L3400 Rear Hydraulics and Log Splitter

[Cedarweed]

I have been putting some time in on the L3400, mostly brush cutting and loving every minute of it. One question has come up that I need some help with and would appreciate input from those in the know.

Rear hydraulics was ordered mainly for use with a log splitter. However, I noticed that the hyd control can be moved from center to one of two positions, and when released is spring loaded back to the center position. I asked the salesman if I can simply restrain it in the appropriate "on" position while using a log splitter. He was not sure, but said he thought that would keep the pump operating continuously and overheat or otherwise not be good for it. He is looking into it and will get back to me.

I don't know much about hydraulics in general, but it seems to me that a control is strictly mechanical in operation, allowing fluid to move in a direction. That should reduce the system pressure requiring the pump to activate to keep the pressure up. If so, would not holding open the rear tractor control simply pass that control on to the splitter, sort of taking it out of the loop, so to speak?

Any help will be greatly appreciated.

Cedarweed

 

[MadReferee]

Hold the remote lever open with a bungie cord. People do it all the time with no problems. Sure, some heat may be generated in the aux valve block but it shouldn't be a problem.

don't know much about hydraulics in general, but it seems to me that a control is strictly mechanical in operation, allowing fluid to move in a direction. That should reduce the system pressure requiring the pump to activate to keep the pressure up. If so, would not holding open the rear tractor control simply pass that control on to the splitter, sort of taking it out of the loop, so to speak?

Yes, it's mechanical however it will not reduce system pressure. The pump on your tractor is always pumping and there is no pressure until some is required to move a cylinder (ignoring any loss thru valves, hoses and fittings). Holding open the spool will reduce or eliminate flow to the 3pt.

 

[HODAK]

If you bungee it in position, make sure there is a "path" for the oil to flow. If your splitter is hooked up, it's control valve should have a center position to allow the oil to flow when your not operating the ram. Not a real big deal, it just means that if there is no circuit for the oil, your relief will activate. Kind of like your loader valve - until you operate it, oil just flows through the valve back to the sump and then through the pump again. If you operate your loader to full travel or try and do something beyond it's capacity, the relief will open. Hope this helps to explain it a little.

 

[Stackwood]

Once again this list teaches me things I didn't know. Thanks for the insight gentlemen.

Stackwood

 

[Cedarweed]

Thanks much to all for your helping answers. If I have it correctly, once the log splitter is attached to the rear remote (rr) attachment, is should then be ok to bungee the rr control handle. The idea being that then there would be a completed pathway for the fluid through the splitter control valving. Until the splitter valve diverts fluid to it's cylinder, the fluid is taking a non-restricted trip through the loop. It is beginning to get clear to me now. However, if I have it wrong, please advise.

Cedarweed

Ps - since acquiring a little operating time, it is also clear to me why so many on this list express so much joy and pleasure in using these machines.

 

[MadReferee]

Thanks much to all for your helping answers. If I have it correctly, once the log splitter is attached to the rear remote (rr) attachment, is should then be ok to bungee the rr control handle. The idea being that then there would be a completed pathway for the fluid through the splitter control valving. Until the splitter valve diverts fluid to it's cylinder, the fluid is taking a non-restricted trip through the loop. It is beginning to get clear to me now. However, if I have it wrong, please advise.

Yes. Fluid will not flow to the splitter valve unless fulid is flowing thru the rear remote (ie. the valve's work ports). Activating the lever does this. Once the fluid flows it has to have a return path thru the log splitter valve and back to the tractor thru one of the remote ports. One of the remote ports will be pressure and the other will be the return, it all depends on which way the lever is moved.

 

[Cedarweed]

Thanks, Mad. With that in mind, I see no reason to not use it that way.

Your comment: "One of the remote ports will be pressure and the other will be the return, it all depends on which way the lever is moved".

That brings up one more question, why two positions + center for the rear remote? Does that dictate which line will be the input side and which the outflow? Not quite sure I see a reason for that if true.

Cedarweed

 

[Stackwood]

My guess is that the lever actuates a gate. Remember, there are really four hoses involved: Two to the tractor and two to the implement. The tractor hoses are dedicated; on is for inflow (pressure) and one is return. The implement hoses have reverseable roles depending on which way you through the lever. That way the lever can control a hydraulic cylinder to open or shut.

Clear as mud, huh?

Cheers

Stackwood

 

[MadReferee]

Stand alone hydraulic valves used on our tractors (loader, stackable remotes, etc) have 3 or more "sections", a pressure inlet section, an outlet section that deals with power beyond and return to tank, and the spool section(s). Factory stackable remote valves are just adding stackable spools to the inlet and outlet sections which are usually integral to the tractor.

So, ignoring the pressure inlet and pb/tank outlet sections as they are pretty much self explanatory, we have the spools. Spools will have work ports, usually two, that take fluid out to and back from the cylinders. When a spool lever is activated fluid will be directed from the inlet section into one of the work ports then on to the cylinder. The other work port will take fluid exhausting from the cylinder and direct it to the outlet section where it returns to the tractor. When the spool lever is activated in the other direction, the direction of the fluid flow in the work ports is reversed. When the spool lever is in neutral no fluid flows to the work ports.

There are several different design for the spools. On most external valves the spool is bacically a metal rod with grooves which direct fluid flow depending on the position of the spool rod. Integral stackable valves may have different internal designs depending on manufacturer, but the end result is always the same.

Please note that there are many different types of spools. The description above is meant to be general in nature, using the typical double acting spool as the example.

 

[Jw5875]

I hope this will help explain.

Basic Hydraulics

JW5875