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Discussion Starter · #1 ·
Sorry if this is a bit long-winded, but I'm hoping someone has some info on this unique find.
I recently purchased a 1961 Willys Jeep CJ-5 with a 1-ton dual wheel rear axle (both coil and 12-leaf springs on the back) and a backhoe mounted on it. It also has a 'dozer blade that hangs from the front axle and attaches to the frame just ahead of the rear wheels. I think the thing was some sort of commercial conversion because there's a tag on the firewall that says "Kaiser Jeep Corp. Special Sales Order No. D-3428-1", and the frame has been plated (very professionally) with 3/8" steel from front to back.
The hoe has a tag that says "Go-For-Digger", but I found no markings on the blade. They both seem to be the same color, though (industrial yellow, now faded to an eye-repelling pink. The Jeep's green). They are powered by a pump mounted on the front bumper driven by a shaft connected to the harmonic balancer. It's also wearing a Koenig steel half-cab. I know Koenig made several differrent accessories for Jeeps, could they have been responsible for the conversion? Any info anyone has on this or similar machines would be greatly appreciated.
The previous owner had stripped everything off the Jeep, and almost all the hydraulic lines (and lots of fittings) are missing and will have to be fabricated.
The problem is that I'm having trouble plumbing the thing.
My first problem is that the pump has one suction port and two pressure ports. I believe that one is a low pressure/high volume port, and the other is a high pressure/low volume port. Is this common in a backhoe application?
The second problem is that some of the control valves seem to be of the power-beyond type (I think). I'm fairly familiar with how open-center systems work, but I've never figured out what is significantly different about a power-beyond system (anyone feel like tackling an explanation of the subject?). Here's a breakdown of the different valve bodies:
The valve that runs the blade lift seems to be an open-center type (1 IN port, 1 OUT port, 2 cylinder ports) with some sort of pressure adjustment.
The valve that tilts the hoe (the hoe rolls back in the bed for transport) seems to be a power-beyond type (1 IN port, 2 OUT ports, 2 cylinder ports), also with some sort of pressure adjustment.
The main hoe valve bank has 6 valves (left stabilizer, right stabilizer, bucket, dipper, boom and swing). The return (a single large port) seems to come off the center of the valve assembly, but there are two smaller ports (presumably one or both are supply), one on each end of the valve body. Are these for the lines coming from the high pressure and low pressure ports of the pump? If so, how do I tell them apart? Or is this what a multi-valve bank looks like in a power-beyond configuration? Does this mean that there are two return ports? Again, how would I tell them apart? Also, which pressure should I run the blade and tilt cyl. from?
Experimentation to find the right setup could get expensive in a hurry. Last time I had a hose made up it was about $1/inch for 2-wire 1/2" hose (plus fittings), and steel lines are a pain to work with. Also, this thing is a hodge-podge of sizes (3/8", 1/2", 1") and fitting types (pipe, JIC, some sort of o-ring).
Any info on anything here will be greatly appreciated. I hope to get some pics up on a web site soon. If you want to see them drop me a line and I'll let you know the URL when I get one.
Thanks in advance.
Thought for the day:
He who dies with the most toys is, nonetheless, still dead.


7,901 Posts
Can't help you, sorry. I saw one of these at an antique show (same one I show my bike at), it was awesome. I little ridiculus, but awesome. I mean, how about doing something else funky, like a CJ-2A earth mover or a CJ-3B roadgrader. I don't know who owned it, sorry, so I can't ask anyone, it was just there.

'81 CJ-8 Scrambled!
GM151/SM465/NP205 twinstick/7"Lift/33"TSL's/IHC D44's 4.10's Lock'd

Discussion Starter · #4 ·
I can help you with the hydraulic questions.
1. the hyd pump probably is a two section pump, most older backhoes had a large pump for the main sections of the hoe, and a secondary section for power steering, dozer blade etc...
2. "power beyond" (pb) it is critcal to plumb the (pb) correctly, you will have three ports to deal with: pressure in, power beyond (pb), and return. the difference between the return port and the (pb) port is the return goes back to the tank, (pb) goes to the next control valve pressure in port. in an open center control valve the shaft seals on the spools are low pressure o rings, the seals are protected fom being over pressurized by being "vented" to the return line. if the return line is plumbed to the next control valve the seals will leak terribly!!!, the spools will be difficult to move when the second valve is calling for pressure, cylinders on the first valve may go "regenerative" when the second valve is calling for pressure ( this is extremely danegerous!! controls can start to work backwards at increased speeds, or intensify pressure to the point of catastrophic failure).
3. I can help you with the rest of your questions a little bit at a time, for right now could you let me know how many control valves are on this thing and how many look like they are power beyond?
4. just thought of something to help you, with all spools centered, blow air into the pressure in port, the port the air comes out of is power beyond, move a spool and the power beyond should shut off.

let me know how else I can help you.
good luck, jjc


1,800 Posts
This may or maynot help. The April edition of JP magazine has an article you might be interested in. Page 53 shows a '50CJ-3a with a trencher on the back and your plow on the front. It really doesn't give you any technical data but it has an email address:

[email protected]

Jim and Peg Marski own the collection of Jeeps that they are featuring. I would imagine they should be able to turn you onto some "real" information.

Good luck! And congrats on your find..... should be fun!!

IN2DEEP 78 CJ5 302 FORD T176/D300 35" BFGS

Discussion Starter · #6 ·
Here is some more, that is probably 'useless'.... I have a 1960 WILLYS-CJ owners manual, that has a bunch of accessories listed, in the back of the manual. There is a picture of a back hoe, but it is listed as 'Ottawa', for the brand-name. There is also a Jeep-a-trench, trench-digger. And, a post-hole-digger. In all, there are over 20 accessories listed. But, I repeat, this is Willys-era, not Kaiser, as you have indicated for your Jeep. I can scan and post the pictures, if you want. But the info is probably of no use.

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