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? About hydraulics

Sdriv1731

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Aug 6, 2018
Messages
17
Location
New York
i went to look at a kubota kx 121 last nite. This machine looked well taken care of. Pretty tight for 2000hrs all paint looks great. Everything worked even the a/c
2 things I noted that I need some help on. After putting the blade down I swung it around and tried to use the hoe to lift the back end off the ground so that the whole machine would be elevated and I couldn’t get the one end up. It seemed to push a little but not able to lift up the whole machine. The owner got in it because he was a bit annoyed that something may be wrong. With his attempt he was able to get the machine fully lifted a couple feet off the ground but it seemed he did it by dropping the bucket to the ground as close to the cab as possible and then pushing the stick outwards therefore lifting the machine up rather than putting the bucket down say 7’ out from the cab and then just lifting straight up. Is thisjust my lack of experience on these machines. Or Is this something showing weakness in the hydraulics? If so is there a better way to do a test before I hand over any$$.
The second thing I noted was turning left or right at a stand still it didn’t seem to just pivot freely. I wasn’t able to just spin in a full circle. Going forward and reverse were fine and the low and hi speeds worked it just seemed to lack power in rotation. Again my lack of experience? Or should the machine just pivot on a dime when pulling the sticks opposite of each other. Please help with any other advise on what to look for as this is my first machine.
 

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Delmer

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I guess that doesn't surprise me. I'm not an expert at anything, there's plenty of people who know mini's and maybe somebody operates one regularly, until they come along I'll give my opinion.

That boom cylinder is under the boom for better bucket lifting power, it won't lift a machine like it would if the cylinder was on top of the boom. Maybe the tracking power is set that way to protect the rubber tracks from abuse? they won't take the abuse that steel will. I've always heard the test of the tracks is if it will go in a straight line or curve off quickly. What are your performance expectations based on?

You're criticizing a very clean Kubota, if I had to guess if there was something wrong with the machine or the operator's expectations, I'd trust the Kubota.
 

Sdriv1731

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Joined
Aug 6, 2018
Messages
17
Location
New York
Yes I have an inclination that I am not very experienced so I am only going by some of the inspection videos I watch online where they are able to push the machine up with the boom. Like I mentioned the seller was very seasoned in excavating and it was very apparent he takes care of his equipment. As for the turning this machine does have steel tracks(see pics) so I don’t think the setup has anything to do with it. From what I remember it did track straight when going forward. Thanks for your input as well as any other advice you have.
 

John C.

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What you describe in lifting the machine against the blade doesn't sound out of order to me. I might note it in an inspection report but not down grade it for condition unless something else was noted. Steering on the tracks is another item that again I would note but not necessarily down grade. I don't know the control systems for the pumps in that machine but would probably say a hydraulic check and tune up would be a good idea for the purchaser. A cycle time check would be a prudent thing to do when you are inspecting machines. It would give a better indication of what your are describing might be a problem in the pumps or just one circuit. Cost for a check and tune would likely be between $1,000 and $2,000 for an experienced mechanic.
 

Sdriv1731

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Joined
Aug 6, 2018
Messages
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Location
New York
Thanks John for your insight. I’m pretty certain I am going to purchase the machine. It is definitely the best overall condition of any machine Inhave looked at. Is there anything I should look at myself again before I sign the papers? He did mention it’s due for oil change and fuel filter and there was 1 hydraulic hose for the thumb that he was going to replace. Other than that it seemed ready for work.
 

melli

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Dec 15, 2012
Messages
260
Location
BC
You are talking about turning the whole machine at a stop (not the house)? With steel tracks, that is not advisable. Your putting undue torque on rollers. I have rubber tracks, and can turn on a dime, but do so only on slippery surfaces, like snow or wet grass (if your ok with chewing up grass).
Lifting machine with boom requires the arm to be close to machine. You can do it with arm extended, but in that case, the bucket does the lifting. With the geometry, the arm isn't supplying much lift force.
The only reason I would be inclined to lift machine (tracks) off ground is to check the rollers for slop (or to replace track that slipped off because I failed to re-tension them...).
I would extend arm and boom off ground, get out of cab, and grab bucket and try to swing the works back and forth, noting play (your checking bearings).
You noted hours, but not price.
It looks good in pics, but it is hard to tell by pics alone. 2000hrs is very reasonable for a used machine, but it depends on how hard those hours are? If the stick bearings are still tight, the drive motor teeth and tracks still in good shape, then probably it saw easy hours. The locale where machine was working should be noted. I live in an area where rock is our soil, and machines just wear out quickly.
My concern is with the big ticket items...engine, drive motors, house bearings and motor/swivel, main hydro motor, etc. A bad hose is nothing, relatively speaking.
 

John C.

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Bottom rollers are not an item where you have to worry about side loading. To check them pick up the track frame and with gloves on try to shake them. They tend to make some razor edges that just love to catch skin and the cut is aggravating for a long time. The rollers will be hard to turn on most machines because of the tension on the seals but it isn't bad if you can turn them and they aren't leaking. Steering the machine isn't going to have any affect on the life of the bottom rollers no matter which type of track you have.

