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Dlaker · 10-06-2018, 09:28 AM

This is likely a physics question that after about 20,000 miles of towing I still can’t seem to figure out. I tow my 2016 25-foot FC using a Blue Ox Sway Pro weight distribution hitch. Consequently, before unhitching and after chocking the trailer wheels, I jack the trailer up as high as it will go to take the pressure off the sway bars to make unhitching them easier, and then lower the trailer back down to un-lock the trailer hitch. All standard stuff. But when I raise the trailer back up to disconnect the trailer from the hitch ball, at the moment of disconnecting, the truck often jerks forward (away from the trailer) if the parking brake is not on. So should I use the parking brake on the TV when unhitching to prevent that lurch forward and release of energy? Would using the TV parking brake make the trailer try to lurch backward while the truck stays put? Seems to me that it's better that the truck moves than the trailer. This obviously also demonstrates the need to always chock the trailer wheels even if on level ground.

CRH · 10-06-2018, 10:10 AM

I always use the parking brake everytime I exit the vehicle....I have a buddy who recently didnt set his brake and thought he was in gear (manual) when he stepped out of his truck on relatively flat ground. As he stepped out with his left foot, the truck began rolling backwards and knocked him off his feet. His right foot got trapped under the pedals. He was dragged upside down until his truck stopped in a ditch.

I set the brake no matter if its auto, manual, flat ground, or whatever. I especially don't want to be between the truck and trailer and have a mishap.

Back to the original question. Yes, my auto truck will sometimes spring loose off the ball if the brake isn't set. Neither the truck nor trailer seem to jolt if the brake is set.

featherbedder · 10-06-2018, 10:23 AM

Quote:

Originally Posted by CRH

I always use the parking brake everytime I exit the vehicle....I have a buddy who recently didnt set his brake and thought he was in gear (manual) when he stepped out of his truck on relatively flat ground. As he stepped out with his left foot, the truck began rolling backwards and knocked him off his feet. His right foot got trapped under the pedals. He was dragged upside down until his truck stopped in a ditch.

I set the brake no matter if its auto, manual, flat ground, or whatever. I especially don't want to be between the truck and trailer and have a mishap.

Back to the original question. Yes, my auto truck will sometimes spring loose off the ball if the brake isn't set. Neither the truck nor trailer seem to jolt if the brake is set.

A word of caution if using parking brake in freezing weather the cables can freeze then cannot release brakes.

uncle_bob · 10-06-2018, 10:32 AM

Hi

The "unhook lurch" can occur with or without the parking brake. It has as much to do with the relative angle of the TV and TT as anything else.

One other note (do as I say ...not as I do ...). Running the jack up to release the WD hitch is one of those things the jack manufacturer gets bothered by. They seem to want you not to do it ....

Bob

pteck · 10-06-2018, 11:00 AM

Agreed that the unhook lurch can occur independent of anything else. Can't really avoid it sometimes. Just depends on the tension that is left in the lashup. I find it's more likely to occur when on uneven ground because of odd angles and pressures to keep things where they are.

As with CRH, I always set the parking brake. I would emphasize this is especially important when under tow. One never wants to only rely on the parking pawl in general, but especially so with 2x the vehicles weight to potentially hold in place.

TG Twinkie · 10-06-2018, 01:28 PM

Quote:

Originally Posted by uncle_bob

Hi

The "unhook lurch" can occur with or without the parking brake. It has as much to do with the relative angle of the TV and TT as anything else.

One other note (do as I say ...not as I do ...). Running the jack up to release the WD hitch is one of those things the jack manufacturer gets bothered by. They seem to want you not to do it ....

Bob

That's because the ratings on their tongue jacks are sketchy. IMHO
If you have a trailer with 1,000 tongue weight and a TV that is equally as heavy at the hitch a 3,500 pound tongue jack should have no problem raising the units high enough to set or unset the WD system.
If your jack fails in this process. Get a new jack with a higher rating.

