How does the 2" ball on my truck provide LATERAL stability? Diagrams, please…
[QUOTE=hank;6335687]
How does the 2" ball on my truck provide LATERAL stability? Diagrams, please…[/QUOTE]
Think lateral in a horizontal plane instead of Snark. Trailer fore and aft is lateral in relation to the column loading of the landing jack. Most horse trailers load from the rear so generally a horse leaping in or out produces a force pushing the trailer forward. Hence a lateral load on the jack column. :yes:
Isn’t that changing the definition of lateral?
I honestly don’t get this. In my 2h straight load gooseneck, 4 ft dressing room-the load is in the BACK. A horse ‘jumping in’ (which mine don’t) does not put his weight in the front of the trailer-it is still well behind the dressing room, thus well behind the jack.
I have never felt a shift from horses loading in it unattached.
To be honest this is the first i have heard of this fear.
But I live in the edge like that.
[QUOTE=LMH;6338851]
Isn’t that changing the definition of lateral?
I honestly don’t get this. In my 2h straight load gooseneck, 4 ft dressing room-the load is in the BACK. A horse ‘jumping in’ (which mine don’t) does not put his weight in the front of the trailer-it is still well behind the dressing room, thus well behind the jack.
I have never felt a shift from horses loading in it unattached.
To be honest this is the first i have heard of this fear.
But I live in the edge like that.[/QUOTE]
I’ll take you at your words “honestly” and try to illustrate the issue.
In the engineering world, lateral loading is defined as force applied from the side. Wind blowing on the side of a building is called a lateral load or wind load. Over a large area, this is significant. Barns have more outside columns than the roof weight would dictate. The reason for the greater number of columns is to resist the wind or lateral loading.
In the context of a GN trailer supported by the landing jack, the concern I speak of is bending the jack column. The jack is designed to support great vertical loads like most columns. but, columns are poor forms to resist bending loads. The jack is most vulnerable to bending such as extended after lifting the hitch off the truck. A horse moving into or out of an unhitched trailer generates a force equal to his weight x his speed. It’s one of Newton’s laws. every action has an equal reaction. The jack column has to resist the horse’s force. If it doesn’t, either the trailer slides forward or the jack bends.
Doesn’t this assume the jack is fully extended?
If it is cranked down seems it would solve the problem.
This discussion made me go out and take a good look at my trailer and consider the points discussed thus far. I have a 16 foot 4Star aluminum stock gooseneck made in '95. I have noticed but not thought much about it but my neighbor has a new Eby stock, gooseneck, aluminum, 18 foot. Her axles are set further back (rear) than mine and her trailer does ‘shift/move’ more than mine when loading, normal conditions and hooked. Now I’m wondering just what variables are the cause of the differences in stability.
I was checking out my jack, it is a heavy duty beast and the bottom is like a skid plate, mounted to rock/tilt and I think it would slide before it bent the jack. From what I see the parts of the jack are as heavy if not more so than the parts of the ball/hitch.
I have all kinds of doubts about safety chains and I think I’m in the minority keeping an eye on the safety battery…I live in a town that manufactures horses trailers so probably hear more trailer stories than most folks.
NO!
can’t give you the physics :sadsmile:but, would definitely Not do:no: it; I :no:think someone more experienced than I , probably told me 
that at some point:confused:
[QUOTE=LMH;6339014]
Doesn’t this assume the jack is fully extended?
If it is cranked down seems it would solve the problem.[/QUOTE]
Not really, Helps but doesn’t solve the problem. Most jacks have an extendable section. One has to extend the foot to lift the hitch high enough to clear the ball. The meeting point of the two sections is loose and weak.
This is purely an internet discussion. I am pointing out a failure mode some folks have not thought of. Everybody gets to make their own judgement of their acceptable risk. Just as with helmets, I will not load my horse into my 3 H GN without the truck. Especially in a training situation as the OP posted. Regardless of the trailer damage… A horse in a collapsed trailer will remember the experience, likely making a poor loader even worse the next time.
Hosspuller–thank you for explaining what you were talking about. I thought you were indicating that the box of the trailer was somehow supported laterally by the hitch.
I’ve been told that the reason to never ever load a horse in an unhooked trailer is that if the horse were to freak out (for any reason…) and start throwing himself around, that the trailer could actually flip. When it is attached to the truck, it is much less likely to be able to flip. Seems like a longshot, but one with potentially devastating results.
Especially since you are apparently doing this to train your horse to trailer, I think you should hook up first.
Good luck! 
