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So far this is the cheapest set up I have designed.
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Quanity
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Part
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Price (each)
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1
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12 Volt Battery
7AH to 10AH
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$30.00 to $60.00
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1
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12 Volt Compressor
150 PSI Tire Inflator
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$10.00 to $30.00
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1
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Filter Regulator Lubricator
25 micron filter
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$40.00
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3
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12 Volt Valve
#10-32 5 port 4-way 3 pos. closed ctr. dbl. sol. valve, 12 vdc, wire leads
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$60.00
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4
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Pneumatic Cylinder
1/2" to 5/8" bore, 3" to 4" stroke
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$20.00 to $22.00
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1
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GWS 6CH Reciever
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$83.00
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3
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ESC 12 Volt
With reverse, 9 AMP Peak
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$28.75
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3
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12 Volt motor
With Gearbox, 10 to 12rpm
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$20.00 to $30.00
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1
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Function Controller
SWITCH 8
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$109.95
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$679.20 to $759.20
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You might be wondering why air powered and not hydraulic? Well hydraulic has less parts and is simpler but phumactic parts
are cheap and readly availble. Room for all the parts could be a problem though for smaller models. It starts with a 12 volt
battery that powers the compressor(150psi tire inflator). Then to a filter/regulator/lubricator assembly. A volume tank is
next and then branches off to 3 seperate 5 port 4 way 3 position dual solenoid valves. These solenoids are controled through
a 6CH tranmitter with a seperate 8 button board wired to one channel on the tranmitter. Now there will be 2 buttons for each
cylinder. As each button will activate 1 solenoid on a valve. When 1 solenoid is activated(depending on which side) will open
a port to 1 side of the cylinder and exhausts air from the other side. The tracks and the swing of the cab would just be controlled
by 12 volt motors. Each motor will have its own ESC. I did look for an Air Motor to power those movements but no one I've
found so far makes one small enough. For the stucture, I would start from scatch and build a CAT 345c.
Why 150 psi? Well its the most the 5 port valve can handle and Bore sizes for the cylinders go from 5/16" to 3".
So if you need more power just go up a bore size or two and you don't even have to run as high as 150psi. Keep in mind though,
these cylinders will get longer as bore size increases. So try not to go too big or scale will be out of specs.
Here is a link to a UK site that has a pneumatic model of a JCB220.
http://www.telepresence.strath.ac.uk/jen/lego/jcb.htm
Pneumatic Cylinder
#10-32 5 port 4-way 3 pos. closed ctr. dbl. sol. valve, 12 vdc, wire leads
6CH GWS
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