Greeting Anton. Firstly let me wish you and yours a very safe, healthy and prosperous new year.
I'm so glad the 'silly season is over. Perhaps life can get back to normal now.

I've modified my nose gear assembly to include the control lever but something is keeping the leg locked as if it were set to static. The small 'locking' link is the same. If there's something hidden, I can't find it. Care to take a look?
The final operation should be, starting with the lever fully back as modeled, pushing it forward should rotate the nose wheel leg to be horizontal and tucked up into the blue foam. Hopefully, the curved actuating bar will reach over the locking mechanism without crashing into it.
Looking at the main wheels, it appears that this might be a step too far in that weight is the enemy and when I add the second system (right hand side) I see a whole lot of weight, and I haven't got the interconnecting hardware modeled yet. Might have to accept a fully streamlined fixed main gear for starters.

WOW, didn't realize file was so big.

Anton, Anton, Anton. Thank you so much. You did a great job, but we're not there yet. I have to have the full ground clearance so the the 'pusher' propeller doesn't touch the ground as the aircraft rotates for take-off or on flare as it lands. I'll look at getting the nose wheel to fully retract and for the mains to come down lower. I practice, there will be lots of changes to make the whole thing strong enough and stable in the 'X' axis as well. This, though, give me the optimism to carry on.
May all your dreams come to fruition in the new year. Doug

Though you might like to see the plane this is for. Not my design but I'm enlarging it to take my 100kilo frame and will putting a more powerful engine to it. The original is called Sgian Dubh which is Gaelic for dark or hidden knife. (usually tucked into a Scotsman's high sock.)

Hi Anton, I trust you had a relaxed Christmas. I didn't. I have to admit defeat once again with my model. As you will see, several changes have taken place, all to get it into the confines of the proposed fuselage. I have also, removed one servo and replaced it with a solid link (gears and chain in reality) Hopefully, I have the lengths of the 2 new arms correct to give about a 3:1 reduction ration. Will the wheel remain vertical without resorting to black magic, only you can tell me. If you're not too busy, please wave your magic wand over it. Perhaps you can also explain, in layman's language, what steps, and in what order, you do to make this thing happen.
If you care to do so, the nose wheel could be controlled by the same servo but you'll need to either raise it, or lower the main wheel prior to ganging them.
You might also want to tell me to piss off, that's ok to.

Main wheels mechanism

Thanks Anton. Yep that's right basically right. Yesterday, I remodeled the lower arm to have only two sections and moved it's top location point.
How did you get the 2 servo's to work off of one slider? In reality, this would be a mechanical connection, turning at the same speed and degrees of rotation. Hopefully, the wheel will remain vertical throughout the operation. If I can't get the SP right, I'll send you the file.
Can this model be copied, flipped, and mounted on the opposite side to have both wheels working in unison? Or do I have to rebuild the whole thing? Later, I would like to add the 'new' reward retracting nose wheel so that the whole thing operates from a single servo slider.

Merry Christmas my friend, tis Xmas day here and now.

Thanks Anton. I'm only interested in the main wheel retract at the moment. Trying to figure how to control the lower leg when the upper control arm is rotated anti clockwise to just over the vertical.

Main wheels mechanism.skp

Whilst experimenting with various joint configurations, Something went wrong and I now get the following message:

SketchyPhysics Simulation aborted due to an error!
An error occured whilst starting simulation:
C;/Users/Admin/AppData/Roaming/SketchUp/SketchUp
2014/SketchUp/Plugins/SketchyPhysics3/sp.tool.rb:1270:in 'block in
active_standard'

Any suggestions please.

Doug

Thanks Anton. I hadn't noticed that group conflict.Will fix it when I'm ready to add the rest of the system.
Again, thanks for your tuition, just hope my 72 year old brain can remember it.

Thanks Anton. Very nice presentation and result. You mis-understood the use of the grass but no matter. That was only an extra. The main thing is that the system will work in reality.
Next question, if I add the main wheel systems to this, will I loose your current 'state' for this part? I would need to edit the sliding tube and then add the rest of the system.

Anton, I've tried, my God I've tried. How the hell do you do it. LOL

Firstly let me explain the changes to my model.
I've reworked some of the parts. Yes, there were(and still are) many modelling errors.
The 2 blue parts make up the 'over-center' lock (o/c).
The purple part is the 'u' you couldn't see. This was originally jamming with the lever when in fully forward position. I've lengthened the tongs.
All parts cleaned up with ttcleanup2(not that I fully understand that particular plugin).

