Guidance on JCB crowd cylinder rebuild (I'm a virgin)

Preface: I might butcher some of the terms so I ask for that pardon in advance.

Owned my JCB 1550B for probably 20 years. Always take cylinders out for rebuild. Took this one out, they had it for three weeks and still couldn't (evidently) figure out which gasket set to replace it with so, I said bring it back (and I'll do it)

Upon getting it back, turns out they had taken the cap off (unscrewed it) and the seals/gaskets that would be on the cap are gone. Why they didn't finish things is beyond me but, they didn't.

So, here I am. Reaching out to JCB to get the correct set. (guy on phone with dealer took serial number but seemed to have difficulties....said he'd call me back and it's been 1 1/2 days so I need to call them tomorrow)

I read another thread here about redoing a (Cat?) cylinder and using a piston ring compressor....never thought of that.

Any special tools I might need? Though I'm not a mechanic, I'm fairly mechanical inclined....and literally nothing scares me away from at least trying. Ok, that's a lie. When I was 17 or so.... my Dad's Maserati died. Turns out it needed a new head gasket. I decided I'd best not try it because I was visiting him in Hilton Head and was leaving about 3-4 days later AND the parts would take a day for delivery.... so I did shy away from that)

I digress.

Back to JCB... cylinder is unscrewed, sitting on my bench. Though I don't have parts yet, I'm VERY open to any guidance & tips that you may have for me...... other than perhaps not to drop it on my toes!! (hard for me to believe that the last time I took it off to rebuild, I wrestled it alone off of the machine & carried it onto the truck (and then reversed the process to install it).... THIS time I craned it with my wife's cousin's Deere backhoe/tractor.

I see lots of seals on ebay for a 1550b. Go there and see.

Enter your serial number here:

https://parts.jcb.com/

You’ll get a parts diagram for your machine, along with corresponding part numbers.

Hey Buddy, Welcome to the Heavy Equipment Forum! Not familiar with your specific backhoe, but I have rebuilt a doz or so cylinders and would be happy to come help you do this one if we were a little closer. They make seal folding tools for installing the seal(s) that go in the gland portion of the cylinder. Sometimes it can be done by hand. It can also be tough to get the nut off the piston on these. Your welcome to call me if I can be of any help with it.

JL Sargent said:

Hey Buddy, Welcome to the Heavy Equipment Forum! Not familiar with your specific backhoe, but I have rebuilt a doz or so cylinders and would be happy to come help you do this one if we were a little closer. They make seal folding tools for installing the seal(s) that go in the gland portion of the cylinder. Sometimes it can be done by hand. It can also be tough to get the nut off the piston on these. Your welcome to call me if I can be of any help with it.

Click to expand...

OMG, do they let the riff-raff in here or what? (speaking of myself of course) I guess some places have no culture nor couth.

Thanks all... update: I tried dealer again....and again...."we'll call you back"... got tired of waiting (and closing in on 5:00) so called a dealer at random in another time zone. He found the part and it's being shipped.

I looked at those on Ebay. Decided I'd rather put the onus on the dealer to get me the correct part than me rummage through those.

I'm going to try to take pictures if I remember. Seals won't arrive until next week which means next weekend is soonest I can contemplate it.

Regarding taking the nut off the piston... would traditional impact gun take care of that? How about a torque multiplier? I've got both so hopefully one or other will work. My issue will be do I have a socket or wrench right off the bat large enough. Will have to see. I've got some larger ones for the other times I've tinkered on the machine.

I'm trying to find a schematic of the cylinder as I've never (ever) done this so am going in blind. Since the shop took at least the top half of the seals out, I have no idea of how they were facing should that matter.

I know it will get done one way or another. I appreciate the welcome.

If the piston nut has been loctited, it may take a propane torch to get the piston hot enough to cook out the Loctite.

Before you go postal on the nut check that it’s not a pinned nut. Some JCB rams have a pin through the nut into the rod to hold it. You need to locate the pin which has a small threaded hole in the end, find a small bolt with matching threads, screw it in, rock the nut to take any pressure off the pin and it should come out easily. Then the nut can be removed without much effort unless the thread has been damaged.

