backhoe cadplan

bluecarpenter · Mar 23, 2004

got the plans the other day on cadplan 821 backhoe. looking the parts over. don't understand the difference between a single stage and dual stage pump. it is calling for a 6GPM single stage i guess i can come up with something close to that. what kind of valve body shoud I look for I would like to add hydrolic stableizers at a later date. they call for a 4 section open center and adjustable relief. says all sections are 4 way ??? 3 position spring centered. that means forward and back spring to center that much i can get what is the all sections is 4 way?
found a 5 spool 7 GPM valve at ( surpluscenter.com ) it has open center with adj. relief pre set. was wondering if that would work. don't want to spend a fortune on one but want to get the right one. would like some input on this. thanks mark

F_22 · Mar 23, 2004

I can't answer the rest of your questions but I know that dual stage pumps are usually used on input shaft horsepower limited applications. In my opinion dual stage is a misnomer because they are really two pumps in parallel, with one having 2 or 3 times the displacement of the other and a relief valve set lower than the smaller pump.

On a log splitter, for instance, when you are in clear wood and the load is low both pumps supply oil to the ram and it moves rapidly. When you hit a knot and the load goes up the larger pump pops off and unloads while the smaller pump then supplies oil at increasing pressure to the ram, but the ram moves slower due to the reduced volume of oil delivered. In this way one can get fast ram movement but still not stall the engine when the load is high.

chocolatehauler · Mar 23, 2004

I built a caddigger 821 I'm no expert, but the way it was explained to me is a duel stage will allow you to do two fuctions at once. Like lift and curl at the same time. As to the valves I chose to let them enginer that. My time looking for the right parts if I could figure that out was worth somthing to me. I had alot of fun putting it togather. Used about fifty lbs of welding rod. Works great to. good for trenching and digging stumps ect. Only thing it's not so good at is digging basements. You can't throw the dirt far enough. have fun /forums/images/graemlins/smile.gif

jrlichina · Mar 24, 2004

You are confusing 2 different components. A dual stage or 2 stage pump has one half a high volume pump(low pressure) and the other is a lower volume pump(high pressure). These are used for log splitters to give good speed through most of the splitting of the log(high volume/low pressure), but when it encounters a knot or harder portion of the log it switches to the lower volume higher pressure pump to get more power to the splitting wedge. Once past that it switches back to the high volume. Now for multi spools valves they can be either "parallel" or "Series". If you need to have more than one spool activated at a time you get a "parallel" valve. Hope this helps.

dourobob · Mar 26, 2004

My buddy and I are just in the final stages of building an 821 and it has been an incredible experience (especially for me - when we started this project I warned him that my choices of shops when I entered high school - a looong time ago - were Latin or Typing and he was still willing to let me into his shop and to teach me).

We considered the Split Hydraulics Option but to the best of my recollection this did not mean a two stage pump (I don't have my book and reference materials at home right now - they are in the shop). I remember talking about a larger pump and a hydraulic set up that would allow full flow to more than one hydraulic circuit.

On the CadPlans website for the 841 model they offer the following description

<font color="blue"> Split hydraulics is a unique feature for the CADDigger Model 841. Each of the two joystick control levers has its own hydraulic supply. This means you can curl the bucket and operate the boom or boom extension with full flow and full pressure at the same time, truely doubling the performance of the machine. Of course to do this a larger engine and pump is required. The Model 841 uses a 18 horsepower engine and 12 gallon per minute pump.Only very few commercial machines offer this split hydraulic system design. This truly is a performance enhancement if maximum performance is a requirement of your machine. </font>

Hope that helps.

We are also thinking of building another machine with hydraulic stabilizers - Did you get plans for these with your 821?

Bob

johnbilt · Mar 26, 2004

HI

I have looked closely at the Cad Digger's also. What do you think about the 3 pt hitch setup? I have read some responses that feel the set up is weak.

Did you cut your own metal or order the complete kit ??

I have a JD990 / 40HP and expect that one of these would make a great trencher and digger. For less bucks than JD backhoe....

John

dourobob · Mar 27, 2004

I have a 52 HP 4WD tractor but I kept getting all kinds of warnings about a 3PH backhoe. Hard on the mounts, too many weak links etc if it is on the 3PH. On the other hand it is probably easier to mount than a frame attached model.

My buddy and I decided on the 821 as a self contained unit because he would not always have access to my tractor when he needed to use the hoe. Also, if we are working on a project together, we have two seperate machines and can be doing different tasks at the same time around a site.

We think this will work well for us.

I am sure there are many opinions out there on TBN regarding the 3PH backhoes but I would go for a frame mount if I was putting it on my tractor.

Just my $0.02

Bob

bluecarpenter · Mar 28, 2004

no I just got the plans. would like to get the kit but not able to afford it right now. a bit spendy. I will probably locate most of the metal myself. I can get some at a scrape yard that has a lot of 1/2 inch plate and other kinds for .15 cents a pound. cheap. /forums/images/graemlins/smile.gif already have some extra pieces of the stuff . I designed and built a bumber for my pickup from scratch with no drawings, just what was in my head so I figure I will manage.