# Minature Hydraulics?



## bnsfconductor (Jan 3, 2008)

I was scrolling through a Precision Scale Model Engineering catolog the other day and came across a page listing minature hydraulic cylinders, fittings, piping etc, and got a crazy idea. I'm working on building a GN Snow Dozer which has a adjustable plow blades on both the front and side of the snow plow, and was thinking about using hydraulics to move the plow blades out and then back in. 
Does any one have any experience using hydraulics in any scale sized application, and do you think this is a good idea?
Craig


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## RimfireJim (Mar 25, 2009)

Craig, 
I'm working on a project at work that is along the same lines, and I'm looking for the same thing. If you find anything, please pass it on.


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## Ray Dunakin (Jan 6, 2008)

Just a thought, but have you checked any robotics forums or websites?


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## lotsasteam (Jan 3, 2008)

http://www.gardentrucking.com/produ...amp;max=10


This will help!
Manfred


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## Mr Ron (Sep 23, 2009)

I don't think there is such a thing as "miniature hydraulics" as such. Hydraulics is just hydraulics. There are some small hydraulic components, but not what you would call "miniature". They are just small full-size components.


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## bob7094 (Jan 3, 2008)

While perhaps not suitable for a scale model, there are LEGO Technic pneumatic kits/components you could experiment with


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## bnsfconductor (Jan 3, 2008)

After giving it a little bit more thought I think a hydraulic system might work but it certainly wouldn't be practical for my application. I think using a servo motor would make better since to power the blade actions. What got me started thinking about this was my old LEGO pneumatic parts I had laying around, when I found out that small bore (.156", .250", .376" are what I found)hydraulic and pneumatic cylinders exist it got me thinking. But when you add all the components (tank, pump, servo motor trigger the pump, plumbing etc) it just didn't seem like it would work out in such a small area considering I've never done anything like it before!


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## Greg Elmassian (Jan 3, 2008)

If you are running DCC, several DCC decoders also will run minature servos, which are small and inexpensive. Zimo comes to mind, some have 2 servo outputs in addition to the motor outputs for the loco. 

Regards, Greg


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## John J (Dec 29, 2007)

There was a guy at Eaglewings Iron Craft's open house a few years back who had a Front End Loader About the size of the Toka Toys one. He had put minuture Hydraulics on the bucket and along with a remote control was able to load a big Kenworthy dump truck he also added hydraulics and remote control. Both had sound cards and made all the proper sounds including the backing up beeper. The dump truck was driveable by romote control and dumped . I was looking for the minature hydraulics and it looks like you just found them for me 

Thanks 
JJ


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## bnsfconductor (Jan 3, 2008)

Greg, 
Sorry I'm a Goodson follower! No DCC for me. But I'm looking for servos, any ideas for sources? I'll try and post some pictures of what I've got built so far. I was orginally planning on just making it a manual system, but I don't know if snow would push back the blade with out some support. This link shows some photos of the different blades extended. 
http://www.railroadforums.com/forum/showthread.php?t=22054&highlight=snow+dozer&page=4 

JJ, 
Contact PSME and send them an email. They have according to thier catolog over 2500 products related to hydraulics and pneumatics


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## bnsfconductor (Jan 3, 2008)

I was reading the article this picture was posted with, and the MOW employee was stating that the blade was pneumatic with air coming from the main reservior on the locomotives. Interesting. I think pneumatics might be possible rather then hydraulics on a scale model.


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## Michael Glavin (Jan 2, 2009)

Pneumatics is likely the best approach IMO, pretty straight forward, simple and relatively inexpensive. Servos would be hard pressed to mimic the mechanical action of a cylinder so to speak… 

Look at R/C aircraft stuff, everything you need is readily available. 

How do you propose to weight your machine? A low center of gravity would be paramount me thinks. 

Michael


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## Greg Elmassian (Jan 3, 2008)

what about miniature linear actuators? electric with a screw thread inside. 

