Pro's and con's on a main pin hydraulic thumb versus a weld on hydraulic thumb.??? I mostly clear timber.
With timber, wouldn't a main pin be a weak link? 6X shear plane on one pin. Plus torsional stress with off center picks? I would think that would contribute to weaknesses and stress cracks. You haven't mentioned if you want a rigid thumb or hydraulic. The other thing to consider is if a rotating grapple would be an advantage. Kinshoffer among others offer some articulating grapples . Just something to think about.
If you never need to remove the thumb for other jobs, main pin/progressive link is the only way to go. Weld-on is easier to remove, but generally not as stout as a main pin.
By weld on, do you mean the mounting and pivot boss for the thumb is welded to the stick? All the thumbs produced in my area are main pin mounts. Basically the stresses put on the main pin are cancelled out by the opposing forces of the bucket against the thumb. Keep grease in the joints and they last a long time.
A rotating grapple is out of my price range an not sure that it would hold up to the type of work i do. But i will try to look at some YouTube videos...
Yes...its all welded to the stick. I currently have a Strickland weld on thumb that i purchased new with the machine. I've had nothing but trouble with it...mostly i believe because the narrow pivot point cant handle the stress. Which is why im here asking questions...
What size machine you got? Are you using a bucket with a rigid thumb? What kinda problems are you having? Strickland isn't exactly junk, so, there's gotta be a reason. Maybe we could offer help while not necessarily purchasing a new implement but properly fitting and adjusting what you've already got.
I eventually had to have the mounting boss replaced, but I used the factory design for over 5 years before I broke it due to a lazy moment. Is yours built less than this?
Case CX130D (About #30,000)...hydraulic thumb. Mostly with a 36" bucket. I also use a USA Attachments brand stumper often. The probems start from the very beginning...the cylinder would bleed off within 4-5 buckets of digging, it would have to be bumped back up. My dealer allowed that was normal...it should be pinned while digging. Soon thereafter within the first 100 hours of use the piston nut came off inside the cylinder. The pins and bushings on the main pivot point dont last anytime which in turn puts the cylinder under extreme angles an it blows the piston seals. Its been thru 4 different cylinders (all new)...an multiple rebuilds. An im not bashing Strickland here cause they have been outstanding while it was under warranty...they even flew a guy in to look at it twice.
I don’t know anything about the quality of Strickland but I have seen some huge variations in quality between various aftermarket attachment brands vs the OEM I work for, so much so there is no way in hell I’d cheap out by buying some of the manufacturers I have seen. most of the hydraulic thumbs I or or our welder have installed have been main pin thumbs.
Mine is very similar. I use mine most all day everyday so it doesn't ever come off. I do believe the narrowness of the pivot point has a lot to do with mine being broke down continuously. The main pin thumb would eliminate the torque being to great.
I agree...100%.
It’s almost like they are trying to take mounting points for a manual thumb and make it work for a hydraulic thumb.
I have been running a chinese thumb for 3 years without an issue that cost like 1/3 other brands, I think it really depends on the design, it is a main pin mount. Also depends a lot on the operator. I am not one of those guys who will push cylinders back, if I am picking up anything that won't compress I am very careful to not put too much force on it. Although that pin is a fair bit smaller then your main pin, it's still a good size pin and would take a lot of force to break. If it's a quality pin, I would say either something in the geometry is wrong putting too much stress on it, or operator error putting too much stress on it.
First thing first, when your stick is vertical, and your buckets side cutters are parallel with the ground, does your thumb hang over the teeth like the image attached? Has the auxiliary circuit pressure been topped out at 2500psi or less? Is your current pedal assembly variable control or all in?
Mine is very similar. I use mine most all day everyday so it doesn't ever come off. I do believe the narrowness of the pivot point has a lot to do with mine being broke down continuously. The main pin thumb would eliminate the torque being to great. It might be a little of both... geometry and operator lol... i might be a little harsh on it but i bought it to use in timber and i unfortunately took my dealers word on it being the right thumb. I shoulda insisted a main pin thumb i now believe.
In the beginning the dealer had the pressure to high...but they reset it to correct psi (2400 if i remember right). The thumb does hang over the bucket as in the picture several inches. Im not sure what you're referring to on pedal assembly.??
Can you tease the thumb with the pedal or does touching the pedal give you 100%flow?
So, next question , do you have a gauge or sensor to monitor pressure. Make sure you don't have the high side of the 2 stage coming in.
I can check it on the monitor i believe but i wont have a chance till about noon today.