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Any plant fitters here?...I have a CAT 307 question..

Alan B - 21/5/12 at 07:00 PM

We have a leak at the top of the main ram....what's involved in fixing it?

Cheers,

Alan

Hector.Brocklebank - 21/5/12 at 07:14 PM

make the arm safe so you can safely remove the ram

remove ram

unscrew end cap

fit full seal kit for said ram.

re-assemble ram

re-install ram

retract all rams, so you return as much fluid to the tank as possible then check hydraulic fluid level.

check for leaks

test your ram(s)

Alan B - 21/5/12 at 07:16 PM

Hector, thanks.

Is it possible to do it by just disconnecting the top end of the ram?

Cheers,

Alan

Hector.Brocklebank - 21/5/12 at 07:34 PM

quote:
Originally posted by Alan B
Hector, thanks.

Is it possible to do it by just disconnecting the top end of the ram?

Cheers,

Alan

not really, as you need to remove the piston from the body of the ram, and to do this you need the ram body in a suitable "pipe" vice to unscrew the retaining cap one you have the retaining cap off, you can withdraw the piston from the ram body.

you then place the piston in a the same pipe vice but with soft jaw covers to protect the pistons chrome finish.

then you remove the pistons inner end, usually a pair of allen style grub screws need to be removed to allow you to unscrew the inner piston end.

(but some are retained by other methods such a external circlips you wont know until you get there)

this will allow you to pull the retainer cap off allowing you to replace its piston seal and body/thread "O" ring.

re-install the retainer cap on the piston, then re-install the piston inner end and install the new seals/wiper to the piston end, then you can re-install the piston into the ram body and tighten it back up.

But in all honesty they can be tight S.O.B's even with the right gear, I would say you should take the ram off and take it to your local agent and ask them to fit a seal kit to it for you.

Alan B - 21/5/12 at 07:37 PM

Again......thanks.

Alan

daviep - 21/5/12 at 08:47 PM

I would definately have a go myself.

Set the boom up with the dipper vertical so that you have enough room to drop the top of the cylinder off the boom and lay the cylinder down horizontal still attached at the bottom of the cylinder. Support the cylinder near the cap so that you can swing on the c spanner / pipe wrench / which ever weapon you choose to remove the cylinder cap with.

Slacken off the cap.

Remove the cylinder from the machine and put in a vice or do something so you can remove the cap and pull the rod.

Remove the cap from cylinder.

Pull the rod and piston.

Take the rod and piston back to the machine and put the rod end on to the pin where the bottom of the cylinder normally lives.

Support the rod horizontal near the piston on something which will not mark the rod, you may have to swing on the piston to remove it so make sure it's quite strong.

Remove piston locking device.

Unscrew piston from rod.

Fit new seal kit and rebuild as per reverse.

Job done.

Cheers
Davie

Alan B - 21/5/12 at 08:53 PM

Cheers......

Great responses...I knew that team LCB would not let me down...

hillbillyracer - 21/5/12 at 09:00 PM

Fitting new ram seals isnt a difficult job once you understand how it comes apart, but as Hector says there's a fair few different methods of construction & therefore different ways they need to come apart. If you do fancy doing it yourself how about posting a few close up pics of the seal cap area & we may be able to see how it comes apart? Most rams do need the whole thing stripped down to do the external seals. If as most do the main cap unscrews it may be best slackened on the machine so it holds it for you, I've done larger rams with the tube left attached to machine for the whole job, the pivot pin holds them better than any vice if it can be supported otherwise ok. Easy for us fellas that have done a few in our time, & it IS a simple enough thing once you see how to do it, however sometimes not knowing a simple detail means that what may be the right way to do one ram could damage another!

However as suggested simply removing the ram & taking it to a local hydraulic specialist could be the best way, doesnt have to be a CAT dealer & an independant hydraulic place will likely be cheaper & possibly even where your dealer may farm the work out to!

Google says it's an 8 ton digger? Lifting the ram off will need a bit of strength, 2 or more needed, it'll be heavy! The dipper ram (one on top of the boom) on my brother's 13ton digger was to do we lifted it on & off with a telehandler.

hearbear - 21/5/12 at 11:08 PM

One other thing to check before removing the hoses can you remove the presure from the system by working the controls with the engine shut down. I did the same job as you are trying but on an International Harvester, the hyraulics were controlled by a hydraulic pilot presure so once the engine was shut down you could not remove the pressure from the ram resulting in the most monumental oil shower in my life.

Hector.Brocklebank - 22/5/12 at 05:24 PM

quote:
Originally posted by hearbear
One other thing to check before removing the hoses can you remove the presure from the system by working the controls with the engine shut down. I did the same job as you are trying but on an International Harvester, the hyraulics were controlled by a hydraulic pilot presure so once the engine was shut down you could not remove the pressure from the ram resulting in the most monumental oil shower in my life.

you only do that once !!!

daviep - 22/5/12 at 07:17 PM

quote:
Originally posted by Hector.Brocklebank

quote:
Originally posted by hearbear
One other thing to check before removing the hoses can you remove the presure from the system by working the controls with the engine shut down. I did the same job as you are trying but on an International Harvester, the hyraulics were controlled by a hydraulic pilot presure so once the engine was shut down you could not remove the pressure from the ram resulting in the most monumental oil shower in my life.

you only do that once !!!

I wish, I've tried hundreds of variations of the hydraulic shower

les g - 22/5/12 at 07:19 PM

before you dive in
please check the rod for damage
quite often the reason for the leak is damage to the rod.
other than that the advice you have been give is all good
cheers les g

les g - 22/5/12 at 07:19 PM

before you dive in
please check the rod for damage
quite often the reason for the leak is damage to the rod.
other than that the advice you have been give is all good
cheers les g

Alan B - 26/5/12 at 01:06 PM

Thanks again guys for all the tips.
We have sent off for the parts manual so we can see how it all fits together, also I will take some pictures later for your comments.

Cheers again,

Alan (and Ken, my dad)

Alan B - 28/5/12 at 01:08 PM

Pics as promised.
Top cap seems to have a wire clip retainer.
Any more input welcome and thanks so far.

Alan

CAT 307-1

CAT 307-2

The Shootist - 29/5/12 at 03:42 PM

Better make sure you don't have a worn bushing 1st.

Often the bush wears causing the slop in the end of the rod. If so you can replace the seal, but a new seal will begin leaking shortly.

Alan B - 29/5/12 at 03:47 PM

quote:
Originally posted by The Shootist
Better make sure you don't have a worn bushing 1st.

Often the bush wears causing the slop in the end of the rod. If so you can replace the seal, but a new seal will begin leaking shortly.

Good call.
We'll do that.....thanks.

Alan