Ok, aside from numerous other factory defects on my Cat 939 like bent bucket arms and pins on the leverage arms that are not available unless you buy the $1800 lever arm, here's the latest blunder from Cat. These arms are on my 4 in 2 bucket and I'm finding out that I'm not the only one with this problem. The clincher is these pups are like $600 each side. This is a factory defect and Cat is ripping off the owners.
By the way here's my bent arms!
The loader arms are an easy fix for a welder-fabricater.Send a picture of a front view of the bucket with the 4 in 1 open if it's not to much trouble.And some more close up pics of the hinge lever.
Come On Cat: Yeah... somethings definitely wrong there... :thumbdown OCR
What are the hydraulic systems relief valve settings currently at?
Not sure on the pressures, I'll have to get looked at when I change them out!
How many hours on this machine?
The hour meter shows 2100 hrs.
How old is the machine and did you buy it new or used?
Odd that it breaks through what appears to be the thicker section of that link and also check the weld onto the side of the 4 in 1 on the top pic to the second pic, looks like some scrapcutter has had a go at that. I had a 931 once that kept bending the tilt cylinder rods like bananas and it was due to too higher relief valve setting.
The broken piece looks to me like the victem of poor operating technique. If you grab something in only one side of the bucket, then squeeze it real hard, it will twist the clam, and if you do it enough, you will get a stress fracture somewhere, and where yours is broken is a likely place. I have not had a 939, but have had several 4in1 buckets over the years. The bent arms could very well be from pushing against something with the bucket curled back, and then driving the tractor forward into it. The arms are very strong when being pulled on, but not so much when you push on them. Once a little bend is started, it will get worse. I think these arms are a weak design from Cat, but if the tractor is used as intended, it will be fine. If you try to use a 939 like it is a 953, you will continue to have problems with it
I've only owned the machine for around 3 months now and these problems were there when I bought it. Regardless of how you bite something in the bucket the relief valve should be set or designed to prevent this type of problem. Regardless, this is poor design on Cats part!
Could be the previous owner has cranked up the relief valves because "it ain't strong enough...", and thereby caused all this damage. Just a thought.
I think you're right on - there's little doubt someone abused the machine before I got it!
Idleup, we have ran into those cracks on our 4in1 buckets on our Cat backhoes, looks like the same design. I wrote it off as being operator error, our guys like to clamp down hard on asphalt they dig up and load into the dump trucks. One point I want to make is be sure to check out what is the most economical way to fix. The first time it happened, I removed the clam shell, special ordered that pin boss-Cat did not have it listed as a separate part, got it flown in, paid to have a certifed welder remove and replace the one side that was broken. The part costs us $800, not including freight or paying the welder. The next time it happened on another backhoe I talked to one of the parts guys and he recommended buying a complete clam shell-cost $1300 but I swapped it out in no time, did not have to run around everywhere and ended up with a new blade edge. I wished we had done the first one like that. The point I am trying to make with this is check with Cat on replacing the whole unit versus only the part that is broke, as far as the arms bending and the boss cracking I agree with everyone else that the pressures are not set right. Be sure to get someone from Cat to talk to about this, I have run into other situations with Cat equipment where they ended covering the repair when technically they did not have to. Its called "good business", just don't explode on them, try to be nice and point out the flaws. Just my .02 cents.
Adapt a Drott 4 in 1 bucket on the cat 939.Problem solved.
:iagree The Drott buckets are much stronger than the Cat ones. I still say this break did not happen all at once. Pressure may or may not be high, but the failure is due to repeatedly sideloading the clam, causing it to flex untill it is weak enough to break. If you set the pressure low enough to not flex the cat clam, then it will nopt pick up very much eiter. It is up to a competent operator to not sideload the clam, and if you do have to pick with only one side, do not squeeze hard, or bad things will happen.
Hello This Machines are built in Telfs a small mountain Village in Austria, i ve also seen some that wear the John Deere Design, that are shipped on a long fright train. Crawler Loaders and Dozers are Products that made Liebherr Famous in Austria, Contractors who hate Liebherr, some would rather use a spade than a liebherr excavator have often Bulldozers from Liebherr. I ve operated PR712 (the most popular dozer in Austria) and the PR 722 (now this Models were replaced by the 4 Series), and for me Liebherr builts the best Dozers, i like the hydrostatic drive, and the controls. And its also about Safty, here in Austria there are not many bulldozers used in numbers. When a Earthmoving and Excavation Contractor has about 10 or 20 Hydraulic Excavators, they have only one or two bulldozers, that are often not operated by one man, the are used on a dump side for example, when there is no more space to dump, a truck driver pushes the dirt away etc. With the Liebherr Control its easier for an untrained worker to use the machine. You can not get "out of power" like machines that have mechanical clutches and brakes etc. Are the John Deere - Liebherr Machines popular with the american contractors and operators? Does the 751 really drink 20gal/hour, we don't use that large Dozers but this seems a lot of fuel to me... Greets from Austria Andy
I would be interested in seeing photos of the whole bucket and not just the broken bosses. In particular I want to see if the front section is bowed. Does it sit square against the cutting edges on the back section? The bent tilt links suggest to me someone was ramming the machine into something like a brick wall in second or third gear. That might explain the broken bosses and the bent links. These buckets are designed to be used as a loader or as a dozer. They are not supposed to be used for pulling stumps or picking large rocks with the clam. I have seen them used effectively for picking logs and piling them but that loads both pivots pretty equally. I have seen some bad engineering from Cat from time to time and I'm not saying that this isn't what is happening here. But the photos that are provided seem to show more abuse to me rather than poor engineering design. Provide some more photos and perhaps we can come to a consensus.
Ok, it finally happened - was just dumping a bucket in a truck and POW the damn arm broke. Does anyone know what a set of these will cost? Thanks
First I would try a local machine shop to see if they could make you a new set of arms, maybe a little "beefier", probably be alot cheaper as well. I had a similiar problem on a 321CLCR with a progressive link Cat thumb. We kept breaking the "dog bones" on the thumb and finally the Cat dealer made some in their shop that had more meat around the pin bosses and a thicker arm, width wise. In the picture below shows the "homemade" dog bone next to the thumb. They made the link the same thickness and width across the whole dog bone.
Wow, that bites! Well, guess it was bound to happen, stressed metal can't hang on forever. I'd try some dismantlers, like Iron Peddlers, for some used ones. As long as the used ones are straight and not bent, and the price is better than new ones, I'd go for it. Then re-inforce them with cold rolled flat stock on the sides. Aside from that, make some yourself as CM1995 suggested. Would probably be just as good as what Cat put on in the first place. Just a thought.
If you give me the serial #, I can find out for you tuesday
I don't have the serial with me but it's a 2006 machine C939 Thanks