Which bearings are you checking by pushing on the bucket side to side?

Does this machine have the button to push on the right side before the thumb works? It is a pain to have to remember to push that button whenever you shift the safety lockout lever on the left side console. Do the gauge indicators work. Do all the lights work? How much up and down play and back and forth play is in the turret? How much play is in the slewing bearing? Did you check for cracks on the boom foot and the boom cylinder boom boss welds? You can check for cracks on thumb cylinder base bracket? How do the attachments look. Does this have a quick attach for the buckets and is it tight? Is it hydraulic or manual and does it work properly? Are there any leaks on the engine? Look for oily dirt. Did you check the antifreeze level? Did you check all the component fluids levels? What is the condition of the fan belt and is it tight? As I recall those are a bugger to adjust. What does the upholstery on the seat look like? Do the adjustments work? Maybe check the heater and air conditioning and turn the fan on to see how much noise and air comes through the ducting. They have filters that are nearly always plugged. How much garbage is stuffed behind and on each side of the seat? Many times the blowers are packed with dirt and debris and make lots of noise if they work at all.

If you are buying you should make a check list and take at least an hour inspecting the machine. If the owner complains just tell him you are exercising "due diligence". If he is honest he will usually start telling you the history of each item he has had trouble with.
 

Sdriv1731

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Aug 6, 2018
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Location
New York
Great information guys much appreciated. I did check all the fluids and they were all at proper levels. The paint, seat and interior of the cab were all excellent condition. I have looked at machines 3 years newer and half the hrs that looked as if they were in a war. I did some tests with the bucket extended and on the ground and pressured from side to side and all was relatively tight. It is being sold with 3 buckets and he demonstrated removing a bucket and putting another on for me as I never saw it done before and those 2 buckets were in very good shape. The third bucket is a grading bucket at that one was clearly used the most and showed a bit more slop but still usable. The thumb is hydraulic and I would say out of any of the bushings or pins that one may need replacements within the next year and yes you need to hit a button before use but I don't see an issue with that as I wont be using it everyday for business purposes. The engine compartment was dry all around (see pic) just a bit of dry dirt. I didn't take notice of the fan belt but its something I will note for next time. The heat and a/c work 100% which is surprising based on other machines I've looked at. The owner told me the bottom glass on the front was replaced after a tree branch hit it and there was a kink in the grab handle that he explained was from the tailgate on his dump truck. So he seemed to be pretty honest about the care of the machine and he has all the original paperwork from when he purchased it.
 

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Sdriv1731

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More pics
 

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John C.

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It sounds like it is time to negotiate a price.

Good Luck!
 

melli

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BC
Bottom rollers are not an item where you have to worry about side loading. To check them pick up the track frame and with gloves on try to shake them. They tend to make some razor edges that just love to catch skin and the cut is aggravating for a long time. The rollers will be hard to turn on most machines because of the tension on the seals but it isn't bad if you can turn them and they aren't leaking. Steering the machine isn't going to have any affect on the life of the bottom rollers no matter which type of track you have.

Which bearings are you checking by pushing on the bucket side to side?
All of the bearings on from bucket right to house. Having replaced half of mine, one can tell how tight they are on mini. It is an issue around here, given we are playing in rock. Can also tell if machine had a breaker on it (kills bearings).

Aside: got to chatting with a life long excavator operator about why sleeve bearings seem to go so quickly on smaller machines. He felt it was because the pins on minis are much smaller than the heavy machines. With less surface area to absorb the torque, they ream out the bearings.

I have to disagree about rollers and side loading. I admit, the newer rollers I put on are heavier duty than OEM ones, and look like they can take more abuse (better design), but I feel I roasted my OEM rollers by turning sharply on rock and turning at high speeds. I think what happened, is by torquing the rollers, I broke the seals, and mud would enter...after a while, I'd find pieces of bearings while plodding along. One could argue they reached their service limit, but I had several pack it in after playing in blasted rock. Coincidence? Plus, sharp turns on rocky ground does wonders to tracks.

YMMV, but I live in a rain forest, most of the time, and bearings don't seem to last. OT - I just had all four wheel bearings in car pack it in, within months of each other.
 

John C.

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In my experience the better test of the implement joints is setting the bucket on the ground and then swinging against it. You should also press up and down on the bucket looking for straight line movement in each of the joints. You aren't going to see that with the bucket up in the air. Breakers do not kill bearings. Operators that don't know how to use breakers kill bearings. Bearings going bad in the implements in my experience is mostly caused by not greasing them in a timely fashion. I've seen mini and full size excavators with auto lube systems that have in excess of 7,000 or more hours with little wear. The rollers that I have seen go bad were either not assembled correctly when new or were worn out and had the flanges riding on the track pin bosses and the track bushings. They are designed to take any kind of side torque that the machine can apply. Broken seals are caused by age, the material you are running in and worn out rollers. Why would you be running a mini in blasted rock in the first place and what would make it any different than running anywhere else? The rain forest on the west coast of North America runs from southern Oregon in the south to north of Juneau, Alaska. I've not seen anything that makes BC any different than the rest of that area.
 
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