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Monkeybusiness
Well-known member
I’d try and get the ‘actual’ flow measured - my Takeuchi claims to deliver 100l/min but the flail speeds pictured suggest the reality is closer to 60l/min. You may get away with the 11cc.
V8Druid
do it as well as you can,but learn to do it better
if it's a piston motor with a dedicated case drain port
can I suggest ..... run a hose ... larger than the 'P' supply line -- from the 'T' port on the motor, (or your CLRV) back to your tank, ideally through your return filter case and give it a try .
if the seal remains in place, your problem is the return, as suspected all along
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mart1602
Well-known member
you need a complete free flow back to tank any back pressure at all will blow the pump seal,dont work the flail to quickly as you can slow the motor down and cause back pressure by putting strain on the motor ,if you have a valve to set between 2 way service or hammer set to hammer as this is direcf return to tank,2 way goes through the valve block and will cause back pressure also check hammer line return filter
doobin
Well-known member
Reversible motor will be a gear motor with extra case drain line. Can’t see how pressure will build up behind seal then.
Mart it’s supposed to be a breaker line but if you read first posts doesn’t seem to be working quite as should.
Mart it’s supposed to be a breaker line but if you read first posts doesn’t seem to be working quite as should.
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mart1602
Well-known member
if your not getting enough flow to run it fast enough and cutting thick stuff it will /can slow the head down and cause a pressure spike the seal will take very little to blow its bloody frustraiting when you think it should work but doesnt i spent days messing around blowing seals etc before i got mine to work properly one other thought i pressume you got flat face couplings? do you know the flow of them especialy the return
doobin
Well-known member
Yes mate as I mentioned earlier I will up then to dn08
Think I might have killed this seal as it blew out again testing it on the Hyundai which used to work fine- spun a bit then popped. Probably worn out!!
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mart1602
Well-known member
pain in the arse or what hope you got a good supply of seals
doobin
Well-known member
Well I've ordered a reversible 14cc motor with a case drain port (smallest I can go and still keep max flow rate within digger specs) along with DN08 couplings plus a 1/4" hose and DN04 quick couplings for my newly fitted case drain line. Will get it fitted, tachno it at full chat and then spec pulleys and belts so that full chat with no other load on machine is around 2400RPM. Fingers crossed that'll be about right.
doobin
Well-known member
Whilst I totally see the logic here, and indeed considered it myself, I'd sooner fit a reversible gear motor for the benefits outlined by others above. This comes with a 1/4" case drain port, so common sense says there should be no opportunity for shaft seal to pop once case drain plumbed in?
V8Druid
do it as well as you can,but learn to do it better
yeh the suggestion was just a 'flying'/loose hose, to prove the point/test the issue
I assume that a geared motor's case drain is plumbed in behind the oil seal somewhere/how, after the bearings
.... as there is no 'case' as such with a geared unit other than the body of the motor in which the gears operate ?? ..... so ... over-flowing one is going to result in the case drain working overtime and a lot of heat being generated ..... think you really need to match your motor choice carefully to whatever the machine'll deliver Ruben
doobin
Well-known member
I
Motor will match machines theoretical aux flow, which as we know is probably higher that reality. So shouldn’t be any bottlenecks.yeh the suggestion was just a 'flying'/loose hose, to prove the point/test the issue
I assume that a geared motor's case drain is plumbed in behind the oil seal somewhere/how, after the bearings
doobin
Well-known member
Ok, update. I bought a 16.5cc reversible motor and fitted it. I then swapped the cogs around to gear it up a little (thinking I'd still need to gear it up further when changing to belts) After tensioning the crossline relief a touch to get it to start up properly, it cut well. However it had a nasty vibration as you turned it up to top revs, and was a little slow to recover. I spent half an hour trimming the flails down a smidge (they were sparking off the sides of the mower with the centrifugal force). No more sparking but still vibration. In use under load it never got to the point of vibration unless you held it clear of vegetation for a couple of seconds. Useable but not right.
So I tachoe'd it. At 50LPM max aux flow, assuming 90% efficiency, I would expect 2700ish RPM. At a realistic max flow of, say, 40LPM, I'd expect 2118RPM. It was putting out a whopping 3140RMP!!
