Boom ram wont fully retract, advice?

[Maxus]

After further inspection and a little use of new (to me) jcb 8010 I've noticed the boom ram wont fully retract, meaning I can't lift the boom all the way, which is annoying when loading a dumper!

As I lift the boom the ram retracts into the cylinder at normal speed, then when getting to about 100mm from the end, slows right down then slowly gets to maximum retraction (or maximum boom height). It feels like the pump is straining when it slows down.

Does anyone know what's going on?

Thanks

 

[doobin]

Probably a boom cushion. The E10s have them- it's to stop shock loading. I'd imagine it's a spring in the end of the cylinder (?) which is why the ram looks like it should go more but won't.

Loading a dumper with a micro is a pain in the arse regardless of which micro. If you have a lot of bulk digging to do it's worth direct mounting the bucket, as a quickhitch just exaccerbates the problem.

 

[Maxus]

Thanks for that Doobin. It's very minor and maybe that's the way it's supposed to be, but I have a feeling somethings not 100% from experience driving the 8008. Definitely feels like it stops short. Probably get used to it after a few more hours on the machine!

 

[Shovelhands]

Even after the cushion, it should pull itself to full stroke, if it’s stoping short then maybe the piston/nut is coming unscrewed from the rod?
As it’s the lift ram, and it works on retraction, unlike most lift rams, then I think it would be best to take the ram off and inspect it. As the piston/nut coming fully detached could be dangerous as the boom could fall suddenly, could cause damage to the thread on the ram rod which might otherwise be saved, and also might stop the inconvenience of being stranded on site with the boom on the ground and no way of lifting it?
if you feel something is not right then it’s never a bad idea to check it over, IMO.

 

[Maxus]

Thanks Shovelhands, I think it probably warrants inspection. The ram does fully retract (judging by the position of the boom), it's the last 40-50mm of travel that is very slow and feels like the machine is working hard to get all the way.

 

[doobin]

Thanks Shovelhands, I think it probably warrants inspection. The ram does fully retract (judging by the position of the boom), it's the last 40-50mm of travel that is very slow and feels like the machine is working hard to get all the way.

That's exactly how it is on my E10.

 

[Mick-the-fitter]

I think the boom cylinder pulls or retracts to lift the boom, so if the nut had come undone in the cylinder it wouldn’t lift at at all, I am going for the cushion restriction, which as it’s been said does eventually get full stroke.

 

[hiluxman]

Yes they have boom ram cushions and yes they slow down for the last inch or 2. So long as it goes all the way to the end your fine.

I've also known them to start to fail but they usually give a full speed bang and stop rather than going extra slow.

 

[Smiffy]

I'm pretty sure the JCBs should have all of the chrome inside the cylinder though atleast the ones I drive I think do.
And I'm not entirely sure if it's with all kit but definitely with JCB kit I've seen in pieces they don't use a spring for the boom cushion rather they have the end port of the ram move forwards and a tapered slot in the seal pack on the ram so as it retracts the seals partially block the port slowing down the hydraulic flow and giving a cushion effect.
If it's the case with that machine if the seal pack has come out of alignment with the port then obviously it would stop hydraulic flow completely stopping the ram for retracting which could give the symptoms you describe

 

[Mick-the-fitter]

What’s the serial number, I’ll have a closer look!

 

[Maxus]

What’s the serial number, I’ll have a closer look!

Jcb08010 k01207431
Thanks!

 

[Mick-the-fitter]

It seems the boom ram has a two stage damper system, slow and slower, when the rod gets to 50 mm Crome showing, it slows again when 25 mm is showing, but will eventually be fully closed.

 

[diggerjones]

Think my kx36-2 does this

 

[Maxus]

It seems the boom ram has a two stage damper system, slow and slower, when the rod gets to 50 mm Crome showing, it slows again when 25 mm is showing, but will eventually be fully closed.

That's not quite how mines behaving. Next time I'm on it I'll send over a couple of pictures or a video, thanks for looking into it

 

[Mick-the-fitter]

Yes it does but it’s designed slightly differently internally!

 

[Mick-the-fitter]

Ok Maxus, photos or vid would be good, has it always done this?

 

[Maxus]

Ok Maxus, photos or vid would be good, has it always done this?

The machine is new to me, 800 hours, 2013, it feels like the boom should go a touch higher but it could just be the way it was designed. It's not causing a problem as far as I'm aware, but thought I'd ask to see if anyone has experience with this. I like my machinery to be in perfect working order! Maybe I'm a little ocd

 

[Mick-the-fitter]

Ok see how you get on, there is a bit of a cave man way to speed it up but I won’t advise!

 

[Canal Navvy]

Anybody going the other way used a piston ring of the correct dimensions but intended for an internal combustion engine in the soft stop of an hydraulic ram ?