BH77 - has anyone considered converting mechanical thumb to hydraulic?

[CDN Farm Boy]

Welcome.

You have come to the right thread to follow.

The only way to have the thumb work in conjunction with ALL the other functions is for it to have it's own valve independent of the rest. Factory B26 does this with a foot operated control valve. jim_wilson has a plan to tie in an aux valve to his system. With mine, I may cheap out and cheat by running another pair of lines to another remote on the tractor (valves are expensive up here in Canada). I'll have to reach by my left elbow to operate but still way better than getting off the machine to adjust. Diverter valve off the boom swing would be the other option -- use boom swing because the need to swing and thumb at the same time is all but non existent but curl and thumb can still be done together which would be the most common of dual operations.

 

[Gundawg]

My first thought were to T into the pressure and return lines with a double acting open center electric solenoid type valve relying on the existing bypass valve but I am not sure this will work.

You are saying this will not work is that correct?

 

[CDN Farm Boy]

You are saying this will not work is that correct?

If I'm understanding you right, you are thinking of mounting the new one in parallel with the existing? If that's the case, it won't work. The fluid will always pick the path of least resistance (whichever valve is open at the time) and nothing will work.

Valves need to be mounted in series, usually the PB port of the first used to power the second. The returns however can be T'd together

 

[CDN Farm Boy]

I got mine up and running last night and a quick test this afternoon. Woo Frickin Hoo! :cool2: Worth every bit of the time and $$.

2 x 10 cyl, 27' of 1/4" hose, some fittings and hose protector, all told, I'm into it for $250. All parts other than the QD's were from Princess Auto. I'd ordered extra male QD's when I did the remote install so I would have them available.

I cheaped out and ran them off one of my other pairs of rear QD's rather than a valve mounted on the BH itself. If I get fed up with having 4 hoses to connect and have an extra $500 burning a hole in my pocket I might switch but for now, I'm up and running. The only mods I've done that aren't easily reversible is to weld 2 mounts on for the hose clamps. If I ever needed to it would take me about 10 min max to remove this and put the mechanical linkage back on.

This is the cyl that will be replacing the mechanical linkage.


I have to cut the base mount off the cyl, turn it 90 deg and weld it back on and also narrow the head mount from 2" to 1.5". The base mount needs to be turned so the ports are on the side.


The ram was mounted and welded in place to ensure that the pin boss was perfectly in line with the cyl body.


The head mount needed to be narrowed to fit in the space of the old linkage


Lines were run on the outside of the stick and then go down inside the hole in the top of the boom


The width of the thumb actually provides some protection for the head port. Lines were plumbed direct to the ram, no QD's at this end as I never plan to use an auger etc.


The lines were fished thru the existing hose protector at the base of the main boom


I've got a 4 spool valve for remotes (3 rear, 1 future front) The BH is run off one pair with 3/8 couplers, the thumb is on the top 1/4" pair, easy to reach with my right hand by my left elbow.


Everything tucks in nice and tight from the operator's seat


If I leave the valve activated for the BH, I can still run the thumb but it is slow (flow is split between 2 open ports). If I neutral the valve powering the BH, the ram works nice and quick. This will give me incentive to order replacement detent kit that I lost the spring out of during install and have been using a cedar shim to hold open for now.

 

[CDN Farm Boy]

Any of you other guys getting close to having your's converted? I've got a few hours on mine now and love it. :cool2:

 

[trihounds]

I'm still waiting on my 3300 which is scheduled to arrive at the dealer mid Sept. Thanks to your advice, I killed the Kubota rear remote and upgraded the tires to the same as yours, which are now 'optional' on the 3300. I'll still have to do the hydraulic mod but I keep checking back to this thread for inspiration and to oogle over the machine.

 

[bumperm]

Bandit67,

Is there any more info on the kit from the company you were dealing with?

bumper

 

[bandit67]

I got busy this summer and communication with them fell off. They were working on it mainly for me and needed input from me, so probably shelved the project when they didn't hear back from me. I'll try to get back with them soon to see if we can get it back on track.

 

[bumperm]

Bandit67,

Thanks! I think there'd be a worthwhile size market for a well designed kit at a sensible price point.

bumper

 

[paulwestski]

The Kubota BH4948 valve kit comes with everything including the foot pedal and linkage for $850.00
You just would need the hoses, cylinder and of course the thumb.
If the BH77 valve mount box is not wide enough, could it be removed and widened slightly?