Now, this might be a step too far but I want to see the operation of the o/c assy when the Earth is moved away. Look closely and you'll see that the weight of the aircraft holds the 2 upward pointing thumbs in contact and thus locked (middle pivot is lower than the 2 end ones). This didn't happen in the previous version as the thumbs intersected each other (not solid).
By 'taking off' (lowering the Earth) the o/c lock should automatically align all 3 pivot points. This is prior to moving the lever. i.e. the wheel must have weight to pull it into it's free position.

The lever needs to be set so that it starts at it's zero point (not mid point) with lever fully forward. Hopefully, the wheel will rise to a point where just an inch or so is still below the blue foam (covered with F/glass)lower fuselage. This is so that in the even of a wheels up landing, the skin isn't dragged along the ground. Main wheels will be same.

If my geometry is wrong, the whole thing should jam up, but I hope not.

For my benefit and those others following this thread, can you explain how you decide the order in which you do things and why.

Asking too much, I hope not.

Do I need to put comment?

Hi Anton. I want to make some changes and improve some of my modelling. Then I'll resend the file but if you don't mind, please keep it on line so that others may learn from what you have to say. give me a day or so.

Cheers.

Me again Anton. Been looking at fixing my problems but have come upon a wall. You've hidden the joints and I can't find any info on how to un-hide them. Looked at 'sections' but that's no help. What plugin do you use?
I've found one reason that stops the wheel from fully lowering. The 'u' shaped fulcrum on the lever it too shallow and jams so as to prevent the lever going fully forward. I have increased the length of the 'u' shaped part whilst keeping the group the same length. In doing this, I've lost your servo and joint connections.
Can you spare the time to guide me please.

PS, I can't see new joints if I try to make one.

Thanks Anton. This raises more questions.
I purged every group with the built in purge function and used SolidSolver to check them out. So what's happening there. Could I have a problem within my program?
I will download the plugin you've suggested to check some other models.

Your solution, whilst proving it can be done, is, I'm sorry to say, incorrect.
The control lever servo, the 'over-center' assembly center hinge and the nose-wheel leg bottom hinge, should all be connected to the 'wooden structure' ie, the airframe. They are not so the model works in a curious way. I'm not at all worried about movement on the ground other than, if model, to prove that the over-center assembly does actually lock. At the moment it only half closes. I will try to correct it with out stuffing up your work.
Cheers, Doug

Desperate measure, one zip file. Hope this works.

Over-center lock mechanism-raised1.7z

Thanks Box, that might be the answer. My model is 4.8mb. Will see what I can delete and try again.

Thanks Anton.

Operation is , push lever forward and wheel should lower until the 'over-center' assembly 'limit stops' meet each other. The wheel is finally locked by the weight of the aircraft acting as a back pressure trying to force the o-c assembly further over center. There may well be errors in the actual sizing of each part but hopefully, the joints will stay centered on each 'pivot point'

Attempt number 3, Not sure what I'm doing wrong but file not showing in preview.Try again.

Edit. What the hell am I doing wrong? Frustration, frustration, frustration.

OK, so I've modeled a lever operated retractable nose wheel assembly for an Ultra-light aircraft. It has 1 servo,7 hinges and 1 slider. My problem is, every time I connect a secondary hinge, my groups change status. How do I over come this problem.

Secondary question, why does 'Solid-solver' insist on breaking groups when a hinge is affixed? ie, item is no longer a solid in it's own right.

I wanted to post the file but there's no simple explanation of how to do it. Copy and paste doesn't work. Who-ever said that SP was frustrating, made to ultimate statement.

So I've got a solid model without any joints or status selected. When I run play, the item falls, spins or whatever it wants to do (as expected) but, it leaves an outline of the 'group box' where it started from. On a much larger model with multiple groups, every one leaves a similar box. How do I prevent them from appearing?

Hi TIG, greetings from South Australia. Your plugin is just what I need but, when I download it, I get this notification in my download page:

TIG_solidsolver_v2.2.rbz

That seems fine but when I click on it to open it, I get the usually 'windows can't read this etc' So how do I load it into SU2014 on win7 64bit system?

Fixed. Made the under-carriage assembly 'magnetic'. Works like my dream now.