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catmastertech
catmastertech, Technician
Category: Heavy Equipment
Satisfied Customers: 1754
Experience:  19 years Cat, 3 years Case
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How to change the transmission on Loader 950G?

Resolved Question:

How to change the transmission on Loader 950G?
Submitted: 2 years ago.
Category: Heavy Equipment
Expert:  catmastertech replied 2 years ago.

Donnie :

The cab must be removed to pull the transmission. You can remove the hydraulic pumps to help with some access. It helps to remove the suction lines for the hydraulic pumps off the tank, it is too tight to clear with them in place. Brackets on the front end of the transmission must be removed as well. The more you can remove the better. The last item will be the mounts, take them off the side of the transmission after you have lifted it slightly.

Donnie :

Are you sure the noise is the transmission? It may only need a pump. (Still need to remove the cab to replace the pump though) Pressure tests would help determine pump issues. Pumps will be noisy when they are sucking air. I would reseal the suction lines and replace the tube if it is damaged. (This has happened to a couple I repaired)

Donnie :

Check the filter and the strainer before condemning the transmission. Cut open the filter and check it for debris. If you don't find any debris, you may not need to pull the transmission. Inspect the tie bolts on the transmission housing, the last 950G I worked on had these bolts breaking and it had to be removed to replace them.

Customer: Thanks a lot. I will definitely check the pump.3 years ago I replaced a vane pump but did nottouch piston pump. Probably this one is making noice. Also machine has oil leacks under oil tank. My question is how to perform the pressure test?Also how heavy is the tranny?
Customer:

Hi.

Customer:

Hi. I also get another info about what happened: in February all oil came out through first solenoid on tranny. Their mechanic has changed that siezed solenoid and put the fresh oil into tranny. After that noice start comes up. I did not know that before, but I have noticed a new solenoid in place and I did call and talk to a service mechanic. Another question: is the tranny in this machine mechanical or

Customer:

its opereted together with hydraulic pump? What would you suggest now to do?

Donnie :

The vane pump is for the implement system. This would make noise when lifting loads. The piston pump is for steering. This would make noise when the machine is turned all the way to the stops.

Donnie :

The transmission pump is a gear pump attached to the housing and all the other pumps attach to it.This pump will make noise all the time and make change tone when shifting the transmission.

Donnie :

The transmission is a mechanical planetary transmission with electronic controlled hydraulic system to apply the drive clutches. The transmission ECM sends current to two solenoids to provide the selected speed and direction.

Donnie :

The pressure tests can be very involved but you can take readings from the transmission filter to check the pump pressure and see if it is low or fluctuating.

Donnie :

For details about this, I need to know the serial number to find the correct information. The transmission weighs about 2500lbs (1150 kg).

Customer:

Thanks a lot for help. Transmission NO is 3JW01930. Transmission serial NO: BJH00957 Converter serial NO: 4AT05926. Is it possible to find any drawings and specs how to overhould tranny? Sincerely XXXXX XXXXX

Donnie :

File is very large and would be impossible to get through here. Have you tried to purchase just the transmission disassembly section from a dealer. The whole book is exspensive but, it is less than a full day service call. Worth it if you will be doing the repairs.

Donnie :

(J) Oil sampling valve for the transmission. (K) Pressure tap for the transmission oil pump.

Donnie :

Transmission pump pressure is 420 psi. 2897 ± 70 kPa

Donnie :

Operate the transmission in all gears and look for pressure dropping in a gear or overtime as the oil warms. If gage is boucing with the noise, you have an air leak in the suction line.

Customer:

Thanks Donnie. How much the transmission disassembly section would cost? Also where can I buy a book?

Donnie :

The dealer is the only up-to-date source. A section can run $25 - $50 USD the whole book is around $800-$1000 USD. It can vary depending on what it comes with. A disassembly and assembly book with specifications is a good start but, the schematic is great for wiring repairs. Tons of information in them.

Customer:

Is it possiible to check the transmission gear pump first for noice? Where is the location of the gear pump on Transmission?

