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Have a 939c 6ds01275, 939c serial 6ds01275, Machine won't…

Have a 939c 6ds01275 ...

Have a 939c 6ds01275

Mechanic's Assistant: What is the complete model and serial number of your machine?

939c serial 6ds01275

Mechanic's Assistant: Are you fixing this yourself? What have you tried so far?

Machine won't move back and fourth I check the pressure on the pump the brake valve has no pressure I check pressure on the pump back of engine has about 3000 psi there another pump that goes behind it I think that runs the motors for the track then there another one behind it I think that is brake pump well it don't move back or fourth parking brake stays on whatvshould I do

Mechanic's Assistant: Anything else you want the construction mechanic to know before I connect you?

That's all I just want to know if the pump that is in the middle does run the drive pumps and I am changing pump very expensive wanted some direction or testing

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Answered in 2 hours by:
10/26/2017
Mechanic: Dan, Technician replied 5 years ago
Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 15,105
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
Verified

Hi my name is***** will be glad to try to help. Give me some time to see what I have for specs on this for you.

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Mechanic: Dan, Technician replied 5 years ago

Check inside the hydraulic filter for fine metal/debris that would indicate a pump or component failure. If found check the pump and drive motor ports for metal/debris as well. Another thing to check is if no pump output is for a failed pump drive coupling.

Product Support Program For Replacing The Hystat Pump Coupling On Certain D4C, D5C Track-Type Tractors And 939C Track-Type Loaders Caterpillar

NOTE: This Program can only be administered after a failure occurs. The decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS5761" as the Part Number and "7755" as the Group Number. Use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.

Termination Date

November 30, 2000

Problem

The(###) ###-####Coupling between the front and rear hystat drive pump may fail and should be replaced on certain D4C and D5C Track Type Tractors and 939C Track Type Loaders.

Affected Product
Model & Identification Number

D4C III LGP (4LS177-256)

D4C III (6BS214-312)

D4C III XL (8CS348-462)

D5C III ( 5HS218-360)

D5C III XL (7PS346-496)

D5C III LGP (6CS250-364)

939C (6DS410-488)

Parts Needed

1 -(###) ###-####Coupling

Action Required

Remove the existing coupling and install a new(###) ###-####Coupling.

Service Claim Allowances

NOTE: This is a 8-hour job.

NOTE: An additional 4 hours may be allowed if the machine has a cab.

NOTE: Resultant damage may be allowed as a part of this program. It must be fully explained in the claim.

Parts Disposition

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

Let me know the results and we can follow up as needed on here.

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Customer reply replied 5 years ago
Ok thanks the coupler is located between three pumps correct will it be broke or something when I pull pump out
Mechanic: Dan, Technician replied 5 years ago

Pull the end pump and disable fuel system from starting and then crank the engine over to see if the pump is turning at engine RPM. If not, the coupler has a problem. If okay you move on to other testing. If metal is found in the filters it indicates a pump or component failure.

The Gear Pump

Rotation is clockwise when seen from drive end.

Type of pump: Gear.

For bench test, use SAE 10W oil at 65°C (150°F).

Test At Full Speed:

Output ... 134 liter/min (35 gpm)

With pump at ... 2400 rpm

At a pressure of ... 690 kPa (100 psi)

Output ... 133 liter/min (34.5 gpm)

With pump at ... 2400 rpm

At a pressure of ... 6900 kPa (1000 psi)

Test At Half Speed:

Output ... 67 liter/min (17.4 gpm)

With pump at ... 1200 rpm

At a pressure of ... 690 kPa (100 psi)

Output ... 66.3 liter/min (17.2 gpm)

With pump at ... 1200 rpm

At a pressure of ... 6900 kPa (1000 psi)

(1) Torque for eight nuts ... 70 ± 15 N·m (50 ± 10 lb ft)

(2) Torque for two pump mounting bolts ... 100 ± 20 N·m (75 ± 15 lb ft)

Torque to install inlet hydraulic line to pump ... 100 ± 20 N·m (75 ± 15 lb ft)

Torque to install outlet hydraulic line to pump ... 55 ± 10 N·m (40 ± 7 lb ft)

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Mechanic: Dan, Technician replied 5 years ago

Also check the linkage to the pumps is moving fully in both directions as it should and is not damaged, worn or disconnected. Let me know the results and what you find inside the filters.

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Customer reply replied 5 years ago
The part number u gave me not good part number for coupler do u have another part number
Mechanic: Dan, Technician replied 5 years ago

Is the drive coupler found to be the problem?

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Mechanic: Dan, Technician replied 5 years ago

Who said it is not a good part number? It may update in their system but it is a good number. That is right out of the Cat bulletin and parts catalog.click this link.

Coupler

also

Coupler

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Customer reply replied 5 years ago
I pulled the pump out no metal in filters nothing the coupler I think is good how can I check the motor drive pumps by the track for metalIs there a port or something I can take offI have sis where do I look into find the breakdown
Mechanic: Dan, Technician replied 5 years ago

Thanks for the update.... You can just disconnect the hoses and look for metal. It will look like metallic glitter in the oil and light. Also if clean you can check for excessive case drain pressure.... The drive motor case drain should have low volume and low pressure case drain with a how run into a bucket from the port and the machine against a loading dock to prevent travel. Slowly engage travel and check case drain. should be low volume. Compare both sides.

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Customer reply replied 5 years ago
I pulled the pump of tool it apart found couple pieces of metal bt I can't figure out where they can from they were in the pump so idk if it's from the pump or from somewhere else can u send me a pic of the coupler and Quinn cat says coupler not offered anymore I'm confused
Mechanic: Dan, Technician replied 5 years ago

The pump cant handle metal.... Will score and ruin the machines surfaces. If that is what you are seeing, the pump will be junk. Some aftermarket part vendors like costex in FL might have an aftermarket replacement,

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Mechanic: Dan, Technician replied 5 years ago

Thanks for the photos. Check that the pistons slide freely and do not stick and are free from scoring, wear, pitting on the machined surfaces and free from debris in the piston bores. check for bushing /bearing/housing wear as well. It is tough to say where the metal is from without further disassembly.... Mark the piston positions for reassembly... do not mix them up.

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Customer reply replied 5 years ago
Hi having some problems with the dealer saying that ain't a good part number and the service letter they can't find
Mechanic: Dan, Technician replied 5 years ago

You are not alone there. I was field service for a Cat Dealer. Most of the parts counter guys do not know what they are looking at or for. There are a few good ones but the technicians looked up their own parts for jobs. I am at a remote location using an internet provider due to the storms here in New England. This is day two without power or internet. It wont let me access the site to open the file but go to avspare.com and submit your e mail to the site to get a log in. once allowed to access login to the auto data rather than parts for cat. You will be able to pull up the bulletin in that section.

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Mechanic: Dan, Technician replied 5 years ago

Please take a moment to rate as that is how the site credits my time helping on the site or let me know if you need more help. 5 star and bonuses are always greatly appreciated.

Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 15,105
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
Verified
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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 15,105
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Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.

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