Greg


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## Michael Glavin (Jan 2, 2009)

Linear actuators would be an interesting approach, but more complicated than a pneumatic system and more likely than not; more fault modes too. 

Michael


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## Michael Glavin (Jan 2, 2009)

Studying the picture above, I don't see any tattle tales of anything pneumatic or hydraulic. Lots of indications its all manual over with mechanical assistance. Note the cables, pullies and then the pins used to gauge the length of the main support arm with what maybe a folding hinge in same? 

Michael


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## bcer960 (Dec 27, 2007)

Has anyone else thought about using del-air or simular switch machines for the project?? On my "to-do" or rather "want to-do" list is a 










but if I do it, I want it to work. I always thought the del-air machines would be a good place to start.

Ray


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## tacfoley (Jan 3, 2008)

Have a look at the LEGO pneumatic stuff - very high quality and low price. 

tac 
www.ovgrs.org 
Supporter of the Cape Meares Lighthouse Restoration Fund


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## Mike Reilley (Jan 2, 2008)

From my ME son...if you want proportional control of a movement...you want to use hydraulics. The oil does NOT compress. If you want on/off control of movement...out or in...pneumatics work OK especially if you use some kind of spring lock that the pneumatics just flip. Pneumatics are hard to control proportionally because the air in the cylinders compresses as you apply force against the ram. The best proportional control that is easy to install are digital proportional servos...most have feedback now so that at a given control position, the servo actually goes to that position and stops...and they're small too. The smallest are about the size of a pile of three quarters...and the RC plane guys pioneered the development of flexible control rods that actually can be made to look like hydraulic cylinders.


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## John J (Dec 29, 2007)

If you have made a snow plow like the one pictured and used Pneumatics where would you get the compressed air?

If you have a minitature air souce then Pneumatics might work. On the other hand If you are in freezing tempatures Moisture in the Pneumatic system might freeze.

Also the Hydraulic fluid in cold tempture may become too thick to run.


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## Greg Elmassian (Jan 3, 2008)

The link that Manfred gave shows the hydraulic pump. 

Yep, I agree about temperature, and also leaks, etc. You would be using it at the worst time, when it is freezing. Not impossible, just more difficult. 

If you are battery, the logical thing is small airplane servos, run by the remote, since many people us the model aircraft remote. 

I would use electric linear actuators, the ones with the screw threads. You could set them up for on/off operation with limit switches. No compressors, no fluid, etc. 

I think a lot of this depends on what you will have for a remote control... what are you starting with? 

All of these suggestions that imply proportional control are for naught if you have a remote that only has on/off. 

Greg


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## Michael Glavin (Jan 2, 2009)

If in fact all that’s required to mimic the full scale operation is the ability to raise and lower the blade via cables and pullies; servos would be well suited. The caveat is the type of servo employed. Servos have been proportional for many-many years (digital proportional control has gone along way providing precision servo control. An Analog servos feedback loop operates at approximately 30-50Hz while digitals report at about 350Hz. Holding and operating torque has been significantly increased too), the problem is they typically have a rotational travel arc of 120* with stops at either end. RC Sail boating enthusiasts have drum winch servos which eliminate same… One can modify standard servos to eliminate the travel arc stops as well. FWIW: servos are designed to move to and maintain a given position; the feedback loop updates the position of said servo and constantly pulses power to hold the commanded position thereof, frequent refresh or update rates afford better precision and holding torque. 

As noted above, pneumatics are not the most desirable for proportional control, BUT it is doable and in fact many companies offer proportional feedback control valves, that said they are expensive and not likely going to find there way into a model train me thinks. 

A pneumatic system offers many possibilities, single and double acting cylinders with or without internal spring compression operators or cylinders and again with or without individual flow controls at the air inlet/exits. Constant loads are well suited, while variable loads would require the aforementioned proportional control for the best repeatable results. In the case of varying loads a spring loaded cylinder would likely serve best as the spring will provide a constant back pressure or force at a given travel range. RC Aircraft uses servo actuated flow control valves for landing gear and such. Small air tanks are used and refilled with a hand pump or a compressed air source. I have several LS or we refer them as Giant Scale RC aircraft with air-operated retracting (some rotate too) landing gear, doors and such works quite well. 