Customer:

Also I've noticed that when you switch directions from neutral to back is faster than from Neutral to Forward. It takes about 0.5 sec delay. What is the problem can be?

Donnie :

To access the pump, remove the cab and then the other pumps. It is bolted to the transmission housing.

Donnie :

Delay when shifting directions is common. It takes time to fill the clutches. Wear or debris in the solenoid or slight leakage around the seals will add to the time. Half a second is nothing to waste money on.

Donnie :

My page is showing you are online and have been their since 2:56 is this right?

Customer:

Thanks a lot Donnie. I did remove the cab and taking pumps out. I have a stupid question

Customer:

How much time and money involve to overhaul tranny if I find the right person to do this job.

Customer:

Would you give me estimation of labour and a list of part which needs to be replaced? One more question: machine has 11180 hours. Is it true that after 10000 hours tranny needs to be rebuild?

Donnie :

!0,000 hours is a bit low for average work loads. I have seen some go past 20,000 hours. If you are working heavy and hard to dig material, expect a shorter life. Sand pits are the most common job here and they hold up very well.

Donnie :

If life is too short, you may need to retrain some operators on how to watch temperatures. The 950G has some memory features. A download could show how the unit has been operated.

Donnie :

I don't have labor schedules available to me. Our local shop can do one in less than a weak. Cost has been in the $15,000 to $25,000 USD range. It varies when large parts and gears are damaged. A Rebearing and Reseal will be on the lower cost side. Some disc will need replacing but, cost is not to high on them.

Customer:

Thanks a lot Donnie. I pulled out the pumps and found out lots of transmission oil between the gear pump and the vane pump.Seems to me that the gear pump seal is leaking and maiby the pump got overheated when the oil level drops down. I think I will just replace the gear pump and reseal the suction line. Filter is clean. Looks like no need to pull and overhaul tranny. I will also check the transmiission housing bolts. My last question before I hit accept is which solenoids are responsable for driving forward? I want to change them or reseal to make shifting faster from N to F.

Donnie :

The gear pump is not sealed. It has seepage by the bearings to lubricate the other pump shaft.

Donnie :

Inspect housings and bearings for heavy wear. Replace worn parts and install all new seals in anything you disassemble.

Donnie :

Pumps are getting close to two grand these days. You can get Classic Parts for rebuilding it much cheaper. Just be sure to ask for the Classic Parts when ordering.

Donnie :


Location of the Modulating Valves (Transmission Clutch)


(1) Number 1 transmission modulating valve (Reverse)


(2) Number 2 transmission modulating valve (Forward)


(3) Number 3 transmission modulating valve (Fourth Speed)


(4) Number 4 transmission modulating valve (Third Speed)


(5) Number 5 transmission modulating valve (Second Speed)


(6) Number 6 transmission modulating valve (First Speed)


(7) Intermediate speed sensors (If Equipped)


Donnie :

Note: The solenoid coils are not designed to be operated at 24 DCV directly. The power train ECM sends a 24 volt PWM signal at a duty cycle which provides an average voltage of about 12 volts to the solenoid coils. Do not energize the solenoid coils with 24 DCV (+battery). The life of the solenoid coils will be drastically reduced if the solenoid coils are energized with 24 DCV (+battery). If the solenoid coils must be energized by a source that is different from the power train ECM, use 12 DCV to energize the solenoid coils.

Donnie :

After you have the noise problem fixed, Have the transmission clutch fill pressures tested and fill times calibrated. This will smooth out most shifting complaints.

Donnie :

This must be done with the 4C-8195 Control Service Tool or a laptop with CAT ET software to reprogram the values into the transmission ECM.

Customer:

Thanks a lot Donnie. You helped me a lot. I will always to come to you for advice and recommend you to my friends. By the way, where are you from. I am from Toronto area. I am hitting the Accept button. Sincerely. Ruslan.

catmastertech, Technician
Category: Heavy Equipment
Satisfied Customers: 1754
Experience: 19 years Cat, 3 years Case
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