Lifting gear legs to replace tires

[johneeb]

Arish,
What a great idea! That is why they employ so many of us engineers on these projects. We will have to give it a new designation, probably the -A (for Arish) model

[Bruce Fenstermacher]

Posted for Frank:

• I vowed I was going to learn how to post photos on the forum, but my computer is on the fritz and I am going to get a new one or see if this one is fixable. Anyway I wanted to show a jack pad I had built several years ago.
  
  I used C clamps and 1 X 4's for years with pretty good results, but a friend has a C-206 and someone made him this jack pad so I copied it. It really works well and is substantial (overkill) enough to use on a Cessna Caravan! Its made from a couple of pieces of 2 1/2 inch X 2 1/2 angle (1/4 " thick) by about 10 inches long (ea). The post is about 10-12 inches long is made from one inch round steel stock. I lined the two pieces that go on the gear leg with leather to protect the paint.
  jackpad 002.jpg
  jackpad 004.jpg
  jackpad 005.jpg

This design with the leg that extends down help with the issue of not having a jack that extends far enough to engage the angle or 2x4 or even the Cessna design pad.

[daedaluscan]

I like that a lot, gets the jack away from the wheel. And the apprehension away from the owner that a tapered channel style pad will roll off.

[GAHorn]

Those tires are the aero-classics from Desser...and they wear very well. Mine are going to be replaced purely due to chronological age.

I'd be very careful about that jacking method. It can place undue bending moment on the gear leg should the airplane shift any at all (due to the leverage of the long-lift-leg.)

[Bruce Fenstermacher]

I'd be very careful about that jacking method. It can place undue bending moment on the gear leg should the airplane shift any at all (due to the leverage of the long-lift-leg.)

So you think any more of a bending force than the wheel itself has on the gear? The axle has a longer arm than the jack extension. So it would be my conclusion you couldn't bend the gear any more than rolling along and hitting a bump. Always good to think these things through though.

[GAHorn]

Actually, I'm more concerned with the bending moment on those 1-1/2 inch angles dropping the airplane. (The axles are immoveably bolted to the gear legs with four, quality AN or NAS bolts spread out over a 4 square inch area, as opposed to two, plain-steel 1-1/2 inch angles which sandwich the gearlegs..... a lot less purchase area, cushioned with cork or whatever, which allows quite a bit of movement.)
Even a "c-clamp" will grab the gearleg more securely.

[Bruce Fenstermacher]

I see your point. I'd have liked a bit wider area in contact with the gear. My first thought when seeing them was the bar had to be welded really well with the end butt weld as it is. I'd have drilled a hole in the bar and stuck the bar in it then welded. Then I saw it looks like the bar is also welded to the right angle and not just a butt weld so this would be better. Perhaps some gussets in the triangle so it won't fold. Of course them we need to get rid of those bolts in favor of some 7/16" fine thread grade 8 bolts.

Good thing we weren't around to share our ideas when Frank made this or it'd be so over built you'd need a hoist to get it in position.

[cessna170bdriver]

You can also take two small lengths of 2x4 and two "C" clamps. Clamp the wood on each side, then use a floor jack on the corner of the wood. Wont gall the paint and is easy to do.

I use two pieces of 1/2" all-thread and large area washers in place of the c-clamps. I use my Honda Civic's screw jack on a couple of stacked 2x4's for the lifting.

[n3833v]

You should have the floor jack so it rolls crossways as the gear relaxes in and out. You don't want it to bind sideways.

John

[cessna170bdriver]

You should have the floor jack so it rolls crossways as the gear relaxes in and out. You don't want it to bind sideways.

John

My floor jack is tango uniform; that's why I used my car jack. I jack it up, let the leg spring inboard; then let it down, recenter the jack and raise it again.

[GAHorn]

image002.jpg

(I'm arguing with my new laptop which has Windows 8. I HATE it! Can't get my saved pics to open, and can't copy pics from a word doc to convert them because Paint apparently won't work with Windows 8. Grrrr.) But the word doc I have here is a pic of the C-clamp and wood method.