Hydraulic system: Buying the parts, assembling and tread plate assembly


First I had to figure out all of the components that I needed to order, and then figure out all of the fittings and hoses for each item and approximate lengths based on potential locations.  I figured out that the hydraulic pump had a built-in pressure relief valve, but since I wasn’t sure on the pressure setting, nor whether it would work, I plumbed in a second relief valve.  The tank requires a low pressure filter that ensures that the pump is supplied clean hydraulic fluid, and is hooked to some large (1-1/4”) barbed fittings to connect to hose.  It has to be large to supply the pump with enough fluid via gravity feed.  Fluid flows from tank to pump, then through the pressure relief valve, (which has a bypass back to the tank via the high pressure filter) then to the valve body, which is open center, then back to the high pressure filter and into the tank.

An open center valve body means that when the valves are in their center position (no cylinders moving) the fluid is free to flow straight through the valve and to another valve or back to the tank.  This makes it easy to stack valve together for a multi-valve system.  In this case there are 3 valves built into one system, but more could be added.

Enough talking, here’s a diagram:

hydraulic schematic

Once I had the schematic figured out, I detailed it out with every fitting and hose so I knew what to order.  I couldn’t be 100% sure, so I made sure to order a few extra fittings and hoses so I could make changes on the fly when it came time to assemble the system.  A note on fittings:  some are NPT (national pipe thread) and some are flared (within the flared family, there are different brands and amount of flare:  JIC 37˚, JIS 30˚, SAE 45˚).  There is also straight thread O-ring boss fittings (ORB) too, which are what screw into the valve body, so there I needed adapter fittings to go from ORB to JIC 37˚ on the hoses.  There are also British Standard and metric fittings to deal with.  Fortunately, most of mine were NPT, JIC 37˚, and ORB.  This is why it takes some serious time to put together a hydraulic system.  Also, hoses need to have some swivels built in to allow you to tighten the hoses up, as a twisted hose will fail quickly.

Now it was time to spend some serious money, new hydraulic components are expensive!  The tank filter, high pressure filter housing, high pressure filter, pressure relief valve, fittings and hoses were all brand new items.  I ordered most of the items from Northern Tool + Equipment, with a few specialty fittings from Discount Hydraulic Hose.  I also bought a few fittings from Runnings Fleet and Farm, a tank from Tractor Supply Company, and miscellaneous fittings from Mills Fleet Farm.

Now that I had all of the fittings, hoses and components, it was time to put it all together and see if it worked.  Hydraulic systems are a bit more complicated than other mechanical systems in that there’s no easy way test it, you have to have all of it assembled and tightened fully.  Hydraulic systems operate at 2500 to 5000 pounds per square inch (PSI), which is a lot of pressure and can kill or seriously injure if things go wrong.  This is only a brief discussion on hydraulics, if you don’t understand it; you should not be working on these items until you know what you are doing.  If you don’t know, research and ask questions.  You are in charge of your own safety, as I can’t fix stupid.

Ok, enough on the disclaimers, onto some pictures of actual work.

First I dry assembled the entire system until I liked how everything was routed and the least amount of fittings.  This also involved mounting the tank, the hydraulic pump, the high pressure filter housing, and valve body.  After the dry fit was complete, I disassembled it, and applied pipe goop to all NPT threaded fittings and tightened them.  Flare fittings seal on the flare, and so don’t need any sealant.

Hydraulic System

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use snag-it and label components in picture for tank, pressure relief, filter etc.

Then it was time to fill it up with some hydraulic fluid, and move on to testing it!!! Keep your fingers crossed!

Also, I found time to trim and attach some tread plate over each track as a nice place to step when getting in and out, and also as a place to mount the hydraulic tank.  I had some nice stainless steel button head allen screws, 5/16” x ½”, that I tapped the tubes and mounted the plates with.  I do like the look of those fasteners!

Tread plate Tread plate Tread plate Tread plate

Next>> Part 14: First test of the hydraulic system

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