Why not jack trailer under the spring plates?

[opnspaces]

For years people have asked where to place the jack in order to jack up a travel trailer. And people always say do not put the jack under the spring pack. This has bothered me for years because it doesn't make sense to me. Now I'm not an engineer by any means. But could somebody please explain why under the spring pack is bad? I mean look at the pictures below. In an under slung axle the entire weight of the trailer looks to be on two very small u-bolts. Am I wrong? It seems that the u-bolts are holding the weight. If the thin u-bolts are holding the weight.and the spring is on a thin perch welded under the axle; How is jacking at that point going to be a problem?


And in a travel trailer with over slung axles putting a block, or even a floor jack under the axle seems like it would be okay. The axle tube is thick enough to hold the trailer in the air with the u-bolts on top. Are we saying the tube is thinner on the opposite side of the axle tube?

[fj12ryder]

I believe if you do some checking, it's the manufacturers that say not to jack up the trailer by the axles and use the frame instead. But, IMO, that is a simple CYA. If they said it was okay to use the axle, then some nimrod would end up jacking in the middle of the axle so they could lift both sides, or some other moronic reason, and then complain when the axle bends: "But it said I could use the axle to jack up the trailer. It's not my fault".

[Cummins12V98]

Who the HE!! said NOT to jack under the spring pack???

This tho is by far a better option especially alongside the road.

Oh yea the RV weighs 19k. I have also used on my 24k DRV.

[MFL]

I have seen a few cases, of people actually putting their floor jack in an obvious wrong part of the axle tube. One case, two floor jacks, one under each axle of a fifth wheel, landing legs down, and the jacks placed between wheels and axle centers. He was packing bearings, too late anyway, so I didn't comment on his placement of jacks, lifting the whole side, with landing legs down.

There is quite a number of adapters for bottle jacks, that will cradle the axle tube, in the U-bolt area. I just made a wooden block, pictured in the recent travel trailer section, asking similar question. Works good for me!

Jerry

[BB_TX]

!4 years on our 5th and I always jacked under the springs and never a problem.

[time2roll]

ONE wheel? I jack under the u-bolt or spring plate. Wheel service only, do not get under the trailer.
ALL wheels? Lift by the frame.

[phillyg]

When it's said not to jack under an axle, it really means directly on the tube. How else would one place a jack if not under the spring pack?

[Learjet]

That is what I do...better than one of those ramps for tire changes which doubles the weight on one wheel and axle....just saying 🙂

[wa8yxm]

Trackrig wrote:
I jack under the spring plates and have never had a problem.
Bill

I hear a ton of stuff when it comes to jacking Trailers and Motor homes and such most of which causes me to think WTF? That makes no sense at all.

Why not put the jack under the spring bracket plate.. The very part that is DESIGNED to carry the weight of the trailer/vehicle?

GOT me and I did study engineering.. I can only think of one answer (Well two) One the person giving the bad advice thinks the fairly small (Bigger than the top of the jack) plate the jack could slip off.. odds of that happening are low and the fact the top of the jack may well NOT pass between the bolts makes it smaller.

Two They are hoping the jack slips (It's more likely to slip on an "other than flat" jack point) and drop the trailer on you.

There is one special case where I'd .. well I'd still put the jack elsewhere..... Removal of the springs so they can be rebuilt (Done that a few times)

[Tvov]

opnspaces wrote:
.... And people always say do not put the jack under the spring pack.....

"people always say"... a lot depends on who sees this thread and responds.

[jmtandem]

I always jack under the spring plate, no issues so far.

[Pbutler97]

I'd certainly put the jack there before I would ever put it on a Lippert frame if you have one of those high quality POS's

[BobsYourUncle]

I always jack under the spring plates and never give it a second thought.
I usually use a squat bottle jack, take it up far enough to get the wheel off, done.

All this hooplah about it'll bend your axel, bend your frame, wreck this wreck that.... Horse Puckey!

Consider how much any RV flexes, bends, heaves and dips on the roads we drive on. It's a hundred times more than lifting an axel a couple inches.

Take it to a tire store and watch how they jack it. Under the spring plates...

[Tyler0215]

I've jacked under the spring for years, No problem.

[rdhetrick]

You're right about the U-bolts - looks pretty weak but the tensile strength of steel is actually quite high. Not to say at all that the U-bolts are overdesigned, but they could be sized properly.

As to jacking there - it's not a matter of "can" it hold...it's more about "is it the safest point to jack from." It is inherently unstable jacking it up by the springs - a gust of wind could shift the loading, or one of the bolts holding the springs could fail. Jacking it directly at the frame minimizes the points of failure.

It's the same reason we should use jack stands when working under a vehicle. The jack itself should hold, but why take the risk - granted, many of us, myself included, do take that risk sometimes - but it's not the safest way of doing it.

[Trackrig]

I jack under the spring plates and have never had a problem.


Bill