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Discussion Starter · #1 · (Edited)
Hi all.

I've got a little tractor I built for messing about the lot that currently has manual steering. It's about the size of the older Sears Suburban GT's. I have a JD 345 front axle on it, BS 18 hp opposed twin for power and a Peerless 820 transaxle. Both the Briggs and the Peerless have been rebuilt (I have to keep busy somehow :cool:).

It can be a bear sometimes to armstrong it around and I'm looking to install a JD 318 hyd steering setup on it to "give me a hand" in consideration of my....ahem....advancing years.

I've got the assorted parts and pieces from a JD 318 steering system (5 port steering valve), but I have to add a hyd pump to my little rig to run it. The JD was junked by a friend of mine and he let me pull all the steering stuff off it before he turfed it. Hyd system was good at the time, but the rest of the JD wasn't worth keeping. He had blown the engine, hydro drive didn't work right and he even he rolled it over into a ditch once so it was kind of bent (crabbed when driven) and just other-wised messed up.

The JD specs (from a downloaded serv manual) are:

Oil Temperature for Hydraulic Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43°C (110°F)
Charge Pump Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 620—1240 kPa (90—180 psi)
Implement Relief Valve Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5861—6722 kPa (850—975 psi)
Charge Pump Flow at 3450 kPa (500 psi) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 L/min (3 gpm)
318 and 420; Steering Valve Pressure in Neutral Position . . . . . . . . . . . . . . . . 620—1240 kPa (90—180 psi)

My rig runs a BS 18hp opposed twin, so the pump would be powered from that by a belt drive. Vert shaft so I'd either have to mount the pump vert shaft wise or make a mule drive arrangement of some sort. My max rpm on the BS is 3400 rpm.

Would this pump be suitable to run the 318 steering gear? GPM seems just about right at the "rated" spec, same with a 1:1 RPM setup:

0.36 cu in DYNAMIC GPF2006PC HYD PUMP
Brand new, DYNAMIC GP-F20 series hydraulic gear pump. Aluminum center section with cast iron end covers.

SPECIFICATIONS
  • Disp. 0.36 cu. in. / rev.
  • Pump Type Gear
  • Rotation CW
  • Pressure:
    3650 PSI peak
  • Speed:
    2000 RPM rated
    3600 RPM max.
  • Flow:
    2.90 GPM rated
    5.22 GPM max.
  • Mount 2 bolt SAE A
  • Shaft 5/8" dia. x 1-1/4" long keyed with 5/32" wide keyway
  • Rqd. Filtration 25 micron
  • Inlet Port SAE 12
  • Outlet Port SAE 10
  • Size 3-7/8" x 5-1/8" x 4-1/2"
Link to pump page: 0.36 cu in Dynamic GPF2006PC Hydraulic Pump | Gear Pumps | Hydraulic Pumps | Hydraulics | www.surpluscenter.com

Plumbing would just be replicating the 318 system, I've got an "in" at the local hyd place so making lines isn't a problem.

I might also add an FEL at some point and am wondering if that pump would be able to run the steering and an FEL (assuming my cylinder size/stroke is worked out before building an FEL). The tractor has a welded frame built out of 1/4 x 4" plate (I do both MIG and TIG in my home shop, Atlas metal lathe in the corner too).

I currently have a bucket/scoop on the front (plow in the winter and a belt diven 42" blower) and lift it it with a winch, but making something hydraulic would be so much nicer to use.

But the immediate concern/question is the pump for the 318 steering.

Thanks.
 

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Hi nobrand and
2492428

To My Tractor Forum...sounds like a very interesting project...fortunately , we do have a few guys on here who are wizzes with hydraulics and should be along to offer a more informed opinion than I can.
 

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Welcome ro MTF!

GM (or Chrysler) power steering pump with a remote reservoir is flow controlled to about 2 gpm with a relief setting of 1250-1450 psi. The reservoir should have a 1 quart capacity.

A pump with a 0.36 cu-in displacement is about the right size for a loader with 2" diameter lift cylinders when driven at engine speed. If running power steering as well as a loader, a flow divider to split off 2 gpm for the p/s and the balance sized for the FEL. The reservoir should be about 2 gallons capacity. The posts for the loader often serve as the reservoir.

The JD specs are for the charge pump on the Sundstrand Series 15 Type U hydro which maintains the fluid charge in the hydro as its first call and p/s and implement lift hydraulics with whatever flow is left over after the hydro demand.
 

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Discussion Starter · #4 ·
I'm looking at the JD manual and the steering valve appears to be arranged like so:

"IN" comes from the charge pump on the hydrostatic transmission.
"OUT" goes to the oil cooler and back to the transmission.
"AUX" connects to the bottom of the hydraulic control valve for the deck and other attachments.
"LEFT" goes to the rear of the hydraulic steering cylinder.
'RIGHT' goes to the front of the hydraulic steering cylinder.

