Kubota K-600 - Replacement Limiter Cylinder

[snkrfsh]

Good day to anyone reading this post,

I'm new to the forum and am so glad I found you guys. What a tremendous resource. Yesterday I purchased a K-600 backhoe for my B8200. It came with the heavy-duty top bar, and everything works and fits my tractor well. When discussing the BH with my neighbor down the road (who I purchased it from), he pointed out the limiter cylinder was never installed. He said it was an optional accessory and he never needed it for his projects. I am reluctant to use it without the limiter - I don't want to bust my tractor or worse yet, kill myself. Has anyone found a replacement online? I read a thread about using the Woods Saf-T-Lok top bar as a solution but that makes the lift worthless. I'm also curious if anyone has added a bucket thumb?

Thank you in advance for any guidance.
snkrfsh

 

[TheOldHokie]

Good day to anyone reading this post,

I'm new to the forum and am so glad I found you guys. What a tremendous resource. Yesterday I purchased a K-600 backhoe for my B8200. It came with the heavy-duty top bar, and everything works and fits my tractor well. When discussing the BH with my neighbor down the road (who I purchased it from), he pointed out the limiter cylinder was never installed. He said it was an optional accessory and he never needed it for his projects. I am reluctant to use it without the limiter - I don't want to bust my tractor or worse yet, kill myself. Has anyone has found a replacement online? I read a thread about using the Woods Saf-T-Lok top bar as a solution but that makes the lift worthless. I'm also curious if anyone has added a bucket thumb?

Thank you in advance for any guidance.
snkrfsh

I had to research that K600 limiting cylinder. Interesting concept and not what I was envisioning from the name.

From what I can find it appears the 3pt hitch on the K600 backhoe is not mechanically locked down. Since there is no down pressure on the 3pt the backhoe will float up when you apply down pressure with the bucket to dig.

Liimiter cylinder to the rescue. Its a SA cylinder mounted at rougly 45 degrees between the top link bracket on the tractor and the bottom of the BH frame and acts as a 3pt hitch lockdown (limiter) when pressurized.

So how does it work, Pressure to the limiter cylinder is taken off the backhoe inlet circuit via an ordinary tee. When tje hoe is digging inlet presdure rises and the limiter cylinder prevents the 3pt from floating up. When the hoe is in neutral the SA cylinder is open to tank and the hoe can be lifted using the 3pt. Tres clever.

Dan

 

[snkrfsh]

I had to research that K600 limiting cylinder. Interesting concept and not what I was envisioning from the name.

From what I can find it appears the 3pt hitch on the K600 backhoe is not mechanically locked down. Since there is no down pressure on the 3pt the backhoe will float up when you apply down pressure with the bucket to dig.

Liimiter cylinder to the rescue. Its a SA cylinder mounted at rougly 45 degrees between the top link bracket on the tractor and the bottom of the BH frame and acts as a 3pt hitch lockdown (limiter) when pressurized.

So how does it work, Pressure to the limiter cylinder is taken off the backhoe inlet circuit via an ordinary tee. When tje hoe is digging inlet presdure rises and the limiter cylinder prevents the 3pt from floating up. When the hoe is in neutral the SA cylinder is open to tank and the hoe can be lifted using the 3pt. Tres clever.

Dan

Hi Dan,

Thank you for the info - do you think any single acting cylinder will work? I am relatively new to hydraulics - it sounds like a simple solution would be buying a SA cylinder, a tee, the necessary hoses and some sturdy bolts. Is it really that straight forward? I've been looking at this site for the parts Single Acting Hydraulic Cylinders | Hydraulic Cylinders | Hydraulics | www.surpluscenter.com

Thank you again,
Coop

 

[TheOldHokie]

Hi Dan,

Thank you for the info - do you think any single acting cylinder will work? I am relatively new to hydraulics - it sounds like a simple solution would be buying a SA cylinder, a tee, the necessary hoses and some sturdy bolts. Is it really that straight forward? I've been looking at this site for the parts Single Acting Hydraulic Cylinders | Hydraulic Cylinders | Hydraulics | www.surpluscenter.com

Thank you again
Coop

As I said all I (think I) know is what I gleaned from a couple cryptic posts on TBN. But it makes perfect sense hydraulically and is kind of elegant.

