BH77 adding hydraulic thumb project.....Soup to nuts.

[Runs With Scissors]

Ok, well looking at the calendar, winter is just around the corner. I promised myself that I would make/install a hydraulic thumb for Stonewall.

I have the basic idea of how I am going to approach it and from reading past posts, I think it will be a cool project.

I have no problem with the welding/machining part of it; I'm looking quite forward to that part; However, the hydraulics part of it concerns me a little.

1. I am unsure of how to control the Thumb's opening and closing. I want to control it using my right thumb and some sort of switch on the joystick. (much like the "big boys" do on an excavator)

2. My biggest question though is this: I have 3 remotes on the back but they are controlled by levers from the drivers seat. I do not want to have to "reach behind me' to control the thumb; So is there some way to add a "electrically controlled valve" or something to those valves, and wire it to the "new joystick"

or do I bypass them altogether and make a "new circuit"?

Here is the "Worlds Worst Schematic" of the basic concept (no laughing...LOL)

Any links to parts "major parts" like the cylinder, "magic valve" or a new joystick with a switch built in, is much appreciated.

Paul

 

[Smokeydog]

Electric switched valves are hard to control grip strength and speed. If that’s a design requirement?

Stacking rocks requires gentle grip and release. Added a hand lever to the foot controlled thumb help me with precision control.

 

[TheOldHokie]

Ok, well looking at the calendar, winter is just around the corner. I promised myself that I would make/install a hydraulic thumb for Stonewall.

I have the basic idea of how I am going to approach it and from reading past posts, I think it will be a cool project.

I have no problem with the welding/machining part of it; I'm looking quite forward to that part; However, the hydraulics part of it concerns me a little.

1. I am unsure of how to control the Thumb's opening and closing. I want to control it using my right thumb and some sort of switch on the joystick. (much like the "big boys" do on an excavator)

2. My biggest question though is this: I have 3 remotes on the back but they are controlled by levers from the drivers seat. I do not want to have to "reach behind me' to control the thumb; So is there some way to add a "electrically controlled valve" or something to those valves, and wire it to the "new joystick"

or do I bypass them altogether and make a "new circuit"?

Here is the "Worlds Worst Schematic" of the basic concept (no laughing...LOL)



Any links to parts "major parts" like the cylinder, "magic valve" or a new joystick with a switch built in, is much appreciated.

Paul

This seems to be a common desire and you have the basic idea.

IMO the simplest solution is to install a new valve in the PB circuit just ahead of the BH valve. It can be manual or electric as suits your preference.

1. Mount the valve any place convenient on the BH frame.
2. Disconnect the inlet hose on the BH valve and reconnect it to the P port on your new valve. This is the one that plugs into the outlet on the tractor.
3. Run the A nd B work port hoses to the thumb cylinder. See note below.
4. If using an an electric valve connect the T port on the new valve to the inlet port on the backhoe valve. Stop here - you are done.
5. If using a manual valve connect the Power Beyond port on the new valve to the inlet port on the backhoe valve. Then install a tee in the tank return port of the backhoe valve and connect the T port on the new valve to the center of the tee. Stop here - you are done.

NOTE:

I would also recommend installing a DPOCV in the work circuit going to the thumb. You can mount the check valve anywhere on the boom or dipper stick and use 4 hoses for that circuit - two from valve to DPOCV and two more from DPOCV to cylinder. The reason I say this is based on complaints from other people about the thumb not maintaining its grip. I have no actual experience but that's probably because of spool leakage causing an almost immediate drop in cylinder pressure . The check valves will provide a positive circuit shutoff and prevent that from happening.

I will be interested in seeing how that all works out.

Dan

 

[GSD-Keegan]

Please keep us posted on your build Scissors! Will be following. Just wondering and a question here. Do you need to be concerned about the new thumb cylinder matching the size of the bucket cylinder? Say you’re grabbing a rock or log, and you use the bucket cylinder for the clamp action. Is it possible the bucket cylinder will over power the thumb cylinder? Resulting in a bent cylinder shaft?? Just curious….

 

[TheOldHokie]

Please keep us posted on your build Scissors! Will be following. Just wondering and a question here. Do you need to be concerned about the new thumb cylinder matching the size of the bucket cylinder? Say you’re grabbing a rock or log, and you use the bucket cylinder for the clamp action. Is it possible the bucket cylinder will over power the thumb cylinder? Resulting in a bent cylinder shaft?? Just curious….

Short answer is yes. Obviously don't want a cylinder with a 1/2" rod.

