Arbocut saw head trouble

[agri knives]

I have a saw head on the 13t. I bought it new and it has been trouble from day one . This week the motor went in bits . It only has about 150 hrs work done . Why would this go in bits . The manufacture won't stand over it either.

 

[Matt L]

Looks like motor is not specced up to deal with the high torque loads of starting and stopping the disc. Especially on a 360 with high flow and pressure 3rd service lines.

 

[agri knives]

Looks like motor is not specced up to deal with the high torque loads of starting and stopping the disc. Especially on a 360 with high flow and pressure 3rd service lines.

The manufacture claims that they have a lot of them out and they don't give trouble. It did blow the seals a few times . So we increased the size of the return pipes as we were told that was the problem.

 

[Mursal]

Try Nelson Hydraulics for a replacement click
They might be able to shed some light on the problem.

 

[Mr Happy]

How have you got this motor piped up it could be stopping suddenly? Ideally the the return line should go straight back to tank so the motor does stop instantly when you stop the flow. Also is there any check valve inline to allow oil to circulate and lubricate the motor. VHS Hyds are the UK adents for Sunfab.

 

[agri knives]

How have you got this motor piped up it could be stopping suddenly? Ideally the the return line should go straight back to tank so the motor does stop instantly when you stop the flow. Also is there any check valve inline to allow oil to circulate and lubricate the motor. VHS Hyds are the UK adents for Sunfab.

I have 3 pipes in it .the third pipe is returned direct into the tank.

 

[Mr Happy]

So the third pipe is the drain line which must go back to tank. The other two must be the main hyd pipes to the saw head I presume. Does the saw head stop dead or slowly run down when you stop the oil flow to the saw head motor?

 

[Stock]

Nephew fitted a saw to his 140 and had to chance the machine settings to allow for a free return similar to the breaker settings, prior to this they tried it on the shears setting it did work but not as smooth....................................

 

[Rod Dumbreck]

If the blade is stopping suddenly, then put a relief valve on the return side to spill oil to the pressure side, this will allow the blade to over run when shut off

 

[Mr Happy]

Personally I'd fit a check valve rather than a pressure relief valve As the cracking pressure is much lower than what you can ever set the prv.

 

[Mursal]

And you let the return dump back into the feed on the overrun, is it?

 

[Mr Happy]

Yes so you have a short circuit to allow the hyd to lubricate the motor when it slows down.

 

[james ds]

I have it back working , with no thanks to the Arbocut , they wanted €1500 for a motor, the sunfab dealer could sell me the pump for €870, but when he went to order it they wouldn't sell him one as it was specked for arbocut and they couldn't supply it to anyone else , so he gave me a Parker motor which he supplies to other saw head manufactures for €1100. The Parker is a much stronger and better motor. So arbocut can keep their crap rip off price motor and stick it up where the sun doesn't shine. I was going to buy a mulcher head from them but that plan has changed now. Very poor service from arbocut.

 

[Pheasant Surprise]

Yes my Seppi mulcher head has a similiar piston motor with a manual swash adjustment to adjust rpm to suit the flow from the hammer line.

Seppi made it very clear that the motor needed to be piped with flow, return and pressure free return to tank with very substantial, I thought at the time quite oversized, pipes back to tank.

The motor is a B&P M4 MV series. It has an integrated pressure limiter and anti-cavitation (for run down lube whilst the motor runs down) valve built into the end block of the motor.

It will often freewheel for 30 or 40 seconds of more after you turn the taps off - there is an enormous amount of intertia in the drum, as it’s solid / slotted with fixed teeth.

It would be doing catastrophic damage to the motor to (a) not relive pressure with massive interia and (b) not allowing the oil to circulate inside the motor during rundown.

 

[v8willy]

I have a saw head on the 13t. I bought it new and it has been trouble from day one . This week the motor went in bits . It only has about 150 hrs work done . Why would this go in bits . The manufacture won't stand over it either.View attachment 760288View attachment 760290View attachment 760292

I have it back working , with no thanks to the Arbocut , they wanted €1500 for a motor, the sunfab dealer could sell me the pump for €870, but when he went to order it they wouldn't sell him one as it was specked for arbocut and they couldn't supply it to anyone else , so he gave me a Parker motor which he supplies to other saw head manufactures for €1100. The Parker is a much stronger and better motor. So arbocut can keep their crap rip off price motor and stick it up where the sun doesn't shine. I was going to buy a mulcher head from them but that plan has changed now. Very poor service from arbocut.

How many forum accounts do you have? Thought more than one was frowned apon....

 

[james ds]

How many forum accounts do you have? Thought more than one was frowned apon....

I got a new phone recently and in setting it up it automatically used the first one I used back at the very start , it's my trade name .

 

[Pheasant Surprise]

so he gave me a Parker motor which he supplies to other saw head manufactures for €1100. The Parker is a much stronger and better motor.

James make sure your new Parker motor has, as said, an over-pressure and anti-cavitation valve(s) option fitted - either integrated on the end of motor block or external to the motor. Otherwise I fear you may be in for a repeat episode in a few dozen hours.

Also the hammer circuit on a 360 can be set to run at a much higher pressure, than the other circuits on the machine and other hydraulics in general. The overpressure valve should be set to cater for that, especially with any sudden stops in the saw blade, which will see the motor taking full pressure with nowhere to go.

The anti-cav valve is also as explained to keep a supply of oil circulating within these motors, when the pressure/supply is switched off, but they continue on the overrun....

 

[james ds]

We have the third pipe going straight back to the tank , and when we turn off the oil flow the blade stays spinning for a long time with no restriction , I'm not sure about the anti cav valve , I'll phone the supplier to check it out , thanks for the good advice.

 

[Pheasant Surprise]

We have the third pipe going straight back to the tank , and when we turn off the oil flow the blade stays spinning for a long time with no restriction , I'm not sure about the anti cav valve , I'll phone the supplier to check it out , thanks for the good advice.

Yes a pressure free return line for the motor case drain is a must.

The motor will have a full stock code stamped on its nameplate, from which you can deduce what valve options are fitted to the block. Take a photo and we can look it up. It’s not hard.

Spinning down for a long time on the overrun, is par for the course for these, but spinning down without oil flowing in the circuit will destroy them in no time.

 

[david853]

I'm the same my Arbocut saw head has given nothing but problems from the day it arrived new. My piston pump has done the exact same, completely destroyed itself. Ive a bigger 3rd line ruturn piped straight into the tank and have the oil pressure set to the recommended pressure, the blade free spins to a stop aswell so no strain on the pump. The dealer is no help whatsoever, just keeps telling me that's the first time they've known that to happen. I put it down to cheat floatation bearings in the pump. And don't start me on trying to source parts from them either. There overpriced scrap. Stay clear and buy a tree shear instead