The "weight transfer" systems as used by Ventrac and Steiner and "draft control" system as used by Power Trac produce the same end results but they do it a bit differently. That end result is to increase the net down-force on the front wheels of the articulated tractor and somewhat reduce down-force on the rear wheels. This increased down-force produces more traction and increases steering response, i.e., it helps keep the tractor from trying to "push ahead" instead of coming around when turning on a steep sideslope.
When mowing with all of these tractors having decks out front, it is necessary to put the hydraulic lift into "float" so that the deck can follow the contour of the terrain independent of the power unit. That means that only a very small portion of the weight of the deck (specifically some of the hitch parts) is actually applied to the tractor.
On the other hand, if you were to raise the deck completely off the ground, all of it's weight is now carried on the tractor wheels. Now the tractor has the greatest amount of traction and steering response possible. The only problem is that with the deck off the ground you can't mow.
So weight transfer provides a compromise between these two extremes. Mechanical springs on Ventracs and Steiner 430s and a hydraulic boost system on Steiner 525s and 230s and some Power Tracs are engaged to apply SOME up-lift to the front hitch. When the front hitch is in FLOAT position this lift tends to raise the deck, but it is not enough to get the deck wheels and rollers completely off the ground. The wheels and rollers just barely touch and therefore can follow ground contours just as you want the deck to do. But a PORTION of the deck weight is now being carried by the tractor and aids in traction and steering. To see just how much transfer occurs, several years ago I did some measurements and calculations for a Steiner 430 with 60 inch deck. The deck weighed 360 pounds. With weight transfer engaged and the front lift in Float, all but about 40 pounds is transferred to the tractor.
On the Ventrac 4000 series tractors, the amount of weight transfer is adjustable to account for differing weights of front attachments and can be completely shut off. On the Ventrac 3000 it is preset at the factory and is always "on." On the Steiner 430, it is basically either "on" or "off" and is normally used only with a mower deck. On Steiner 525s and 230s it is hydraulically adjustable to accomodate attachments of different weights.
One additional side benefit of having weight transfer is that it also increases the front hitch lift capacity when lifting a heavily loaded slip scoop. I also use it to "fine-tune" the float when using a power broom and power leaf blower.
When mowing with any of these units on level to slightly sloped terrain you won't notice any particular benefit from the weight transfer system. However, if you operate on side slopes you will see a dramatic difference between having weight transfer "on" or "off." (You really can't do this experiment on a Ventrac 3000 since it's weight transfer system is always "on.")
On articulated tractors not equipped with a weight transfer system, when operating on side-slopes you often need to slightly lift the deck to get the needed traction and steering. This works, but the deck is not really following ground contours. Therefore, the operator has to constantly tweak the lift hydraulics to try to keep the deck positioned to produce as level a cut as practical.
Hope this helps.
JackIL
