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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 5166
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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International 125C track loader with a power shift

Customer Question

International 125C track loader with a power shift transmission. Very strange thing, the opposite of what is normally the issue. It only happens after the transmission gets good and warm. When I shift into reverse, in order to get it to shift I have to
DECELERATE and let the pump pressure drop before it will go into gear. Once it's in reverse, it won't slip.
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  Dan replied 1 year ago.

Hi my name is***** will be glad to help. First check the transmission filter/strainer/oil for signs of metal/debris indicating an internal mechanical problem... If clean the next step is to have the pressures checked and confirmed to OEM specs. to isolate a potential pump, control valve, or other issue. Let me know

Customer: replied 1 year ago.
The machine had broken a range selector valve spring. I removed and serviced the range selector. At that time I removed the suction screen and it was sparkling clean, no residue from clutches or anything. I refilled with new fluid and changed the pressure filter. The machine has a transmission/steering/main pressure gauge, which is in the normal area of the gauge at all times. Although to get it to shift into reverse when it's fully warm, I have to decelerate until the gauge is on the low end before it will engage the gear/clutch servo. I'm not sure how the cooler valve works, it appears to be a spring but I thought it should be temperature activated. I haven't checked the lube or cooler pressures but I will when I get a chance. But I'm not sure how they would affect the shifting issue. It's almost like the main pressure is too high when it gets warm, which is counter-intuitive. The gauge stays fairly steady between cool and warm.
Expert:  Dan replied 1 year ago.

Thanks for the update. Do you have the shop manual with the testing and adjusting section for the pressures? I worked at a Komatsu Dresser dealer in the past but I looked and I do not have the manual for this particular model or I would give you the pressure specs. I did see that there are several manuals for this machine on E bay for engine, transmission, etc for a reasonable price.

I recommend getting an accurate mechanical guage on it so you can monitor what the actual pressures are doing when trying to shift to reverse and compare them to specs. It sounds like you might have a valve hanging up possibly but I would check the pressures first to see what they are doing which will show us what direction to go. If you are low on lube pressure it is usually a sign of a weak pump unless you have a stuck lube spool as lube is the first thing you lose when you either have excessive internal leakage or a failing pump. Let me know

Customer: replied 1 year ago.
I've got all that stuff, the first thing I do when I get something is get all the literature for it. I'll try to check it Saturday, it's suppose to be nice weather here. I'll go dink around and push some trees and get it warmed up then I'll check it.
Expert:  Dan replied 1 year ago.

Sounds good. Another thing is if you are losing lube it will effect all speeds and directions and cause you to run hot. If you have a digital temp gun, check to see what the temps are when this starts happening in case it is in fact excessive. As we both know metal expands under excessive heat which could cause a problem with valves sticking as well. did you note any scoring on the spools that would indicate they are sticking? If so you can sometimes get away with cleaning them up with some crocus cloth if they are not to bad. Rule of thumb is anything you can catch a fingernail on is unacceptable. Let me know

Customer: replied 1 year ago.
Steering and trans range 150-175. All gears forward 165. All gears reverse 150
Cooler Range 40-85 All gears forward and reverse 60
Lube Range 10-25 All gears forward and reverse 15
So it seems everything there is ok. The temp range 220 or less. this one was 180 and I had worked it pretty hard to get it hot.
There aren't any range of pressures on the range selector, so I didn't see the need to check that. I know it's getting pressure, probably too much on the reverse circuit which is why I have to idle down to get it to drop into reverse.
Thoughts ?
Expert:  Dan replied 1 year ago.

Thanks for the update. Pressures look good actually... sounds like a possible worn synchronizer not allowing the gears to slow down to mesh properly by matching the RPMS. I do not have the parts manual for this model unfortunately. If you do can you upload the synchronizer assembly?

Customer: replied 1 year ago.
it's a power shift. Ergo: it's an automatic with clutchpacks a torque converter and such, so it doesn't have synchronizers. It's got to be in either in the range selector (which I replaced both springs because one had broken spring and I serviced it while I hand it out) or the pilot control valve.
Expert:  Dan replied 1 year ago.

Thanks for the update. Do you by chance have the parts manual in PDF format that I can review? Its been a long time on this model as Dresser was next... then Dressta.... Also does your manual have a power flow chart for FWD and REV?

Customer: replied 1 year ago.
I'm thinking its either in the pilot control valve or God forbid, in the range selector valve. I replace the springs and cleaned it up. It had a broken spring when I bought it.

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