So with a gearing factor of 1.5, that poor flail head was doing approx 4170RPM! Looking back, I shouldn't have swapped the cogs, even for the theoretical approx 2700RPM- just wasn't thinking straight. So I changed them around again, so it should be doing 2093RPM. I tachoed it again at around this, so if the tacho is reading wrong it's reading wrong fairly consistantly
Which can only leave the assumption that the Bobcat is putting out around 54-55LPM at full chat with no other load, assuming 95% efficiency as it's a brand new hydraulic motor. If this is the case then impressive. If the motor is 90% efficient then even more impressive.
What do you guys think? It cuts LOVELY now, once pass over and then back again and it's like there was nothing there- it's set pretty low. Smooth and quiet- I was worried about the noise before I realised the speed it was going originally! Revs drop quickly when you use other sevices, but this is I think normal for flails and with careful technique it's still very efficient on banks.
I think I'll spec some pulleys and belts so that it reads 2500RPM on the flail rotor at full chat and get it to work.
Very glad I bought the 16.5cc motor rather than the 14cc, which was only rated for 49LPM.
Also, how quick should it stop with the crossline relief? I've only tightened it up just enough to start without relieving and starting slowly, but when you let off it stops pretty dead? If you run it in single acting mode (which seems to work) it takes a good few seconds to run down.
Oh, and I upped the fittings to DN08 too- good job, with the theoretical flow that seems to be going through the motor. Good shout Rory.
So I tachoe'd it. At 50LPM max aux flow, assuming 90% efficiency, I would expect 2700ish RPM. At a realistic max flow of, say, 40LPM, I'd expect 2118RPM. It was putting out a whopping 3140RMP!!
So with a gearing factor of 1.5, that poor flail head was doing approx 4170RPM! Looking back, I shouldn't have swapped the cogs, even for the theoretical approx 2700RPM- just wasn't thinking straight. So I changed them around again, so it should be doing 2093RPM. I tachoed it again at around this, so if the tacho is reading wrong it's reading wrong fairly consistantly
Which can only leave the assumption that the Bobcat is putting out around 54-55LPM at full chat with no other load, assuming 95% efficiency as it's a brand new hydraulic motor. If this is the case then impressive. If the motor is 90% efficient then even more impressive.
What do you guys think? It cuts LOVELY now, once pass over and then back again and it's like there was nothing there- it's set pretty low. Smooth and quiet- I was worried about the noise before I realised the speed it was going originally! Revs drop quickly when you use other sevices, but this is I think normal for flails and with careful technique it's still very efficient on banks.
I think I'll spec some pulleys and belts so that it reads 2500RPM on the flail rotor at full chat and get it to work.
Very glad I bought the 16.5cc motor rather than the 14cc, which was only rated for 49LPM.
Also, how quick should it stop with the crossline relief? I've only tightened it up just enough to start without relieving and starting slowly, but when you let off it stops pretty dead? If you run it in single acting mode (which seems to work) it takes a good few seconds to run down.
Oh, and I upped the fittings to DN08 too- good job, with the theoretical flow that seems to be going through the motor. Good shout Rory.
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V8Druid
do it as well as you can,but learn to do it better
mine takes quite a while to run down Doob, but it's a much bigger head
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Monkeybusiness
Well-known member
My concern with the E27 is the potential for oil overheating - the hydraulic tank is tiny (can’t be more than 20l in there?) and I don’t think there is an oil cooler (but I’ve only seen mine in the flesh for about half an hour, so may have missed something!)... It’s going to get warm running a flail at full chat unless I’m missing something...
doobin
Well-known member
There’s an oil cooler, and I might add a second fan into it.
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mart1602
Well-known member
should take a while to run down doob ,if it stops quickly theres a chance of blowing the seals out
doobin
Well-known member
New flails fitted, chains and sprockets swapped for pulleys and belts to get the full chat speed to 2430RPM, plus welded some PFC to beef the ends up internally. Spins up smooth as silk and cuts like a beast.
V8Druid
do it as well as you can,but learn to do it better
where'd you source the CLRV from Doob? .. looks a nice compact unit .... what size ports is it?
doobin
Well-known member
Flowfit. It's a 1/2" one.
V8Druid
do it as well as you can,but learn to do it better
that explains why it looks so ''compact''
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