Any differences in pre/post war B model landing gear legs ?

[Guest]

Hi all,

Maybe you know something about this, hope so.

I am making a landing gear jig around 2 undamaged, no signs or repairs or bends landing legs.

The RH leg may be a prewar and the left looks like a postwar.

The jog holds a left and right side by side which is nice for comparison and I also have a left and right to fix so I need a dual jig.

This part has me perplexed;
a) the angles on the two legs seem to all be the same.
b) the cabane struts are the same
c) the "V" legs are 5/16" different on one than the other
d) axle angles match
e) this is the big one! The axle tip and brake plate are about 7/16" farther outboard on the right (prewar) than the left (post war).

I can make the jig so as to accommodate both but wonder if this is manufacturing variation, difference in designs, difference in drawing/design versions, undetectable damage?

How concerned should I be about seeing this difference.

Dave

[Hank Jarrett]

Re: Any differences in pre/post war B model landing gear legs ?

I have also been really curious about this. How big is your jig and how portable? My 45 is on the gear but there are no bungees yet and it would be pretty easy to pull the legs off and check them on a jig. We are only about two hours apart by car and I will be taking them off sometime in the future to build the new wood parts for the cabin roof.
Chuck and I have talked several times about building a jig to repair and build gear legs.

Hank

[Guest]

Re: Any differences in pre/post war B model landing gear legs ?

Hi Hank,

will send pictures later

Chuck is a trucker as I recall and that's good cause I think it will take truck to transport it!

actually it will fit in a pick up

Dave

[Hank Jarrett]

Re: Any differences in pre/post war B model landing gear legs ?

Just wondering if it would be easier to move the gear or the fixture. Any other unmounted gear legs available in the mid Atlantic area?

Hank

[N96337]

Re: Any differences in pre/post war B model landing gear legs ?

I'd say just a tiny difference in tube lengths will show a big difference at the ends, Dave. The way these planes were pumped out in the 40's, by different people using the jigs, maybe one guy not getting it seated just perfect, or a tube that was just a tiny bit long or short, or welding quick and pulling it right out to get another started, would lead to a variance in parts. As long as the wheels align, I'd say it'd track pretty well and never show up. I don't know??? I do know I need to do a jig on this end of the world too....
John

[Guest]

Re: Any differences in pre/post war B model landing gear legs ?

Yes tiny differences make a big diff. I discovered that one gear had been slightly bent and merely straightening the two tubes that are parallel to and close to the floor boards fixed it quite a bit.

I am still finishing the jig. The axle stub portion is not complete and will not be until I remedy that slightly bent gear (the blasted one).

The toe out in the lasted gear can be seen by comparing the tubes over the axle stubs to the channel on the floor, the blasted one is skewed too mush and this can also be seen in the picture with the angle iron as a ruler. Ignore the fact that the vertical channel between the axles is off center.

Attached pictures of the jig and also the "alignment fixture".

It also appears that the cabane strut on the blasted tube may be stretched or just plain too long.

If I had it to do over again I would have used 4" x 2" x 1/4" rectangular steel tube, would have been cheaper and faster.

[PA1195]

Re: Any differences in pre/post war B model landing gear legs ?

When you're done adjusting reinforce the lower gear legs to reduce twist.

[Guest]

Re: Any differences in pre/post war B model landing gear legs ?

thanks for the suggestion but these legs are spares or for resale so I won't make any mod's to them

Dave

[cvavon]

Re: Any differences in pre/post war B model landing gear legs ?

Dave could it be that the brake plate is that way because the older shinn brakes were narrower then the newer ones if i remember there are two widths of break lining for shinns?

[N96337]

Re: Any differences in pre/post war B model landing gear legs ?

That looks great Dave! Nice job!!
John

[Guest]

Re: Any differences in pre/post war B model landing gear legs ?

straightened the axle but the cabane is still too long, it must have been made that way

[Guest]

Re: Any differences in pre/post war B model landing gear legs ?

That looks great Dave! Nice job!!
John

Thanks John.

It has been interesting, it's like you said, they are all a little different.

I put a third one in and it was yet slightly different than the other two.

So I learned a few things about a repair jig;

1) the attach points and bungee location have to be fixed so they fit the plan but the axle location needs to have some float
2) align the axle visually with the jig lines as references to what is perpendicular to the fuselage axis
3) don't try to make them all come out the exactly the same like you would if you were building from scratch
4) don't use a come-a-long to straighten things because when you go to release it you have to make it momentarily tighter and then it releases and snaps back

Dave

[N96337]

Re: Any differences in pre/post war B model landing gear legs ?

#4 is a really good point!! Hadn't thought of that!
I'd also imagine, with all the gearlegs that went through the factory jigs, there was a certain amount of 'slop' in the jig at any attach points or bolted points....especially towards the end.
Did you set your jig up to do straight axels as well?

[Guest]

Re: Any differences in pre/post war B model landing gear legs ?

#4 is a really good point!! Hadn't thought of that!
I'd also imagine, with all the gearlegs that went through the factory jigs, there was a certain amount of 'slop' in the jig at any attach points or bolted points....especially towards the end.
Did you set your jig up to do straight axels as well?

I made the axle station so you can bolt on a plate that holds the lugs for the axle so you could make it work for any axle shape.

Slipping a tube over the axle that has an i.d. just hair bigger than the axle o.d. and then comparing that tube with the jig lines seems like a very good method and then you don't need to make any more plates.

Dave

[Guest]

WOW! I could not find it.
Thanks!
Dave