Case Drain – KX41-2V

[xenophon.nl]

I'm looking to rent a hydraulic flail mower for my Kubota KX41-2V and I've run into a bit of a snag with the hydraulic setup. The mower I'm interested in requires a case drain, but I’m having trouble locating where this should be connected on my excavator.

Here’s the situation:

• I’ve been told that there should be a valve somewhere to convert one of the hydraulic aux line to a case drain. However, despite searching, I haven’t been able to find anything that looks like it could be a case drain connection.
• I need to figure out if there’s an existing connection I’m missing or if I’ll need to add one.

Questions:

1. Should there be a case drain connection on my Kubota KX41-2V? If so, where exactly should I be looking?
2. If I can’t find a case drain connection, how can I add one? Are there any specific parts or modifications needed to make this work?

Any advice or guidance would be greatly appreciated. Thanks in advance for your help!

I also included some pictures and diagrams.

 

[Kjell]

Many japanese excavators have a multi purpose service circuit line without a free return connection to tank and I always add a T and a ballvalve to have a free return to tank. I bought a KX 61-3 in 2006 and i remember I always opened a valve under the floor above the mainvalve when working with breaker and i belive I added this valve because I have checked my workshop manuel this morning and I cant fiind any free return valve in the workshop manual. But, you ask for a case drain but on the pictures it seems like your looking for a free return valve and thats two different things. A case drain is normally a third hydraulic line used with some 2 directional hydraulic motors and a free return to tank is something you need on a 1 directional hydraulic motor or a breaker to not destroy the sealings in it.

 

[xenophon.nl]

Many japanese excavators have a multi purpose service circuit line without a free return connection to tank and I always add a T and a ballvalve to have a free return to tank. I bought a KX 61-3 in 2006 and i remember I always opened a valve under the floor above the mainvalve when working with breaker and i belive I added this valve because I have checked my workshop manuel this morning and I cant fiind any free return valve in the workshop manual. But, you ask for a case drain but on the pictures it seems like your looking for a free return valve and thats two different things. A case drain is normally a third hydraulic line used with some 2 directional hydraulic motors and a free return to tank is something you need on a 1 directional hydraulic motor or a breaker to not destroy the sealings in it.

Yes you are right, I am mistaken asking for a case drain. What I need for the mower is indeed a free return line. I tried to edit the post to make it less confusing, but I don't see an option to do that.

Basically the question sort of remains, do I really need a free return line, or would the 'normal' return line be also fine? And if I need, where and how can I ‘T’ into a return line?

 

[Kjell]

The reason why you need a free return is, your auxiliary valve is made for a cylinder and closes the return side before it closes the pressure side to avoid play in the cylinder. This means that there will be a pressure peak on both the high pressure side and the low pressure side every time you stop the mower whitch evetually will kill the low pressure side.
Normally the line on the right side of the boom is the return line. Put a T-adapter or a three way valve where the returnhose ends at the valve on your first picture and a T-adepter on the hose between the valve and the tank and connect them. You will need to drain the hydraulic tank or use a vacumpump to do this.
If you use T-adepter on both sides you will need 2 hoses and a ballvalve between the T-adpters.
If you use a 3 way valve on the curved steelpipe between the valve and the returnhose you may need to support its weight in some way.

 

[xenophon.nl]

...a T-adepter on the hose between the valve and the tank and connect them...

Do you mean to add a T on hose 060 on this diagram? These hoses all have hose clamps, so the free return line will never have pressure? I do not need to install a check valve?

It feels strange to go from pressure connectors to a hose with hose clamps.

 

[Kjell]

I prefer a threaded connection if possible.

1. There is a threaded connection on T-pipe 040.
2.There is a manifold after 100 that seems to have threaded connections.
3. Change the 90 degree bend at A to a T.

I checked in the workshop manual but didn't find any more information.

You have to check in your machine what is possible.

If you are downsizing the new connection you can't use a 3 way valve, only a ball valve between the 2 T- connections. It is ok if some of the flow goes through the main valve.

 

[xenophon.nl]

Based on your advice I got it installed. Ik had to bend a bracket to hold the valve. I shortened the handle a bit and I can now turn it by opening the right cover. I did make the T by cutting the return line because the access was sort of doable. Thank you! If you see any mistake please let me know