Komatsu pc250 SLOOOWWW bucket dump function.

[typ4]

As the title says, the dump is very slow, all other functions work fine and pressures are pretty good, just found them in schematic and need to convert to psi then double check.

The ,I assume , pressure switch on the long block of the pilot lines for that function we just discovered is broken. My co worker wanted to continue on diagnosing but I told him wait till we get a new switch.
Do those switches control stroke or pressure?
Also on the bottom end of the spool is a spacer and line that ive not seen on other equipment.
THis is first Komatsu ive worked on and its nothing like a deere. LOL
Thanks in advance
Russ

 

[TreeHogger]

Hi Russ - I will be interested in hearing what you get for a reply... Today I am taking the bucket cylinder off my 490D Deere, as it is doing the same thing (bought it this way). I am assuming that it is bypassing within the barrel of the cylinder itself...(It would make some sense, as the surface area the hydraulics 'push' against, is smaller on this side. As opposed to the 'curl' function.)

I have not heard of the switch(s) you refer to... You mention being familiar with Deere, maybe you could inform me if I have something like this too?

Or is this something unique to newer equipment (my machine is 1990)?

Thanks, and good luck Sir!
~ Mark

As the title says, the dump is very slow, all other functions work fine and pressures are pretty good, just found them in schematic and need to convert to psi then double check.

The ,I assume , pressure switch on the long block of the pilot lines for that function we just discovered is broken. My co worker wanted to continue on diagnosing but I told him wait till we get a new switch.
Do those switches control stroke or pressure?
Also on the bottom end of the spool is a spacer and line that ive not seen on other equipment.
THis is first Komatsu ive worked on and its nothing like a deere. LOL
Thanks in advance
Russ

 

[typ4]

I should note that all the cylinders have been repaired on this machine.
Ill gladly help you out when you get your cylinder back on. We have 2 490D's and ive been veri intimate with them both.LOL
There are no bank of switches on it , the pump controls are all hyd. Also pull your bucket spool valve, they get nicked up from packing passing thru and stick.

 

[TreeHogger]

YIKES - I do not like that you replied with being intimate with your 490's!

I am hoping that this repair does it (and then pull the swing motor, it is leaking like sieve!)... Yes, if the cylinder is not the problem I will indeed contact you. Not looking forward to messing with any of the pilot spools.

~ Mark

 

[typ4]

The spools in the 490 valve are very easy to work on.

And you should look at your sig line.LOL

 

[TreeHogger]

Good to know that they are easy to work on, as while I dropped the bucket cylinder off tonight to have it gone through, I truly feel as though the real problem is in the pilot controls...

What, kind Sir, is the 'sig line'? Might you mean pilot spool/control?

Thanks,
Mark

P.S. Outrageous wheelie on the sand!!

 

[typ4]

No your signature line about your little hoe, lol Just giving it back since ive been intimate ,lol
The buggy is my only hobby, 2840 type 4 vw turbo with GM fuel injection

 

[TreeHogger]

Ahhh, very good - a little slow here, and maybe too serious in my worry on the new machine!!

However, I will take you up on your thoughts/advice if I have to dig into the pilot contols.... Also, know anyone that wishes to sell a PDF of the service/repair manual for a 490D?

Thanks,
Mark