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Ed de Chazal wrote:



>The problem of a bent cylinder rod as Scott reports may or may not have

>anything

>to do with bottoming out the cylinder internally.  What would bend that (very

>strong) rod?   How would the forces be applied to accomplish this?  



After reading the several replies to my original question and having spent

several hours a few days ago getting the main gear cylinders setup, I think

I can shed a little light on the situation.



If you look at how the system performs in each direction it becomes pretty

obvious that if you don't allow the cylinder to bottom out on the down

stroke, when the o/c links stop the gear from any additional outboard

motion, something is going to have to give.  I see 3 possible scenarios if

there's still piston travel left when the downlocks snap into place.  First

possibility, nothing happens... the hydraulic pressure will just force the

o/c links into a more tightly locked position and the system will become

static at that point.  Second possibility, the actuator attachment arms on

the o/c link fail allowing the cylinder to reach the end of its travel...

highly unlikely considering the geometry and materials being used, although

I suppose the attachment fittings could fail over time if the bolt holes

became elongated and the assembly started to move with every cycle.  Third

possibility, the gear locks down, the o/c links stop their motion and the

actuating rod flexes to allow the piston to bottom out in the cylinder.

Also highly unlikely, given the current thickness of the piston rod, but

the most likely eventuality of the three.  The obvious solution to

precluding any of the former things from happening is to have the actuator

reach the end of its travel at the same time the o/c links snap into place.



I personally don't see a way to bend the piston rod in the retraction

phase, as when the gear-up pressure is applied to the actuator that piston

rod is in tension, and there's no force that could be applied to it by the

actuator that would impose a bending moment on it anywhere through its

travel.  Needless to say (but I'll say it anyway) there needs to be a means

to stop the inward stroke to keep the wheel from pressing itself through

the upper wing skin.  Naturally, if you can adjust the inboard mounting

position to a location where the final location of the gear coincides with

the bottoming of the piston in the cylinder you've solved the problem and

everything is hunky-dorey.   Prudence would recommend, however, that you

provide some means for adjusting the upstroke to allow for expansion of the

tire with altitude, or to be able to fine tune the upstroke should you

change tires and need to make allowances for a different tire width.  The

stop sleeve which is supplied with the LC20 kit is the obvious answer.  I

will likely have to have longer sleeves fabricated as I want to be able to

have stop nuts at both the rod end and behind the sleeve.  Until I'm ready

for final assembly, however, and I make that last adjustment of the up

travel, I'll be using a pair of washers between the stop sleeve and the end

of the actuator... a dab of super glue will keep them temporarily attached

to the sleeve until I arrive at its final required length.  My plan is to

have the stop sleeve, its locknut, whatever spacer is required, the locknut

against the rod end, and the rod end itself all in intimate contact so

there's no possibility of anything moving after everything is adjusted.  I

may even just fabricate a single locknut which is the exact length required

to create that solid piece between the sop sleeve and the rod end.  Time

will tell.



Sorry for the long-winded dissertation, but I felt that additional

clarification of this matter was called for.  Thanks to everyone who

responded to my original question, you laid out the road map to my

understanding of exactly how all that hardware in the gear well relates.



   <Marv>