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some hydraulic help please !

bmckenzie

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Nov 25, 2013
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76
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northern california
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self employed
I have a 2007 Takeuchi tb135 excavator with 2000 hours on it. I bought it with 1700 hours and did my work that I needed done right away and now I have a chance to fix a few things. The machine travels in a curve in high speed so I start with the basics and tension both crawlers to spec. ,no change. Next I raise machine up and mark both tracks and one side travels faster than the other, both sides show a difference when pushing the 2 speed button, one side not as much. Next I have local tractor mechanic check the pressure on all the pumps and all are in spec so we check pressures at the final drives and they are also in spec but one side has more flow on the case drain than the other side.(Forgot to mention that both finals are factory drives that came on the machine new so no different ratios ) Next I changed hydraulic fluid (aw46), filter, checked strainer and every thing is clean as new. Then I bite the bullet and put a new factory final drive on the slow side, when I get done I hit the button and it kicks into high speed , works great. THE PROBLEM SWITCHED TO THE OTHER SIDE !!!. I switched pump lines 1 and 2 and no change, I switched main relief valve lines , no change. I have went through the factory troubleshooting guide. Now what ?? Will the hydraulic gurus out there help please ??:Banghead
 

lantraxco

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Jan 1, 2009
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Elsewhen
Possible causes of speed differences start at the controls, then the spool valve, then the swivel joint (seals bypassing) and finally the motors themselves. It sounds like you had a case of one motor being more worn internally than the other, so you put one factory fresh drive in, which made the less worn one suddenly the more worn one. Maybe.
 

bmckenzie

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76
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northern california
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self employed
Possible causes of speed differences start at the controls, then the spool valve, then the swivel joint (seals bypassing) and finally the motors themselves. It sounds like you had a case of one motor being more worn internally than the other, so you put one factory fresh drive in, which made the less worn one suddenly the more worn one. Maybe.

Thanks for your input. One would think that finals would last a lot longer that 2000 hrs . I tore the old one down a ways and couldn't find any abnormal wear. Any idea how one would test the swivel joint for bypassing fluid ?
 

lantraxco

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I would tend to agree with you, depending on how it was used and how much travelling it was doing. Also how well the hydraulic oil was maintained and if it was the correct fluid. A failure in a cylinder, or contamination coming in around rod seals can do some damage too.

The case drain flow is the indicator, excess flow means something is bypassing internally a lot more than it was designed to, so there's excessive wear or something is out of flat allowing a gap.

The best way to tell if the swivel joint seals are bypassing from the general consensus here is to check it with a heat gun after operating the tracks hard for a while. If the swivel is markedly warmer than it should be then it's bypassing. There are also cycle time specs if somebody has a manual out there.

Keep in mind that none of these small machine that I have ever seen tracked straight new from the factory, and several I worked with veered slightly one way in low and the other way in high. Obviously if your machine is off enough to be annoying there's an issue though.
 

rondig

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Jul 24, 2013
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517
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fort macleod alberta
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excavation
Case drain leakage can be caused by a bad multi function valve in the motor. A fancy relief valve. Put a Guage on A port of motor and plug B Port. Compare the pump pressure to the test pressure. That will give you delta p (pressure difference) if it is too high then you are losing too much to case drain. Case drain is the number one test to check for motor issues....the leak comes between the piston slippers and swash plate....not really noticeable by eye.
 

rondig

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fort macleod alberta
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excavation
If motors test good then check load sense pressure...I have seen the load sense orfice be slightly plugged by dirt and reducing the stroke on the pump....when testing a load sense piston pump pressure is only one part. A piston pump will put out full pressure at very little stroke but volume will be almost zero. Make sure both pumps are stroking equally. And fully stroking.
 

truecountry

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Sep 24, 2007
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clarksville va
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Shop Manager and Tech
Hmmmmmmmmmmmm ok before u tear into hydraulics it is electrical over hydraulic so pressures are good ...Ill give u a point I had a skid steer 277c with 5300 hours it would walk circles always turn to left in high speed I got into it the wiring going into gear drive where it was plugin pulled apart only 2 wires even had contact once I wired them up I had both turning same speed
 

msllc

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Mar 6, 2016
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MID-ATLANTIC = VA
If you have verified a high return on the case return, then it sounds like you know exactly which travel motor is to blame. While it does not sound fun, it sounds pretty straight forward to me. If money is of the ut most, then you could swap both travel motors from left side to right & right side to left. If the machine travels differently, then you know the motor is in deed bad, or at least bypassing too much.
 

bmckenzie

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Nov 25, 2013
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76
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northern california
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self employed
I had changed the motor with the higher case drain ( the one that was also traveling slower ), then the other side was slow. I swapped pump 1 with pump 2 hoses which the manual says that each track motor is supported by a different pump, and nothing changed. My next course of action is to get a gauge with 6 foot hoses and a bunch of adapters and start checking pressures as it is operating , starting at the pumps and working my way to the final drives. At some point I should arrive at the problem, I just hope sooner than later!
 

ericscher

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Sep 12, 2014
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196
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Central Ohio
Hold on, hold on...

I'd like to know why McKenzie is so sure there's something wrong. Not being a wiseguy here... my question is sincere.


I too have a TB135 (2004) and my machine drifts to the left or right on high speed.

Understand, I don't mean that she's turning a corner or anything, she just drifts a bit.


Considering how precisely matched everything on a tracked vehicle has to be to NOT drift a little, I'd be amazed if it didn't.


Hence my question...

Why do you think the drift on your machine is outside of what would be considered normal?
 

bmckenzie

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Nov 25, 2013
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76
Location
northern california
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self employed
Yes it is quite the drift , it would turn a complete circle in about 100' travel . slow speed is perfect, tracks straight as an arrow. Want to get somewhere a little distance away and hit the rabbit button and one can only travel 5 feet or so without having to feather the travel sticks
 

ericscher

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Sep 12, 2014
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196
Location
Central Ohio
Yeah, that does seem like a lot.


Honestly, I've got nothing.

I'll ask some folks I know for an opinion.
 

bmckenzie

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northern california
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? , no I did not, I received a new factory Takeuchi drive and installed, I didn't think to check tags as the motors looked exactly the same. Thanks , I will do some looking at tags.
 

CharlieMurphy

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Oct 11, 2015
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12
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MN
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Hydraulic Specialist
Pumps dont produce pressure.. They only make flow. Pressure is the result from resistance in the system.
 

TCM

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Aug 29, 2009
Messages
73
Location
Kingston Ontario
Maybe a drive mother swashplate not actuating fully in high speed or not at all? You say they work good at slow speed.
 

bmckenzie

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Nov 25, 2013
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76
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northern california
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yes they work great on slow speed , what is a mother drive swashplate ?. sorry I am new to hydraulics . also when I first start up cold it works better (still not right , but not as big of a difference) then as the fluid warms the speed on one side drops off to the point it is almost in slow speed.
 

TCM

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Aug 29, 2009
Messages
73
Location
Kingston Ontario
Sorry drive motor swashplate. The swashplate angle changes (when you select high and or low speed) in the drive motor increasing or decreasing the displacement/volume in the cylinder block in turn changing the speed of the motor. Faster = less power/torque, slower = more power/torque.
 
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