Can I use a WDH on a DP

bjbear wrote:
Although it is true that a DP with air suspension will compensate for extra weight on the hitch receiver by raising the rear of the coach, that is not the primary purpose of a WDH.

The WDH does 2 important jobs.

1) Reduces the load on the rear axle and distributes it between the front axle and the trailer axle(s). Even though the coach may adjust the air to raise the rear of the coach, it does not affect the extra loading on the rear axle. If your tongue weight pushes you over the GAWR or your tire rating, then you should use the WDH.

2) The second purpose (and in my opinion the most important) of the WDH is to reduce the torque loading on the receiver. When the tongue weight exerts a downward force on the ball, it induces a twisting force (torque) on the receiver. The resulting torque has 2 components. First, is the static loading. This is the tongue weight when the rig is not moving. The second is the dynamic loading which is the resulting force on the ball when the vehicle is moving. For example, when the coach goes over a bump, the hitch moves down and then rebounds. This downward movement can exert many times the static loading as the suspension stops the downward movement and rebounds. The WDH counteracts this dynamic loading greatly reducing the torque on the receiver. This is especially critical if using a hitch extension of any kind.

So the bottom line, is that if your tongue weight exceeds the rating on your receiver OR you are using a hitch extension, you should use a WDH. This is true even if you coach air suspension can keep your coach level.

The following diagram illustrates the effect of a WDH.