Kubota L48 hydraulic quick connects for backhoe - can they be used to power 3PH hydra

[jgoodma1]

I’m going to try to put together an after-market 3PH linkage for my Kubota L48 TLB (it didn’t come with one) and the factory linkage is over $2000. I’d like to include a hydraulic top link and I’m wondering if I can use the quick-connect ports that normally supply the backhoe to feed the hydraulic top link cylinder after the backhoe has been removed?

 

[Fallon]

I’m going to try to put together an after-market 3PH linkage for my Kubota L48 TLB (it didn’t come with one) and the factory linkage is over $2000. I’d like to include a hydraulic top link and I’m wondering if I can use the quick-connect ports that normally supply the backhoe to feed the hydraulic top link cylinder after the backhoe has been removed?

You could feed a valve stack but not an impliment. I assume that's a power beyond port you are talking about & the valves are on the hoe (like tractor hoes, less clear how the real TBLs are setup). If the hoe valves stay in the tractor on the TBLs you could easily use those valves.

 

[aczlan]

Fallon is correct. If you have a pair of hoses that have to be connected together when the tractor is running, you can feed a valve (which can then feed a cylinder), but you cannot directly feed a cylinder.

Aaron Z

 

[jgoodma1]

Fallon is correct. If you have a pair of hoses that have to be connected together when the tractor is running, you can feed a valve (which can then feed a cylinder), but you cannot directly feed a cylinder.

Aaron Z

Thank you both. Yes, what I intended was to feed a new valve which would feed the cylinder. The valves that actuate the backhoe are on the backhoe assembly.

 

[aczlan]

Thank you both. Yes, what I intended was to feed a new valve which would feed the cylinder. The valves that actuate the backhoe are on the backhoe assembly.

You should be good to go as long as you buy a valve that is a "Power Beyond" valve (some valves are not rated to have more than a couple hundred PSI on the "out" port, Power Beyond valves are rated for the full pump pressure on the out port).
This is important in your case as the 3 point will be downstream of your new valve and if you try to lift it with a heavy load, it could put full pump pressure on the out port.

Aaron Z

 

[Smokeydog]

My B20 had a line with QDs you broke to connect to two lines to the backhoe. B26 same way. When removing the backhoe had to reconnect the line. Same for a Rhino backhoe I once had. Simple operation.

M59 has three QDs on the tractor that connect to three lines on the backhoe. Power to swing has separate pump. Then two valves on the tractor that had to operated to switch from backhoe VS 3pt mode. Little more complex. Don’t know enough if QDs could ever be used in 3pt mode. There is a kit to have additional 3 sets of rear remotes for -$2K. Not sure of all the differences between the L48 and M59.

Teeing into 3rd valve front loader option?

Have seen sets of lift arms at the scrapyard from the city/county mower tractors. Think they remove them for drawbar pull behind mowers.

 

[Fallon]

You can't tee into an open center (power beyond) system. At least on the supply side. You can on the tank conections.

There is always full flow going through the power beyond loop. It goes through every valve & back to the tank. When you actuate a valve, it diverts flow from the loop to the cylinder or other impliment. Every other valve downstream gets starved & doesnt work until you release the upstream valve. Ignoring funky internal plumbing on loader valves & backhoe valves permitting at the same time within the same valve body only 1 valve in a loop can be actuated at once (try to move the 3pt when lifting your loader sometime, it wont hurt anything). If you tee the line it will just flow in the direction of least pressure & never do any work.

The 2 backhoe QDs are just an input from & output back to the power beyond loop. Plumbing in additional valves into those QDs will work as well as the backhoe valves (which is generally really well).

Closed center hydraulics work differently, but arent found on smaller tractors. Big ag machines, excavators, etc.

 

[jgoodma1]

Thanks for the explanations. My L48 also has 3 QD’s for the backhoe. I am a complete novice with hydraulics. I think I understand what you’re saying regarding the 2 QD’s that operate the digging action of the hoe...that one is the supply from the pump and one is the return. And what you said about downstream cylinders not working while the top link cylinder is actuated makes sense to me too.......because fluid operating the top link cylinder returns to the pump and never makes it to downstream cylinders, is that correct? I think I remember reading that one advantage of the L48 over other compact TLB’s was that it had 2 pumps for the backhoe so it could operate with a more complex motion ......closer to that of a full sized backhoe......than compact hoes with only one pump for the hoe. That 3rd QD supplies the hydraulics to swing the boom. If...if I wanted to add a second cylinder for a true top & tilt, could I do that using the 3rd QD? But I don’t understand why there is not a 4th QD that would return fluid to the pump when swinging the boom. If there is a quick explanation that won’t take too much of your time, I’d greatly appreciate it.

 

[Smokeydog]

Two independent supplies from two different pumps. Common return.

The M59 has two manual valves under the seat to switch operation from backhoe to 3pt operation or back. The manual even talks of an interlock. I maybe wrong but don’t think it was made to operate the 3pt hitch and the backhoe circuits at the same time.

Rear remotes are an option. I have had excellent customer service from Messicks. They might have have some old stock, good advice or options for your hydraulics and 3pt arms. Shop manual has good section on the hydraulics. Don’t want to damage your machine. But if you or anyone else figures out how to utilize the backhoe hydraulics while using the 3pt hitch that would be interesting.

 

[jgoodma1]

Thanks, I'll call Messicks.