Wouldn't that arrangement mean the valve is essentially a "bypass" when in the center position?

And if it is in bypass, wouldn't that mean I can use the gp-f20 pump to actuate the system the way it is"?

I've also go the two spool implement valve from the 318. Would that work for the (eventual) FEL controls? According to the JD serv manual, the two spool has a float detent, which would be great when using a snow plow or snow blower.

I'll also plumb in the stock Hyd cooler from the 318 for good measure. Easy enough to put it in the return line somewhere.

I'm familiar with hydraulics, but not this commercial/industrial stuff. My Hyd background is aerospace, which is like we're going to the same party but hanging out with a different crowds once we get there. I'm looking to learn a bit as well as build something.
 

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Discussion Starter · #5 ·
Ah, hold on. Looking at the diagram for the 318 hydrostatic drive section, I see internal valves for charge and implement relief. Looks like I might have to find a way to add one to my system since the GP-F pump is just a straight up pump and the steering/implement valves only have return provisions.

Probably should look to add a filter and maybe an accumulator (IE: as a hyd damper for when valves are closed to protect the pump) in the system somewhere too.
 

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Discussion Starter · #6 · (Edited)
Here's the diagram I'm looking at:

2492444

#1 is the hydrostatic unit, #5 and #6 inside the unit are the relief valves.

Rethinking the accumulator thing. None is indicated in the diagrams, thinking I might need one is probably my aircraft background coming out again. Last thing you want to do at 35,000 feet is cavitate a pump, probably not as big a thing in a terrestrial application.
 

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Discussion Starter · #7 ·
I am considering the GM PS pump idea. The only thing is I;m not sure if my BS 18hp opposed would have enough umpfh to run the PS pump, the Hyd pump and drive the tractor since the belt drive I have in my mind would be driving it all at once.

Two pumps also means I'd have to give up the idea of driving a separate alternator, which I've been wanting to do since the BS oem one doesn't generate many amps. Somewhere around 5 amps IIRC. Everything is LED on my rig, but it still only has the little BS OEM alternator in there. Right now, I toss the charger on the battery after every use, just to be sure it's ready to go next time.

The BS would probably be pressed to drive an alt and a pump, let alone a second pump.
 

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I've seen a few homebuilts that used a GM power steering box from a 60's to 80's GM car or truck,which are self contained ..and designed to be used with their P/S pumps...
I'd think the pump wouldn't take much HP,and would only put a burden on the engine while steering it or raising the bucket on a loader...alternators dont drain much HP once the battery is charged fully and only when a heavy electrical load is applied..
I run a GM alternator off a 5 HP and a 6.75 HP engine and they don't bog down much ,I did have to do some juggling with pulley sizes to find a sweet spot though..spin them too fast,the engine bogs down..
I use them to boost low or dead batteries on my tractors and pickup..sort of a gas powered jump starter..
 

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Discussion Starter · #9 ·
I think I have the layout mostly figured out.

I'll have to redo the frame a bit and slide the engine forward approx 5 inches. There's more than enough frame in front of it to do it. That will let me put a new muffler under the frame (the original is rusted out and needs to be replaced anyways) and free up some much needed room to mount accessories behind the engine.

I'll use a gm remote res pump since I can mount it vertically (like the BS 18hp). Same with the GP-F pump. Each will have it's own belt.

The GM PS pump will be direct drive, so I will have steering whenever the engine is running.

The GP-F I'll repurpose a car AC clutch (new take off from another project) I've got hanging around so I can toggle it on/off as needed. That should allow me to disengage it in order to make it easier on the little BS starter when trying to spin it all. It will be fairly easy for me to spin out an adapter since I have a 10" metal lathe on hand.

Space allowing, I might be able to get a mini-style alternator in there as well. That would also be direct drive. I'll have to see exactly how it works out for space once I get into it.

That will mean I'll have to make a stack of pulley's on the BS output shaft. One for drive, one for PS, one for Hyd pump, one for ALT and on the very lowest point one to drive the front blower. There's plenty of room on the current sheave adapter, it sounds like a lot though.

Perhaps I can eliminate one sheave and drive both ALT and PS off the same one, but that will likley mean an idler pulley in order to get good engagement on both accessories. I have to think more on that one.

Another problem I'll have to overcome is the length of the drive belt. It's already pretty long, but 5" further away means another 10" of belt. It might be fine like that, it might not. What I might do is add a double pulley on a bearing somewhere between the transaxle and the engine sheave, effectively splitting the one long drive belt into two belts.

reservoir i'll just make something out of aluminum and use the space I have available in the body. I should be able to get a couple gallons in there and ideally, the PS and GP-F pump would be able to use the same tank/fluid. It just means two lines out/in instead of one.

