Backhoe BT750B Auto return conversion to Manual

[Ken speirs]

Hello,
My Backhoe BT750B, off a B20 tractor, was smashed by a tree when stored for the winter and I've searched with the dealer for the replacement parts but the electrical parts for the auto return are no longer available. So I'm looking at options for converting it to a manual swing. Has anyone done this and can help point me to the right direction. Thank you

 

[PoTreeBoy]

Hello,
My Backhoe BT750B, off a B20 tractor, was smashed by a tree when stored for the winter and I've searched with the dealer for the replacement parts but the electrical parts for the auto return are no longer available. So I'm looking at options for converting it to a manual swing. Has anyone done this and can help point me to the right direction. Thank you

I assumed from your other thread that you had a burned out solenoid. As you say, parts are NLA from Kubota but that doesn't mean they're not available through other channels. For example, the solenoid coil may be 54077-5 from a Husco distributor.

Post a picture or two of the damage we're dealing with.

 

[Ken speirs]

Thanks for your response. Here are a few photos. the previous owner had troubles with the auto return , so I’m thinking of bypassing it completely or other alternative…. Just beginning
to learn and explore options. All feedback and advice welcome.

 

[PoTreeBoy]

Thanks for your response. Here are a few photos. the previous owner had troubles with the auto return , so I’m thinking of bypassing it completely or other alternative…. Just beginning
to learn and explore options. All feedback and advice welcome.

1. I'd abandon the auto return. Even if it was working, it's of marginal value. I don't think any current models have it. Parts are hard to come by and I get the impression it's not very robust.
2. Theoretically, you might be able to convert the swing valve section from solenoid to manual. But determining what Husco parts are required would be time-consuming, and not cheap. Then you'd have to come up with the linkage parts to convert that joystick to resemble the other one.
3. I would replace the entire valve. A monoblock valve like this to replace the existing sectional valve can be had for $500-800. (I think the two center handles can be reversed to face the other direction.)


I'd try to find a 7 spool valve while you're at it. This would furnish control for a future hydraulic thumb. Notice the third center handle in the picture below.

There are several considerations
• Although this implementation doesn't require it, I'd try to get a power beyond adapter with the valve. In the future, you could run a tank line from the bh to the tractor sump.
• Control lever orientation - ideal valve mounting orientation would be like the existing. You'd need to make sure the controls are accessible from the operator position.
• The original joystick linkage would be discarded if a valve with its own linkage, like on the valves pictured above, is used.
• Installation would include new mounting holes, probably new holes to accommodate the controls, and probably new fittings to adapt from the new valve to the existing hoses.

@TheOldHokie could add to this conversation for sure.

 

[Ken speirs]

Wow, this is incredibly helpful and clear, and still I am freakin intimidated to do it, not having any experience working on tractors. But one must forge ahead.

 

[PoTreeBoy]

Wow, this is incredibly helpful and clear, and still I am freakin intimidated to do it, not having any experience working on tractors. But one must forge ahead.

OK, you have your tractor issue fixed I see, so onward with the hoe. I have conversed with the expert and he mostly agrees with the way I have you going.

He prefers a separate electric valve if you ever want a hydraulic thumb. If you get a thumb, you want hydraulic, not manual. Reminds me that I finally decided to go electric if I ever add a thumb. But that's partly because I'd have to add a section to my Husco valve and cobble up the linkage. It's your call whether to get a 6 or 7 spool valve. If only $100-150 more, I'd get the 7. You don't have to use it, but you'd have it.

