Attention: TDR Forum Junkies 
Cut and pasted from the Reese Hitch Products website:
"Operation of Reese Weight Distributing Hitches
#ad
The Reese differences are in construction materials, welding, manufacturing processes and hook-up. Adjustment is simple because of the easy-to-operate snap-up brackets that allow spring bar tension to be adjusted by changing links in the support chains. This lets you adjust for various trailer tongue weights within the spring bar weight range by applying tension on the spring bars until the car or tow vehicle is level. Rather than merely supporting the trailer tongue weight (TW), weight distributing hitches apply leverage between the towing vehicle and trailer causing the TW to be carried by all axles of the tow vehicle and trailer. When TW is distributed in this way, trailers with greater TWs can be towed, resulting in a more level ride which reduces stress on the rear of the tow vehicle and provides greater steering and brake control.
<TABLE border=0 cellSpacing=0 cellPadding=0 width=440 align=center><TBODY><TR><TD></TD><TD></TD><TD>#ad
</TD></TR><TR><TD align=middle>Without Weight Distributing Hitch</TD><TD>#ad
</TD><TD align=middle>With Weight Distributing Hitch
</TD></TR></TBODY></TABLE>
Pay particular attention to the bold, italicized sentences.
"Operation of Reese Weight Distributing Hitches
#adThe Reese differences are in construction materials, welding, manufacturing processes and hook-up. Adjustment is simple because of the easy-to-operate snap-up brackets that allow spring bar tension to be adjusted by changing links in the support chains. This lets you adjust for various trailer tongue weights within the spring bar weight range by applying tension on the spring bars until the car or tow vehicle is level. Rather than merely supporting the trailer tongue weight (TW), weight distributing hitches apply leverage between the towing vehicle and trailer causing the TW to be carried by all axles of the tow vehicle and trailer. When TW is distributed in this way, trailers with greater TWs can be towed, resulting in a more level ride which reduces stress on the rear of the tow vehicle and provides greater steering and brake control.
<TABLE border=0 cellSpacing=0 cellPadding=0 width=440 align=center><TBODY><TR><TD>
</TD><TD></TD><TD>#ad</TD></TR><TR><TD align=middle>Without Weight Distributing Hitch</TD><TD>
#ad</TD><TD align=middle>With Weight Distributing Hitch
</TD></TR></TBODY></TABLE>
Pay particular attention to the bold, italicized sentences.
