle differential, or "power divider." This takes incoming power from the driveshaft and splits it between the two drive axles.

Power is therefore divided between the two axles, and between each wheel on each axle. The power splitting is almost never equal, for it is automatically and constantly adjusted according to conditions at the moment.

Standard differentials, as clever as they are, are rather stupid in the power splitting function. They send power to the axle and wheels which are spinning the fastest. This is fine when going through corners, as more power to the outside wheel will tend to push the truck in a more stable fashion.

But if the wheel is merely spinning on mud, snow or ice, it will get even more power because the differential doesn't know any better. This is true, too, of the interaxle differential, because it will send power to the axle whose wheels are spinning faster. If the rear axle is on ice, it will get even more power.

However, most interaxle diffs come standard with a locking device which stops the differential action and splits power 50-50 between the two axles. Most axles do not have locking diffs, so the wheels can still spin uselessly. Locking the interaxle diff, tho, will likely result in at least one of the four drive wheels grabbing onto something and pushing the rig out of a slippery predicament.

Nowadays, some axles can be ordered with locking differentials, either automatic or driver controlled. These are something to consider if you're interested in traction, which is priceless when you encounter slippery pavement or tough going off-road. Locking diffs are useful in single- or tandem-driving axles.

A variation on this theme is automatic traction control, which is a cheap option with today's anti-lock braking systems. ATC is electronically engaged whenever the wheels begin spinning; the electronic brain gently applies brakes to stop spinning wheels and sometimes cuts back engine power, as well. Fleet experience shows it works as well as most mechanical locking devices.

 

[mangus580]

Keep in mind, the supercharger theory may still hold some value.... That truck is listed as having a Detroit Engine, which were usually supercharged.

Food for thought...

 

[gimpyrobb]

A detroit requires the supercharger to run.

 

[emmado22]

Technically, it is both, but ask any trucker what a twin screw is and he'll tell ya it's a tandem axle, way before he thinks of the supercharger...