Noticed today that one of the bearings (?) (the inner sleeve that the holding pin goes through and rotates about) is cracked. Rather than being a split ring... well... I guess it IS a split ring. Only thing is, it's split in two places!!!

It might not matter but bugs me so now I have to get one of those. I thought I had one. Actually, I KNEW I had one (two actually) but they're for the bucket pins not the cylinder pins.

sigh.... not one thing it's another.

So what's it called?

You take the pin holding the cylinder out. Pull cylinder off and set it on table. You look in hole where the pin was and there is a 'washer' in there or something. I've been looking around Ebay for something however, have no idea what to call it. (I do realize I'm probably going to be stuck going to a dealer but figured I'd try)

Split washer? Doesn't sit right with me
Split gasket? nope
Split bearing? don't like it either


I'm totally blank on what it might be called.

I think you're talking about a bushing.

Yep, I think you're right, thank you.

This forgetfulness might be one of my early signs....

So I've received the seals in the mail today. In the meantime, found out I've snapped a Zerk fitting and one of the bushings is cracked. Today, I ordered new bushings and a half dozen straight zerks and a half dozen angled.

I'll probably wait until the weekend to to this but I've been contacting dealers (three so far) trying to get a schematic for the cylinder and what gasket goes where.

So far, I'm three out of three with little to no help on that so I just now, emailed JCB USA in Savannah....of course, it's 5:00 and it's an email, I couldn't find their phone number in the 50 seconds I had prior to 5:00.

Anyone know how I can get a schematic for this cylinder? (don't forget, the original service shop has removed all gaskets on the cap. I have no idea if they removed any interior gaskets and won't know until I take it apart.

Ask your dealer for a picture? I believe the parts book will show a breakdown.

Post a pic, it should be easy enough to figure out. The wiper seals point out to keep out dirt. The U cup goes in next place down, or the groove it fits, open part of the u facing the pressure, backup ring behind the U if there is a backup ring. The bushing should only fit one place to.

Preface: I probably won't touch this until this weekend

That said, I have some ....how to describe them.... "split plastic bushings"
I saw a video on a CAT cylinder getting repaired and I think these were used on it for the purpose of helping to guide the piston (or cap?) down into the cylinder and try to prevent things from getting pinched.

Some of these are what I'd call 'hard' plastic and flat sided (as though the flat edge rides against the cylinder) I have a couple round "O" rings... then I have a larger flexible gasket that is flat on the bottom (probably hugs the piston) and on the OUTSIDE of it, goes to a flattened "V" where the flat spot on the "V" is likely the actual sea.

Give me couple minutes....

Just took picture and will format it to post.

Upper left corner, the yellow items seem to be hard AND have a split in them. Inside them are traditional "O" rings.

Top middle, more hard plastic and also split

Top right, these are the items that based on a prior video I saw, I think are to help guide the assembly in without pinching (but I don't know that)

Lower left, is VERY hard. If it's plastic, it's much different than those above it. Is it metal? I doubt it but it's very hard and not pliable.

Lower center, Orange 'O" ring, outer seal is the one I mentioned above with the flattened "V" on the outside that I suspect does the actual sealing of the piston.

Lower right: Green is an "O" ring, blue items have an O ring INSIDE them (if you flip them over, they're "U" shaped and the O ring rides inside the "U"

I'm also going to presume this kit is designed to cover several cylinders so I might not need/use everything in it. (that tiny O ring in upper left is curious as I'm not sure it will fit anything)

I think I just now figured out what you meant by "U" cup...!!!

I might just disprove that you can't teach an old dog new tricks!!

Pay very close attention to the above post. A number of years ago I discovered the said pin after I sheared it off and destroyed the threads on both pieces. The machine shop that repaired it had never seen that pin before and said that they would have done the same thing. I have never forgotten that lesson. LOL

My end cap was undone by the shop, I can take it off with my fingers. Is this where this lock screw would go? (I don't see one anywhere) I rotated the cap and don't see anything on it. I saw those dimples but realized they're above the threads.