Case 550 LT dozer won't move

rmg · May 21, 2016

Have a friend who stuck his dozer in mud and water, I mean up to the floorboards! I pulled him out with a big winch truck. Dozer tracks would not turn when I tried to pull him, but engine had no load on it in either forward or reverse when in gear. Powershift trans. He has spent all week cleaning the mud out and tracks still will not turn. My question is this dozer supposed to roll with the trans in neutral, because it will not. It doesn't want to move in any gear you put it in, and motor has no load on it in any gear. Blade, hydraulics and engine all work fine. He has owned for 12 years and never had any problems with it. Said he never heard anything unusual before or after he got stuck in mud. Does anyone have any idea what could be wrong? Thanks.

2x4 · May 22, 2016

coupling stripped out?

Buddy · May 22, 2016

Dozer should roll freely when pulled.
Remove the floor plates and check if mud/stick or something is obstructing the brake linkages.

OldFarmall450 · May 22, 2016

It may have been what he did trying to get unstuck...final drives ?

CJinMI · May 22, 2016

It should roll unless the brakes are applied, the parking brake linkage is
hooked to both sides but has nothing to do with the drive (clutch) cutout,
so that doesn't fit your symptoms...
I doubt he trashed both sides -drives-,to where their locked & not affecting
the tc.. Which model Straight 550 ,550 H,E,G?
I'd pull the floorboards as suggested, might as well pull the belly pans to
they needed it anyway, use jacks now they weigh to much to handle, clean it
up hope for the obvious. I'm no expert but operated/worked on them, I'll try to help
where I can.

rmg · May 22, 2016

He did remove the floorboards and bottom pans and supposedly cleaned out everything. I never thought about the brakes being stuck, but if they were stuck wouldn't the motor load up if the trans was in gear and working? I have seen a final drive lock up before but doesn't seem like both would go at same time. He seems to think trans pump is not working but that still doesn't explain why it doesn't roll. I don't know if it's a 550G or what, have looked at it many times, just don't remember but I will look again. Thanks for all replies.

CJinMI · May 23, 2016

I might have jumped in to soon, guessing a 550.
I've been thinking about the symptoms, then wondered do
E,G,H, models have spring parking brakes, your friend should know,
so I checked the parts book and it looks like it. I'm not sure how it's set up
but if so, with no trans pressure they won't release. I also see a switch on the brake
valve, solenoid on control valve, wires, connectors + what else?, and I
think we all know what those things + ag and construction conditions mean.
I may be way off but am trying to figure what would effect both sides
with your symptoms, good luck, let us know.

JFoshee · May 23, 2016

It has been a long time since I worked on these, but I thought the 550's had a transmission pressure gauge on the dash. If it is in the green the pressure should be fine. If not, look for why it has no pressure and post back with what you find. Also, the G (and maybe other models) has a microswitch in side the left console that is activated when you actuate the safety lever. I have seen these switches get out of adjustment, get loose, or just go bad. If this switch doesn't work properly the brakes will not release. Also, check the wiring when all the mud gets off. It is possible for mud to push on wires and dislodge a connector. Possibly one going to this microswitch.
Hope this helps. It would be great if you could get the model of 550. There were some changes from year to year.

rmg · May 26, 2016

Finally had a chance to look at dozer myself today. It is a 550G and does have a trans pressure gage on dash. Checked microswitch on safety lever and it tests ok. All solonoids and wiring seem to be ok. Took suction tube from bottom of rear end, cleaned it and suction screen in line. Filled with new oil. Started and showed no pressure on dash gage. Disconnected suction line and poured oil in hose and still would not pump or show pressure on gage. I believe pump is not working and brakes are locked and trans is not working. It rained 5 inches here today and when it dries up some will test pump pressure at back of engine. It looks like it may have to come out. Gonna try to narrow it down and be pretty sure before I go that far. Thanks for all the help.

Case 550 LT dozer won't move

rmg

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JFoshee

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