Moving on, a few pointers
• Cleanliness is important; a little dirt can cause untold grief. Clean and degrease that area before opening the system. Plug or tape any open fittings to exclude dirt, water, etc.
• Label or mark any hose you remove and the port you remove it from. Crossing connections can also cause misery. I've used an engraver, marker punches, and colored wire ties. Do not rely on permanent markers; hydraulic fluid removes it.
• I think you indicated you have the WSM for the B20; is the backhoe included? Please post the hydraulic diagram in the backhoe section. Here's the L35's:


Also, I think there will be a control valve image, similar to this, please post:

You'll notice those valves and ports are labeled. This will be useful later. Print out the valve layout so you can write down the colors or markings you use as you disconnect hoses.
• Remember to take pictures as we go along. Could you post a picture of the valve similar to the first one you posted but more directly head-on?
• Looks like you have some body work to do on the pedestal; I'm not going to address that. Do you have the top?
• Budget - you should be able to buy a valve for ~$500 and I'd budget maybe $300 for other stuff, mainly hydraulic fittings on the valve. If you select a valve with the same orientation as the existing, you can reuse the hoses, at least all but maybe two. There are cheap valves out there; one of the pictures I posted above from eBay has one for <$200. But the title and the picture don't agree so there is some risk.
• Tools, etc. - You'll obviously need wrenches to fit the hose nuts and fittings, and to remove the mounting bolts and nuts. Be prepared to drill new holes for mounting and to accommodate the levers. You may want to bend the levers later to fit your taste.

If this is agreeable, post those figures and pictures and we'll proceed.

 

[Ken speirs]

Thank you. ill need to finish up harvest before I can start on the backhoe project. Since the tractor is running at full power now I can bring the backhoe in under protection and order parts.
~I’ll take a head on photo of the hydraulic tomorrow and post.
~As for cleaning, I simply buy a degreaser at the hardware store, and any suggestions on cleaners?
~yes, 7 spool: adding hydraulics for a thumb: noted. I have searched for after market thumbs but have not found any, any suggestions?
~ yes quite banged up. The top is worse but I’m actively working on straightening it. The main body isn't too costly I may order one from kubota.
~I think you indicated you have the WSM for the B20; is the backhoe included? Please post the hydraulic diagram in the backhoe section. Here's the L35's. yes, I have the backhoe WSM, and will post soon.
~earlier you wrote: 3-I would replace the entire valve. A monoblock valve like this to replace the existing sectional valve can be had for $500-800. (I think the two center handles can be reversed to face the other direction.)
Looks like the two front levers face directly out forward to the backhoe, if reversed they would point directly at by legs correct? Just trying to wrap my brain around this. It seams that option would be difficult also.
~yes, finding a monoblock similar to my orientation. best to send more images of mine and ask for further advice in location the correct one. thanks!

 

[PoTreeBoy]

Thank you. ill need to finish up harvest before I can start on the backhoe project. Since the tractor is running at full power now I can bring the backhoe in under protection and order parts.
~I’ll take a head on photo of the hydraulic tomorrow and post.
~As for cleaning, I simply buy a degreaser at the hardware store, and any suggestions on cleaners?
~yes, 7 spool: adding hydraulics for a thumb: noted. I have searched for after market thumbs but have not found any, any suggestions?
~ yes quite banged up. The top is worse but I’m actively working on straightening it. The main body isn't too costly I may order one from kubota.
~I think you indicated you have the WSM for the B20; is the backhoe included? Please post the hydraulic diagram in the backhoe section. Here's the L35's. yes, I have the backhoe WSM, and will post soon.
~earlier you wrote: 3-I would replace the entire valve. A monoblock valve like this to replace the existing sectional valve can be had for $500-800. (I think the two center handles can be reversed to face the other direction.)
Looks like the two front levers face directly out forward to the backhoe, if reversed they would point directly at by legs correct? Just trying to wrap my brain around this. It seams that option would be difficult also.
~yes, finding a monoblock similar to my orientation. best to send more images of mine and ask for further advice in location the correct one. thanks!