The specification is called column load rating and generally provided as part of the cylinder specs. We can do the math ....

Dan

 

[Runs With Scissors]

Electric switched valves are hard to control grip strength and speed. If that’s a design requirement?

Stacking rocks requires gentle grip and release. Added a hand lever to the foot controlled thumb help me with precision control.

So you have a separate "joy stick/foot pedal" that is mechanically connected to your valve?

And this gives you "finer" control?


Paul

 

[TheOldHokie]

So you have a separate "joy stick/foot pedal" that is mechanically connected to your valve?

And this is give you "finer" control?


Paul

Lot of hoes and excavators have a foot pedal with mechanical connection to a manual valve. He added a hand lever to his foot pedal.

Commodity electric valves are binary - fully closed or fully open. There is no way to control actuator speed. You push the button one way and its full speed closed. Push it the other way and its full speed open.

Dan

 

[Runs With Scissors]

This seems to be a common desire and you have the basic idea.

IMO the simplest solution is to install a new valve in the PB circuit just ahead of the BH valve. It can be manual or electric as suits your preference.

1. Mount the valve any place convenient on the BH frame.
2. Disconnect the inlet hose on the BH valve and reconnect it to the P port on your new valve. This is the one that plugs into the outlet on the tractor.
3. Run the A nd B work port hoses to the thumb cylinder. See note below.
4. If using an an electric valve connect the T port on the new valve to the inlet port on the backhoe valve. Stop here - you are done.
5. If using a manual valve connect the Power Beyond port on the new valve to the inlet port on the backhoe valve. Then install a tee in the tank return port of the backhoe valve and connect the T port on the new valve to the center of the tee. Stop here - you are done.

NOTE:

I would also recommend installing a DPOCV in the work circuit going to the thumb. You can mount the check valve anywhere on the boom or dipper stick and use 4 hoses for that circuit - two from valve to DPOCV and two more from DPOCV to cylinder. The reason I say this is based on complaints from other people about the thumb not maintaining its grip. I have no actual experience but that's probably because of spool leakage causing an almost immediate drop in cylinder pressure . The check valves will provide a positive circuit shutoff and prevent that from happening.

I will be interested in seeing how that all works out.

Dan

Dan, I am still learning the lingo, but a P-port is the "pressure side" and the T-port is the "return side"?

Here is a revised WWS .....Does this look about right?

Also, what would you think about using an electric valve, but stepping down the size of the lines between the DPOCV and the cylinder, to decrease fluid flow?

Do you think that would give me "more/finer control"? (I'm not sure how to define "control" )

Or do they make an "electric valve" that you can control with a "rolling switch" (i.e. like the rolling switch on the top of a computer mouse) so I could roll it open one way and roll it closed the other.

 

[Runs With Scissors]

Please keep us posted on your build Scissors! Will be following. Just wondering and a question here. Do you need to be concerned about the new thumb cylinder matching the size of the bucket cylinder? Say you’re grabbing a rock or log, and you use the bucket cylinder for the clamp action. Is it possible the bucket cylinder will over power the thumb cylinder? Resulting in a bent cylinder shaft?? Just curious….

I will definitely keep this thread updated.

I do not know the answer to your question though.

In my "minds eye" there should be some sort of "pressure relief protection" in the system already, but you bring up a great point.

 

[TheOldHokie]

Dan, I am still learning the lingo, but a P-port is the "pressure side" and the T-port is the "return side"?

Here is a revised WWS .....Does this look about right?

Also, what would you think about using an electric valve, but stepping down the size of the lines between the DPOCV and the cylinder, to decrease fluid flow?

Do you think that would give me "more/finer control"? (I'm not sure how to define "control" )

Or do they make an "electric valve" that you can control with a "rolling switch" (i.e. like the rolling switch on the top of a computer mouse) so I could roll it open one way and roll it closed the other.

You nailed it with that diagram.

The low cost electric valves are strictly OPEN/CLOSED. No way to meter the flow. You got to spend considerably ( like in a lot) more money for that functionality.

Whether or not thats a ptoblem probably depends mainly on your usage and preferences. You have almost 7 GPM of glow at rated engine speed so a single cylinder with a short stroke is going to cycle PDQ. Flow restrictors will slow it down. Reducing line size will have no apprecable effect other than unnecesarily heating the oil up.

Manual valve with lever control has a lot of advantages but one big disadvantage - it requires you remove one hand from the other controls to operate it. That may or may not be an issue for you.

