Homemade jack pads

[jask]

I see no problem with the design using a good quality bolt.
I have never weighed an aircraft main but I don't think I could bend that bolt.

[rjcthree]

I like this idea a lot, C/S the bolts makes it even better. I?d buy a set. It hits on my biggest C/C concern.

[Hornet2008]

When jacking does the gear leg move outwards? I have the Avery type jacking arrangement and as it rises the gear leg moves outwards.

[Bicyclops]

Originally Posted by Hornet2008

When jacking does the gear leg move outwards? I have the Avery type jacking arrangement and as it rises the gear leg moves outwards.

I didn't notice it move significantly, though you might expect it to have done some. With the Avery style pad you are sticking a tube into the end of the hollow axle and putting a jack, what, about 10" or so outboard of that. That's what I used to get it off the ground while I was installing the jack pad and I did notice the flex to which you refer. You are basically levering it up and it's no real surprise that it bends as if it were in the process of a hard landing. Where the jack pad is mounted is putting the lifting force right into the gear leg instead of out at the end of the axle.

I was wondering if my new setup would wind up putting the auto jack up on an edge. That's the main reason I wanted the jack bolt to be the full width of the jack. I was hoping that the head of the bolt would prevent it falling off if it came to that. It didn't move on the bolt at all and, as you can see in the picture, there is still space before the jack hits the bolt head. Though it isn't obvious in the picture, the tire was well off the pavement. I'll have to jack it up again and see if I can get a measurement of any outboard movement, but I didn't notice any the first time. My impression is that it went straight up.

Ed

[KitfoxJoe]

Really like the idea! Where can I buy some 6061 alum 1"by 11/4" Thanks Joe

[ty1295]

Using 1/2" Bolt and 29k psi as point the bolt starts to bend, shows it would be around 5,800 lbs. Hopefully nobody built an RV that heavy.


A 1/2" bolt will shear @ around 10,000 lbs


I suspect bolt size is not a problem.

[Bicyclops]

Originally Posted by KitfoxJoe

Really like the idea! Where can I buy some 6061 alum 1"by 11/4" Thanks Joe

https://www.aircraftspruce.com/catal...ges/6061t6.php

They've also got 2024 T3 which would be stronger, but not in that exact size.

Ed

[Bicyclops]

Originally Posted by ty1295

Using 1/2" Bolt and 29k psi as point the bolt starts to bend, shows it would be around 5,800 lbs. Hopefully nobody built an RV that heavy.


A 1/2" bolt will shear @ around 10,000 lbs


I suspect bolt size is not a problem.

I'm using a 1/4" bolt with a sleeve of 4130 around it, bringing it to 3/8" OD. I think that the ultimate strength of the bolt isn't the issue, anyway. I wouldn't worry about shear. Bending would be the potential problem and I don't think it will.

The hole in the jack pad is probably the vulnerable part. It could oval at some point. We'll see. I wanted to reduce the stress on the tapped threads by carrying the load in shear as much as possible. I could have set a heli-coil, I suppose. If the threads start getting loose, I will. It's not like it's going to get used very often, anyway. At annual to rotate the tire and grease the bearings and maybe once more if I manage to wear out a tire in between annuals. If it holds up through one flat tire repair away from home, it'll have been well worth the effort.

Ed

[AndyRV7]

Originally Posted by Bicyclops

I was wondering if my new setup would wind up putting the auto jack up on an edge. That's the main reason I wanted the jack bolt to be the full width of the jack.

Brilliant job!

The first time I had to jury rig a solution to a flat tire I used the smallest (lowest!!) scissor jack I could find and put it under the small bolt that holds the wheel pant to the axle nut. Clearly not a robust solution but it served the purpose. But YES, it does tip the jack. It worked but I wouldn't try it again unless under the worst circumstances.

I learned 2 things. First, you need a small or large amount of extension away from the wheel or you cannot get the jack close enough to sit under the jack point. Two, you probably need some amount of height added to the jack point as well, or the jack will likely be too tall to fit under the jack point.

Thanks for the ideas. I am going to take a look at the problem again using you solution. I like the fact that I can build something using hand tools!!

Incidentally, when I saw your mount, I presumed it was temporary. So in my mind, I could fabricate something that wouldn't fit under my wheel pant because I could carry it in my flight bag and attach it as needed with an open-end wrench.

Thanks for sharing!!

[Pilot135pd]

What about using the holes where the tie down rings screw in? I bought a couple of Category8 bolts at Tractor Supply, screw them in and put the jack under that and it lifts the entire wing. I got the idea here https://antisplataero.com/products/quality-jack-points