I would think the SA cylinder would be sized to match the digging force from the backhoe. You are not limited to SA cylinders - A DA cylinder with breather installed in the unused port works just the same and is possibly cheaper/easier to find.

I would love to see a picture or two of the limitet cylinder hookup points on your hoe.

Dan

 

[snkrfsh]

Dan, I will take some photos of the rig when I have a minute. Might not be today but I'll follow up.

 

[TheOldHokie]

Dan, I will take some photos of the rig when I have a minute. Might not be today but I'll follow up.

Sounds good - my curiosity has been piqued.

You also need to measure the center to center distance on those points when the 3pt is fully raised and when lowered to BH operating height. That will give you the retracted and extended length needed for your cylinder.

Dan

 

[Russell King]

@TheOldHokie
Here is a link to a similar thread that this OP posted on yesterday.

There are some pictures there that might help with understanding the system

 

[TheOldHokie]

@TheOldHokie
Here is a link to a similar thread that this OP posted on yesterday.

There are some pictures there that might help with understanding the system

I think I understand the sysrem.

It's a "hydraulic brace" that limits upward travel on the 3pt. It's extended by elevated inlet pressurc at the BH valve when the backhoe valve is shifted and locks the 3pt down. When inlet pressure drops because the backhoe valve is in neutral It's open to tank and can be collapsed allowing the 3pt to operate normally.

I would just like to see some pictures of the mounts to aid in selecting a replacement aftermarket cylinder.

Dan

 

[snkrfsh]

Sounds good - my curiosity has been piqued.

You also need to measure the center to center distance on those points when the 3pt is fully raised and when lowered to BH operating height. That will give you the retracted and extended length needed for your cylinder.

Dan

Good morning Dan

Here are some photos of the top bar and the connectors where the limiter would attach. Please ignore my janky bolts and the current "limiter" I am using - that setup was for travel only.

http://imgur.com/a/FROWI5B

 

[TheOldHokie]

Good morning Dan

Here are some photos of the top bar and the connectors where the limiter would attach. Please ignore my janky bolts and the current "limiter" I am using - that setup was for travel only.

http://imgur.com/a/FROWI5B

Thanks - excellent pictures and that shows exactly how the limiter is attached.

The blue bar appears to be a repurposed top link and is doing the hold down function provided by the limiter cylinder. It does that fine abd there is no need to replace it. The only thing you would gain using a cylinder is the ability to raise the 3pt.

If you want to replace that hold down with a cylinder you need to take a couple measurements and buy one wirh the correct length. As I said earlier a DA cylinder with the proper length is probably cheaper and easier to find.

Dan

 

[snkrfsh]

Thanks - excellent pictures and that shows exactly how the limiter is attached.

The blue bar appears to be a repurposed top link and is doing the hold down function provided by the limiter cylinder. It does that fine abd there is no need to replace it. The only thing you would gain using a cylinder is the ability to raise the 3pt.

If you want to replace that hold down with a cylinder you need to take a couple measurements and buy one wirh the correct length. As I said earlier a DA cylinder with the proper length is probably cheaper and easier to find.

Dan

Hey Dan, you're correct - I used the top link as a temporary solution. Glad to hear it's sufficient for the job. That said, I would like to replace it with a cylinder. Which measurements do you recommend me taking? I can measure the length of the top link, which I assume is the short measurement. I can also measure the width where the limiter attaches to the hoe and top bar. Do I need a fourth measurement for the extended length of the cylinder?

Thanks for your help with this, I think we're on the right track.

