Digger flail

[steven1784]

Hi guys I'm new here so please take it easy on me
I've got a massive headache going on with a digger flail that keeps blowing out the seals
I've had a look on here but it's going pretty much over my head so can somebody please simplify how to make this flail stop blowing out the seals?
It's got 1 feed and 1 out,same thing on my digger

 

[doobin]

They just do mate, even with a case drain and cross line relief.

Basically I think it's nigh on impossible to get the cross line relief set just right so that it won't bypass under load yet the cross line relief does it's job when you let off the aux. I've given up and I know a couple of others on here have too. Diggers don't make great flail carriers anyhow.

The cross line relief basically absorbs pressure spikes generated by letting off the aux flow but the flail rotor of course wants to keep spinning! These pressure spikes are what blows the seals.

 

[Shovelhands]

Are you running your digger on free flow return?

 

[steven1784]

They just do mate, even with a case drain and cross line relief.

Basically I think it's nigh on impossible to get the cross line relief set just right so that it won't bypass under load yet the cross line relief does it's job when you let off the aux. I've given up and I know a couple of others on here have too. Diggers don't make great flail carriers anyhow.

The cross line relief basically absorbs pressure spikes generated by letting off the aux flow but the flail rotor of course wants to keep spinning! These pressure spikes are what blows the seals.

I must've changed the seals at least 6-7 times now and I just can't believe it keeps happening I was only cutting docks and grass!
I've seen flails cutting branches and that but they don't seem to have any problems?

 

[doobin]

I must've changed the seals at least 6-7 times now and I just can't believe it keeps happening I was only cutting docks and grass!
I've seen flails cutting branches and that but they don't seem to have any problems?

You could try adjusting your cross line relief falve (the square box the pipes go in to)

 

[steven1784]

Are you running your digger on free flow return?

Hi it's piped just like a normal digger as it's a fairly old machine that I've got a fitter told me to run a extra return line but I don't know what to pipe it from or how to do it?

 

[steven1784]

Are you running your digger on free flow return?

It's on a 2.5ton New Holland E2.9BS

 

[steven1784]

You could try adjusting your cross line relief falve (the square box the pipes go in to)

I'm going to sound stupid but what will that do?

 

[doobin]

I'm going to sound stupid but what will that do?

It will let it go into cross line relief at a lower pressure, might help.

 

[doobin]

Hi it's piped just like a normal digger as it's a fairly old machine that I've got a fitter told me to run a extra return line but I don't know what to pipe it from or how to do it?

The free flow return will reduce back pressure- just needs a line direct to tank rather than through the valve block as the existing one goes.

 

[Steve]

Definitely do the free flow return first to reduce back pressure & heat.

 

[DaveDCB]

I have a very good flail, it ran lovely on the 3cx & cat mini but it’s terrible on my jcb 57c - slow and blows seals all the time! Spent loads on difficult hydraulic setups etc .
Finally given up with it and pay pay my hedge man to do the extra bits, when he eventually retires I’ll probably buy a dedicated hedge cutter for my tractor and go down that route instead ..

 

[V8Druid]

You could try adjusting your cross line relief falve (the square box the pipes go in to)

doesn't look much like a CLRV to me Doob, more a manifold to lash the case drain into the return ... which if it isn't totally free flow to tank is gonna blow seals, with no where for the drain to go - freely

plus without a CLRV (or an NRV tee-ed into the lines, as a cheaper option), it is gonna blow seals for a past time, when the feed P is shut, the rotor is still spinning and the motors contents are gonna want out of confinement, they have one option ... the seal's gotta give

 

[V8Druid]

I'm going to sound stupid but what will that do?

the CLRV forms a safety relief system ...
when the pressure feed is shut off to the motor and the rotor is obviously still doing it's multiple RPM,s the oil in the motor (and what's left in the P line)needs somewhere to go, as the motor becomes a pump effectively ...
the CLRV is set at a quite low pressure and allows that oil which the motor is now trying to pump out of the return line, some where to go - back into the P line ...
it will do a closed circuit loop, round and round the P/T lines, through the CLRV, until the rotor stops spinning and the oil is no longer mobile ...
other wise the seal is the path of least resistance and you still have a couple of hundred BAR of oil pressure trying to go SOMEWHERE!!

this was discussed somewhere else in here recently @steven1784

 

[V8Druid]

oh.. and a free to tank case drain line'd be a pretty good idea too ... that'll have enough resistance already, having to 'climb' the dipper
the case drain looks to be the top hose on the motor's body ... the other two ports on the back end of the motor should be labelled P & T (hopefully)
as the guys say the T line ideally needs to be an unrestricted, free flow to the tank ... if it's going back through a valve block of any sort, there will be an inherent resistance there somewhere

The free flow return will reduce back pressure- just needs a line direct to tank rather than through the valve block as the existing one goes.

Definitely do the free flow return first to reduce back pressure & heat.

 

[V8Druid]

the CLRV forms a safety relief system ...
when the pressure feed is shut off to the motor and the rotor is obviously still doing it's multiple RPM,s the oil in the motor (and what's left in the P line)needs somewhere to go, as the motor becomes a pump effectively ...
the CLRV is set at a quite low pressure and allows that oil which the motor is now trying to pump out of the return line, some where to go - back into the P line ...
it will do a closed circuit loop, round and round the P/T lines, through the CLRV, until the rotor stops spinning and the oil is no longer mobile ...
other wise the seal is the path of least resistance and you still have a couple of hundred BAR of oil pressure trying to go SOMEWHERE!!

when I mounted Alex's Bomford up for his Mec, I achieved the CLRV by simply tee-ing a NRV into the lines, allowing the oil to flow in a closed loop from the motor's ports when P was no longer feeding the motor, until it ran down to zero rpm
View attachment 46243
P pressure kept the NRV closed, until it wasn't pressurised, at which point the closed loop operates ..... worked well

@steven1784

 

[6feetdown]

I have a very good flail, it ran lovely on the 3cx & cat mini but it’s terrible on my jcb 57c - slow and blows seals all the time! Spent loads on difficult hydraulic setups etc .
Finally given up with it and pay pay my hedge man to do the extra bits, when he eventually retires I’ll probably buy a dedicated hedge cutter for my tractor and go down that route instead ..

How do you blow a seal nearest I got in the water was about 6 feet away

 

[DaveDCB]

How do you blow a seal nearest I got in the water was about 6 feet away

Google Steve Irwin if that’s your kinda thing