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Discussion Starter #1
I'm upgrading the hydraulic pump on a JD-400 with an FEL and Backhoe. The pump - new in the box - came with the tractor when I bought it. I confirmed it's the right size for this tractor. I'm trying to figure out what the parts do as I know little about them.

Photos of:
PTO output spline
Old pump with output spline adapters/collars
New pump
New pump gizmo
Adapters/collars

The new pump is laid out in the order of the parts. The two collars or adapters DO NOT rotate inside the big chain gizmo.

Questions:
What is the yellow gizmo and what does it do? The hole thing rotates so it doesn't seem like it would be a clutch. I suppose I could Googlebang around, but would rather have an expert ID what it is and the function.

The yellow chain gizmo is in a clam-shell with rubber ring seals. Is it filled with fluid?

Are there any parts missing from the assembly for me to install it?
 

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The yellow-covered gizmo is baffling me, too. I don't understand what its purpose is. It seems to simply be being used as an adapter between the pump shaft and the splined pto shaft. But why so complicated?

Instead of the gizmo, could the shaft-pto adapter from the old Cessna pump be used with the new pump? All you need to do is spin that pump. It's not complicated -- connect pump shaft to pto shaft. Often, love-joy couplers can be found to match both shafts.

Unless that gizmo is somehow reversing the shaft input, because the pump rotation direction doesn't match the pto rotation? But I would just get the correct pump rather than go through a complicated gizmo.

Hopefully someone more knowledgeable will come along who recognizes the gizmo.

--
 

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I think the yellow thing is just a safety cover to retain those roller chains in case one ever broke..
The idea of the chain coupler is to allow two different shafts to be joined together by two sprockets and the double roller chain,same as using two lovejoy couplings and the rubber insert,but the chain is a lot stronger and allows for some misalignment without strain on the pump shaft..
 

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Discussion Starter #5
I agree to all - which is why I posted. That gizmo is waaay to complicated not to have a specific function. And is likely way too expensive for the guy to buy it for the heck of it.

Yup - I could just plug the pump on to the output shaft - which is why the gizmo seems to have importance.

My best guess is it absorbs any minute misalignment or out of balance which would transfer a wobble harmonic into the pump.
 

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You need a mount for the pump, otherwise the pump will spin when the hydraulic pressure builds.

The yellow cover is to contain the grease that needs to be packed around and through the chain for lubrication. Unless the seals are very loose, the cover spins with the coupling. Without the cover, the grease gets thrown off and lands everywhere in the vicinity.

All coupling are sensitive to misalignment. Those with elastomeric elements, like the Lovejoy, are somewhat less sensitive than those using gears or chains. The shafts can be bushed to the same size by finding the master link in the chain and turning the coupling halves end for end. This makes the job of aligning easier. After the pump is mounted, use a straight edge along both coupling halves at the top (12 o'clock) and on the side (3 or 9 o'clock) to ensure alignment. Any daylight between the straightedge and the flat of either coupling half is unacceptable. Move the pump in its mount and/or add shims as necessary to achieve alignment, then mark the pump and shim stack locations for reinstallation after the coupling is reassembled and in place.

That type of coupling has a lot of rotating mass and very limited "give", especially when brand new. Any misalignment is going to play havoc with the bushing in the front end of that pump. The elastomeric element in a Lovejoy is actually more forgiving for this type of application.

What is the displacement of the pump and the rpm of the PTO?
 

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The old Cessna pump is very low-profile compared to that new pump, and used a compact solid coupler. It probably only protruded a few inches forward of the tractor.

If you use that bulky chain coupler in combination with that new longer hydro pump, you may find that the whole apparatus sticks out too far in front of the tractor. It could be vulnerable to damage, and may even interfere with the FEL crossbar.

I would look for a compatible Lovejoy coupler at McmasterCarr. They are very reasonably priced.


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Discussion Starter #8 (Edited)
Thanks Tudor and Urban guy.

The pump has a heavy mount you can see the top of in the first photo. I can easily fabricate a bracket for it. When assembled, the pump is in about the same place as the Cessna pump. Maybe a tad farther out, but not much.

Tudor - you validated the pump and rpm's in an earlier post on my main thread: Refurb: JD-400 with backhoe/front loader
It's a Dynamic model GP-F10108PC (pump spec is attached as PDF)

So.... this begs the question of whether I should use a different/better coupler. You both mention the Lovejoy coupler - is it a better choice? What style/model would you recommend?

https://www.lovejoy-inc.com/products/
 

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Discussion Starter #9
Specific pump spec in both PNG and PDF (easier to read)
 

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I'm going to throw out a word of caution too.

