1. Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!
  2. ALL NEW MEMBERS READ THIS FIRST!! Thank you for joining Heavy Equipment Forums! If you are new to forums we communicate with "Threads", please search our threads to see if your topic may have already been answered and if not then click "Post New Thread" in the appropriate forum. This will allow all of our members to see your question and give you the best chance to be answered. After you've made a number of posts you will graduate to Full Member status where you'll see a few more privileges. Following these guidelines will help make this the best resource for heavy equipment on the net. Thanks for joining us and I hope you enjoy your stay!!

Jcb 3cx thumb

Discussion in 'Tractor/Loader/Backhoes' started by Steve328, Oct 13, 2017.

  1. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    hello gentlemen, I recently ordered a much needed thumb for my 3cx. I few questions I have if anyone is familiar with this machine. I have a hammer circuit now that's plumbed up to the top of the main boom. I was thinking I could use this plumbing for the new thumb vs trying to route new hoses which would be a pain does it matter that they're 1/2 lines? And for the hammer circuit should I just loop it back to its self to seal the loop?
     
  2. jcb jeff

    jcb jeff Senior Member

    Joined:
    Nov 23, 2014
    Messages:
    379
    Location:
    United Kingdom
    If you have a hammer circuit this is normally single acting so you get a feed and a return back to tank,
    You will need to have a double acting circuit for a thumb if not you will require putting a control valve / c top with releif valves on the hammer feed line as to make it a feed only into the block and able to split to open/close thumb and pipe the return from the new control block back into the hammer circuit return.
    These valves can be electric operated or bowden cable operated.
    If you have a extra dig on this machine you can use this circuit as well but need to still put a diverted control valve on.
     
  3. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    Thanks Jeff, I was only thinking of using the plumbing going up the boom its maybe 1/2 or 3/4 not sure. I was thinking looping the Hammer circuit to its self and disconnect the switch. I didn't even think to use the hammer hydraulic supply to a new valve. I'm wondering if that would be cheaper than the diverter valve I bought to use the extra dig circuit as you suggested. The valve was 1k not counting lines and hoses.
     
  4. Jock

    Jock Well-Known Member

    Joined:
    Oct 24, 2012
    Messages:
    55
    Location:
    Australia
    Gday Steve,

    I played with these a fair bit back when I was doing my apprenticeship, few years ago now but. We used to do a lot of mods on the 3CXs tilt hitches, extra circuits, grabs etc. We did do a thumb, from memory we went the way jeff suggested and bolted a 6 port diverter to the top of the dipper and used the e-dig circuit. Only thing with doing this is to double check that circuit has adjustable circuits reliefs, you'll need to set the piston side relief at a lower setting to prevent damaging the thumb cylinder when your're crowding the bucket. You'll also need to fit the e-dig lock pin each time you plan on using the thumb to prevent it creeping or accidentally moving.

    The other option is ctop and use the hammer supply but ctop can be a bit jerky as it's on off unless you spend big and go for a proportional setup. Make sure you fit reliefs as well, the hammer circuit won't protect the cylinder from damage by the bucket as mentioned above

    I can't really see any dramas with using the hoses as you suggest, does your machine have powered sideshift? Not sure what model you have (gear or piston pump) but the valving underneath is pretty self explanatory, especially if it's gear pump. Cap it off, pull out the hammer switch and then supply your oil to the hammer hoses. Either by another slice in you control valve (exxy) or putting a 6 port diverter under the back of the machine and diverting one of the other rear end functions eg. powered sideshift. I did once get a bit sneaky and used one of the loader valve spools to supply a grab. Ctop with shuttle valves to work the pilot circuit and a 6 port diverter to divert from the loader lift spool (that was an expensive one though)

    A 6 port diverter on the e-dig circuit mounted on the top of the dipper would be by far the cheapest option though
     
  5. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    I think the best bet for me not being experienced in hydraulics is the diverter valve. I wasn't aware that the extra dig had to be pinned. I was thinking I could switch back and forth and use both functions. I wanted to mount the valve under the machine as to not have hoses sticking out everywhere.
     