• Cleaner - Canadian version of Simple Green, ZEP, B52, Gunk engine cleaner, any degreaser
• Thumb - Most of the current production backhoes have a backhoe option, but it wasn't available on the L35, or B20 it appears. I'm hopeful that a current factory thumb would fit, but so far I haven't found one to measure. Having the thumb pivot from the same pin as the bucket is ideal but not a deal breaker. Several years ago, someone added a thumb to his BT900 (L35 equivalent to BT750). In that thread, he wrote where he got the thumb. I'll try to find it and post a link. Some design and welding will be required, so this is a separate project.
• Control levers - I think those operators can be reversed by removing two screws and spinning them around. Notice on your existing setup that the stabilizer levers point toward the seat and then turn up. You can bend the levers to suit. Likewise, the existing joysticks start vertical and are bent toward the operator. With a torch, you can customize it .
• Valve - since you're in Canada, I looked in Prince, but no-go. I'm not familiar with other vendors. You could save some $ if you find one with the same port threads as the OEM, so you could reuse fittings. Maybe remove one and measure.

 

[PoTreeBoy]

Here's a link to RaleighL35's thumb project:

2003 TLB L35 BT900 Backhoe Hydraulic Thumb

I wanted to share my latest project on the L35. I could not find anywhere on the internet where someone else has attempted this type of thumb installation. Long story short, I Frankensteined a way to add a hydraulic thumb that is as close to a factory option as possible when it was never...

www.orangetractortalks.com

He used a weld-on kit from Gentec.

 

[Ken speirs]

Here are two photos of my current spool.
~I’m assuming it’s not possible but one must ask. Can I simply remove the far right configuration and Get a single spool to replace.
~a weld on kit for a thumb wouldn’t be a problem, thankfully I am a welder.
~I can always order from the states and have it shipped to the boarder or a friend.

 

[TheOldHokie]

Here are two photos of my current spool.
~I’m assuming it’s not possible but one must ask. Can I simply remove the far right configuration and Get a single spool to replace.
~a weld on kit for a thumb wouldn’t be a problem, thankfully I am a welder.
~I can alway order from the states and have it shipped to the boarder or a friend.

Thats a sectional cintrol valve and you can replace that one section with a different style but it has to be the same base model as the current one.

For a thumb I am a proponent of a completely separate electric control valve with push button controls on the joystick. Cheap and readily available.

Dan

 

[Ken speirs]

Thats a sectional cintrol valve and you can replace that one section with a different style but it has to be the same base model as the current one.

For a thumb I am a proponent of a completely separate electric control valve with push button controls on the joystick. Cheap and readily available.

Dan

I wish I understood the advice I’m getting from you all, with such little experience with hydraulics and tractors I must ask more questions. Where would I start looking for a sectional control valve As you’ve mentioned. And the thumb? Thank you

 

[PoTreeBoy]

Let's do a Reset here, or at least a Pause. From your first pictures, I thought the damage to your valve was more extensive than what the last ones show.
• To answer your last question, yes a single, standalone valve could be installed. You wouldn't even have to remove the old section, but you'd end up with another control stick, which would be unhandy. You certainly don't want a solenoid valve here.
• I notice the hoses are disconnected from the swing sections. Any reason why?
• The damage I do see is that the other joystick isn't centered. Can you correct this and confirm that the two middle levers function correctly?

My thought is, if there is no damage to the existing valve, maybe we can do what you originally proposed, replace the solenoid section with a manual section. I'm attaching a link to my third function project below. It plus RaleighL35's project may help you understand things.
• I'm headed toward removing the existing section and replacing it with a manual section. I may be able to help you with a section leftover from my project; give me a couple of days.
• You'd have to modify the joystick linkage to be similar to the other joystick.
• You would have to shorten or, at least, lengthen the threads on the tie-rods to accommodate removing the spacer. This would also affect the mounting hole on that end. There appears to be a spacer, valve section, then end section in your setup. While you could theoretically leave the spacer, I'd remove it so that the linkage can mirror the other side.
• Hand-ness - I mentioned this earlier, maybe on another post. The section # you mentioned earlier is what RaleighL35 used on his thumb project; it is right-handed so the spool connection is on the bottom. Kubota mostly uses, and you need, a left-hand section. And, no, you can't just flip them around.
• Spool connection - The connection from the control lever to the valve spool is a clevis and tang arrangement. While it would work either way, our valves have the clevis end on the spool. The section I used on the third function had a tang on the spool. It's not a deal stopper, just be aware that you may encounter it.
• Working Port Reliefs - Port reliefs are used to prevent damage to the equipment from excessive external forces/loads that cause excessive pressure from the cylinder. Husco uses cartridges that screw into the valves. I see that your valve has a relief on top of the swing section, probably has another one on the bottom. None of the aftermarket valves I've seen have them.

