Alternative 3rd function?

[orangetree]

<dup>

 

[ovrszd]

How does it put any more stress than a bucket or forks on the hydraulics? I'm trying to rap my head around your line of thinking.

Can you do this with a bucket or forks?

Can you pick up more with your open hand or clenched fist?

 

[orangetree]

Things like logs have high polar moments and inertia. You pick them up, and all the spools in the hydraulic valves are closed when you transport.

Every bump, turn, or change in speed, and it pushes against the grapple, lift arm and bucket cylinders. That push is translated into a hydraulic pressure surging in the closed hydraulics On your FEL and grapple.

Thanks for this - it's a great point. The grapple hydraulic circuit probably has it much worse, but the same leverage also works on the FEL.

Thankfully (or NOT) the FEL has a "relief valve" of sorts, even with the valves closed ....

tractor falls over if leverage(on FEL) is too high

although as you say, the impact/impulse into the system - on all parts bearing the load - is going to be much higher as you bounce around, when there is a cargo with a high leverage

 

[orangetree]

I created a dedicated thread for how to solve the "check valve" / accumulator / overpressure issue

fix overpressure, sag: check valves, accumulators?

I have two problems where I've seen advice on TBN to solve with a "check valve": a cylinder "sags" - eg, my snowblower chute deflector. Set it at the angle i need; a minute later the deflector has drooped down. a grapple can experience very high pressures when, say, it's closed on a long tree...

www.tractorbynet.com

 

[2manyrocks]

Thanks for the name. Yes, that function sounds like it applies to the concern here - although in a ~month of reading about this I don't believe I've seen anyone else refer to it ... at a minimum it's highly uncommon on everyday TLB/grapple/etc (?)

@davedj1, @2manyrocks, @LouNY discuss "check valves" on several pages of this thread - and in the (few) other threads discussing this same overpressure risk, the phrase seems to be used the same way. I'm trying to understand what folks are proposing; those uses do not seem to be a reference to an "accumulator" type device.

Is this some sort of overpressure device that, rather than shunting the fluid to tank, just "short circuits" the cylinder, allowing it to open/close as necessary to avoid damage? As I am picturing it, if say the normal hydraulic OP valve is set for 2000psi, this "grapple saver" would be substantially higher, say 3000psi. Thus it would only ever open when the valve to the grapple circuit is closed and the grapple is isolated from the rest of the system.

View attachment 743091

Maybe I should start a new thread about this, don't want to completely hijack this one

I am only referring to a check valve as a potential solution because that's what the Messick's video mentioned as protection for the hydraulic system. Please understand that I know next to nothing about hydraulic systems and would like to learn more so I don't damage my tractor out of my own pure ignorance.

 

[npalen]

Yes it would work.
You will need a Pressure in hose, a power beyond hose to carry on through the system, a return to tank hose plus your two lines for your grapple. Also be aware that when using that valve your other functions will not function untill that loop is pressurized to a greater valve then another function.
I would not install a check valve I have read of the possibility of applied stresses creating an excessive pressure condition. All a check valve would do if that happens is restrict the excess pressure to the system prior to the check.
I run my FEL remotes off a rear SCV and it works, but just as your idea will require letting go of any other hydraulic function to activate the new one so does mine.
Yes, I saved a bit of money and it works I do find myself reaching across my body to use both hands on hydraulic levers at times.
If doing it again I would use a electric diverter valve and wire the switch into the loader joystick,
I may end up doing so one of these days when I get "a round to it".
View attachment 740745
View attachment 740746
Not much more money and less hose footage and fittings.

You can add relief valves but they would need to be plumbed into a tank return line

Nice looking tuits there!

 

[npalen]

Thanks for this - it's a great point. The grapple hydraulic circuit probably has it much worse, but the same leverage also works on the FEL.

Thankfully (or NOT) the FEL has a "relief valve" of sorts, even with the valves closed ....

tractor falls over if leverage(on FEL) is too high

although as you say, the impact/impulse into the system - on all parts bearing the load - is going to be much higher as you bounce around, when there is a cargo with a high leverage

I'm afraid that "polar moment of inertia" is being used out of context above.

Polar Moment of Inertia - Definition, Formula, Uses, Types

Polar Moment of Inertia - Click to learn the definition along with its types, uses, formulas, and the differences between moment of inertia.

byjus.com

 

[orangetree]

I'm afraid that "polar moment of inertia" is being used out of context above.

Polar Moment of Inertia - Definition, Formula, Uses, Types

Polar Moment of Inertia - Click to learn the definition along with its types, uses, formulas, and the differences between moment of inertia.

byjus.com

Wrong person quoted

 

[LD1]

Thanks for the name. Yes, that function sounds like it applies to the concern here - although in a ~month of reading about this I don't believe I've seen anyone else refer to it ... at a minimum it's highly uncommon on everyday TLB/grapple/etc (?)

@davedj1, @2manyrocks, @LouNY discuss "check valves" on several pages of this thread - and in the (few) other threads discussing this same overpressure risk, the phrase seems to be used the same way. I'm trying to understand what folks are proposing; those uses do not seem to be a reference to an "accumulator" type device.

Is this some sort of overpressure device that, rather than shunting the fluid to tank, just "short circuits" the cylinder, allowing it to open/close as necessary to avoid damage? As I am picturing it, if say the normal hydraulic OP valve is set for 2000psi, this "grapple saver" would be substantially higher, say 3000psi. Thus it would only ever open when the valve to the grapple circuit is closed and the grapple is isolated from the rest of the system.

View attachment 743091

Maybe I should start a new thread about this, don't want to completely hijack this one
EDIT: thread created check valves, accumulators, overpressure; oh my

That would be a cross-over relief valve

They make them, and they are common. But it will only protect the pressure surge IF and only IF the external forces are trying to extend the cylinder. You would have no protection in compression without a relief back to tank

 

[jigs_n_fixtures]

Thanks for this - it's a great point. The grapple hydraulic circuit probably has it much worse, but the same leverage also works on the FEL.

Thankfully (or NOT) the FEL has a "relief valve" of sorts, even with the valves closed ....

tractor falls over if leverage(on FEL) is too high

although as you say, the impact/impulse into the system - on all parts bearing the load - is going to be much higher as you bounce around, when there is a cargo with a high leverage

Just for clarity: If the diverter is running the grapple, and sharing the function of the bucket hydraulics, the hydraulics to the grapple are isolated from the relief valve in the FEL valve when the diverter is closed. That is where the overpressure issue arises.