Hydraulic Question

[adey2004]

Hi there, newbie here,

Designing and building my first ever mode. a Cat 316 long reach and Cat 954d, i will be building the models in 1:10 aminly from laser cut 3mm alluminum glued together, i will post images of the design and fabriaction works as it progreses, howver i have a few questions,

1. What is the best Pump / tank configuaration looking for around 17 - 20bar

2. I am trying to calculate the pushing force of the stick based on a 12mm cylinder at 17 bar and this equates to 13.7kg at the cylinder, the cylinder is connected to the stick 40mm from the pivot point and the arm is 300mm in total length, can some one confirm the foce at the end of the stick.

3. i am trying to design the excavators with at least 10kg of lifting force in all areas, boom, stick bucket etc, is this comparable to the ready made excavators out there, (with 2 12mm Cylinders i can lift a total of 12kg on the Boom)

4. Could some one please provide detailed picture of there valve spool assembly as i cant seam to work out how to interface the servos and the spool valve, (i will post a copy of my design later)

5. what is the best radio to use, i will need 10 no. proportional channels and various switched channels, alternatively i have been looking to control via WIFI Bridge with camera etc using a play station contoller, does anyone have any experiance / info on this,

6. and finally, is there anyone from england on this site who can meet up and share some ideas?



lots of questions i know but if youcan help would be gratefull

Cheers

Adey

[adey2004]

Photos of the design Stage

http://i863.photobucket.com/albums/ab200/adey2004/valveisometric.jpg

Spool Valve.

http://i863.photobucket.com/albums/ab200/adey2004/ValveControlSurface.jpg

Spool Valve

http://i863.photobucket.com/albums/ab200/adey2004/image4.jpg

http://i863.photobucket.com/albums/ab200/adey2004/image3.jpg

http://i863.photobucket.com/albums/ab200/adey2004/Image2.jpg

http://i863.photobucket.com/albums/ab200/adey2004/Image1.jpg

Everything will be cut out of 3mm Alluminum, the spool valve will be machined by a prototyping company

Adey

[JAMMER]

A Jung pump would be a good choice. I have one in my excavator and it puts out 30 bars. Ed

[Grainfarmer]

Great engineering and design!

Here´s the link for the pump:
http://www.jung-fluid.de/home.html

[carp]

Hi, its going to have wheels?

1.rc4wd do a pump for 129$ or you can get a jung from germany i emailed them in feb and they quoted 74euro + tax and shipping for 0.30cc pump so can get it delivered for just under £100 i think. as for a tank i was going to use a spare tank i have from a nitro heli, not sure if it will work though

2. not really sure

3. pass

4. im using valves from fumotec, check here to see how they mount second post on page

http://www.modell-baustelle.de/index.php?page=Thread&threadID=5749&pageNo=5&dde8be12

5. currently have a futaba 8fg bought as 8 channel but can be 14channel by a free software download, you can also try specktrum/airtronics/robbe all good radios

6. not sure if it still happens but there used to be a meet once a month in yate or somewhere near there.

hope this helps a little

[Finster]

Nice drawings so far, I love watching scratch builds and I'll be watching this one. Just curious, why 8 hydraulic circuits? I counted the usual ones on an excavator and you seem to have a surplus, so what are they for?

[Madda]

There is a program where you can calculate all the forces, google for it, I will give the link later when I get home. It was payware though.

Since here you can ask questions related to hydr I would like to know what should be the tolerances when making valves and cylinders?

[adey2004]

Hi the 8 valves are for

1. Boom
2. Stick
3. Thumb
4. Bucket
5. Breaker
6. Rotaing bucket!
7. Grapple
8. On the 316 the plough or out riggers.

The cost is the marginaly the same if its 1 or 10 so i thought i would go with 8. For around £250 in stainless

The 316 will more than likely have a wheeled under carridge but the 974 will have tracked.

I will look a the jung pump because i have designed the rear balest areas as the tank / filled with lead balls as apparantly if i want to klift 10kg at 1.2m then the model needs to weigh 20kg with 11kg of ballest?

Still cant get the calcs to work with the stick cylinder, would it look wrong / off scale if this cylinder was twice the diameter of the main boom ones, or alternatively if there were two?

If anyone gets some time, could they try and crush a set of scales with there stick only and see what kind of forces are the norm

Cheers

Adey

[carp]

where are you getting valves made for 250 quid? depends how scale you want it to look i guess, my boom cylinders are 16mm and my stick is 20mm

[adey2004]

Just done calculations based on a 16mm cylinder at 17bar is around 35kg force, that seams good enough and 20mm is around 54kg, like it

I will pm you the link for the machining company, Also got a quote to cut all the parts out of 3mm ally for around £300 each model, assuming i can fit it on an 8x4 sheet

Adey

Where abouts are you based?

[Madda]

I meant this program: http://hidraulicapractica.com/software/hydraulic-calculations-2-0-program-for-pc

[apfubar]

Quick question, how do you plan to mount the servos?

Just looking at the length of the spool valves, I am not sure if you have enough room? Also all the model valves I have seen are rotary not linear(like the real thing)... Not sure why this is... possibly vertical space or it is just easier to deal with the rotary motion of the servo without converting it to a linear one..

Cheers,
AP.