It all sounds a bit complex, but it makes sense in my head. Guess I'll have to see if I can translate it into metal this spring.

The big question right now is if I will need a pressure relief/safety valve on the GP-F pump. I believe I will, but it will also only be running the loader and accessories now so I'm not sure either way. I'm thinking when the control valves (accessories, not steering) are neutral, it's not problem as I believe they just bypass to return. It's when i'm calling for work from the system that i might need the safety valve.

Time to read some more "specs" pages.
 

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I'm familiar with hydraulics, but not this commercial/industrial stuff. My Hyd background is aerospace, which is like we're going to the same party but hanging out with a different crowds once we get there. I'm looking to learn a bit as well as build something.
Same party, but the two crowds have slightly different meanings for the words spoken. Aerospace uses closed center hydraulics, as does heavy construction and farm equipment. Small mobile equipment such as our GTs, use open center hydraulic systems where the fluid has free passage from the pump, through all valve sets, and back to the reservoir. When a valve is shifted to do work, then pressure climbs to a level to do the work, or if the work is too hard, then to the relief setting where most of the fluid is dumped back to tank while maintaining the set pressure until that valve is re-centered and the primary pressure drops back to nominal zero. Accumulators don't work on open center hydraulic systems.

Yes, your utility pump (GP-F) will need a relief valve right after the pump. The return for the relief is commonly directed to a T at the pump's inlet to join with flow from the reservoir.

While some have made use of the charge pump on the Sundstrand hydro in their tractor for FEL duty, it results in a slower than desirable set up which is also subject to the demands of the hydro charge circuit and the power steering which can leave the loader with no flow to work with.in some circumstances.

Typically, a pump for FEL duty will draw up to about 4 hp from the engine. The one on my GT will draw up to 6 hp only because it also operates my log splitter at a higher pressure, than is normal for a FEL A GM p/s pimp will draw up to 2 hp when loaded. Neither pump is loaded during engine start. The starter on the Onan in that tractor has no problem spinning the engine, hydro, and the auxilliary pump at - 25°F.

A 37 amp alternator will draw 3/4 hp when under full load. The engines for most GTs with lighting circuits have alternators in the flywheel that can produce 12 - 20 amps. If yours doesn't, you should be able to shop around for a blown similar engine that does.

Available real estate for a 2 gallon reservoir is in short supply on a GT. The pair of 2x4x1/8 rectangular posts for my loader have a total nominal 2 gallon capacity (1.6 gallons usable) and do not require real estate above and beyond what is necessary for the loader structure.
 

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Discussion Starter · #11 ·
Same party, but the two crowds have slightly different meanings for the words spoken. Aerospace uses closed center hydraulics, as does heavy construction and farm equipment. Small mobile equipment such as our GTs, use open center hydraulic systems where the fluid has free passage from the pump, through all valve sets, and back to the reservoir. When a valve is shifted to do work, then pressure climbs to a level to do the work, or if the work is too hard, then to the relief setting where most of the fluid is dumped back to tank while maintaining the set pressure until that valve is re-centered and the primary pressure drops back to nominal zero. Accumulators don't work on open center hydraulic systems.

Yes, your utility pump (GP-F) will need a relief valve right after the pump. The return for the relief is commonly directed to a T at the pump's inlet to join with flow from the reservoir.

While some have made use of the charge pump on the Sundstrand hydro in their tractor for FEL duty, it results in a slower than desirable set up which is also subject to the demands of the hydro charge circuit and the power steering which can leave the loader with no flow to work with.in some circumstances.

Typically, a pump for FEL duty will draw up to about 4 hp from the engine. The one on my GT will draw up to 6 hp only because it also operates my log splitter at a higher pressure, than is normal for a FEL A GM p/s pimp will draw up to 2 hp when loaded. Neither pump is loaded during engine start. The starter on the Onan in that tractor has no problem spinning the engine, hydro, and the auxilliary pump at - 25°F.

A 37 amp alternator will draw 3/4 hp when under full load. The engines for most GTs with lighting circuits have alternators in the flywheel that can produce 12 - 20 amps. If yours doesn't, you should be able to shop around for a blown similar engine that does.

Available real estate for a 2 gallon reservoir is in short supply on a GT. The pair of 2x4x1/8 rectangular posts for my loader have a total nominal 2 gallon capacity (1.6 gallons usable) and do not require real estate above and beyond what is necessary for the loader structure.
Given the JD 318 parts I'm using and the GP-F pump specs, what would you recommend for a relief pressure?