It looks like the original used a solid coupling and a torque arm. The solid coupling is just that, a solid connection, so both ends should be tight with set set screw or two. The torque arm should be against something solid; like, the frame. The arm should be contained in a slot parallel to pump shaft to transfer torque and still allow some movement to relieve stress from pump shaft. So a solid coupling and flexible mount.

Your making a solid mount and a flexible coupling, which will also work, maybe better, as long as the solid mount is solid and the alignment can be maintained.

I think the original method was chosen because it will be difficult to make a good solid mount.

I'll be keen to see the outcome. Did the original pump fail? If so how did it fail, i.e leaking due to side load? Sometimes the connection between the torque arm and the retainer wears or something gets bent and puts stress on the pump shaft causing failure.

BTW, those chain couplings are way too expensive for me. I buy Love-Joyy equivalent for $20.00.
 

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Discussion Starter #12
I'm going to throw out a word of caution too.

It looks like the original used a solid coupling and a torque arm. The solid coupling is just that, a solid connection, so both ends should be tight with set set screw or two. The torque arm should be against something solid; like, the frame. The arm should be contained in a slot parallel to pump shaft to transfer torque and still allow some movement to relieve stress from pump shaft. So a solid coupling and flexible mount.

Your making a solid mount and a flexible coupling, which will also work, maybe better, as long as the solid mount is solid and the alignment can be maintained.

I think the original method was chosen because it will be difficult to make a good solid mount.

I'll be keen to see the outcome. Did the original pump fail? If so how did it fail, i.e leaking due to side load? Sometimes the connection between the torque arm and the retainer wears or something gets bent and puts stress on the pump shaft causing failure.

BTW, those chain couplings are way too expensive for me. I buy Love-Joyy equivalent for $20.00.

Yes to all Mr Nerd -
The chain setup protrudes a little further, but doesn't interfere with FEL, although it WILL be more exposed to being struck by debris. I don't anticipate a problem fabricating a robust bracket for the pump mount. I can weld some 1/4" plate bolt on and come out from the frame ends. I can also make a cover-cage to protect it above and below. Below are some photos of the original positioning.

I believe he was going to replace the original because the FEL and Backhoe moved slowly and he thought a bigger pump was needed. What he failed to do was flush the system, which was full of water and spooge. The new pump IS a good upgrade, but new hoses and cleaned out system will do wonders for operation.

**************************************

I'm back to the original question: Which coupler is a better choice for this application.
Will the Lovejoy be a simpler, less failure prone solution?
Is the chain coupler hard to mount and align to the point it may cause pump failure?

I'm looking for the BEST setup. Since the pump and coupler were 'free' - I don't mind changing things.

*
 

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Discussion Starter #13
Tudor may have another suggestion, but these (or similar) are what I had in mind:

https://www.mcmaster.com/lovejoy-couplings


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If you look at the Lovejoy website there are several flavors of the motion control type couplings. They are variations of what you selected from Mc-M. I'm wondering if there is one better for this application.

https://www.lovejoy-inc.com/products/motion-control-couplings/

I looked at the Mini-soft and Miniature Jaw (L) as options. They seem to lend their designs towards vibration and misalignment forgiveness.

Thots?

*
 

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If you look at the Lovejoy website there are several flavors of the motion control type couplings. They are variations of what you selected from Mc-M. I'm wondering if there is one better for this application.

https://www.lovejoy-inc.com/products/motion-control-couplings/

I looked at the Mini-soft and Miniature Jaw (L) as options. They seem to lend their designs towards vibration and misalignment forgiveness.

Thots?

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I would probably just go with that option at McMaster. It's the basic/standard lovejoy coupling that is tried and true, and low cost. Offered in lots of different shaft sizes, so easy to pair up.

If you want to fine tune it, some of those other options might offer a few advantages. But I doubt you'll really notice any difference. Here's an FAQ that might help you choose:

Jaw Coupling Overview - Features & Benefits, Design Basics, and Element Options | Coupling Answers | Where the World Turns for Coupling Knowledge


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If I got drive coupling for free, I'd use it. I didn't mean to come off all thou shalt not doeth; after all, that $100 pump (the chain coupling probably worth more) will likely last 10 years, even with a little misalignment, and then you buy another one.
I was trying to suggest that the original setup was fine, with a little maintenance.
 