CRH · 10-06-2018, 01:33 PM

Quote:

Originally Posted by featherbedder

A word of caution if using parking brake in freezing weather the cables can freeze then cannot release brakes.

I still set the brake. Yep, i have a truck that has a cable that occasionally freezes. I carry a piece of PVC with a hook on the end in the bed. On cold mornings, I have had to yank the cables to release the brake.

uncle_bob · 10-07-2018, 07:54 AM

Quote:

Originally Posted by TG Twinkie

That's because the ratings on their tongue jacks are sketchy. IMHO
If you have a trailer with 1,000 tongue weight and a TV that is equally as heavy at the hitch a 3,500 pound tongue jack should have no problem raising the units high enough to set or unset the WD system.
If your jack fails in this process. Get a new jack with a higher rating.

Hi

One *might* note that AS has upgraded all the power jacks to ones with higher ratings for the current model year .....

One gotcha is the assumption that the truck side also weighs some specific amount. It certainly is going to be less than the total weight on the rear axle, but how much less? The drive shaft / differential / axle are all still on the ground so they come out of the math. Do you have the gold brick collection in the bed of the truck?

Bob

2partners · 10-07-2018, 09:34 AM

Hi,

I hope this isn't a "duh" statement since we are new, but... In our brief history we have found that sometime when we get into a campsite it's just enough off level that it makes it difficult getting the W/D bars off, at least with our setup. What we are trying now is once we get close to the campground on level road we stop and just remove the bars so we have one less thing to take time doing when people are waiting for you to get out of the way. I suppose this isn't a good idea if your rig would sag in the middle. Ours doesn't. I wonder if this would help your situation?

Chris

franklyfrank · 10-07-2018, 10:33 AM

Quote:

Originally Posted by TG Twinkie

That's because the ratings on their tongue jacks are sketchy. IMHO
If you have a trailer with 1,000 tongue weight and a TV that is equally as heavy at the hitch a 3,500 pound tongue jack should have no problem raising the units high enough to set or unset the WD system.
If your jack fails in this process. Get a new jack with a higher rating.

The 3,500 # jacks Airstream installs are puny, especially with the longer trailers. On my previous 30' international I replaced it with a 4,500# and what a world of difference.
I will be swapping out the one on our current 30' Classic this winter now that I got 2 years out of it.

jamieb1086 · 10-07-2018, 02:58 PM

After you get the bars off, chock the trailer and allow a bit of distance between the tires and the chocks. Get in the truck, take the brake off, put it in neutral to let the vehicle move to take the pressure off the ball. Set the brake, put it in park, chock the trailer tightly, then raise the hitch off the ball. A lot less movement now that I’ve been doing this.

Dlaker · 10-07-2018, 03:23 PM

Quote:

Originally Posted by uncle_bob

Hi

The "unhook lurch" can occur with or without the parking brake. It has as much to do with the relative angle of the TV and TT as anything else.

One other note (do as I say ...not as I do ...). Running the jack up to release the WD hitch is one of those things the jack manufacturer gets bothered by. They seem to want you not to do it ....

Bob

Thanks for all the good information. I too have found that it often depends on the relative angle between the TV and the trailer, and the same goes for getting the WD bars unhooked. If the TV is heading slightly downhill compared to the level trailer, then the WD bars unhook very easily. But I think that keeping the parking brake on no matter what is a good practice. On another note, with these Blue Ox WD bars, if you don't raise the trailer, how the heck can you get them unhooked without breaking an arm (or worse)? Sometimes I have to raise it as far as the jack will go and then hand crank it a bit more.

Dlaker · 10-07-2018, 03:25 PM

Quote:

Originally Posted by jamieb1086

After you get the bars off, chock the trailer and allow a bit of distance between the tires and the chocks. Get in the truck, take the brake off, put it in neutral to let the vehicle move to take the pressure off the ball. Set the brake, put it in park, chock the trailer tightly, then raise the hitch off the ball. A lot less movement now that I’ve been doing this.