 

[bumperm]

$850 sounds a little pricey. Surplus Sales has cylinders and one suitable might be around $150. I bought the mechanical thumb with my BH77 and that thumb's mounting will lend itself to mounting the cylinder with no issues. I've only had the new tractor for a couple of weeks now, so the mechanical thumb is still a "wonderment" to me, being as my previous hoes were thumbless :c)

I just went out and sat on the hoe. I'm 6'1" and not nearly as limber as I get older . . . can't imagine where a foot pedal would fit in the limited space available for my big feet.

My current project is adding hydraulic chute deflection on the B2782 (front blower). Got the tractor with 3rd function, so the additional parts will only be about $200 (cylinder $108, hoses, fittings and shipping the rest). I'll make the brackets and weld things up.

bumper

 

[jim_wilson]

I got busy this summer and communication with them fell off. They were working on it mainly for me and needed input from me, so probably shelved the project when they didn't hear back from me. I'll try to get back with them soon to see if we can get it back on track.

I started doing some research into what it would take to come up with a kit also - and unfortunately had to put it aside as the good weather work took over all my free time.

I'm hoping that maybe this winter I have some time to look into this again and start sourcing out some parts. I've got the thing pretty much worked out as far as the basics go - now just have to get the details straight.

 

[jim_wilson]

The Kubota BH4948 valve kit comes with everything including the foot pedal and linkage for $850.00
You just would need the hoses, cylinder and of course the thumb.
If the BH77 valve mount box is not wide enough, could it be removed and widened slightly?

Which hoe is that kit meant for? $850 doesn't seem like that bad of a price.

There really isn't a lot of room to add another valve onto the BH77 valve stack IMHO. It could probably be done - but it would take some serious reworking of the hoe itself.

 

[paulwestski]

Which hoe is that kit meant for? $850 doesn't seem like that bad of a price.

There really isn't a lot of room to add another valve onto the BH77 valve stack IMHO. It could probably be done - but it would take some serious reworking of the hoe itself.

To ALL Reread my post
That is the valve kit ONLY.
It does not include the Cylinder, Thumb, Hoses or Fittings.
That is the valve kit for the BH92.

The complete Hydraulic thumb option on a BH92 is a $2200.00+ option.

The valve shroud on the BH77 is removable and could be split and widened to fit one more valve section.
The least expensive option would be using the electric diverter valve on the boom swing valve.
Only hassle would be the 12v power connection to unplug when dismounting the hoe.

 

[jim_wilson]

To ALL Reread my post
That is the valve kit ONLY.
It does not include the Cylinder, Thumb, Hoses or Fittings.
That is the valve kit for the BH92.

The complete Hydraulic thumb option on a BH92 is a $2200.00+ option.

The valve shroud on the BH77 is removable and could be split and widened to fit one more valve section.
The least expensive option would be using the electric diverter valve on the boom swing valve.
Only hassle would be the 12v power connection to unplug when dismounting the hoe.

I think you need to take a closer look at the hoe if you've got a BH77 . The valve stack is not mounted behind that cover - it's mounted below the "floor" of the backhoe unit - and the control rods run up inside that shroud to the controls. There really isn't any space available to fit another valve into the stack without doing some real surgery to make space available for it.

The BH77 does not mount the valves the same way that the BT hoe on the B26 does for instance - where , if I remember correctly - the valves are mounted up inside the "stand" on the hoe - and the foot control for the thumb valve - just goes thru the side into the valve itself.

There's also no guarantee that the valves used in the BH92 - are the same as the ones used in the BH77. Have to do some parts cross referencing to see if they'd even interchange.

 

[paulwestski]

I think you need to take a closer look at the hoe if you've got a BH77 . The valve stack is not mounted behind that cover - it's mounted below the "floor" of the backhoe unit - and the control rods run up inside that shroud to the controls. There really isn't any space available to fit another valve into the stack without doing some real surgery to make space available for it.

The BH77 does not mount the valves the same way that the BT hoe on the B26 does for instance - where , if I remember correctly - the valves are mounted up inside the "stand" on the hoe - and the foot control for the thumb valve - just goes thru the side into the valve itself.

There's also no guarantee that the valves used in the BH92 - are the same as the ones used in the BH77. Have to do some parts cross referencing to see if they'd even interchange.

I need to make a correction the factory hydro thumb option on the BH92 is $2900.00, that is the complete installation, valve, cylinder, hoses, thumb.

I never intended for any one to think that the BH92 kit was a direct bolt up to a BH77, It more of a reference of what just the valve portion of the project costs.

I still think the easiest and cheapest option is the diverter connected to the boom swing. I may even go that route on my BH92. I could install everything for less that the cost of just the factory valve kit.

 

[jim_wilson]

I need to make a correction the factory hydro thumb option on the BH92 is $2900.00, that is the complete installation, valve, cylinder, hoses, thumb.

I never intended for any one to think that the BH92 kit was a direct bolt up to a BH77, It more of a reference of what just the valve portion of the project costs.

