Fitting a hydraulic thumb using an electronic diverter valve

[honey_badger]

Hi -
I want to make a thumb for my jz70 and would ideally like a hydraulic one. Would I be doing something drastically bad to install an electronic diverter valve on the boom switching the pipes from the bucket crowd into controlling a thumb, with the diverter operated via one of the joystick buttons?
Cheers

 

[TiltyShaun]

Do you not have a hydraulic service line to put it into?

If not then a diverter would work!! I had a manual thumb and wished I went hydraulic until I put the ENGCON on and very rarely use the thumb now unless bush clearing

 

[V8Druid]

Hi -
I want to make a thumb for my jz70 and would ideally like a hydraulic one. Would I be doing something drastically bad to install an electronic diverter valve on the boom switching the pipes from the bucket crowd into controlling a thumb, with the diverter operated via one of the joystick buttons?
Cheers

what size is your plumbing on the crowd ram? ...
might struggle to find a 6x2 diverter easily, over 1/2" BSP ...
some one on here has found one recently with 3/4" ports, but the working pressure was a bit low ..... and it was bloody expensive ...
also be aware it'll need a 1/4", direct to tank, drain line for body leakage in the valve .. probably .. most do

personally, id run a couple of extra lines up the boom from a diverter, in say the blade service, or better still the boom slew ..... er, .. just googled the JZ70 and it don't have one .... fit a 'pedal' on yer blade lever, so's you can operate it with yer foot ... Robotplant on CEF did it to a few of his Hitachis .... very successfully

swapping between crowd and thumb'd be a bit of a PITA, I'd have thought, as it'd be nice to be able to use them both simultaneously

 

[honey_badger]

Do you not have a hydraulic service line to put it into?

If not then a diverter would work!! I had a manual thumb and wished I went hydraulic until I put the ENGCON on and very rarely use the thumb now unless bush clearing

One of those ENGCON gadgets looks like it'd be a fair bit of kit but i don't think i'd be able to persuade bossman to invest in one of them yet unfortunately, only just getting there with the talk of a thumb...
It's a farm digger so does a lot of clearing brush/fallen trees/stumps and picking up the occasional sod of a rock when making tracks...

what size is your plumbing on the crowd ram? ...
might struggle to find a 6x2 diverter easily, over 1/2" BSP ...
some one on here has found one recently with 3/4" ports, but the working pressure was a bit low ..... and it was bloody expensive ...
also be aware it'll need a 1/4", direct to tank, drain line for body leakage in the valve .. probably .. most do

personally, id run a couple of extra lines up the boom from a diverter, in say the blade service, or better still the boom slew ..... er, .. just googled the JZ70 and it don't have one .... fit a 'pedal' on yer blade lever, so's you can operate it with yer foot ... Robotplant on CEF did it to a few of his Hitachis .... very successfully

swapping between crowd and thumb'd be a bit of a PITA, I'd have thought, as it'd be nice to be able to use them both simultaneously

My brief search into diverters told me 6x2 was what i was looking for. I've not thought seriously about it yet I was wondering if it was a plausible idea to have one piped up from the crowd ram. I've not checked the plumbing size, didn't realise I might have an issue finding a diverter that had the right pressures and sizes.

Can you better explain the purpose of that direct to talk line thats needed? Its for leakage from within the body of the diverter - say when the valve is switched and some oil escapes and ends up between lines? Or another purpose?

That sounds like a good idea using something that's not boom service to run the thumb. So you'd suggest fitting a diverter near the main hydraulic block for the blade service and then running piping up the boom? Seems like it'd be neater than a diverter fitted on the boom by a long shot too.
I have heard about people saying the thumb ram has to be weaker than the crowd ram? Does anyone know if this is true, and if so why so? Surely an equal match would be optimal?

 

[V8Druid]

One of those ENGCON gadgets looks like it'd be a fair bit of kit but i don't think i'd be able to persuade bossman to invest in one of them yet unfortunately, only just getting there with the talk of a thumb...
It's a farm digger so does a lot of clearing brush/fallen trees/stumps and picking up the occasional sod of a rock when making tracks...




My brief search into diverters told me 6x2 was what i was looking for. I've not thought seriously about it yet I was wondering if it was a plausible idea to have one piped up from the crowd ram. I've not checked the plumbing size, didn't realise I might have an issue finding a diverter that had the right pressures and sizes.

Can you better explain the purpose of that direct to talk line thats needed? Its for leakage from within the body of the diverter - say when the valve is switched and some oil escapes and ends up between lines? Or another purpose?

