jono rocky Posted November 9, 2015 Posted November 9, 2015 There are lots of practical uses for a pneumatic hoist for lego models like in trucks, forklifts, other trucks, earth moving machines, the other trucks not mentioned, Serials car hoist and oh trucks. Quote
aminnich Posted November 9, 2015 Posted November 9, 2015 Think about all the different vehicles a telescopic sight actuator could be used for. And start off long one for cranes, a medium sized for dump trucks, and small ones for multi staged outriggers Quote
MaxSupercars Posted November 9, 2015 Posted November 9, 2015 (edited) It would be possible only in pneumatic version... because in normal LA you got a screw inside... so there must be more screws in a such tiny space... And why pneumatics? Because of expanding space that you do not have when minimized... see video: BTW... Effe developed this large LA that can you get 3D printed from shapeways.com Max... Edited November 9, 2015 by MaxSupercars Quote
aminnich Posted November 9, 2015 Posted November 9, 2015 The longer actuator is fine, but I'm not looking for one that doubles its length, I looking for a triple or quadruple its initial length Quote
bonox Posted November 10, 2015 Posted November 10, 2015 and you won't find one in LA size. Those real units, even at the smallest end, are still relatively heavy walled steel units of moderate section but, crucially from the perspective of a toy manufacturer, are pinned at both ends and don't have kids applying huge bending/lateral loads to the rams. To build something like that in the size of an LA not only requires some pretty funky narrow walled seals, but it'll be so fragile you'd probably not even be able to assemble it without it one of the 3 or 4 sections buckling. Heck, even if you put a friction pin in one end and tried to jack up that dump bed, the bending of the assembly of the pin would probably cause the thing to fail. Max also keeps posting that crane picture of mine and each time he does I think about how I should have cleaned the table a bit more first Quote
bonox Posted November 10, 2015 Posted November 10, 2015 another thought - those multi-stage things are all single acting cylinders, which would be a significant departure from the new and current (or v2 and v3 styles if you will) pneumatics and would involve going back to the old v1 style since you might need a vacuum block for retraction. The market for such a device must be so vanishingly small that the only way you'll get one is to make it yourself, or substitute as I suggested by building your own. You'll always have to accept that a generic modular product won't have highly complex (either to design, to manufacture or to operate) parts suitable for very limited applications. It's a little like asking the makers of raspberry pi to produce a small, cheap, accurate and robust load cell capable of measuring a gigatonne. You could try a palfinger style with multiple single ram cylinders supported around a central column, with each tail connected to the previous head to get the reach. Quote
aminnich Posted November 10, 2015 Posted November 10, 2015 Everyone is looking at this idea from a pneumatic stand point. I'm not, personally I dont use them so I'm looking at from a LA perspective. I'm thinking a screw inside a screw inside a screw, that way they all twist out at the same time and would be able to hold the position because of the screw mechanism. I think I'm going to have to reinstall auto desk inventor and make a moc up of my idea. I was hoping efferman would have found his way here by now :) Most of the ones in life are hydraulically driven, but for our sake the pneumatics would never hold up to the lift force, but the LAs could Quote
dr_spock Posted November 10, 2015 Posted November 10, 2015 Someone already patented a multi-leg telescopic linear actuator: https://www.google.com/patents/US6435048 Why don't use some different diameter model railroading metal tubes driven by string like Jennifer's boom? You could probably get 3 sections out of it. It might be easier. Quote
Lipko Posted November 10, 2015 Posted November 10, 2015 another thought - those multi-stage things are all single acting cylinders That's not true, there are double acting versions. Quote
syclone Posted November 10, 2015 Posted November 10, 2015 Maybe a bit strange question, but which would be the best place a HOG on a small, low car? Quote
Zerobricks Posted November 10, 2015 Posted November 10, 2015 Maybe on the rear bumper, or the rear bodywork? Quote
bonox Posted November 11, 2015 Posted November 11, 2015 Most of the ones in life are hydraulically driven, but for our sake the pneumatics would never hold up to the lift force, but the LAs could what makes you think that? You need a thicker wall for a screw thread because of the material difference between the major and minor diameter of the threads. Then you've got a brilliant stress riser in the threads and a need to drive one thread at a moving offset from another in a small compact package. And compounded by a need for cheap manufacturing and significant market use. And then you have to make sure it's robust enough that you don't get the whole lot returned to you, broken, looking for refunds. Not saying it can't be done, am saying there's probably much simpler ways to do it, all of which will end up pretty big due to available materials and expected applications of use. That's not true, there are double acting versions. cunning, but I stand by my single acting call based on the picture of the dumper at post #544. It's already pretty thick, and only has two extending sections I can see. The truck version has an additional two for 5 complete sections. Quote