  6. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    I'm really surprised that this machine doesn't have a spare valve somewhere.
     
  7. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    So what does proportional mean? How does the thumb provide clamping force against the bucket with out pushing it back or vs verses. Does a relief valve operate when a certain pressure is reached and allowing the overage to go back to tank. Sorry for all the questions but I'm thinking of returning the diverter valve and getting a proportional foot valve and kit that's designed for the machine.
     
  8. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    Finally got the thumb installed. Ami was great to deal with. Perfect fit
     

    Attached Files:

  9. Billrog

    Billrog Senior Member

    Joined:
    Mar 27, 2016
    Messages:
    551
    Occupation:
    band mill , backhoe and dump truck
    Location:
    Armstrong, British Columbia
    Looks good !!!
     
    Steve328 likes this.
  10. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    So I was working on the hydraulics today. My plan was to remove all the hammer circuit hoses and cap the feed and use the return as the return for the pressure relief return for the thumb. So I got everything from the hammer circuit removed, capped the feed and return and when I start the machine up I hear squealing from I think the front valve for the loader. And when I increased rpm it just didn't sound right. Hydraulic oil level reads fine and I operated every cylinder thinking it was air. Any input please share. Thank you
     
  11. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    Here are the two caps
     

    Attached Files:

  12. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    This is the hammer circuit I removed. The two 45 fittings that are next to each other went up the boom and where connected by a temp loop and the t fitting was the return and the 90 by its self was to the hoe block. I'm thinking I just need to connect the two caps in the previous picture together with a section of hose and I'm good. But I'm not sure if I can use it for a return for the thumbs pressure relief.
     

    Attached Files:

  13. jcb jeff

    jcb jeff Senior Member

    Joined:
    Nov 23, 2014
    Messages:
    379
    Location:
    United Kingdom
    Steve 28
    The first picture you got under the valve block i think the one you got capped is also a return from memory
     
  14. jcb jeff

    jcb jeff Senior Member

    Joined:
    Nov 23, 2014
    Messages:
    379
    Location:
    United Kingdom
    What is your serial number i might be able to find the fitting instructions for the hammer circuit so you can back track.
     
    Steve328 likes this.
  15. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    Thanks Jeff here's the serial number jcb3cx4tk02015786. I think I need to connect them capped lines together and hopefully I can use it as a return. It goes right to the tank.
     
  16. greg9504

    greg9504 Well-Known Member

    Joined:
    Aug 29, 2005
    Messages:
    138
    Location:
    Ottawa Ontario Canada
    Steve, I haven't studied what you did too closely but check if the circuit for the hammer is double acting. I have installed a thumb on a JCB 212s (2cx in Europe) which has a factory hammer circuit. I was able to plumb right into that circuit. In my case the valve for the hammer is double acting, with one side unused. So I just caped the return line for the hammer that goes directly to the tank, and pumped the other side of the valve to the thumb. I have a very detailed video here which shows everything (hydraulics start at about 3:30 mark):


    Take a look and see if your valve looks similar.
     
    hookedondiesel and Steve328 like this.
  17. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    Greg mine doesn't look the same. I don't have any spare controls ether. My foot pedal works the extend boom. I have a diverter valve and a pressure relief to add so I will toggle between extend hoe and thumb. now that I'm learning more im pretty sure the two capped lines need to be connected back together. I just don't understand how the hammer would operate if that was a return.
     
  18. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    Jeff this looks like it
     

    Attached Files:

  19. Steve328

    Steve328 Well-Known Member

    Joined:
    May 24, 2016
    Messages:
    49
    Occupation:
    Master electrician
    Location:
    Rhode Island
    On the schematic the t's labeled 14 where piped up the boom and looped together.
     
  20. jcb jeff

    jcb jeff Senior Member

    Joined:
    Nov 23, 2014
    Messages:
    379
    Location:
    United Kingdom
    ham1.JPG h2.JPG
     
    Steve328 likes this.