Hey Guys

Im trying to figure out what is on my D6 9U for a hydraulic system, I cant seem to find any numbers any where.  The little bit that ive found on the net says that they had a #46 system on them but my question is, is that what every 9U had on it ?  Ive overhauled most of the cat and modernized it quite a bit and im on the down hill slide of the reapairs.  I need to figure out why the blade wont stay up.  From all the way up its on the ground in a matter of seconds...  So if anyone has any info on the hydraulics of these old girls id be very appreciative if you shared lol.

Hi, Xtremist.
If you can post some photos of what you have, I am pretty sure that somebody smarter than me will be able to identify your system. Not all Cat crawlers had Cat systems. There were a goodly number of after-market systems too.

Azfer your rapidly descending blade rams, that could be worn ram piston seals, wrongly set or failed relief valve or bypassing in the control valve, or any combination thereof, though it would HAFTA be a helluva bypass in the control valve to cause that quick a drop.

I'll let those with more knowledge than me step in here now.

Just my 0.02.

if the rams are like those fitted to d46/7u series they have valves in the piston if these are faulty that could be the cause.

i would be looking at the rams first. it is cheaper to replace the ram shaft than to recrome it if scored or pitted. seal kits for the rams are available as we had ours redone. our machinist cut the eye off the old shaft, machined a new bit of bright shaft to size, threaded it and after centreing the whole thing in the lathe welded the eye to the new shaft, then skimmed the weld smooth worked out to be the same cost to do both as the quote just to recrome ONE old shaft let alone labor and parts to dismantle and then rekit the ram

heres a few pictures, if that helps.  One ram is leaking bad, the chrome is all buggered up, and i have a parts cat here so ill throw on a different cylinder but i would have thought that even just one should hold up the c frame and dozer......?  on a totallly unrelated note does anyone know what a track group (rails/30'' pads) weigh for a d6c ?heres a few pictures, if that helps.  One ram is leaking bad, the chrome is all buggered up, and i have a parts cat here so ill throw on a different cylinder but i would have thought that even just one should hold up the c frame and dozer......?  on a totallly unrelated note does anyone know what a track group (rails/30'' pads) weigh for a d6c ?

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whoops not sure why there are a bunch of sets of the same pictures.

Xtremist wrote:

whoops not sure why there are a bunch of sets of the same pictures.
 

I'm not sure eather but every time I add a pic then cut and past it doubles the pics ... It helps to add pics last

Hi Xtremist, Back in the day Caterpillar had a wierd system of having a seperate Parts Book for each attachment/system. I don't have the Parts Book for the basic No.46 hydraulic system but I do have the Parts Book for the 6A & 6S blades, oddly the hyd. cyl. parts are listed in that book. I have attached all three pages as I don' know your S/N.
Craig

                         

id love to track down a book as soon as i can figure out what it actually has for a system....is it a #46 ?  the serial number on this machine is 9u2657 so its an earlier one....

I just edited the pictures in my last post and rotated them.
The parts book you need is the Caterpillar No. 46 Hydraulic Control Parts Book. These books are sometimes available on ebay, just keep looking.
Your rapid blade drop can be caused by several things but the most obvious is the failure of the lift cyl. lift rod seals causing a low oil situation. Prolonged operation with low oil will cause pump failure.
While you shop ebay also look for the Caterpillar Operation and Maintenance Instructions for your machine, it will save you time & money.
Craig