Happijac failed while driving down the interstate!

You are talking weight of truck front and rear.

To figure weight on jacks it would have to be with camper only.
And how one would figure that I don't know.

abslayer wrote:
I have a Adventure 980 RDS dry weight 3400 Lbs that has all four 4150 jacks , and have had no jack failures

I have a 3000# dry weight camper and it has 4560 on the front and 4160 in the rear. The reason for bigger on the front is that it has more weight on them then the rear.

I have a Adventure 980 RDS dry weight 3400 Lbs that has all four 4150 jacks , and have had no jack failures

Thanks again for coming back so promptly.My truck is a Landrover Defender crew cab 130. The camper doesn't mention a model number, Just Adventure.manufactured by Caravans Unlimited Inc in the USA The weight is1450 lbs. I don't have a font/rear weight, but whatever it is it should be well within the capability of the Acme screw. Both my failures have been on the front.

Diggerwalker wrote:
4150s on the front. The Zed bracket was distorted by the now bent jack, that took all the weight as the other jack failed. There was no clicking or groaning. The inner part of the jack, like the previous failure,can now be pushed in and out freely. It is no longer held by the nut,I assume.
I'll certainly see if I can straighten the bent one out, but confidence is severely dented in the jack system right now.

Interesting that the 4150's are on the front. They are the light weight capacity of the jacks.

4150/Acme screw =1500lbs
4500/ball screw =1900lbs

From your info it looks like you have a 130 Adventure Camper...I can not find any data on it so:

Do you have any Idea what the weight of your camper is?
And if so, the frontal weight v/s the rear?

All of are interested in your situation. Most of us rarely have any issues with the rear 4150 jacks. Maybe we should.

Jim

4150's use an ACME screw and not a recirculating ball system. It's impossible for them to back spin. The one-way safety brake is only used and needed on the recirculating ball type (4500/4600) to stop them from back spinning. If the 4150 failed it must have broken a weld to separate the nut from the inner tube.

4150s on the front. The Zed bracket was distorted by the now bent jack, that took all the weight as the other jack failed. There was no clicking or groaning. The inner part of the jack, like the previous failure,can now be pushed in and out freely. It is no longer held by the nut,I assume.
I'll certainly see if I can straighten the bent one out, but confidence is severely dented in the jack system right now.

Diggerwalker wrote:
I've now had my second Happijac4150 collapse on me.No warning, just bang!Fortunately it fell onto my partially withdrawn vehicle both times otherwise the camper, would have fallen onto its side.The additional problem,on both occasions, it twists & bends the leg that takes all the load so you end up replacing two! The failed jacks were 1998 vintage ( my latest episode twisted a brand new jack, replaced after the first episode) Can anyone say if the 'failsafe' feature spoken about, is a fairly recent addition? I would say in conclusion, that if anyone else has experienced similar problems, do check the leg that took the 'twist' as I nearly missed the problem. Alive to this problem with the latest collapse, I was quick to spot the bent leg which also included a twisted Zed mounting bracket.
I'm a U.K member and demountable campers with Happijacks are as 'rare as hen's teeth' here, so any help or comment would be helpful.

Collapse? This would not be a fault of the described roll pin problem.

Are the 4150's on the front of your camper?

Are you saying that the bracket/jack mount that attaches to the camper gave way or what?

There has been no instance reported on this TC forum of a 4150 or 4500 collapsing.

Any jack that is grinding/groaning/clicking should be serviced immediately...

As an additional note. There was a post that someone did that said they were able to remove a slight bend in one jack leg that was bent when someone bumped their camper and it toppled.

Jim

I've now had my second Happijac4150 collapse on me.No warning, just bang!Fortunately it fell onto my partially withdrawn vehicle both times otherwise the camper, would have fallen onto its side.The additional problem,on both occasions, it twists & bends the leg that takes all the load so you end up replacing two! The failed jacks were 1998 vintage ( my latest episode twisted a brand new jack, replaced after the first episode) Can anyone say if the 'failsafe' feature spoken about, is a fairly recent addition? I would say in conclusion, that if anyone else has experienced similar problems, do check the leg that took the 'twist' as I nearly missed the problem. Alive to this problem with the latest collapse, I was quick to spot the bent leg which also included a twisted Zed mounting bracket.
I'm a U.K member and demountable campers with Happijacks are as 'rare as hen's teeth' here, so any help or comment would be helpful.

stevenal wrote:

stevenal wrote:

Upon further thought on the subject, I believe there is a design flaw here. It's not clear in the picture, but the threads don't stop at the collar, they extend to the hidden top of the rod. The inside of the collar is cylindrical, un-threaded. The joining pin then crosses a gap from collar to shaft so that the force on the pin is a bending moment. In my experience, roll pins are used where they are subject only to shear forces such as the pin located a bit higher in the photo. I'll be inspecting my other 4500 once the camper is off the truck again.

I agree that using a roll pin in that application is not right. Roll pins are only designed for shear so it might be best to take the screws to a machine shop with a lathe and turn the shafts down to the minor diameter of the thread and then have a sleeve machined to fill the void. Match cross drilling the sleeve could be a bit tricky but the roll pins would be back in a shear situation.