Constant pumped flow hydraulic output on Kubota L4630

[swa]

Just bought a 1989 McConnell Swingtrim hedgecutter. Needs some work but is basically operational.

It requires a constant flow of 12 L/min (Litres per minute) that goes into a hydraulic control box before returning to the tractor. The hydraulic control box has three ram functions to position the cutter bar, and a motor on/off that opens the flow to drive it. The motor also has a low pressure release pipe that goes back to the hydraulic tank.

My issue is with the hydraulics and how I should set them so that I have a constant pumped flow going through to drive the functions as directed by the control block.

On the Kubota L4630 I have three external ports using two spools at the back (see picture). #1 is a single port and number 2 is a double port. Another picture shows the control levers in the tractor.

Question; which ports to use to get a constant pumped flowpath and what (if any) controls to use on the tractor?

Question; anyone know the best rev setting on the tractor to get a pump flow of 12 L/min

 

[RandyT]

Assuming 3 hoses. The 2 that go to the control box would be connected to port 2 in detent. The motor drainback hose or case drain I think could be connected to port 1 with it in detent for non-pressure float.

 

[hayden]

You could use the 2 port control (control #2) to supply pressure and return to the attachment. But you will have to hold the control level on all the time while using it. In my experience these Kubotas do not have a detent for constant-on like is needed to operate a motor. So you will need to cobble together some way of locking the control on in the correct direction.

As for the case drain, it really needs to go directly to the hydraulic reservoir and not be shared with the hydraulic return line. Return lines typically have too much back-pressure, which is why case drains are separate lines in the first place. If you try to use the return line you are likely to blow out the seal on the trimmer motor.

As for flow, the specs say 37 lpm which would be at max engine rpm. So 12 lpm would be at about 1/3 of rated engine rpm. But I would also expect those specs, and the ability to get that flow out through one of the remotes is optimistic, at best. You might also want to keep an eye on hydraulic oil temp while running the machine. I think the hydraulics are typically used for very intermittent operations, so continuous use will heat things up a lot more, and a lot faster.