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Lack of power with Cat 950B loader

CJLennon

Well-Known Member
Joined
Jul 24, 2009
Messages
62
Location
Chapel Hill, NC
Yup, that's right, a 950B. We are into old iron here. We have this 950B that runs fine when cold and for about the next 2 hours. All of a sudden, the machine won't pull. Both forward and reverse won't pull and no mater what gear you are in, no difference. It's like the brakes are locked but we know they are not. The motor is strong because the hydraulics work perfect and don't bog the motor down when you use the bucket. The transmission is not slipping because the motor doesn't race like it would if the clutches were slipping. When this problem happens, we let the machine cool down and it works again perfectly until 2 or 3 hours later when it happens again.

My initial thought was the torque converter. So, two questions come to mind:

1.) Did anyone ever have a problem like this on a 950 or any other machine? If so, what did you find?

2.) Does any one know anything about the torque converters used on these 950s? Could they function properly, quit multiplying torque and then start again after they cool down?

As always, thanks to all. When you have this much old iron, you need all the friends you can find!

Chris
 

AmerIndependent

Site Sponsor
Joined
Nov 4, 2009
Messages
359
Location
Riverside, CA
Occupation
Caterpillar Powertrain Rebuild & Repair Specialist
Could be the torque which operates hydraulically and could lose power as the oil heats and thins. The pump could also produce this symptom for the same reason as well as a suction leak all of which can be easily troubleshot with a couple gauges installed on the filter housing and torque outlet relieve valve.

As always, we recommend checking screens and filters before troubleshooting.
 

mikef87

Senior Member
Joined
Aug 22, 2007
Messages
433
Location
waltham
Occupation
owner/operator/mechanic/laborer/truck driver
I have a feeling it could be the charge pump for the tranny, I had a dozer do that to me before. Let us know. Or PM me for more advice.
 

CJLennon

Well-Known Member
Joined
Jul 24, 2009
Messages
62
Location
Chapel Hill, NC
Well, we got it figured out. Pulled the valve body and tore it down. There is a plate on the opposite side of the valve body from the two tubes that are the oil input and output to the converter and this plate holds two of the springs and valves in place. There are two "O" rings that seal the pressure and one was cracked and the other was just flattened out and leaking. Replace the two "O" rings, put it back together, held a prayer session and fired it up. Seems to work OK (for now). Many thanks to the AmerIndependent guys for giving me the advice that got me to the problem. They really hung in there for me. And, thanks for all that responded. Nice team work!

Chris
 
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