 

[TheOldHokie]

Hey Dan, you're correct - I used the top link as a temporary solution. Glad to hear it's sufficient for the job. That said, I would like to replace it with a cylinder. Which measurements do you recommend me taking? I can measure the length of the top link, which I assume is the short measurement. I can also measure the width where the limiter attaches to the hoe and top bar. Do I need a fourth measurement for the extended length of the cylinder?

Thanks for your help with this, I think we're on the right track.

Measure the eye to eye length of the top link as adjusted and shown in your pictures. That is the extended length for the cylinder.

Then remove the two pins securing the blue top link and use the 3pt to raise the backhoe. Wirh the hoe raised measure rhe center to center distance of the pin holes where the blue top link was attached. That is the retracted length needed for your cylinder.

Then all we need worry about is making sure the ends on the cylinder will fit the attachment points. Simple as that.

Dan

 

[Donystoy]

I'm new to the forum and am so glad I found you guys. What a tremendous resource. Yesterday I purchased a K-600 backhoe for my B8200. It came with the heavy-duty top bar, and everything works and fits my tractor well. When discussing the BH with my neighbor down the road (who I purchased it from), he pointed out the limiter cylinder was never installed. He said it was an optional accessory and he never needed it for his projects. I am reluctant to use it without the limiter - I don't want to bust my tractor or worse yet, kill myself. Has anyone found a replacement online? I read a thread about using the Woods Saf-T-Lok top bar as a solution but that makes the lift worthless. I'm also curious if anyone has added a bucket thumb?

Thank you in advance for any guidance.
snkrfsh
[/QUOTE]

Just for reference, this picture shows the bars that were on the Woods 650 that I had on my B7200. These bars I altered when I built the subframe and brought the hoe 6" closer to the tractor.

 

[snkrfsh]

Measure the eye to eye length of the top link as adjusted and shown in your pictures. That is the extended length for the cylinder.

Then remove the two pins securing the blue top link and use the 3pt to raise the backhoe. Wirh the hoe raised measure rhe center to center distance of the pin holes where the blue top link was attached. That is the retracted length needed for your cylinder.

Then all we need worry about is making sure the ends on the cylinder will fit the attachment points. Simple as that.

Dan

Dan, I purchased a manual for the backhoe - here is the limiter diagram if you're curious. As you can see, the hydraulics attach to a tee as you recommended. According to the spec sheet, the limiter spread is 42"-48" (also in the screenshots below). I will try and get measurements today.

http://imgur.com/a/uk7hN2c

 

[TheOldHokie]

Dan, I purchased a manual for the backhoe - here is the limiter diagram if you're curious. As you can see, the hydraulics attach to a tee as you recommended. According to the spec sheet, the limiter spread is 42"-48" (also in the screenshots below). I will try and get measurements today.

http://imgur.com/a/uk7hN2c

Good. I think that 42-48 is the stabilizer spread not limiter length.

Dan

 

[GreensvilleJay]

ok, curious
just what does this 'limiter' do and how ?

 

[TheOldHokie]

ok, curious
just what does this 'limiter' do and how ?

It's a hydraulic strut that gets hoe inlet pressure when diggong and locks the 3pt arms down. When not digging it is open to tank and will automagically retract when you raise the 3pt.

Dan

 

[snkrfsh]

Hi Dan,

Winter is here and I had to swap out the BH for my scraper blade. I did measure the link bar and it was 23". I didn't get to measure the extended measurement.

 

[TheOldHokie]

Hi Dan,

Winter is here and I had to swap out the BH for my scraper blade. I did measure the link bar and it was 23". I didn't get to measure the extended measurement.

Isn't 23" the length of the bar with backhoe lowered to digging height?
That would be the extended length.

Dan

 

[snkrfsh]

Isn't 23" the length of the bar with backhoe lowered to digging height?
That would be the extended length.

Dan

yes, you're right - that's with the backhoe full extended and ready to use.