Rocking suspension

Generally dual levelling valves are much more stable than the single valve setups.

I have come across this issue before on another truck. Dual leveling valves but one was replaced with the wrong valve. One was more sensitive than the other, so the sensitive side dumped/filled the bags on that side much more rapidly. Swapped it out so they both matched and it was all good.

 

Leveling valves should be for axle not for side. Check if some mechanic messed up it.

 

A levelling valve for each side is actually a legitimate factory option from most manufacturers. Typically found on trucks that run off pavement often. Very rare to see on a highway spec truck.

 

Kenworth used them on trucks early to mid 2000s and i am sure others. They were most common on the 8 bag suspensions. I removed one valve on the ones that i could not get to work right for long and ran the valve on LFD. It may have been intended to stabilize cornering but i have no idea.

 

I can only imagine. I have hauled oil in trailers and milk in a straight truck. That's a big tank.

 

What is the effect of that?

Does it improve traction?

 

Stability mostly I think. Rather than all 4 corners being equal pressures, the bags on each side are equalized.

With a single valve, the truck will lean if its loaded heavy on one side. With dual valves, the heavy side will get more pressure in order to keep the frame level.