L1720 FEL Cylinder Hose Fitting Size/Type & General Rebuild Q's?

[evantwheeler]

Kind of a simple/silly question, but reading through the manual I have and also scouring the internet, I cannot find any info on the fitting type or size for the 1720 hose to cylinder connections. I want to take the cylinders off for a rebuild and want to have caps & plugs on hand before doing any disconnecting. The connections from the hose to the 90 elbow at the cylinders appear to be a JIC type of fitting as there are only 3 threads showing on the male part of the elbow (hose end is female). IME, if these were straight pipe threads, there would be more threads showing, and I also cannot see any taper to the threads, but kind of hard to eyeball that with only 3 threads....

If anyone has any info to share on the type of fitting, it would be greatly appreciated. Not as concerned about the size, but if someone knows off hand, that saves me from breaking out the calipers.

Is Messicks the best place to get cylinder rebuild kits?

Does anyone think the rust on the end of the attachment cylinder rods is something that should be addressed? I have not spent any time trying to clean them up, but I suspect they won't clean up enough to be able to hold pressure. The bucket stop is what limits retraction travel, anyone know if there is an internal spacer that also keeps them from fully retracting? I would hate to rebuild the cylinders, not address the rod corrosion, and sometime in the future retract the rod too far for some reason and waste the head seals.

 

[TheOldHokie]

Kind of a simple/silly question, but reading through the manual I have and also scouring the internet, I cannot find any info on the fitting type or size for the 1720 hose to cylinder connections. I want to take the cylinders off for a rebuild and want to have caps & plugs on hand before doing any disconnecting. The connections from the hose to the 90 elbow at the cylinders appear to be a JIC type of fitting as there are only 3 threads showing on the male part of the elbow (hose end is female). IME, if these were straight pipe threads, there would be more threads showing, and I also cannot see any taper to the threads, but kind of hard to eyeball that with only 3 threads....

If anyone has any info to share on the type of fitting, it would be greatly appreciated. Not as concerned about the size, but if someone knows off hand, that saves me from breaking out the calipers.

Is Messicks the best place to get cylinder rebuild kits?

Does anyone think the rust on the end of the attachment cylinder rods is something that should be addressed? I have not spent any time trying to clean them up, but I suspect they won't clean up enough to be able to hold pressure. The bucket stop is what limits retraction travel, anyone know if there is an internal spacer that also keeps them from fully retracting? I would hate to rebuild the cylinders, not address the rod corrosion, and sometime in the future retract the rod too far for some reason and waste the head seals.


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The hose swivels could be JIC or NPSM. IIRC they were NPSM on my B1730 loader. Remove one and size and type will be obvious.

EDIT: Quick look at the manual says ports are JIC-8 (3/4-16 UNF). Its pretty safe to assume the hose swuvels are the same.

Rods look pretty bad - polish with some very fine abrasive cloth and cross your fingers.

What makes you think the cylinders need rebuiilt? If they do I would chuck those rusty relics and stick brand spanking new ones on. I think these were roughly $150 each and were quick pin on replacement for the OEM cylinders on a B1730.

Dan

 

[evantwheeler]

The hose swivels could be JIC or NPSM. IIRC they were NPSM on my B1730 loader. Remove one and size and type will be obvious.

EDIT: Quick look at the manual says ports are JIC-8 (3/4-16 UNF). Its pretty safe to assume the hose swuvels are the same.

Rods look pretty bad - polish with some very fine abrasive cloth and cross your fingers.

What makes you think the cylinders need rebuiilt? If they do I would chuck those rusty relics and stick brand spanking new ones on. I think these were roughly $150 each and were quick pin on replacement for the OEM cylinders on a B1730.

Dan

View attachment 101991

Thanks Dan. The right side attachment cylinder is leaking from the head. Makes a mess. Was thinking to just rebuild them both while the bucket is off. I hadn't considered new, probably not a bad idea given the condition of the rods. I'll do some research on that.

I wasn't aware of NPSM threads, so read up on those this AM. Will grab both JIC and NPSM caps & plugs so I am covered when it comes time to remove the hoses. Appreciate the input.

Evan

 

[TheOldHokie]

Thanks Dan. The right side attachment cylinder is leaking from the head. Makes a mess. Was thinking to just rebuild them both while the bucket is off. I hadn't considered new, probably not a bad idea given the condition of the rods. I'll do some research on that.

I wasn't aware of NPSM threads, so read up on those this AM. Will grab both JIC and NPSM caps & plugs so I am covered when it comes time to remove the hoses. Appreciate the input.

Evan

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The ports in the cylinders are SAE-8 - just get four plugs. You can use the plastic thread protectors from them as caps for the male SAE end on the elbows.

i have never seen an NPSM cap.

Dan

6409-8

 

[007kubotaguy]

The hoses have #10 JIC ends.