It's a little unclear in the manual, but it looks like the 318 system works at around 900-1000 psi. I'm not used to the way they lay out specs, I'm used to seeing system operating pressure plainly listed. Probably because I'm used to dealing with MIL spec and CoC.

If I were to take a WAG at it, I'm thinking around 1000-1500 psi for system relief.

I'm also probably going back to one pump running it all since the reservoir-less PS pumps all seem to have a drawback in some way (IE: non-removable pulley, no return pipe threads, etc) and I'd rather not set up a right angle belt drive if i don't have to.
 

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Discussion Starter · #12 ·
whipped up a quick diagram using the JD 318 system as the template:

2492545

Anyone see why that wouldn't work?

All steel lines except where I need hoses for movement. I'll either reuse the JD lines (if they fit with minimal shaping) or just double flare up my own JIC flares.
 

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whipped up a quick diagram using the JD 318 system as the template:

View attachment 2492545
Anyone see why that wouldn't work?

All steel lines except where I need hoses for movement. I'll either reuse the JD lines (if they fit with minimal shaping) or just double flare up my own JIC flares.
The diagram is bang on, but double flare JIC? I've only seen single flare JIC 37° fittings used.

The pressure relief for such a system on a GT would be set at about 1000 psi, depending on the sizes of the cylinders.
 

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Discussion Starter · #14 ·
The diagram is bang on, but double flare JIC? I've only seen single flare JIC 37° fittings used
I guess I’m just used to double flares. I’ll have to double check what is one the JD lines. They’re out in the detached garage and too cold right now to go digging through bins. If single will do, so much the better.

I’m trying to remember what the pump drive coupling is called, but I can’t for the life of me remember. The piece that looks like a two part keyed coupling to go between the pump shaft and belt drive.
 

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Discussion Starter · #16 ·
Lovejoy coupling.
Thanks. I had “Thomas coupling” stuck in my head and couldn’t get past it. TC is a flexible drive coupling made of a stack of plates that we used on some helicopter transmission drives.
 

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Discussion Starter · #17 ·
Ok. Call me crazy but I'm going to try and make my rig hydraulic drive (ish).

Was talking with a friend of mine and mentioned I was pulling my tractor down to the frame for a rebuild. He told me he had a bunch of old case 446 parts out back in his shed.

Long story short: hydraulic motor with splined shaft, travel control valve and the Hyd pump are now out on the shelves in my garage.

No lines, but I can figure those out myself from a couple manuals I've downloaded. Schematic make it look like I'll need to add another cooler for the drive. All these Hyd coolers might be a good thing for me though, pretty easy to use a fan to draw off some heat to maybe pump a little bit into the cab in the winter.

Plan is to run the pump of the brigs 18hp and run the current MST off the case drive motor. considering if I just want to use pulleys and belt, maybe a chain drive, maybe something I haven't thought of yet.

That means the Briggs will only be running a couple pumps, which it should be plenty for.

Transaxle gears will be a bit irrelevant at that point, but it does mean I can leave it in a forward gear and not have to worry about breaking that little internal drive chain that the peerless 820 uses for reverse.

Also have in the back of my mind that I might take a smaller car/SUV rear axle and cut it down to width for the tractor and maybe drive that with the 446 hyd motor would need to build a coupling, off set drive or something like that). I've cut axles down before, but since this is slow speeds I can just cut it down and worry less about if it's all balanced. Big bonus is the axle would then be tough as heck. Tougher than anything I would be throwing at it. If I get the right one, I can probably also reuse the brakes on the axle.

Now that I'm thinking about it, if I make my selection of axle carefully, I might be able to even get a locker for it (ARB airlocker, limited slip, etc). I just have to make sure the center section is small enough to fit under the tractor and not hang too low.

I must be crazy.......:ROFLMAO:
 

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Discussion Starter · #18 ·
Was thinking about how to get the case drive motor to the peerless 820 transaxle. I was thinking about splined pulleys and a few other methods.

All of them would have required a fair amount of work on the lathe and mill. It's going to take a while to put this all together, but I don't want to be two years in building just the base tractor before starting to build the mini-loader.

A case 220 hi/low rear axle/gearbox showed up on ebay. I started thinking about all that time and work (not to mention the weight carrying capacity of the 820 is 600 lbs) vs the price on the case axle.

I ended up buying the Case axle. Shipping was as much as the axle. Combined cost was a little high, but I decided that this rig is going up a level (LT to GT) and this was a needed addition.

But I'll be able to make mounts and bolt it up. That will give me the same drive line of a 220, minus a few non factory bits (lines, etc) and that big (compared to the 820) axle should up the weight capacity in the rear a good amount.
 
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