953 trans problem ????

[lillyroger]

I test drove a 1986 953 loader.Even with the engine at maximum working revs the fastest the machine would travel was about 1st gear in a power shift machine. The machine still had plenty of track power eg it will spin its tracks as I pushed into the heap. Another fault was if i lifted or dumped the bucket i lost all drive. Any information will be graetly appriciated

 

[pushcat]

A 953 doesn't have a transmission, it's hydrostatic drive. If your engine is low on horsepower it will rob power away from the drive system first. Possible plugged filter or bad valve.

 

[BigYellowIron]

Does the track speed increase if you lower the engine rpms a little????

 

[lillyroger]

Does the track speed increase if you lower the engine rpms a little????

No I dont think it does. Engine doesn,t lack any power it is a hydralic problem. Because if it was lack of engine power either the travel and the hydralics would make the engine labour and there is no sign of that.This is a question for the more expert readers and not for the novice to guess at. I have asked our local cat dealer and they seem to think it is a servo valve either leaking or in need of adjustment . If any body can assist it will be appriciated

 

[BigYellowIron]

I ask that question because that is a comon sign of of a filter bypass valve in the HPCU bypassing. This can be due to several things. Wrong viscosity of oil in the trans. Filter plugging. or a weak bypass spring. When the engine rpm is lowered the displacement of the charge pump is less and the oil will not bypass as much. This is a quick simple test we as a Cat dealer suggest to our customers.

Does the track speed increase the warmer the machine gets?

BTW
your response came across a little rude, when you ask a broad question like that, people have to ask simple questions to get more info.

We are all here to help!

 

[aongheas.macask]

I ask that question because that is a comon sign of of a filter bypass valve in the HPCU bypassing. This can be due to several things. Wrong viscosity of oil in the trans. Filter plugging. or a weak bypass spring. When the engine rpm is lowered the displacement of the charge pump is less and the oil will not bypass as much. This is a quick simple test we as a Cat dealer suggest to our customers.

Does the track speed increase the warmer the machine gets?

BTW
your response came across a little rude, when you ask a broad question like that, people have to ask simple questions to get more info.

We are all here to help!

Big Yellow Iron,
I agree its probably a charge pump flow problem cos when he lifts or uses bucket he loses travel drive which would indicate all the oil going to servo and not to swash the travel pumps.
Innes

 

[Cmark]

Hi guys

In my humble view, you're all on the right lines looking at a charge oil flow issue. Correct, clean trans filter and oil viscosity is vital in the hydrostats.

Big Yelow Iron asked you exactly the right question as a first step to solving your problem.

When the engine rpm is lowered, the reason this can make the tractor speed increase is because the underspeed override valve is linked to the throttle mechanism and is opened at the same time. The underspeed override valve, in simple terms, bypasses the tractor's engine speed sensing system which works by sensing the delta pressure across a venturi as the charge oil nb.flows through it, hence the importance of oil viscosity and filter cleanliness.

Lillyroger, please go back to the machine and carefully assess if ground speed increases as you slowly move the governor lever back towards idle.

Good luck...

 

[lillyroger]

Thank you all for your replys, my sarcasim was a result of a reply stating that the machine was hydrostatic drive and did not have a transmission. I have since been in contact with the tractors owner that advised me that the tractor does infact travel faster at lower revs. The local cat dealer,s first answer to the problem was that It was an engine problem, A very simpistic answer from a sevice tech that had no idea. I can now go to the dealer with your information and hopefully save a apprentice spending time looking for a problem with the engine etc. But they still charge out at $110.00 per hour.

 

[pushcat]

Thank you all for your replys, my sarcasim was a result of a reply stating that the machine was hydrostatic drive and did not have a transmission. I have since been in contact with the tractors owner that advised me that the tractor does infact travel faster at lower revs. The local cat dealer,s first answer to the problem was that It was an engine problem, A very simpistic answer from a sevice tech that had no idea. I can now go to the dealer with your information and hopefully save a apprentice spending time looking for a problem with the engine etc. But they still charge out at $110.00 per hour.

