Backhoe Design Ideas

[dfkrug]

Here's the thing about the shutoff... I'd need to shut off both hoses.

Why is that? Think about it....you need to shut off only one hose.

If I went with a ball valve, I'd need two per side. That means I'd need to turn four valves every time I switched from one side to the other.

That's a total of ONE ball valve, on the down pressure work port of ONE of
the 2 outrigger cylinders. Like this one: https://www.surpluscenter.com/item.asp?UID=2009090312165965&item=9-7281-4&catname=hydraulic $23
This approach will give you almost the same functionality as 2 independent
spool valves, and it is about $15 cheaper than going with a solenoid-
activated spool valve like the HydraForce one I used for my thumb.

I don't recall what 5-spool valve you bought, but if it is a stack valve,
rather than a monoblock valve, you can likely buy one (or two) more
sections for it.

 

[Iplayfarmer]

Why is that? Think about it....you need to shut off only one hose.

Now that I follow your suggestion and think about it I realize that if one hose is blocked then there's no circuit. Fluid going either way will be blocked.

I don't recall what 5-spool valve you bought, but if it is a stack valve,
rather than a monoblock valve, you can likely buy one (or two) more
sections for it.

My valve is a hand-me-down from another machine. It's a complete unit. I'm pretty sure there's no adding valves.

 

[Brad_Blazer]

Why is that? Think about it....you need to shut off only one hose.

Why didn't I think of that? I'd still put in 2 valves, put the legs down, then close the valve on the high side for final leveling. With just one valve, you could still go up or down with the open leg to level.

 

[Iplayfarmer]

Why didn't I think of that? I'd still put in 2 valves, put the legs down, then close the valve on the high side for final leveling. With just one valve, you could still go up or down with the open leg to level.

I'm thinking put the two ball valves in and leave them open most of the time. In the rare instance that I need the stabilizers to work independently or if I notice some sway due to fluid running between cylinders, I can close one or both valves.

Done. $50.

Just for the record, I bought a bunch of the steel a month or so ago. I keep wanting to start cutting and welding, but I'm afraid to start until I get the whole design drawn up. I suppose that's good. Even the stuff that I thought was done and never going to change has changed a little as I make adjustments to the rest of the design. There's going to come a time, though, when I have to just start fabricating and figure the rest out as I go.

I've learned my lesson about keeping only one copy of my plan. Now I'm e-mailing the plan back and forth from work to home. I have copies on both computers plus all the email servers and cyber stuff out on the net.

 

[rawinok2]

I just joined the Bynet yesterday so forgive my ignorance of what all is going on with your project (too lazy to read through it all !).
Like the fellow on U-tube, I too have built a "Ground Hawg'' trailerable backhoe ().I wish I had his setup ! But with a Lincoln buzz box, a cutting torch, and a chop saw, I was able to turn out a pretty decent project in about eight weeks time. I have used it now for about two weeks and must say that I am amazed of what all it can do. I am presently using it to dig a drainage ditch on the back of my property. I have encountered many rocks and roots, and so far, have been able to deal with them with little difficulty.
Since the unit is very light, all digging must be done within a few feet of the stabilizer feet. This is not a problem because by reaching out with the dipper arm and pushing down with the boom, the stabilizer feet lift up out of the ground. You then curl the dipper arm in or out to locate yourself exactly where you need to be. Then you take your bite by curling the dipper arm and bucket simultainously. It takes some practice. I would imagine that it is nothing at all like the big units, but I wouldn't know.
I was going to attach some photos of mine but I guess it's not going to let me do that.
B.T.W. "ubuilditplans.com" offers plans for a three point unit as well.

 

[Iplayfarmer]

I answered one question last night. That is the question of whether to go with a PTO pump or use the tractor hydraulics. I picked up a used pump and reservior from a guy on Craig's List. (Have I mentioned that I love Craig's List?).

The guy had the pump left over after he retrofitted a 3 pt. backhoe to run off of his tractor hydraulics. Judging from the size of the cylinders on this guy's backhoe, I may have a little more flow than needed. Another indication is that the reservior is pretty large... over 11 gallons. I have some larger cylinders, and I may go back to the drawing board with the larger cylinders. The next step is to mock up a simple hydraulic circuit with this pump and time the motion on some cylinders. That will tell me empirically what kind of results I'll get.

 

[J_J]

An over-sized pump is no big deal, you just slow the engine down to the volume you need. The other way to get the GPM's you need to the cylinders is to use a flow divider. It will split the volume 50/50, 70/30. or whatever divider you can find.

 

[Iplayfarmer]

An over-sized pump is no big deal, you just slow the engine down to the volume you need. The other way to get the GPM's you need to the cylinders is to use a flow divider. It will split the volume 50/50, 70/30. or whatever divider you can find.

I've known that the tractor's hydraulics would be marginal at best. I like the idea of being able to run at a slower speed when needed or increase the throttle when I want more speed.

My only concern with the larger pump is that the tractor may not have enough power to run it. Keep in mind I only have 15 hp at the PTO. I know it will run it fine with no load, but when I put a good heavy load on it, will it kill the tractor before it can build enough pressure to do the work?

 

[J_J]

Although I don't know the cu in of the pump, A large pump will only draw the power it needs to operate. As soon as the pump is turning, it has potential pressure, and if the pump is running at low volume, 2 or 4 GPM's, it still is going to get the work done. The larger pump only becomes a problem, when it is running at full rpm, and you put a heavy load on the system, then the pump may stall the engine, because it now requires more HP, which you don't have. Once you know what that limit is, you can operate within set parameters.

 

[Iplayfarmer]

Although I don't know the cu in of the pump, A large pump will only draw the power it needs to operate. As soon as the pump is turning, it has potential pressure, and if the pump is running at low volume, 2 or 4 GPM's, it still is going to get the work done. The larger pump only becomes a problem, when it is running at full rpm, and you put a heavy load on the system, then the pump may stall the engine, because it now requires more HP, which you don't have. Once you know what that limit is, you can operate within set parameters.

It seems to me that a large pump is like running your car in a higher gear. It goes a lot faster, but can't do it if there's much of a load. The inverse is also true that a small pump is like driving around all day in 2nd gear.

There is an up side to the limitations of a larger pump... the engine will stall before the machine will tear itself to bits. It's all academic speculation for now until I can hook her up and get some real data.

Would the flow divider you suggested get around the issue of stalling the engine at full RPM?