Choosing the right thumb

[cruzair]

Background: I have a drott/case cruz air 45 rubber tire excavator purchased for use as a site machine for landscaping projects. It has a digging and a ditching bucket with a separate knuckle, but I never switch buckets because of effort involved.

My current project is building a terrace using granite boulders too big to fit in the 30x50" bucket. Chaining boulders works, but is no fun for a single operator. I think that a hydraulic thumb would be a big improvement for speed and accuracy, but I'd hate to spend $5-10k for something that doesn't do the job.

Other possible use for this will be handling firewood logs.

I'm currently leaning towards a rockland bt-h which is 12x55". This narrow thumb is lighter (critical for high center of gravity rubber tired machine) and less than most thumbs. Since it's a weld-on, it wouldn't interfere with all-to-rare bucket changes like a pin mount.

I've also considered getting a used grapple, but the thumb seems like it would be more versatile since it would
always be on the machine.

Any advice would be much appreciated.

 

[DKinWA]

I'm not familiar with the machine you have, but here's a common thumb manufacture around here. Most of the machines I've run have a PSM thumb on them. It works well and allows you to use the teeth of the bucket to pick up small things. I don't know what they cost, but I'm sure they're not cheap.

 

[Alan]

"Home Made" thumb

Personally, I like a fixed thumb. Granted, a hydraulic one is more convenient but there's also more to go wrong. If cost were no object I would probably go hydraulic.

This link will take you to a tale about a thumb I built last year. If you've got some talent with metal and a couple days you can build something that suits your needs.

http://www.snowplowing-contractors.com/alans_excavator_thumb.html

I built a boulder wall with that setup last fall and was lifting stuff that would pick the machine up on one track unles you kept the load in close. Going off the corner was OK and that's the most stable position on a tracked machine. The Drott has stabilizers on one end, doesn't it?

Write to me at ajnadeau1@verizon.net with questions and I'll help any that I can.

 

[cruzair]

Thanks for the reference to PSM. The site mentions mounting a pin attached thumb on a quick coupler, a combination I'd never considered. A coupler would certainly make my second bucket more practical.

Do most quick attach couplers that grab pins affect digging or breakout force enough to notice? I found several that claim to avoid this "issue" but they require attachments modified to suit or purchased from single source vendor. I saw some pretty sloppy couplers when shopping for [old] equipment. Are current versions stable and solid (and safe)?

The drott cruzair does have rear stabilizers which make it far more stable;lots of give in those big loader tires. They were also available with center stablizers as an option I wish mine had after some unplanned rocking action on side lifts. I've included a picture. Since the stick is set up with hydraulics for the ditching bucket, extra cost for a cylinder seems worth it for additional range of motion.

Here's the weld on alternative I was considering. Since a weld on thumb's pin is ~1ft from the bucket pin, it will have a bigger maximum opening which I expect to come in handy for larger rocks. This is the same for fixed/solid or for hydraulic.

 

[Taylortractornu]

Cruzair when I was 17 I boult a small thumb for my old 75 Ford 3550 hoe. I found out how great it was now Im 24 and building one for my PC50 Komatsu excavator Im going with a bucket pin mount because I have a narro stick t work with. I also like the way it can follow the radius of the bucket out farther. I made mine from 1 inch by2 bar stock for the backhoe , Now that I have a table burner I Made the one for the excavator from 3/4 inch plateI made a pattern for the torch to follow and burned 2 tines out. Ill try to post a few pics. I like your Cruzair, I got to operate an olderone a few years ago that swung and ran the stick with one pedal and ran the bucket with another and boomed up with the right hand lever. The left hand did nothing but hold on. Then I ran another that one hand swung it the other ran the boom and your feet ran the boom and stick. Id like to know how yours is set up. They are very handy machines on good ground I run a Leibherr rubber tired excavator for a friend on occasions. Il ltry to get a few pics of my thumb's progress. When my brother was in business we had a local heavy equipment repair and welding shop make one for his 100 Komatsu excavator. He left his machine there a week and they made it for about1200 dollars if i remeber right. He was there part of the time to get the features he wanted. It also had 4 pivot pin holes to get the right spacing he wanted like the 1st hole was for tin and other crushable trash and the 4th was for larger logs.

 

[9420pullpan]

go with a linkage thumb!!

i would definately spend the extra money and buy a thumb that uses the bucket linkage to mount. instead of buying a weld on thumb. the welds crack all the time.

 

[9420pullpan]

check out this awesome hydraulic thumb. it works with a quick disconnect. this is a great design!

 

[CascadeScaper]

Esco makes good buckets, but CWS, HPF, or PSM make much better thumbs, IMO. If the cost of getting a hyraulic PSM thumb and quick coupler setup wouldn't have been about $6,000 versus the $3,000 Cat brand thumb and coupler, we probably would have gone that route with our 303CR, but our sales guy cut us a smokin deal on the Cat thumb. Also, weld on or manual style thumbs just aren't quite where it's at. Try stacking a wall without being able to rotate the rock with the thumb and the bucket, it would be tough, that's for sure. If you just need a thumb to pick up objects and load them into a truck, etc, then a weld on stlye would be just fine, but any type of work that requires you to manipulate the placing of the object in the "jaws" calls for a hydraulic thumb.

