why not run PTO chipper infeed from tractor power beyond, instead of separate PTO hydraulic pump

[orangetree]

I have a 6" pto wood chipper coming shortly. As most/all small units do, it has a dedicated PTO driven hydraulic unit.

Various threads indicate this is roughly a 3gpm pump. My tractor hydraulics are 6-7gpm, and I'm obviously not doing _anything_ else with the tractor while the chipper is running.

Why not skip the separate hydraulic pump, and have a pair of cables made to run to my rear remotes, just like my bh, etc.

Besides having slightly less stuff to maintain, i also have a toy project that could use a small hydraulic unit.

 

[orangetree]

seems obviously OK - but since I don't see any of the usual mfg's offering a discounted option omitting the pump, thought it was worth asking...

I'd assume the valve for the motor is open-center, but if not, not terribly expensive to replace it. Maybe I'd need a restrictor since I'd be ~doubling the flow. Reviews online indicate that the valve may be 3-4x too large for the motor anyway (hypothesized to be a cost cutting measure due to plentiful cheap ~20gpm motor variable valves, but no (cheap) ~3-5gpm units). [this I'm just repeating from other threads - have not researched yet; we'll see how much range the variable has for me, before upgrading].

 

[BukitCase]

The valve itself could be what bites you in the azz - valves intended for hyd motors are almost ALWAYS "free-wheeling" in neutral - otherwise (especially if they run any sort of FLYWHEEL setup) that sudden (attempted) stop can tear things up.

You CAN buy single, simple "motor control" valves, I have one plumbed into the feed from my hoe for my hydraulic sickle bar trimmer - link is sorted by price -

Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com

Directional Control Valves,Hydraulic Valves,Hydraulics, PRINCE MONOBLOCK VALVE Brand new PRINCE. For control of cylinders, motors, etc. Open center,

www.surpluscenter.com

HTH... Steve

 

[oldnslo]

Simple answer is yes you could potentially run the infeed from tractor but you would have to verify a few items.
1) can the feed roll motors shaft seals handle the added back pressure from tractor connections via quick disconnects?
2) what style flow control is on the feed rolls? I suspect priority with excess to tank.
3) most like require check valve in return line to prevent trying to flow backwards.
4) Heat dissipation - does your tractor have adequate oil cooling for continuous flow operation since priority flow control will introduce heat.
5) Safety interlock function should be the same but would need to ensure that flow from tractor does not stop if emergency reverse of feed rolls is required. Not sure if smaller units reverse or just stop.

there may be other concerns that I have not mentioned

 

[orangetree]

The valve itself could be what bites you in the azz - valves intended for hyd motors are almost ALWAYS "free-wheeling" in neutral - otherwise (especially if they run any sort of FLYWHEEL setup) that sudden (attempted) stop can tear things up.

You CAN buy single, simple "motor control" valves, I have one plumbed into the feed from my hoe for my hydraulic sickle bar trimmer - link is sorted by price -

Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com

Directional Control Valves,Hydraulic Valves,Hydraulics, PRINCE MONOBLOCK VALVE Brand new PRINCE. For control of cylinders, motors, etc. Open center,

www.surpluscenter.com

HTH... Steve

This is just for the feed roller, not the flywheel, which is pto driven. so shouldnt be any inertia / suddent stop concerns that an OP valve cant handle?

The directional motor valve would have this OP valve built in i would think - and seems so from your link?

 

[orangetree]

1) can the feed roll motors shaft seals handle the added back pressure from tractor connections via quick disconnects?

I believe this motor valve would be on my power-beyond path**, so the "return to tank" must be presurized (?). is this what you're referring to?

** although maybe i could make the return path tank/low-pressure with a different rear remote valve?

 

[oldnslo]

Yes on possible power beyond concern as well as quick disconnects and tractor directional valve adds back pressure on the return flow. Some motors seals are good for 30 PSI or less and some a few hundred PSI. If Geroler style motor probably good for higher pressure but still something that should be considered

 

[orangetree]

Yes on possible power beyond concern as well as quick disconnects and tractor directional valve adds back pressure on the return flow. Some motors seals are good for 30 PSI or less and some a few hundred PSI. If Geroler style motor probably good for higher pressure but still something that should be considered

I haven't yet dealt much with hydraulic motors, so please forgive if this should be obvious, but i'm not sure i'm following:

is this backpressure you're refering too simply as the poppet closes during disconnection, and/or some residual pressure caused by momentum (movimg fluid + check balve + fast stop = residual pressure past the check valve)?

 

[ROUSTABOUT]

I have a 6" pto wood chipper coming shortly. As most/all small units do, it has a dedicated PTO driven hydraulic unit.

Various threads indicate this is roughly a 3gpm pump. My tractor hydraulics are 6-7gpm, and I'm obviously not doing _anything_ else with the tractor while the chipper is running.

Why not skip the separate hydraulic pump, and have a pair of cables made to run to my rear remotes, just like my bh, etc.

Besides having slightly less stuff to maintain, i also have a toy project that could use a small hydraulic unit.

Because of shock loads not intended for your tractor hydraulics.

 

[BukitCase]

Yes on most, this one

Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com

Directional Control Valves,Hydraulic Valves,Hydraulics, PRINCE MONOBLOCK VALVE Brand new PRINCE. For control of cylinders, motors, etc. Open center,

www.surpluscenter.com

would be my choice for your app. First one on that link does NOT have the built in relief, most others do. 8 gpm should be more than you need for the infeed, PLUS - the ports are SAE, so a few less irritating NPT's to deal with (I personally HATE 'em, anywhere on my antiquated gear gets done ONCE with adapters to either JIC or SAE and the NPT part stays there til I'm dead)... Steve

Oh, also I didn't check ALL the rest, but the above link has everything you need INCLUDING 3 detents (saves you the $$$ for a bungee cord :=)