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That type of coupling has a lot of rotating mass and very limited "give", especially when brand new. Any misalignment is going to play havoc with the bushing in the front end of that pump. The elastomeric element in a Lovejoy is actually more forgiving for this type of application.
Keep in mind that the weak link in this coupling arrangement is the 1/2" diameter pump shaft and its supporting bushing. The stability of the supporting structure for the pump mount may also be questionable, considering the forces applied by a FEL, resulting in possible misalignment.

As a general rule, roller chain couplings are used for base equipment such as pumps mounted on concrete or heavy steel bases. Lovejoy couplings are more likely to be used for mobile applications where mounting plates may be more subject to flexure.

The coupling and pump may have been free, but the combination will be expensive down the road. You want a flexible coupling to accommodate the expected misalignment. Don't overthink which Lovejoy to get other than for the right shaft sizes and horsepower.
 

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Discussion Starter #17
Keep in mind that the weak link in this coupling arrangement is the 1/2" diameter pump shaft and its supporting bushing. The stability of the supporting structure for the pump mount may also be questionable, considering the forces applied by a FEL, resulting in possible misalignment.

As a general rule, roller chain couplings are used for base equipment such as pumps mounted on concrete or heavy steel bases. Lovejoy couplings are more likely to be used for mobile applications where mounting plates may be more subject to flexure.

The coupling and pump may have been free, but the combination will be expensive down the road. You want a flexible coupling to accommodate the expected misalignment. Don't overthink which Lovejoy to get other than for the right shaft sizes and horsepower.
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BINGO! Thank you Tudor - that went to the heart of my question. When my friend and I (he's in the photo) saw that coupler we both had the same reaction: Whoa - this thing is bigger and more complicated than the pump! It clearly had some design purpose as the old pump has a straight, solid, coupler. Not knowing a whole lot about hydraulics, the question that came to mind is....WHY? Was it needed - or was it an overkill for this application?

The answer is - as I see from all the responses: It's an overkill. It may even be detrimental to the pump.

THANK YOU - to all who contributed. I will select a Lovejoy coupler more appropriate to this setup.

In addition, I will fabricate a bracket with a cage to both mount the pump and provide protection from objects hitting it from above or below. It's sort of hanging out in the war zone when the FEL is being operated.

Back to my original thread: Refurb: JD-400 with front loader and backhoe
 

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Discussion Starter #18
Trying to figure out what components to use. The dilemma is the PTO output shaft, which is splined.

The first photo shows the adapters which came with the Kana chain coupler. One is splined for the output shaft and the other has a woodruff keyway for the pump.

Here's the stack OD for each:

PTO shaft: 1" splined
Shaft adapter: 1 1/2" OD with splines inside
Pump adapter: 1 1/4" OD w/keyway
Pump shaft: 1/2" w/keyway

The pump side Lovejoy hub isn't a problem. However, the output side hub has two ways to go: on the spline shaft or on the splined adapter. The adapter has a 1-1/2" OD, so do I select a hub to go over it? ~ OR ~ select a 1" hub to go over the PTO shaft? The problem with this is the hub has a keyway - not set screws.

When I look at the McMaster Lovejoy selection chart I'm confused. I've got the 1" spline going to a 1/2" shaft w/keyway. I can't figure out the selection 'shaft size' where they list 2 dimensions: 1" x 1/4" on-up. What are the two dimensions?

Am I making this too complicated?
Do I select each side separately?

HELP!
*
 

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The two dimensions are shaft diameter and key size.

Select the hubs separately.

Unless Lovejoy stocks a hub that matches your PTO splines, you need the extra bushing, and you'll have to get someone to cut a key slot in it to mate with the one in the hub.

Note that a key does not have to be square. There is rectangular key stock available for situations where a bushing may not have sufficient meat to make a key slot to accommodate a square key. Optionally, a square key can be filed or ground down to fit a shallower slot.

Make nice with the machine shop instructor at your local high school or community college for some assistance with this aspect of your build.
 

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Yes, order/spec the two sides separately. If you don't see what you're looking for listed on the McMaster website, just give them a call. They are real helpful. Have all the specs available so you can accurately describe what it is you need. Shaft diameter, # of splines, etc.

If McMaster can't find it for you, the next step is to call Lovejoy directly. I am fairly certain they make a splined bore for pto shaft adapters. Failing that I might even be okay with a 1" round bore with at least 2 opposing set screws, or maybe a clamping coupler.
 
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