L35 Third Function

RaleighL35 posted this thread about adding a section to the Husco backhoe valve to control a hydraulic thumb: https://www.orangetractortalks.com/forums/threads/2003-tlb-l35-bt900-backhoe-hydraulic-thumb.56902/ It started me thinking about doing the same thing to the loader valve to add a third...

www.orangetractortalks.com

 

[TheOldHokie]

I wish I understood the advice I’m getting from you all, with such little experience with hydraulics and tractors I must ask more questions. Where would I start looking for a sectional control valve As you’ve mentioned. And the thumb? Thank you

Dont feel like the Lone Ranger - I would say the majority of folks here are hydraulucally challenged

Sectional valves are modular assemblies composed of individual "slices" that are bolted together to form a complete valve assembly. A complete valve assembly consists of an input section, one or more work sections, and an outpur section
Work sections contain the spools and come in many different flavors - e.g double acting, singke acting, motor control, erc. This allows you to bulidxa custom assembly with the exact combination of functions your application needs. Heres a pic of a typical work section.




Sectional vslves are specific to an OEM so different brands dont interchange. The sections must all be the same make and model from a specific manufacturer.

The electric valve I mentioned are standardized componeents that are electrically controlled. The are inexpensive and easily added as independent valve to something like your hoe. This tyoe valve can be placed just about anywhere on the hoe and operated with a coupl pushbutton swiches added to the joystick of your main valve. Heres a picture of what they look like.



Clear as mud??

Dan

 

[PoTreeBoy]

Ken
• Please post a shot of your tractor hydraulic diagram, as well as one of the backhoe.
• This is very important anytime the backhoe is connected to the tractor's hydraulic system. You wrote that you have a WSM; do you also have an Operator Manual? This is from the L35 Op Man, but yours may be similar. The directional valve must be switched when the backhoe is mounted. Failure to do this can have worse consequences than stated in the manual.

 

[Russell King]

Another basic concept on valves to consider:

Electric valves as shown above are 100% on or off, there is no feathering the flow of the valve.

The manual valve shown above reacts with flow in relation to the position of the handle so can be feathered (moved slowly and slightly).

 

[PoTreeBoy]

Another basic concept on valves to consider:

Electric valves as shown above are 100% on or off, there is no feathering the flow of the valve.

The manual valve shown above reacts with flow in relation to the position of the handle so can be feathered (moved slowly and slightly).

Yeah, I can't imagine trying to control backhoe swing with on-off, I can shake 'er around pretty good with analog. Kubota may have used some tricks in that control box, but we're xxxx-canning it.

 

[PoTreeBoy]

I wish I understood the advice I’m getting from you all, with such little experience with hydraulics and tractors I must ask more questions. Where would I start looking for a sectional control valve As you’ve mentioned. And the thumb? Thank you

• @TheOldHokie, the resident hydraulic guru, started a tutorial. You can get the basics here:

Kubota Hydraulic Info and Q/A

To the admins - if this is out of line or inappropriate please delete it. I am starting this thread to give folks a chance to learn the basics of Kubota tractor hydraulics. Its the number one topic here and multiple people have asked for something of this sort. Its an open discussion. Feel...

www.orangetractortalks.com

• I may have a lead on a section. eBay or similar. Husco dealer/distributor will be expensive.
• As I posted above, probably Gentec or Kubota for the mechanical parts. Let's keep that on a separate thread, especially with a change in plan on the valve. I don't think there's room in your console to add a section like RaleighL35 did.