 

[coopers]

PSM makes good thumbs but I'd go with CWS. All of our large excavators have CWS quick couplers which take the pin grabber buckets, and the progressive linked thumb. The only draw back with CWS's QC attachment is that with the 200 class excavators, it adds quite a few inches, which means the bucket teeth dig into the bottom of the boom. Happens all the time with ours. Nothing you can do other than not buy the QC attachment. The local Pape dealer up here uses pretty much only CWS products.

Blake
WA

 

[Alivia9465]

Chat

Be specific, this is not a private chat.

 

[CascadeScaper]

Cat's dedicated hydraulic QC's are AWESOME! I've used the ones that have "hooks" on the bucket where you just manuever them onto the lower stick pin, curl in and she's connected. Since the pivot point is in the same place there is no loss of breakout AND you don't beat the crap out of your boom. Our Cat rental place puts all of these style couplers on their excavators so all of their attachments crossover very nicely. We swapped over to a breaker very fast, it's a great system.

 

[coopers]

It's funny, Pape up here in North WA only really carried CWS it seemed, or at least had them on their rental units, but now I'm seeing more and more of them putting on PSM thumbs. I didn't like the PSM thumbs but they seemed to redo the desing and they are pretty nice. In fact, one of our new 160's has CWS bkts. and all but a PSM thumb, more curve to it then the CWS, pretty nice.

Blake
WA

 

[G60syncro]

I work in the design dept of an attachment manufacturer... Let me tell you that as a designer, a pin mounted thumb is the preferred setup!! Sure you can slap on a weld-on thumb and call it a day but it always seem to end up as a compromise. It's easier to get more rotation out of an hydraulic pin-mounted thum than a weld-on. Also, calculating that rotation is much easier.

Say you have a bucket with a 40" tip radius, a pin-on thumb will need a 40" tip radius, end of story!! On the other hand, a weld on tumb will travel on an arc that's offset from the bucket's turning arc. Typically 6" to 8" off. If the weld-on thumb is the same length as the bucket's tip radius, you'll reach a point where both arcs cross and the thumb "caves" into the bucket. To remedy that, Add the value of the offset to the length of the thumb.

If you add a pin grabber attachment, you also add another couple inches of tip radius and your 40" thumb quickly turns into a 56"-60" affair welded onto your machine. That is if you want to keep the tip of your thumb out of the bucket at all times. Some operators don't care for that, but they have to be extra careful when curling up the bucket so it does'nt jam the thumb.

If you can get a quick coupler attachment regardless which type and and hydraulic or even stiff-arm thumb that is pin mounted, you'll thank yourself over and over for the added productivity and better dexterity with the machine.

My 2¢... spend it as you will!!

 

[coopers]

What exactly to you mean by pin mounted? Is the excavator picture I posted above a few threads what you're talking about?

Blake
WA

 

[Ford LT-9000]

The John Deere Coopers posted is the way thumbs are mounted here as we use CWS thumbs and buckets we don't use that style quick conect thou we use CWS wedge bar system with the bar and two bolts.

Mechanical thumbs are usually welded to the stick but you don't see many of them around anymore unless its a old machine.

The other manufactures we use is Weldco Beales (WBM) and we also use Accurate Fabricating.

 

[nedly05]

:thumbsup We have 1 hydraulic thumb, and 1 manual. The hydraulic thumb gets used much more. I am not partial to either setup, we have a kobelco 70SR with the manual thumb, and we went manual due to the price. I shopped around and found one for 776 buck trucked to our shop. We recieved it on a Friday, I welded it on on a Saturday, and we used it on monday. It sure isn't a pin mounted hydraulic thumb, but we built a 3300 foot road thru the mountains with it this summer and I sure was glad to have it.The other thing about a manual thumb is no hydraulic lines to tear off, and no piston to damage. I like both styles as long as my machine has a thumb!

 

[G60syncro]

What exactly to you mean by pin mounted? Is the excavator picture I posted above a few threads what you're talking about?

Blake
WA

That's a pin mounted thumb indeed. It even has what is called a progressive link. With a weld-on thumb we try to get around 130* of rotation, a pin-mounted unit typically reaches 140-150* and if you add the progressive linkage we can easily reach up to 180*.

They are more expensive though, because of the added machining and assembly operations required for the extra linkage.

 

[dayexco]

what is your URL for the buckets, attachments?

 

[G60syncro]

what is your URL for the buckets, attachments?

I just changed my signature... check the link in it... BTW, the website pictures may not be the best up to date stuff for now... I'm in the midst of completing our new bucket lineup and I'll be moving onto other excavator attachments shortly. These will include rippers, rakes and thumbs.

 

[roadrunner81]

I ended up making my own, I personaly thought alot of the minis with thumbs made localy were missing something. The thumb I made only added about 150lbs to the stick and handles all sorts of objects of varying size. I think I used AR400 for the steel and ordered the cyl. from king cyl. I think.

here's a pic I can get close ups if you like.

http://www.kanopykingdom.com/KK KUSTOMZ.htm