TV Sucked Left by Trucks

[cekkk]

I've been happy for about three years with my Equalizer setup. But it may not be set perfectly. On interstates large trucks that pass me suck the TV a tad towards them about when their tractor overtakes the TT. It's brief and no problem control-wise, but is this normal?

Rig is level with around 40# air pressure in the bags and front end has just a little lighter feel than when not towing. I've had another WDH setup where the front axle was very bouncy, so I know the difference. I have not put it on a CAT scale since doing so a few times when the rig was new.

[lawdes]

I get that with my 38' TT, propride hitch. Sometimes it really gets close! I think it is similar to an airplane wing. the air moving around the truck overtaking creates an area of low pressure between the "wave" of air, and the truck itself. Since the air pressure on the opposite side of the trailer is greater, it tends to push into, or sucked into the area of low pressure. that is the same reason a wing lifts an airplane.

[trail-explorer]

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28538239.cfm

[JD_and_Beastlet]

mkirsch wrote:
You don't feel it as much with a 5th wheel because the pivot point between the truck and trailer is over the rear axle, and the trailer has no leverage on the truck.

Same thing for a Hensley or a ProPride 3P, because the pivot point is projected some four feet forward by design. We have the 3P and there is no turning felt - just the sensation of the rig being pulled slightly towards the passing truck.

[Terryallan]

Yes it is normal. Even he big trucks, and busses feel each other when they pass.

[mkirsch]

You don't feel it as much with a 5th wheel because the pivot point between the truck and trailer is over the rear axle, and the trailer has no leverage on the truck.

[valhalla360]

As long as there is control isn't being lost, there is nothing unusual about it. 5th wheels and MH's also experience it but due to their suspension setup, the feel is generally less.

[Vulcan_Rider]

cekkk wrote:
On interstates large trucks that pass me suck the TV a tad towards them about when their tractor overtakes the TT. It's brief and no problem control-wise, but is this normal?

Yes it's normal.
Congratulations on your steady hand on the wheel.
A minor inconvenience can become major if the driver over-corrects.

It is a complicated process; first the wake from the truck pushes against the back of the trailer, which tends to make the front of the TT go slightly toward the passing truck.

Then when the wake gets to the front of the TT (back of the tow), it tries to push the back of the tow vehicle slightly and makes it feel like the tow is going toward the truck.

If you only notice one deviation from straight during a pass, you are lucky and/or have a good setup.

I too like US routes that are not Interstates.....but you have to be extra careful when stopping. Not many things in little towns take motorhomes and big trucks into consideration when they lay out the parking lots.

[DRSMPS]

This is pretty normal with a TT. Keep an eye on your mirror and watch for semi's and busses that may pass. The alternative is to take the back roads if you can. I do this as much as possible and it is a much more enjoyable drive (as long as you aren't in a hurry).

[cekkk]

Thanks, guys. 3oaks, I looked at the first few posts of that link and am now so glad I asked RV.net and not my son-in-law, who, being a real rocket scientist, would have explained the whole of the physics to me! :S

[3oaks]

Recent thread on same topic:

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28538239.cfm

[2oldman]

yes it's normal for a tt. 5er, not so much. MY 5er and MY truck.. no suck at all.