Blakbird Posted November 11, 2015 Posted November 11, 2015 cunning, but I stand by my single acting call based on the picture of the dumper at post #544. It's already pretty thick, and only has two extending sections I can see. The truck version has an additional two for 5 complete sections. The telescopic actuators on most dumpers are indeed single acting. There is no need to provide pressure to retract the bed since gravity will do that, and the addition of a retract fluid area would reduce the rod diameter and increase the chances of buckling. However, double acting telescopic actuators do exist for specialized applications. I'm working on one right now! Quote
Kman860 Posted November 12, 2015 Posted November 12, 2015 The telescopic actuators on most dumpers are indeed single acting. There is no need to provide pressure to retract the bed since gravity will do that, and the addition of a retract fluid area would reduce the rod diameter and increase the chances of buckling. However, double acting telescopic actuators do exist for specialized applications. I'm working on one right now! Can you post it here when you're done? Quote
Saberwing40k Posted November 12, 2015 Posted November 12, 2015 Blakbird is an engineer by profession, so he might not be working on a Lego one, but I'd still like to see it. Quote
Kman860 Posted November 12, 2015 Posted November 12, 2015 Blakbird is an engineer by profession, so he might not be working on a Lego one, but I'd still like to see it. :blush: Quote
Saberwing40k Posted November 12, 2015 Posted November 12, 2015 Oh, since Jim posted this as something that could be talked about, I'm going to go on a mini rant about how I missed out on an eBay lot that included 9398, 8455, and 8043, among other things, all for far less than buying those things individually. It also makes me rather disappointed that decent Technic lots almost never show up, which I sometimes like, because you know you'll get some cool stuff. Most people can't even be arsed to do a simple google search before throwing stuff up on Ebay. Also, Lego still does not have the Arocs pneumatics, or any other new parts, for sale. Rant over, let's get back on topic. Quote
MaxSupercars Posted November 12, 2015 Posted November 12, 2015 (edited) Max also keeps posting that crane picture of mine and each time he does I think about how I should have cleaned the table a bit more first Bonox... :D ...yeah... I found your photo in Effe's Custom Parts Topic saved to my smartphone and forgotten the author... sorry when I do not write your name... :D ...but your photos kick me to buy 2 of 3D printed LAs designed by Effe for my supercrane in work... Thanx... :) Max... Edited November 12, 2015 by MaxSupercars Quote
Samer Posted November 12, 2015 Posted November 12, 2015 (edited) Please tell me if this is the wrong place to ask: When I connect the pneumatic pump (rotates using a motor) to a switch and a valve, after few rotations one hose blows! What should I do to absorb the potential extra pressure of the pump when air has no way to escape? I know from 42008 that this should not happen but couldn't figure out how. Edited November 12, 2015 by Samer Quote
Saberwing40k Posted November 12, 2015 Posted November 12, 2015 Perfect place to ask, actually. I don't know why, but I have never had that problem. My solution would be to add an air tank in the system. Quote
dr_spock Posted November 12, 2015 Posted November 12, 2015 Please tell me if this is the wrong place to ask: When I connect the pneumatic pump (rotates using a motor) to a switch and a valve, after few rotations one hose blows! What should I do to absorb the potential extra pressure of the pump when air has no way to escape? I know from 42008 that this should not happen but couldn't figure out how. Have you tried a different hose? Perhaps that blown hose didn't have the same amount of grip as the other ones. Or there is grease or dirt on the connection. Quote
Blakbird Posted November 12, 2015 Posted November 12, 2015 Blakbird is an engineer by profession, so he might not be working on a Lego one, but I'd still like to see it. Yes, I am talking about a real one not a LEGO. Sorry, I cannot tell you about it! Quote
Saberwing40k Posted November 13, 2015 Posted November 13, 2015 Oh well. But that's just the aerospace industry, right? Quote
Samer Posted November 13, 2015 Posted November 13, 2015 Have you tried a different hose? Perhaps that blown hose didn't have the same amount of grip as the other ones. Or there is grease or dirt on the connection. No dirt everything is fine, but few hoses come from very old set, I'll check if I isolate them. Quote
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