You shouldn't have put trans. problem in the headline then.:Banghead If you can't explain what your problem is properly, how are you going to understand what people are recommending to find the solution.:beatsme

 

[aongheas.macask]

You shouldn't have put trans. problem in the headline then.:Banghead If you can't explain what your problem is properly, how are you going to understand what people are recommending to find the solution.:beatsme

.
As a heavy equipment mechanic I know how difficult it is to diagnose a problem without seeing the machine, advice can only be given relating to the quality of info received, if I was test driving a machine with a view to buying and had no tech knowledge I think $110 per hour for a Cat mechanics opinion would be cheap(can't he do a deal with the seller?) and could save thousands in the long run. only my humble opinion

 

[lillyroger]

.
As a heavy equipment mechanic I know how difficult it is to diagnose a problem without seeing the machine, advice can only be given relating to the quality of info received, if I was test driving a machine with a view to buying and had no tech knowledge I think $110 per hour for a Cat mechanics opinion would be cheap(can't he do a deal with the seller?) and could save thousands in the long run. only my humble opinion

aongheas.macask,
I fully agree with your reply , but ( Local cat dealer) was that the engine must be low on power etc. I am not a qualified mechanic but I have been operating ,maintaining and when required rebuilding earthmoving machines for over 25 years , so I think I have a good general understanding of most machines.I just get annoyed when so called experts( our local cat dealer) waste my money by not really thinking there diagnosis through. I have heard some fantastic reasons over the years when reporting faults to dealers and to be honest most of the time they will try to bull sh_t there way out of rectifiing the fault. So sorry if I sound sinical

 

[Cmark]

Hey Lillyroger, your cynicism can be, in my opinion, sometimes justified.

Machine manufacturers can make a great machine, but have to (or have chosen to) outsource their sales and service to independent franchises. These are, by definition, indepenent companies with their own management and workers.

Even though the manufacturer closely dictates how the dealers go about their business, a company is, as I am sure you all will agree, only as good as it's people. I've been both an employee and a customer and have dealt with fantastic people who knew their job inside out and would call customers from home to ensure their needs were being attended to, and people at the opposite end of the scale who errm.., wouldn't.

I suppose my point is, some companies get that yellow and black (or orange, green, red ...) stripe over their door and think that automatically makes their every word gospel . Yes, the have access to all the latest and greatest technical information, but it still needs a human to interpret this and apply it to a customer's needs, and if that human isn't in the building, then it's only a building with a stripe over the door...

(What is a church?)

Wow, I've just re-read this and I sound even more cynical than you. I really should say that I have met many many more good, capable people than bad ones.

 

[Smokerench]

Great post guys. I am working a 953C problem now that is very similar. Today I read in the manual that the governor limit switch actually engages when the lever drops in the wide open notch, and when I stopped it short of the notch and switch engagement, the problem disappeared. I had already recalibrated the controls with the code 5 calibration submode which didn't solve my problem. And it also had not only slow movement when loaded on a slope, but it also got to where the machine lunged in work mode, and came to stops while in the "rabbit" travel mode. The hydraulic tank filter, case drain filter, charge filter,primary/secondary/and water separator fuel elements and the engine speed sensor have all been replace with no results. Tomorrow I think I start to look at the underspeed system which appears to be disabled when the throttle is not fully open to try to find the solution to this. With the way that the machine moved on in this state of "almost full throttle" it is tempting to let the switch dangle out of position and do my own engine speed maintenance just like the 953,953B machines I wore out before this one, but I am afraid something else will rear it's ugly head if I don't find the problem and fix it.

Any advice on this would be appreciated. This is a 2ZN 2003 Model. Owned since new, 7100 hours on it. I've already talked to our Whayne Supply Cat dealer about checking it out, they are three weeks out to get to it, and I am going to be swamped in the next week when the spring rains end. The sales people are more than ready to get me a 953D on site, and I get a chill up my spine every time I think of putting the payments out for that shiny fat-girl.

 

[Cmark]

First things first. Check your engine RPM at high idle. Should be 2325+-50 RPM.

Don't guess this. Use a good phototach. Then check it agrees with what the ECM is seeing. (Submode 18).

Then check what the RPM is at full travel speed. Above 2200 RPM means a transmission problem. Below 2200 RPM means an engine problem. (Usually. There's a couple of exceptions to this rule, but it should put you on the right track)

 

[CM1995]

Welcome to the Forums Smokerench!:drinkup

Unfortunately I am of no help for your situation as I am not a mechanic but we have several knowledgable members here at HEF that can help.

