Loader broke 420 loader lift cylinder

[arkvet]

Broke a cylinder piston on the bucket cylinder this weekend doing to loader work. Bucket cylinder was in full extension and bowed and snapped under pressure. I've attached a picture.

I'm looking for some suggestions / opinions on my options for repair / replacement. I really use this tractor hard. I use the loader a lot and I've got lots of acreage where this tractor (4300 HST) is pushed to the limits.

I've seen the old thread on using larger aftermarket cylinders with some modifying but honestly I don't have much experience with hydraulics so my venture over to surplus center yielded lots of head scratching. I would consider a DIY approach using aftermarket cylinder(s) or would consider replacing just the piston. I'm assuming I'd need to replace all the rubber parts during this process too. Looking for advice on each of the available options and a ballpark cost for each option.

Thanks!

 

[arkvet]

When I try to find a replacement rod... I find an OEM rod that appears to be $400!!! Is this right? If this is all that's available to repair my existing cylinder then there's no way I'm fixing this one. I'll go aftermarket and make the mods.

 

[ovrszd]

I went thru this problem with my old Kubota L4400. I couldn't find an aftermarket cylinder that was matched to the original. Could get close. But close don't count in this game. Gotta be matched. So aftermarket solution meant buying two cylinders and losing a pinch of rollback. So I bit the bullet and bought an OEM replacement cylinder for $487.

After that experience I altered my methods of use so I wouldn't cause that failure again. The bucket curl cylinders are designed to stand straight out pull from loads in the bucket. They are not designed to stand forces trying to collapse them. That's when they bend and or bend/break. I destroyed mine with a tree puller on.

 

[arkvet]

The bucket curl cylinders are designed to stand straight out pull from loads in the bucket. They are not designed to stand forces trying to collapse them.

You know, before staring at an expensive broken part this kind of wisdom never came to mind

Were you able to buy the whole cylinder as a unit or did you buy and replace just the rod? If I'm gonna spend that kind of money on the part I want it to be a quick switch.

 

[Tx Jim]

What's your loaders SN? I found this one for later SN AH171215 ROD ASSEMBLY, 28 ADD 286.21 USD . Have you considered having a machine shop build you a rod?

 

[LD1]

If you want to look aftermarket, you have to know the specs of your cylinder.

What is the diameter of the piston, stroke length, retracted length, pin-hole diameters and style.

There are literally hundreds of configurations of cylinders. I am sure JD isnt the only one out there using that exact cylinder. So If you could dig up some specs??

Theirs a company called baileynet.com that usually has a pretty good selection of cylinders.

As to the "how" it happened....ovrszd is right. They arent designed to handle compression forces. 9 times out of 10 when you see a problem like you have, someone has dumped the bucket ALL THE WAY (cylinder at full length) and then proceeded to do some heavy back-dragging. The bucket edge has a lot of leverage over the cylinder, and if you have good traction, you are capable of making way more force on that cylinder than it can handle. And honestly, I am really suprised that you damaged a cylinder instead of popping a hydraulic line.

 

[arkvet]

What's your loaders SN? I found this one for later SN AH171215 ROD ASSEMBLY, 28 ADD 286.21 USD . Have you considered having a machine shop build you a rod?

I'll have to look at the SN when I get home. Honestly though, even at ~$300 FOR A ROD I'm thinking I'd be better off looking at aftermarket cylinders with similar specs. The end mount mods should be easier that rebuilding the the existing cylinder that already has ~1400 hours on it. I haven't considered the machine shop route and may if the aftermarket cylinder can't be found.

If you want to look aftermarket, you have to know the specs of your cylinder.

What is the diameter of the piston, stroke length, retracted length, pin-hole diameters and style.

There are literally hundreds of configurations of cylinders. I am sure JD isnt the only one out there using that exact cylinder. So If you could dig up some specs??

Theirs a company called baileynet.com that usually has a pretty good selection of cylinders.

As to the "how" it happened....ovrszd is right. They arent designed to handle compression forces. 9 times out of 10 when you see a problem like you have, someone has dumped the bucket ALL THE WAY (cylinder at full length) and then proceeded to do some heavy back-dragging. The bucket edge has a lot of leverage over the cylinder, and if you have good traction, you are capable of making way more force on that cylinder than it can handle. And honestly, I am really suprised that you damaged a cylinder instead of popping a hydraulic line.

Anyone out there know those specs for the bucket cylinder? Your last paragraph describes how I broke it exactly. I wish it had been a hose! If I can find the specs I can surely find a comparable cylinder.

Some have expressed concern over using an aftermarket cylinder that is bigger... Being the bucket cylinders I'm not as concerned with it affecting safety issues. The lift cylinders (if they allowed for a higher / heavier lift) then that would increase the safety risks... The way I look at it is I've filled my bucket with a heaping load of lime multiple times. It was a strain on the loader for sure. Bigger bucket cylinders wouldn't change a thing. Bigger lift cylinders would. Someone correct me if my reasoning is wrong.

 

[LD1]

Well, you can take some quick measurments.

First, measure the ends (mounts). Pin diameter, and width of the cross-tube that the pin goes though.

Then you can measure the length, from pin center to pin center when fully retracted. That should get us started. IT is probably a 2" or 2.25" cylinder (or whatever metric is close)

 

[arkvet]

will do! Thanks LD1. There are several things that will be concrete measurements that I can get easily. Fortunately I have a cross section to measure the rod diameter so I won't even need calipers for that one I'm curious as to how critical the stroke length is? As long as it's "long enough but not too long" (the bucket will go through its full range of motion) then is it acceptable? The range of motion is limited by the frame and not the cylinder, correct?

 

[LD1]

The range of motion is limited by the frame and not the cylinder, correct?

Depends on the design. But generally, yes the stroke is mechanically limited. But only on the dump cycle. When you curl, it is limited by the cylinder running out of travel. So if you get a cylinder that is a smidge shorter when retracted, it could damage things.

And one with a longer stroke, will likely be longer when retracted, giving less curl-back. So best bet is try to match the retracted length to what you have. And if the stroke is a little longer, you will hit the stop. If its a little shorter, it just wont dump as far.