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D4H LGP - tranny engages but does not move

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
Have you inspected the pump suction screen and filter for debris from a component failure
Changed the transmission filter early on (one of the very first things I did). The filter was clean with no debri or anything else. Have not pulled the suction screen as I believe you have to drain out all the tranny fluid (31 gallons?) to do that.

Recall that this recent issue of dozer not moving was a spontaneous occurrance and did not happen while working the machine. The dozer was working fine, steering normal lft and right, etc., Shut off and next morning did not move. Thus, I would not be very suspicious of a slow leak or a partially clogged suction cut, etc as these would (I would think) be gradual failures during working.
 

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
UPDATE:

YOu guys have been great. I managed to get the dozer back to the barn so I have power tools, powerwashers, welders, etc to do some work. The dozer did not like it too much, particularlky going up hill and I could only really move in 1st gear but made it with out too much strain. May have learned a few things on the trip.

First, I really did nothing to make it move. I played with levers and valvesto make sure everything was moving free. But did nothing that would have changed anything.

The brake(s) are definately at least partially engaged. I beliebe this because the dozer is obviously "dragging" and when moving and taking ot out of gear, it is liker slamming on the brakes. Abruptly stops the second it comes out of gear.

I believe it is both brakes because the dozer moves in a straight line, I can steer rt & lft, but when I let go, we go in a straight line. This would suggest to me that both brakes are applied equally. Agree????

I don't think it is the barking brake as this has been broken since I owned it. The valve is free (moves up and down) and automatically returned to the up position (disengaged)

Now moving the dozer and making a sharp right turn (90 degrees), the dozer would not turn and had to literally jam the handle back to engage the brake. After m,making the turn and releasiong the handle we were back to normal drag. After that it did steer but upon releasing the handle it would feel like the brakes were slammed on before releasing and moving forward again.

So, we have something not right with the rt brake/steering and something causing both brakes to be at least partially applied. The brake petal (B) and the rt brake (A) both go into box C (see photo).

I am just guessing because I am not a mechanic and know less about dozers as this is the first one I have ever owned.

Does this all sound logical that the problem is in box C (whatever that is officially called)?
Isd there anyway to test this hypothesis?

Any thoughts and advise would be appreciated.

IMG_2460.JPG
 

DMiller

Senior Member
Joined
Feb 21, 2010
Messages
16,599
Location
Hermann, Missouri
Occupation
Cheap "old" Geezer
I do not have a layout on one of these but sounds as you are on the right track. As to the straightline, can still be just one brake dragging as the steer works by releasing a clutch to the side you want to turn to and these machines generally have no differential just a spool for the bevel(ring) gear.

Needless to say, anything bound or binding up needs to work free on these to keep from having problems.
 

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
Dont believe it is the parking brake. As I said, it has always been broken, the valve (outside lever) at casing, moves up and down freely, is in the up (disengage position), does not move further up (even with a crowbar).

Is there anyway to test the operation of that box (C)?
Plan to take the top off to see what is inside after I clean things up abit.
Also plan to do some oopressure checks on P1 and P2 today.
Still have no idea where the check points are under the floorboard to check as suggested
 

koecon

Well-Known Member
Joined
Apr 13, 2013
Messages
65
Location
Highland Ca.
Occupation
Heavy equipment consultant
Box (C) is the steering clutch and brake valve and there should be test ports or plugs on the front to test pressures.
I think you will find a problem with the parking brake valve inside that valve.
 

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
there are only plugs (look like freezeout plugs) on the front.
Parking brake does not go into this box
Parking brake linkage is screwed and would need to find parts or modify to get operational (but again, valve is free and unengaged)
 

koecon

Well-Known Member
Joined
Apr 13, 2013
Messages
65
Location
Highland Ca.
Occupation
Heavy equipment consultant
On an 8PB the parking brake valve is bolted to the steering clutch and brake valve down low on the valve. It has a spring and poppet inside that may be the issue. A bad poppet, seat or spring will cause this issue.

There are 4 plugs below the ones you saw to remove and install 6V3965 test nipples in to test clutch and brake pressures.
 

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
Koecon,
there are no other ports than the 3 shown in the photo below.
Is 6V3965 a part number?
Not look really appealing to pull these plugs!
IMG_2464.JPG
 

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
I am going to separate my posts into 2 (maybe 3 separate ones.