I have a 953C BBX with 4K hours.

 

[Smokerench]

Thanks for the advice Cmark. I found this forum through a search that had you sending a guy to this thread, and here I am. I will take your advice and compare that RPM reading to what the ECM is reporting. And take her up to full track speed and find if I am above, on, or below that 2200 mark. I should be able to post the results here by tomorrow about the same time I originally posted my first message.
I am the only person who runs this machine, and for about the last six months I have felt that I have been losing power on heavy pulls up slopes. I am mainly a operator, but by owning these machines I have kind of had no choice but work on them, so thanks for taking the time to add your expertise on my problem. With this situation with the dealer too busy to help me out, it seems I am pretty well on my own. I am rushing my nephew just a little on the undercarriage he is putting on the old rusty 953 LGP just in case though. he he

Oh and CM1995, thanks for the welcome and enjoy that BBX, these machines are the Cat's-meow (corny, I know) when they are working right.

 

[Cmark]

Apologies Smokerench, I should have also said welcome.

You'll find a hodfull of knowledge here on every aspect of muckshifting, and the only payment required is to pass on your own experience. :thumbsup (and maybe a couple of photos )

 

[Smokerench]

No Problem. I was so wound up with getting such a quick response that I buried myself in the manual till 1 am. I found submode 18 and also checked online at a local tool supplier and found a phototach in-stock. I think you are 12 hours ahead of me so I should have some results sometime Saturday morning in your time.

Sounds like a good deal passing on experience for experience. And what I lack in know-how I should be able to make up for in pictures. It is like a regular museum around here. 955-H,K,L, some still running. 60-s to 80-s Macks, Sidewinders. We were known for never getting rid of our old stuff, and with the price of scrap it turned out to be a pretty good idea. Time to bloody some knuckles.lol

 

[Smokerench]

I got the tach test done yesterday. The Rpms on the machine with the phototach put me right in the area of the 2330. The Ecm was reading just a little lower, but not by much. During full speed tracking, the Ecm read that I was at 2190. If I went by the difference of what the phototach was reading, it put me just above the 2200 mark at 2210.

I did get an E-mail from a friend that told me they had the same type problem where they found a bad bushing on the governor pivot that turned out to be their problem. Mine seems to be solid, and with no play.

I have talked to a guy that has done minor work on the tractor before and he says he will work me in this week to put the gauges on the machine to see if he can zero in on the problem.

As figured, with the rain now ended since last mid-week, the phone is ringing off the hook so I am preparing the old 963 till I can get the undercarriage finished on my normal backup machine. Moving it daily will be a bit of a headache, but it will work.

Thanks for all the input, it was was great.:notworthy I'll try to get back here with some info if this problem is fixed, and I am still open to any knowledge added here also.

 

[Smokerench]

The problem has never been resolved on the 953C to date. A mechanic for Whaynes Cat dealership of 23 years who runs his own shop kept it for 2 months tinkering with it and came up with no solution. The RPM speed sensors and track sensors, pedal sensors have all been replaced. The wiring harness was scrutinized for rubbing, all connections cleaned. The filters and oil were changed already at the start of the problem. The hydraulic pressures were checked and passed. He mentioned that one of the swash plates could be stuck. I have not used it but only as a backup in the last year as I put a pile of money in the 89 953 and made it my main tractor again.
The problem with it has not gotten worse, but I have become more familiar with the symptoms. Sometimes it will start and turn strong, but it lunges at times as it did once when the engine speed sensor went bad. If you idle it or shut it off it will usually start turning very slowly as if the brakes were on, and when the pedal is release it darts off forward at good speed till you turn again. It still turns, still counter rotates but does it as if it were fighting to do it.
If you shut it off or idle it again it sometimes comes back with a jerk lunge occasionally, but it turns very fast and normal feeling. I find myself trying not to stop at these times as it will keep going till you pause or idle.
Any ideas about this demon would be appreciated. I think I may soon take it to Cat and let them throw the big bucks at it for a while. My 953B is almost ready with a new motor and the 953 is still going strong. I have thought of trading it for a 953D model, but after all this, I am afraid of the new technology and wonder if my 90 s tractors could hold me out till retirement. :beatsme Thanks guys.