 

[Ken speirs]

Let's do a Reset here, or at least a Pause. From your first pictures, I thought the damage to your valve was more extensive than what the last ones show.
• To answer your last question, yes a single, standalone valve could be installed. You wouldn't even have to remove the old section, but you'd end up with another control stick, which would be unhandy. You certainly don't want a solenoid valve here.
• I notice the hoses are disconnected from the swing sections. Any reason why?
• The damage I do see is that the other joystick isn't centered. Can you correct this and confirm that the two middle levers function correctly?

My thought is, if there is no damage to the existing valve, maybe we can do what you originally proposed, replace the solenoid section with a manual section. I'm attaching a link to my third function project below. It plus RaleighL35's project may help you understand things.
• I'm headed toward removing the existing section and replacing it with a manual section. I may be able to help you with a section leftover from my project; give me a couple of days.
• You'd have to modify the joystick linkage to be similar to the other joystick.
• You would have to shorten or, at least, lengthen the threads on the tie-rods to accommodate removing the spacer. This would also affect the mounting hole on that end. There appears to be a spacer, valve section, then end section in your setup. While you could theoretically leave the spacer, I'd remove it so that the linkage can mirror the other side.
• Hand-ness - I mentioned this earlier, maybe on another post. The section # you mentioned earlier is what RaleighL35 used on his thumb project; it is right-handed so the spool connection is on the bottom. Kubota mostly uses, and you need, a left-hand section. And, no, you can't just flip them around.
• Spool connection - The connection from the control lever to the valve spool is a clevis and tang arrangement. While it would work either way, our valves have the clevis end on the spool. The section I used on the third function had a tang on the spool. It's not a deal stopper, just be aware that you may encounter it.
• Working Port Reliefs - Port reliefs are used to prevent damage to the equipment from excessive external forces/loads that cause excessive pressure from the cylinder. Husco uses cartridges that screw into the valves. I see that your valve has a relief on top of the swing section, probably has another one on the bottom. None of the aftermarket valves I've seen have them.

L35 Third Function

RaleighL35 posted this thread about adding a section to the Husco backhoe valve to control a hydraulic thumb: https://www.orangetractortalks.com/forums/threads/2003-tlb-l35-bt900-backhoe-hydraulic-thumb.56902/ It started me thinking about doing the same thing to the loader valve to add a third...

www.orangetractortalks.com

-Hoses are disconnected for no reason that I know of. I got this backhoe for free, I’ve never used it and the previous owner that sold me the b20 said that when stored it was hit by a tree. I think the main impact was on the hydrolics on the arm (a whole nother repair that I haven’t mentioned. first I wanted to find out if the other part ( auto return) was by passable. Here’s photos the other damage.
-the brake in hydraulic connection ( thinking I’d weld it, but not sure if it’s a good idea??) and the whole hydrolic cylinder is slightly bent, plus’s the boom is dented. Anyhow…
-the lever is just out of place, it needs a o ring clip (not sure the name) to secure it from the outside of the metal casing that is bent. It also has a place for two bolts see photo that I can’t figure out where these attach.
+I haven’t looked at your link yet. Will soon. Spent the morning getting the backhoe out from the field under cover in the carport.

 

[TheOldHokie]

-Hoses are disconnected for no reason that I know of. I got this backhoe for free, I’ve never used it and the previous owner that sold me the b20 said that when stored it was hit by a tree. I think the main impact was on the hydrolics on the arm (a whole nother repair that I haven’t mentioned. first I wanted to find out if the other part ( auto return) was by passable. Here’s photos the other damage.
-the brake in hydraulic connection ( thinking I’d weld it, but not sure if it’s a good idea??) and the whole hydrolic cylinder is slightly bent, plus’s the boom is dented. Anyhow…
-the lever is just out of place, it needs a o ring clip (not sure the name) to secure it from the outside of the metal casing that is bent. It also has a place for two bolts see photo that I can’t figure out where these attach.
+I haven’t looked at your link yet. Will soon. Spent the morning getting the backhoe out from the field under cover in the carport.

Hoses are generic items and easily made to order.