Dan

 

[TheOldHokie]

Dan, I am still learning the lingo, but a P-port is the "pressure side" and the T-port is the "return side"?

Here is a revised WWS .....Does this look about right?

Also, what would you think about using an electric valve, but stepping down the size of the lines between the DPOCV and the cylinder, to decrease fluid flow?

Do you think that would give me "more/finer control"? (I'm not sure how to define "control" )

Or do they make an "electric valve" that you can control with a "rolling switch" (i.e. like the rolling switch on the top of a computer mouse) so I could roll it open one way and roll it closed the other.

View attachment 116573

BTW - with the plumbing as discussed all of the BH functions are in series with the thumb. If you slow the thumb way down it will also slow ALL of the BH functions way down when the thumb is being used That could get real annoying.

Dan

 

[Smokeydog]

If the BH-77 had a thumb option? Cost?
Could probably custom make with a few OEM components like the valve. You are a pretty clever fellow.

Foot pedal on the M59 seemed awkward so modified to suit me. Modified to suit me. Very similar foot pedal B26 was better OEM.

Operated a 4-lever Ford backhoe for decades so an extra lever is no problem.

 

[Runs With Scissors]

So with a manual valve, the thumb can be "feathered" a little?

If that's the case, I wonder if the manual valves lever could be controlled using a linear actuator?

Basically having the best of both worlds.


Edit: One of my main concerns with a foot/hand operated one is the lack of space. I ain't tall but, I ain't skinny neither, so although I technically "fit", space is at a premium.

 

[Runs With Scissors]

If the BH-77 had a thumb option? Cost?
Could probably custom make with a few OEM components like the valve. You are a pretty clever fellow.

Foot pedal on the M59 seemed awkward so modified to suit me. Modified to suit me. Very similar foot pedal B26 was better OEM.
View attachment 116584
Operated a 4-lever Ford backhoe for decades so an extra lever is no problem.

I did ask the dealer when I bought it and there was no option for a BH77 at the time.

I am pretty sure there is no current option either.

 

[D2Cat]

If the BH-77 had a thumb option? Cost?
Could probably custom make with a few OEM components like the valve. You are a pretty clever fellow.

Foot pedal on the M59 seemed awkward so modified to suit me. Modified to suit me. Very similar foot pedal B26 was better OEM.
View attachment 116584
Operated a 4-lever Ford backhoe for decades so an extra lever is no problem.

I like that hammer and the longer handle!

 

[fried1765]

If the BH-77 had a thumb option? Cost?
Could probably custom make with a few OEM components like the valve. You are a pretty clever fellow.

Foot pedal on the M59 seemed awkward so modified to suit me. Modified to suit me. Very similar foot pedal B26 was better OEM.
View attachment 116584
Operated a 4-lever Ford backhoe for decades so an extra lever is no problem.

I sometimes miss my 4 lever Ford.

 

[TheOldHokie]

So with a manual valve, the thumb can be "feathered" a little?

If that's the case, I wonder if the manual valves lever could be controlled using a linear actuator?

Basically having the best of both worlds.


Edit: One of my main concerns with a foot/hand operated one is the lack of space. I ain't tall but, I ain't skinny neither, so although I technically "fit", space is at a premium.

We just had a similar discussion in another thread. You can buy a foot actuated manual control valve. Given your fabricating skills fitting it to the BH77 should be a fun weekend's work.

Or roll your own lile that postrr did.

Dan

 

[Smokeydog]

I like that hammer and the longer handle!

Swing lock pin. Long handle for reach. Picture shows the storage slot.

 

[cthomas]

Hope it turns out better than the locking cylinders on the 3 point from about a month ago. Could you install a cable from the rear remote to a kind of foot pedal. Thinking like a transmission cable(heavier duty) to a foot pedal(that hooks to your boot).

 

[TheOldHokie]

So with a manual valve, the thumb can be "feathered" a little?

If that's the case, I wonder if the manual valves lever could be controlled using a linear actuator?

Basically having the best of both worlds.


Edit: One of my main concerns with a foot/hand operated one is the lack of space. I ain't tall but, I ain't skinny neither, so although I technically "fit", space is at a premium.

The only thing I ever operated that had a foot pedal was a Case Extend-a-hoe. I thought it was a great third hand. This looks like it would be a simple and affordable solution.

Single foot pedal valve / two-way pedal valve for excavator

ISO9001 certified single foot/two-way pedal valve for excavators. Fits Komatsu, CAT, etc. 6m warranty, 3.7kg, ships in 3-5 days.

imaraengineeringsupplies.com

Dan