I still think the easiest and cheapest option is the diverter connected to the boom swing. I may even go that route on my BH92. I could install everything for less that the cost of just the factory valve kit.

As a general rule - going with Kubota factory parts is going to be costly.

I'm pretty sure a package with all of the components to put a hydraulic thumb on the BH77 could be put together - using high quality parts - could be put together for a good amount below $2900

 

[bumperm]

I finished adding a hydraulic chute deflector on my B2782B front blower. I modified the cylinder right angle fittings by drilling and tapping for 1/4-20 set screws that I center drilled .052" to make flow restrictors for the 4" stroke 2" diameter cylinder . . . this allows nice smooth, not too fast controllable operation using the 3rd funtion valve with joy stick mounted push buttons. Cost was $208 for all parts from Surplus Sales.


3rd function valve for front loader implements (and my snowblower chute deflector)





Reason I mention this is that is should be possible to use the same 3rd function valve to run a thumb. Downside (?) would be having to route the 1/4" hydraulic lines back aft from just in front of the cab where the quick connects are. The buttons to control the 3rd function valve could be paralleled off the existing joy stick buttons (in the wiring harness below the joystick) as they are momentary and most probably normally open (NO). This would mean a 4-pin electric plug back aft, but that's quite doable. The whole project should cost maybe $300 - $400, and that includes cylinder, lines and quick connects.

Comments or suggestions welcome before I bury myself in another project :c)

bumper

 

[jim_wilson]

I finished adding a hydraulic chute deflector on my B2782B front blower. I modified the cylinder right angle fittings by drilling and tapping for 1/4-20 set screws that I center drilled .052" to make flow restrictors for the 4" stroke 2" diameter cylinder . . . this allows nice smooth, not too fast controllable operation using the 3rd funtion valve with joy stick mounted push buttons. Cost was $208 for all parts from Surplus Sales.


3rd function valve for front loader implements (and my snowblower chute deflector)





Reason I mention this is that is should be possible to use the same 3rd function valve to run a thumb. Downside (?) would be having to route the 1/4" hydraulic lines back aft from just in front of the cab where the quick connects are. The buttons to control the 3rd function valve could be paralleled off the existing joy stick buttons (in the wiring harness below the joystick) as they are momentary and most probably normally open (NO). This would mean a 4-pin electric plug back aft, but that's quite doable. The whole project should cost maybe $300 - $400, and that includes cylinder, lines and quick connects.

Comments or suggestions welcome before I bury myself in another project :c)

bumper

If you've already got this setup in place - that might be a good way to do it.

After looking at my BH77 for quite a while - a couple of things became apparent to me:

one - adding another valve to the existing stack to operate the thumb cylinder - would not be completely impossible but it would be very involved and sourcing the correct valve to go into the stack would likely be very expensive

two - the *best* option to operate a thumb is a foot pedal IMHO. There are other options , but the foot pedal is the best and most convenient way to operate the thumb.

Given those those two things - it looks like the easiest way to add a valve to control the cylinder on the thumb - is to find something that can get plumbed in line (in-line meaning either before or after the existing valve stack) - and then control that with a foot pedal mounted on the side of the control tower. There appears to be enough space under the floor of the hoe to mount a valve - and enough space inside the tower and an opening that would allow installing a pedal with linkage to control that valve. There was some decent discussion about this back a few months ago and I just sort of faded out of it because my summer projects took over all my time.

I'd still like to do this - maybe if I can get some sort of heat out into my barn I can spend some time working on this during this winter.

I did also find a place that would do customer cylinders for not too outrageous prices - so in my mind the last big hurdle to mentally work out is the figuring out the exact right valve to use to control the thing.

 

[bumperm]

Jim,

I tried to see where a foot valve might fit earlier on. Being 6'1", 34 inseam and big feet, and nowhere near flexible, seating is somewhat cramped - - I feel fortunate just to get my feet up on that little platform, moving them with finesse to control much of anything is unlikely.

I measure the retracted length of the manually adjustable thumb arm on my BH77 hoe at 19-1/4" pin center to center - since I didn't have hydraulics hooked up as tractor was at another location, I guesstimated stroke at 9-1/2". "Surplus Center has a cylinder (their 9-4945) with perfect retracted length of 19-1/4", 10.75" stroke, and diameter of 2.25".

I've read other threads re. appropriate cylinder size for the thumb on other backhoes, and the concerns of pressure relief valves, curl cylinder overpowering thumb cylinder, or vica versa, and the risk of damage, etc. Couldn't find anything specific about the BH77 though . . . anyone made the conversion yet? And if so, what size cylinder?

thanks much,

bumper