Issues with Denarco DT 3500

[Hillbillybjopkr]

Ok guys. Have a question for you on something none of us can figure out. My stroker has this odd quirk. Most of the time we don't have a problem we can't fix. But for a couple 3 yrs we've had this issue none of of us...even the mechanic...can't seem to figure out. My front grapples (knives) have this habit of locking up. It only does it in the afternoons when it hot and my hydrolic temp gauge is at the half way mark or slightly above. Unually happens when I hav ahold of big/heavy sticks.....sometimes on lighter stuff....when it's really hot. I either have to close the back clamps enough to turn on the soft-clamp or tap the top saw button to get them to open. And when they open the snap open. We've replaced the cylinder up front, a couple of valve's in the box in the head, flushed the hydralic system, and nothing changes. The guy we have come out as our mechanic know's of another Denarco just like mine that does the same thing. And still has no clue of what's goin on:beatsme So...has anyone heard of this or had this same issue. It really freaks me out when i'm throwin a big stick to the shovel below me and I can't get rid of it.....just waitin for one of my drive cables to pop and all hell break lose....:Banghead

 

[Firewood79]

Electrical?

That would be my guess. We have a DM 3500 and had an issue with the a solenoid. Ours was located in front of the swing motor and next the cab.

 

[acswan]

If your machine is the same as ours and has a butt saw, the 2 hyd. blocks are identical, except the one in the head is alum. the rear one is steel.There is a Sun check valve cartridge near the 2 ports for your knife arm hoses, switch it for the one in the back and see if your trouble goes to your holding arms, I had to replace one in our machine last winter, same symptoms.

 

[Hillbillybjopkr]

Will bring both ideas up to the power's that be tomorrow.....we'll see what happens lol

 

[acswan]

Sorry, was at our machine today, it was the cartridge directly opposite the knife arm hose ports, sun part code CKGB XCN, It's a load holding pilot op. check valve it's supposed to hold your arms from creeping open under load but if it sticks it they won't open at all.

 

[Hillbillybjopkr]

that make's perfect sence. so lemme guess....when I turn on the the soft-clamp it bypass's that check valve? That the only thing i've been able to do to get it to release.

 

[acswan]

On our machine it was the holding arms that were sticking, operator had to tap the top saw, butt saw or snap the front arms open to get the rear arms to release,I think it had more to do with spiking the pressures than trying any particular function,I switched valves back to front and within 2 or 3 trees the front arms locked up.Replaced the valve and haven't had the problem since.Not sure how the soft clamp works, our guys never use it, i'll look at the schematics monday and see if they somehow bypass the holding valve.

 

[Hillbillybjopkr]

on my rig...the "soft clamp" come's on when you hold the holdin clamp button for like 2 sec..i don't really have a option not to use it...unless i hold the over ride trigger. that's how I wack them lil feathers on the white fir that usually just fold under the knives on the back-pull. All i have access to is the parts book...dosen't have any schematics in it....anything you find out would be awesome. I definatly have a hell of a list of thing i need to do to her this winter when she's in the shop lol

 

[John C.]

As I recall the soft clamp is on whenever the rollers are run or the stroker is run out. If it doesn't work the knives with hold the tree too tight and either pull the bark off or stall the wheels or beam. The other symptom is that your hydraulic system will tend to overheat because of the extra pressure it takes to jam the stick through the knives.

Does anyone else have a different explanation?