Hydraulic In Row Mower?

[corym]

I'm considering building a small hydraulically powered in row mower for my three point hitch to mow under the vines in my small five acre vineyard. I don't have enough time to weedwack between vines anymore and I do have a small Kubota BX2680 tractor with BX2419 rear remote hydraulics. It seems fairly easy to build one in concept, just connect a hydraulic motor like a Cross Hydraulic Motor 40MH05DACSC to a lawn mower spindle and an 18" blade and build the housing and mounts. The problem is I really don't know much about hydraulics. Everything else I can fab up. My research seems to indicate that I cannot just connect the Cross 40MH05DACSC hydraulic motor to two of the double action quick connects on the back of my BX2680. First it seems if I do the motor will be damaged by the flow stopping too abruptly. Second I think perhaps the return back pressure from the quick connect is too much and will cause seal leakage. Can anyone who's done this or is a hydraulics expert provide some insight or point me in the right direction? Will my rear hydraulics BX2419 designed for an application like this or will the constant flow cause damage?

I would gladly buy one of these things but they're pretty hard to fine for any moderately reasonable price and I need one that's a smaller diameter 18-24" because my vines are quite close together.

Example Mower

Cheers!

 

[MossRoad]

If you're going to run a hydraulic motor, you need a motor spool valve. That lets the motor spin down when you shut it off.

https://www.baumhydraulics.com/images/PDF/terms_hydraulic_control_valve.pdf

 

[MossRoad]

Oh, and welcome to TBN!

 

[corym]

Thanks for the welcome, TBN is a great resource! Long time listener first time caller. With the motor spool valve does it have to have another run of hose directly back to the tank or could I plumb that to the return quick connect? I see a number of these undervine mowers out there that appear to only have a line in and a line out for hydro. Some have a case drain plumbed as well.

 

[texasranger556]

Couple thoughts (I'm no hydraulic expert).

Your remotes are probably plumbed upstream of your 3 point hitch, feeding the 3 point through the power beyond port of the SCV. In other words when you actuate your remote, will the 3 point raise simultaneously? Perhaps not an issue if you don't need the 3 point to raise while the motor is running.

On my JD, the remote QDs are connected to the SCV via 1/4" hard line so not meant for continuous flow. I don't know how your tractor is set up, but those are two obvious things I can think of that could affect your results.

Regarding back pressure, hydraulic mowers like lane shark recommend returning to reservoir rather than the remote QD.

Ideally you would want an anti cavitation valve for when the motor is spinning down, but if your cutter head has low inertia (strings for example), can probably get away without.

 

[ericm979]

There's a relief valve you can plumb in to the mower so the motor is not damaged by slamming to a stop. I think it's a crossover relief.

But your remote valves probably do not have a detent so you'd have to hold it open with one hand or bungie it down. It may be a better idea to buy a motor spool valve with detent and plumb that into your tractor.

You could run the motor output directly to the tank rather than to the rest of the system as other posters have suggested.

The other problem you will have is the limited flow from the tractor. Tractordata says 6.2 gpm but that may be "combined" steering and main flow, which is a bogus number as you can't actually use them together. Even if it is 6.2 that's all of 9hp (assuming 2500 psi).

 

[ptsg]

Over here, we run those undervine mowers attached directly to the brush mower to work on vineyards and orchards, basically making 2 jobs in one pass.

Being that you plan on doing the implement yourself, you can size the hydraulic motor to your tractor, so it has the right RPMs. Also, you can getaway without a motor spool valve by using a couple Tees and a check valve between both lines to the motor. This will let the motor spin down without damage when the spool is in Neutral.

The ones we have here, are either spring actuated like the one on the video you shared, or hydraulically actuated. There is a rod attached directly to a spool valve, once the rod hits the vine, it will retract the mower, then pull it back out after.

Here are a couple examples:

 

[ericm979]

The hydraulic retraction is pretty slick.

 

[MoKelly]

I’m impressed you can even consider building something like that from scratch.

Good luck!

MoKelly .