So, FIRST POST:

Other than screw with linkages, I really have done nothing. Because I felt it was work too hard for too long, I had parked it near the barn with [plans to move it today. This morning, the dozer is working just fine (minor issue) – the brakes were not dragging and the dozer had all the power it had in the past. I hate fixing things without any idea why. But, first things first – fix all the handles and levers.

Took apart all the linages associated with the brakes. Every single bearing is shot – essentially nonexistent. Hammers, crowbars, oil, and wedges to get it all apart. I need all new bearings. See images 2 (parking brake) and image 1 (brake/steering)

If anyone has the parts manual for this machine and all the bearings, that would be a big help. Plan on calling cat but without a parts diagram, might be difficult. Guess I need to invest in a parts catalog, but in the meantime, any help would be appreciated.

Will see where we are when all the linkages are back to good working order without any slop.

Again, if anyone has the part numbers for all these bearings, it would be a great help

IMG_2466.JPG

Above, what left of steering/btake bearings

IMG_2467.JPG

Above what left of parking brake. Broken rod not shown
Thanx again to everyone.
 

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
SECOND POST:

Pressures:

P1 (back of transmission, left top port)
Low idle: 50
High Idle: 350
Apply foot brake: 350
Rt brake ½: 350
Rt Brake, Full: 350 (drops to 250 for split second as lever moved back to free position)
Lt Brake, ½: 350
Lt Brake, Full 350 (drops to 250 for split second as lever moved back to free position)
In Gear (low rpm): 45-50*
In gear (high rpm): 350
NOTE: transmission not engaging at low rpm (deaccelerator fully depressed)

P2 (back of transmission, right lower port:
Low idle: 0
High Idle: 0
Apply foot brake: 0
Rt brake ½: 0
Rt Brake, Full: 0
Lt Brake, ½: 0
Lt Brake, Full: 0
In Gear (low rpm): 0*
In gear (high rpm): 350

*transmission in gear but not engaged. `This is kind of a new development but may simply be because fluid is a little low from when I changed the pump.
 

koecon

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Joined
Apr 13, 2013
Messages
65
Location
Highland Ca.
Occupation
Heavy equipment consultant
Koecon,
there are no other ports than the 3 shown in the photo below.
Is 6V3965 a part number?
Not look really appealing to pull these plugs!
IMG_2464.JPG
Down another 4 to 5 inches!
The 6V number is for the test nipples, need machine serial number!
 

koecon

Well-Known Member
Joined
Apr 13, 2013
Messages
65
Location
Highland Ca.
Occupation
Heavy equipment consultant
SECOND POST:

Pressures:

P1 (back of transmission, left top port)
Low idle: 50
High Idle: 350
Apply foot brake: 350
Rt brake ½: 350
Rt Brake, Full: 350 (drops to 250 for split second as lever moved back to free position)
Lt Brake, ½: 350
Lt Brake, Full 350 (drops to 250 for split second as lever moved back to free position)
In Gear (low rpm): 45-50*
In gear (high rpm): 350
NOTE: transmission not engaging at low rpm (deaccelerator fully depressed)

P2 (back of transmission, right lower port:
Low idle: 0
High Idle: 0
Apply foot brake: 0
Rt brake ½: 0
Rt Brake, Full: 0
Lt Brake, ½: 0
Lt Brake, Full: 0
In Gear (low rpm): 0*
In gear (high rpm): 350

*transmission in gear but not engaged. `This is kind of a new development but may simply be because fluid is a little low from when I changed the pump.
50 PSI is too low, could be low oil or a leak, need machine serial number!
 

N00bie

Active Member
Joined
Sep 15, 2017
Messages
27
Location
AR, USA
Control-1-1.jpg
koecon,
Thank you so much for the effort you put in getting these schematics. Unfortunately they do not show what I need. I need all the components, the bearings, seals, spacers, etc., within the linkage shown in the image attached. It took about an hour on the phone with CAT, buit I have a bunch of bearings and stuff arriving in the CAT box tomorrow. We will find out tomorrow if they are the correct ones.

Other than that linage there and the parking brake linkage (which also has bearings, seals, and spacers), everything else is tight. We shall see in a few days.

Thank you and everyone else again.
 

koecon

Well-Known Member
Joined
Apr 13, 2013
Messages
65
Location
Highland Ca.
Occupation
Heavy equipment consultant
The exploded view shows the shaft, bearings,seals etc. and a parts list should be with it.
Anyway if we helped please click the like button to show appreciation! Good luck and hope to hear back from you!
 
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