Mike suggested the possibility to utilize flexible control rods for cylinders, this is most definitely a possibility with the correct type of control rods (there are many offerings and materials in play). However in some circumstance the range of motion given a flex control cable maybe a limiting factor. 

In the case of the snow plow depicted previously, it appears to me the main support arm appears to be fixed, with graduated fixed variable pin placement intervals to set the blades angle of attack and again it appears the only thing operated thereafter is the ability to raise and or lower blades to set the cutting swath. 

Michael


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## Dwight Ennis (Jan 2, 2008)

*Servo City* has an array of servos and accessories including sprockets designed to fit the servos and regular shafts for chain drives (they also sell the chain). These are what I generally use to R/C the throttle in my steamers as one can increase throttle throw with them. Check 'em out.


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## lotsasteam (Jan 3, 2008)

http://www.youtube.com/watch?v=pISp...r_embedded

More youtube hydraulics at right:also lego hydraulic

Manfred


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## Cougar Rock Rail (Jan 2, 2008)

Craig, have a look at this website: 

http://www.firgelli.com/ 

They build linear actuators that act exactly like servos, or can be toggled with analog controls too...lots of choices depending on how complex you want control to be. 

As for the hydraulics, I have done quite a bit of research on them because I'm building a hydraulic rail crane, but the more I learn about them the more I'm leaning towards the linear actuators because of the complexity and cost of hydraulics. The hydraulic pumps are relatively noisy, too, just like the real thing. 

Keith


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## bnsfconductor (Jan 3, 2008)

That's a lot of info everyone's given me so far. This is what I know about the prototype, the only pneumatic piece is the large main arm, which is then (I'm making an assumption) is then locked into place with the pin that is visible. The other movements of the plow blade is done through a system of pulleys and cables. So I'm thinking the only reason the large arm is pneumatic is to position the are length, rather then to hold the pressure of the plow in the snow, but I could be wrong. What do you guys think?

Second, I've found a source for scale cable (along with pulleys) in various thicknesses (from .005 on up) that are various stranded (1x3, 7x7 Hollow strand, 7x13 etc) so I think solving the problem of using cables and pulleys move the blade might be do able, but I don't know how well the cable would stand up the stresses of plowing snow. PSME says that this are suitable for operating rigging, but how much stress would they be able to take. But again in the picture it doesn't seem like the cables are under much stress, but rather the main arm.




I'm open to suggestions in terms of remote control, but I think in the actual world situation there wouldn't need to be much adjustments constantly. That's why I think limiting the complicity of the project might make it easier. If indeed the pneumatics only are there on the prototype to move the main arm in and out, couldn't it be possible just to move the arm out mainly on the model (but then the stresses on the locking pin might be to hard?). 
Here's a side view of a snow dozer


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## Cougar Rock Rail (Jan 2, 2008)

Hi Craig, 

Looking at the picture of the real plow, it looks a lot like a road grader wing with the adjustable (via pins) links, and then the vertical winch. I would think all you need is an electric motor/servo working the same way they do with sailboats. They wouldn't keep adjusting the braced link often. Maybe the reason they had air on board was to keep up pressure in an air accumulator so that it would provide some cushioning if the wing hit something solid? It could also have an air piston with limited travel, so that's why the braced link is still used. If that wing is similar to old bulldozer blades, it's just gravity that holds the wing down, and if you want the blade to be more aggressive (and float less) then you do it by angling the 'angle of attack' of the blade, if you know what I mean--so that is something you will want to build in to your model. It will take a little trial and error to find the right angle of attack to keep the blade from floating but also not so aggressive it keeps digging in sharply and trying to roll the plow off the rails. 

Keith


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