Forces on frame w/WDH on a grade

-Fab Rotating, Hitch Mounted Skid Wheels for RVs



They have bigger ones (higher weight rating)

Code: UF48-979014

Retail:$102.59

Price:$84.95

Shipping Weight: 17 pounds



Ultra-Fab Products Motorhome Accessories - UF48-979014

Clamp these sturdy steel wheels onto the square crossbar of your low-profile RV's rear hitch to help prevent tail dragging when backing up. Rotating wheels protect your undercarriage from unnecessary damage.

Features:

Unique casters clamp onto the rear trailer hitch receiver of your RV to help prevent tail dragging and digging in while backing up
Mounting brackets and hardware included
Wheels rotate for full range of motion
Sturdy steel construction and extra-durable roller bearings are long-lasting
1/4" Thick urethane layers outer edge of each wheel
Provides anti-skid barrier
Ensures that wheel lasts even longer by avoiding metal degradation



Specs:

Application: low-profile motor homes that are up to 30' long and have 2-1/2" x 2-1/2" square hitch tubes
Wheels can be attached to 3-1/2" x 3-1/2" tubing with longer bolts (not included)
Wheel diameter: 4"
Quantity: 2 casters
1-Year warranty



48-979014 UltraFab Swivel Skid Wheels - Hitch Mount - For Low-Profile RVs up to 30'

I learned to remove the WD bars on the Equalizer. If the hitch wants to touch down/drag simply put some boards under the rear wheels of the truck. I keep some 2 x 12's that are six feet long for this purpose and they work fine on my driveway that causes a problem as described.

I put a permanent bend in one of the bars, so you can imagine the stress that was being inflicted on the trailer frame. When I did this I flipped the bar over next trip and it straightened back out (mostly). Now I remove the bars and use the boards. I thought about a caster or roller under the hitch but the boards work fine.

John,

That was very informative. Thank you.

My trailer does have a super slide and the frame looks really beefy.

I will keep an eye on things however.

Todd

Daystorm,

Your camper looks like it has a super slide and as such the trailer may be made stronger on the A frame. Don't know what A frame or even more so, header setup you have. The A frame may not necessarily be the weak link.

We had a good discussion a while back on this hitch angle question and the forces. We sort of nick named one set of forces in the hitch as "back flex" when the truck is on the level and the camper up hill from it or the camper on the level and the truck going up hill.

Then there was "truck lift" We nicked name that what happens to the back of the truck when back flex occurs. The spring bars load up, truck lift occurs and then the bars settle back closer to the normal loads.

However this was all going forward. Going back words like in your case, the truck receiver "might" be the weak link. Going forward and over high up RR crossing and back down, creates back flex and truck lift but the receiver is pulling all the time going forward.

When in reverse and the TT going up hill, the receiver is under different loading being pushed by the truck. You have 1,200# WD bars on a receiver rated for how much? 1,000# or is it larger? The older F150's where on lower ratings. Don't know what the new ones are.

When backing up, the receiver is driven down and going up hill creates another dynamic with back flex and until truck lift occurs.

Point: Keep an eye on the receiver for a permanent bend downwards or cracks. If your receiver has lots of rating above the WD bars, this helps reduce the concern.

Actually taking the WD bars off totally and backing up on a marginal rated receiver may be even worse.

Hope this helps

John

Wow, it's hard to believe enough force is applied to snap those bars like that.

My lightweight trailer has a sticker warning on the frame against the use of bars over 1000 pounds' rating. I'd hate to see what that force would do to my A-frame with the use of bars that are too heavy for them.

Shown is a 1200lb Reese bar. Snapped going into a seriously off camber turn entrance at a truck stop earlier this year. You make a right off hwy, then an incline that slopes to the left as you make a second hard right that slopes downhill. You end up facing the direction you were coming from. Heard a snap and a "ting ting ting" looked back and saw this. No damage to trailer, bracket, nor hitch.

My truck shows a 6 degree slope that lasts about 15 feet. Then it goes to 2 degrees for about 15 feet and then 0 the remainder.

I've been doing this for a year now so I guess if something was going to break it would have happened already.

daystrom wrote:
I have an Equal-i-zer brand hitch with 1,200/12,000 lb bars.

My trailer's tongue is 1000 lbs loaded weighed using the bathroom scale method.

I have to back into my driveway when storing the trailer. My driveway has a slight incline from the street and then it levels out.

My question is what kind of forces are going on to the frame of the trailer and/or truck when the trailer is going up the incline while the truck is still somewhat level?

Yes, the force applied by the spring bars increases as the trailer goes up - and the force applied goes down as the trailer goes lower. How much depends on the spring bars and the angle. You called it a slight incline, so it may not be more than 1200 lbs.

My thinking is the spring bars are lifting the rear of the truck up until it levels out.

The spring bars are lifting even when level, otherwise there would be no point in using them. :)

I guess I'm just wondering if I have too much force on something while backing up with the potential of breaking something?

The Equal-i-zer doesn't have chains - right? If it did, you could just loosen a link or two when entering or leaving the driveway. But I wouldn't expect a problem - because the shock and bounce of driving down a level road will multiplying the 1000 lbs load the bars are putting on the frame. Driving slowly across a slight incline may put as much as 1500 lbs on the frame - but without the shock and bounce. Also remember that there are two spring bars, so 1500 lbs is still only 750 lbs per frame rail.

But I am speculating because I don't know the construction of your trailer frame, how the Equal-i-zer bars are attached to it, or what the tow-vehicle to trailer angle really is.

I have to back up a pretty steep incline, and jacknife nearly 90 degrees to put our Keystone Outback away. Never remove Equalizer bars, never had any trouble. Same goes for previous TT. So been doing it for over ten years with no issues.

N-Trouble wrote:
The bigger question I am dying to know is where do you get a 1000lb bathroom scale?? LOL...

Barney