 

[rbargeron]

Hi Evan, I'm an old L345/L305/L355 fan - always nice to see somebody getting to know one.

About those loader cylinders - the 1720 was made in the US so has standard JIC fittings, hoses, etc. - widely available at car parts stores etc. or local hydraulics shops. They have nice end caps that unscrew with a pipe wrench or channel locks. You can take the caps and rods out with their pistons and take them to a hydraulics shop where they can match up the seals, wipers, etc. - usually the most cost-effective way to freshen loader cylinders - especially U.S. made ones.

Replacing cylinders can get tricky - both ends have to match the pin bores, widths etc of what's there - the originals fit exactly - unless they are bent its way quicker to put new seals & wipers in them. And don't worry much about the rusty rods - with the bucket rolled all the way up they are still partly extended (see pic). Take care, Dick B.

 

[evantwheeler]

The hoses have #10 JIC ends.

Thanks.

 

[evantwheeler]

Hi Evan, I'm an old L345/L305/L355 fan - always nice to see somebody getting to know one.

About those loader cylinders - the 1720 was made in the US so has standard JIC fittings, hoses, etc. - widely available at car parts stores etc. or local hydraulics shops. They have nice end caps that unscrew with a pipe wrench or channel locks. You can take the caps and rods out with their pistons and take them to a hydraulics shop where they can match up the seals, wipers, etc. - usually the most cost-effective way to freshen loader cylinders - especially U.S. made ones.

Replacing cylinders can get tricky - both ends have to match the pin bores, widths etc of what's there - the originals fit exactly - unless they are bent its way quicker to put new seals & wipers in them. And don't worry much about the rusty rods - with the bucket rolled all the way up they are still partly extended (see pic). Take care, Dick B.

I do understand that the bucket stops keep the cylinders from retracting any further and in normal use, those rusty rods will not retract through the cylinder head seals. I am curious if the cylinder will physically retract further if it wasn't limited by the bucket stop?

 

[TheOldHokie]

I do understand that the bucket stops keep the cylinders from retracting any further and in normal use, those rusty rods will not retract through the cylinder head seals. I am curious if the cylinder will physically retract further if it wasn't limited by the bucket stop?

I would expect them to retract up to the paint.

Dan

 

[rbargeron]

Probably very little extra retracting stroke is provided. The stroke of curl cylinders is fixed by how far the bucket pins move from full up to full down. But the top pin is located up at the corner of the boom. So a cylinder is used that has a barrel length long enough for the stroke - but has enough rod projection when retracted to reach the bucket pin. (see post #13 below)

 

[evantwheeler]

I would expect them to retract up to the paint.

Dan

As would I. Just seeing if the hive mind has actual knowledge of this specific unit and how it all works. A spacer could be present internally to physically keep those rods from retracting any further, but probably unlikely.

 

[TheOldHokie]

As would I. Just seeing if the hive mind has actual knowledge of this specific unit and how it all works. A spacer could be present internally to physically keep those rods from retracting any further, but probably unlikely.

All you have to do to find out is unpin one bucket end and retract the cylinder. I see no need for a spacer and would not expect one. But I also find it strange to have that much rod exposed at rollback.

Dan

 

[rbargeron]

All you have to do to find out is unpin one bucket end and retract the cylinder. I see no need for a spacer and would not expect one. But I also find it strange to have that much rod exposed at rollback.

Dan

or you can use a measuring tape and see that the cylinder barrel is about the length of the stroke, but because the upper pin mounting point is so far from the bucket, the retracted rod needs to project from the cylinder enough to reach to it. More modern loader designs move the upper pins down closer to the bucket - and use cylinders with less rod projection.

 

[TheOldHokie]

or you can use a measuring tape and see that the cylinder barrel is about the length of the stroke, but because the upper pin mounting point is so far from the bucket, the retracted rod needs to project from the cylinder enough to reach to it. More modern loader designs move the upper pins down closer to the bucket - and use cylinders with less rod projection.

I understand the geometry - a tape measure does not answer the mans question about internal stops. Personally I think its a poor design choice.

Dan

 

[rbargeron]

I agree the model 1720 loader was a too-quick answer to Kubota's need for a U.S. made loader option on this series of tractors (L305,345, 355). Its bulky and not removable - but on the good side its sub-frame adds a lot of strength to the machine. I don't mean to belabor the point but the piston on the top end of the retracted rod IS the internal stop. Take care, Dick B.

 

[TheOldHokie]

I agree the model 1720 loader was a too-quick answer to Kubota's need for a U.S. made loader option on this series of tractors (L305,345, 355). Its bulky and not removable - but on the good side its sub-frame adds a lot of strength to the machine. I don't mean to belabor the point but the piston on the top end of the retracted rod IS the internal stop. Take care, Dick B.

Not only do you continue to belabor the point you continue to entirely miss the point. The clue is in the question I was answering and quoted.