And this sounds like a good solution. Thanks for this idea, will try later this week.

pteck · 10-07-2018, 03:36 PM

Quote:

Originally Posted by Dlaker

On another note, with these Blue Ox WD bars, if you don't raise the trailer, how the heck can you get them unhooked without breaking an arm (or worse)? Sometimes I have to raise it as far as the jack will go and then hand crank it a bit more.

I've definitely been in situations like this. A strategy if one knows the TV is going to have a nose up attitude relative to the trailer is to run the rear axle of the TV up on leveling blocks to take some tension off the WD blocks. Or preemtively remove the WD bars while still on level roads.

I'm fortunate that my TV has hydraulic suspension with the ability to adjust it's height over a 5" span. It's helped on so many boondocking occasions and is worth its weight in gold to me.

I imagine a TV fitted with rear airbags might have a similar capability should the situation arise.

Countryboy59 · 10-07-2018, 03:55 PM

I always chock wheels and use the parking brake after I put a little tension in the system when unhitching the Hensley. Makes it easier to pop the stinger if there’s a little tension. Other than that, I never use the parking brake.

The Colonel · 10-07-2018, 05:23 PM

Guess there’s a lot of good advice here, but this is what I do. When getting on site I get to level side to side, then chock both sides, I have dual axles and use the step on chocks that go between the tires. I then have dw who is then in tv release brakes and put it in neutral. That releases any forces one way or the other and let’s me know if there is a problem to deal with. I then put the tongue jack down and raise to front up to release bars. Lower then and disconnect to from tv. Have dw apply brakes while tt comes out of tv and clears hitch then have her pull fwd. works well for me. No surprises

featherbedder · 10-07-2018, 06:51 PM

W/Reese dual cam just raise w/jack then release snap ups then lower arm leaving bars hanging take off then lower release coupler latch raise again pull forward then lower front to level, no strain no chance of injury. Word of caution use pipe to release and raise snap ups.

uncle_bob · 10-08-2018, 07:17 AM

Hi

On a factory tour a month back I saw that all the power jacks now have 4500 pound stickers on them. I assume that makes them better than the old 3500 pound sticker jacks. What the real ratings on any of them are in this or that situation .. who knows.

====

The stock recommendation for pretty much any of the "removable bar" type WD hitches is to take them off before you start into the campground and put them back on once you are out of the campground. Anti sway likely isn't needed at campground speeds. WD tends to get weird when your truck and trailer are at sharp angles to each other. Yes, this all *assumes* you don't bottom out (or break the rear axle) when the WD is removed. Hopefully you thought that through when you picked your tow vehicle ....

Bob

DreamStreamr · 10-08-2018, 07:39 AM

Simplest solution, I found it in my tv’s owner manual. Not just about towing, either.

When stopped, place tranny in Neutral then set the parking brake and put tranny in Park. Reduces tension at the coupler so lessens the truck’s lurch when released from coupler. Then chock trailer wheels before raising coupler jack. Has helped me a lot in unhitching, saves time and “tension”.

Hiho Silver · 10-08-2018, 07:42 AM

Quote:

Originally Posted by uncle_bob

Hi

====

The stock recommendation for pretty much any of the "removable bar" type WD hitches is to take them off before you start into the campground and put them back on once you are out of the campground. Anti sway likely isn't needed at campground speeds. WD tends to get weird when your truck and trailer are at sharp angles to each other. Yes, this all *assumes* you don't bottom out (or break the rear axle) when the WD is removed. Hopefully you thought that through when you picked your tow vehicle ....

Bob

"stock recommendation"? I would disagree. I use a blue ox, with my F150 towing a 27' Flying Cloud. This would not work for my rig, and yes I am level with the bars on, but might drag the bottom of the hitch with the bars off and any type of incline. I like to stay level with the bars on when backing into a campsite, works for me!