That sounds like a good idea using something that's not boom service to run the thumb. So you'd suggest fitting a diverter near the main hydraulic block for the blade service and then running piping up the boom? Seems like it'd be neater than a diverter fitted on the boom by a long shot too.
I have heard about people saying the thumb ram has to be weaker than the crowd ram? Does anyone know if this is true, and if so why so? Surely an equal match would be optimal?

fair chance of snapping your dipper if they're fighting each other ....
tank drain is to remove any excess oil in the valve block and prevent any pressure build up in it, in the shuttles/spools or they'd hydraulically lock .

 

[Davedb]

fair chance of snapping your dipper if they're fighting each other ....
tank drain is to remove any excess oil in the valve block and prevent any pressure build up in it, in the shuttles/spools or they'd hydraulically lock .

No different than a fixed thumb tho for chance of snapping dipper? If your thumb ram ain’t strong enough it would get bent I’d imagine

 

[V8Druid]

No different than a fixed thumb tho for chance of snapping dipper? If your thumb ram ain’t strong enough it would get bent I’d imagine

hmm debatable ... two sources of active force and differing leverage moments .... an interesting one

 

[TiltyShaun]

My thumb had several fixed positions. You grabbed with the bucket. Very useful. It did get very slightly bent. You have to be sensible as you don’t realise the force the hydraulics put out. They will find the weakest point to bend or break!!

 

[Mogman]

A simple relive valve in the ‘thumb’ ram will stop any drama

 

[honey_badger]

No different than a fixed thumb tho for chance of snapping dipper? If your thumb ram ain’t strong enough it would get bent I’d imagine

thats what I thought, only main difference is that the ram for the thumb would be mounted higher up than the selector on a fixed thumb?

My thumb had several fixed positions. You grabbed with the bucket. Very useful. It did get very slightly bent. You have to be sensible as you don’t realise the force the hydraulics put out. They will find the weakest point to bend or break!!

I was thinking that, thinking that I'm going to have to make it extremely beefy on the mounts so that I don't have to end up remaking bent parts of it.
Has anyone here ever built their own hydraulic thumb?

A simple relive valve in the ‘thumb’ ram will stop any drama

Good idea. I'll need to do some research into pressures though so that I get something thats just before any breaking points. Hydraulics in this depth is fairly new to me.

 

[Davedb]

You’d want a cross line relief valve if you were going for that idea they have adjustment screws on them so you could set it to let the ram move when you put too much pressure on the thumb

 

[Grifferr]

I think the cross line relief valve would be annoying. It would let go when you want to get a good grip.

 

[Grifferr]

Also if you make your own it would be good to find a ram with both pipe conection's at the top like a jcb leg ram. It just means it is neater and no worries of damage to pipe's when thumb is not being used.

 

[V8Druid]

Also if you make your own it would be good to find a ram with both pipe conection's at the top like a jcb leg ram. It just means it is neater and no worries of damage to pipe's when thumb is not being used.

I've seen kits recently to fit steel plumbing to rams to achieve this .... might have been flowfit ... but easily achievable with some steel pipe and fittings .... or banjo the close line to the port and secure the rubber line to the cylinder ... did it with my tilt rams on the VA-r

 

[honey_badger]

I've seen kits recently to fit steel plumbing to rams to achieve this .... might have been flowfit ... but easily achievable with some steel pipe and fittings .... or banjo the close line to the port and secure the rubber line to the cylinder ... did it with my tilt rams on the VA-r

View attachment 9348

Thats very smart looking, but both connections at the top would still be a good idea if a ram like that is findable.

 

[honey_badger]

I have been looking at thumbs that pivot on the quickhitch/bucket pin at the bottom of the dipper, I can see advantages of making one that mounts there instead of on the dipper. Any reasons I shouldn't mount one there?

 

[V8Druid]

I have been looking at thumbs that pivot on the quickhitch/bucket pin at the bottom of the dipper, I can see advantages of making one that mounts there instead of on the dipper. Any reasons I shouldn't mount one there?

good geometry like that ... just need longer pins and get the shape right so it'll stow under the dipper and allow the bucket full crowd

 

[V8Druid]

Thats very smart looking, but both connections at the top would still be a good idea if a ram like that is findable.

as said .... pretty sure Flowfit were doing kits to 'steel up' the closure port ...

 

[V8Druid]

as said .... pretty sure Flowfit were doing kits to 'steel up' the closure port ...

found 'em ..... https://www.ebay.co.uk/itm/Flowfit-...ve-Kit-for-Double-Acting-Cylind-/312589812369

 

[V8Druid]

You’d want a cross line relief valve if you were going for that idea they have adjustment screws on them so you could set it to let the ram move when you put too much pressure on the thumb

take yer pick ....
https://www.ebay.co.uk/sch/i.html?_...l+Cross+Relief+Valve+Inline+1+"+BSP+&_sacat=0