Forst ST6 Feed Roller Problem

[Gary Prentice]

Yesterday our ST6 had an hydraulic leak which, I think, caused the rollers to lose power. They'd turn (forward and reverse) slowly then stop.

 

The leak was in the top of the hydraulic tank, which forms the bottom of the rotor chamber, so we drained the tank, welded up the crack and then re-assembled everything. But, now we've only got forward/in operation of the feed rollers. The emergency mechanic stop doesn't work, the electrical stop button doesn't work and the rollers won't go into reverse!

 

Using the backwards/forwards control buttons, the lights on the electric modules attached to the manifold (?) hydraulic control thingy switch on and off, both turning off when you touch the stop button ( but the rollers still continues to run!)

 

Think that somethings airlocked, somehow, we've tried bleeding the system. Some of the pipes have a hole in the attachment nut, so when you loosen the nut and wiggle the pipe oil/air can escape. But no change.

 

We have tried running the machine for 15-20 minutes to see if it self bleeds - no change, but most of the time checking the tank the oil's got air bubbles in it.

Now officially totally stumped, we're thinking that because the rollers are in-feeding instead of reversing, this isn't a stress control/ rev sensor/electrical issue but who knows.

 

Any thoughts or experiences, has anyone changed the hydraulic oil and had problems?

 

 

[Mike Hill]

Sounds like a solinoid problen to me.Or the electrics powering it.

 

Run 12v to it and that should open it. Then you eliminate two things at once.

 

I take it the tank never went so low in fluid that you might have damaged the pump?

 

[Gary Prentice]

Excuse my ignorance Mike, but which bit is the solenoid? The black relay-like box with the little light that lights up when you touch the switch to forward/reverse the roller?

 

The pipe from the tank to the pump exits at the bottom of the tank, as does the return, so I think the pump is ok. We drained probably ten litres, maybe more, from the tank to weld  it.

 

 

[monkeybusiness]

I’d say electrics too - is there any chance something got fried when the welder was out? Did you disconnect the battery before welding? 

Hydraulic systems run at huge pressure and air locks don’t tend to be an issue (providing the pump gets oil). Check all the wiring would be my first port of call. 

[Gary Prentice]

Battery was disconnected during the welding.

 

just really odd if an electric fault developed after a fairly small fluid loss. I think last night we only put a litre or so in, trying to find out where the leak was

Edited February 10, 2018 by Gary Prentice

[Mick Dempsey]

Can’t help Gary, but I hate weekend chipper conundrums.

 

Can’t relax till it’s sorted.

[dig-dug-dan]

Silly question, did you disconnect the battery before welding?

The electrical problems could be a bad earth, which in turn may cause a rolller issue.

There should be a breather within the hydraulic circuit somit should not need bleeding

[Gary Prentice]

Battery was disconnected before welding.

 

ill check the earths tomorrow. Hoping it’s not electric, I hate electrics on that machine

[monkeybusiness]

If you’ve got hydraulics working in one direction it is definitely electrical I’m afraid (unless it is linkage controlled spook block, which I’m sure it probably isn’t although I’m not personally familiar with the Forsts). 

[Gary Prentice]

There goes my Sunday

thanks for all the help everyone.