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Case 1845C drives on start up

elektro21

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I've been wanting to get an older, inexpensive Skidsteer for quite some time to do all the heavy lifting jobs around the house. To my luck, I happened across a 1988 Case 1845C and picked it up in my price range. Of course in that low of a price range that means something is wrong with it :)

So I have the 1845C at home and up on jackstands. Got it all cleaned up and rewired the engine harness to remove the push start button that was placed by the operators seat. Now I am down to the drive motors and pump. When starting the 1845C the left wheels immediately start turning at quite a rapid pace backwards. They will plunge the skidsteer backwards until you push the left control quite a distance forward to 'neutral' the drive motor. (before I received the machine someone had removed the shocks off the steering control arms) I drove the machine onto the trailer and off the trailer when transporting it home. Seemed to have plenty of power to move itself around. I did not try to dig with the machine, but the gentleman I purchased it from said he was moving some dirt with it.

I have hooked into the the charge pressure test port and I am measuring ~250psi as the charge pressure. I ran the machine in the forward and reverse directions it does not seem to change the charge pressure much. I know most of the troubleshooting information says to load or stall the drives...but at this time i have no way to perform this task. I have picked up one tip a long the way as far as the problem of the wheels moving upon startup and not being able to neutral them. (without moving the swashplate control lever on the left side an extreme amount) Is that the roll pin inside the linkage to the swashplate might be broken.

Does this sound like a broken roll pin or perhaps the main relief valve might be stuck? I wanted to get some community opinions before I tear into this thing when a simpler repair might be in order.

Thanks to all who reply!
 

funwithfuel

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You said the centering dampers were removed at some time. I would start there. Go through your centering procedure. If you can't establish neutral , then I would look for sheared roll pins or damaged swash plates. The fact your charge pressure doesn't drop off is a good thing.
 

elektro21

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You said the centering dampers were removed at some time. I would start there. Go through your centering procedure. If you can't establish neutral , then I would look for sheared roll pins or damaged swash plates. The fact your charge pressure doesn't drop off is a good thing.

I read through the centering procedure in the manual. I believe it to be inadequate in my situation due to the travel on the dampers...seems all of my slack would be taken up in the fine adjustment rods on the steering controls. I was hoping that was going to be the solution when i first bought it. This appears to be as you suggested, something like a roll pin that is sheared and not allowing the swash plate to move properly. As far as I can tell the swash plate is sitting in the rearward travel position, hence why it wants to move when it is fired up (and all pressures seem normal). I can get the motors to cycle forward and reverse...you can tell something is not quite right however with the position of the damper in correlation with the fwd/Neu/rev travel of the motor.
 

funwithfuel

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OK, let's back up. Someone may have removed the levers from the shafts. Disconnect all the linkage but the levers. Start it up. Does it start tracking? Exercise the lever through its range. What you are looking for is something that feels ridiculously loose compared to the other side. Pay attention to where neutral is and where travel begins. Is it repeatable? Does the neutral point move around? If it's consistent, pump should be fine. Now adjust your control linkage to work, which may require repositioning the lever on the shaft. If not go deeper.
More often than not, the swash plate is broken vs a roll pin. Fingers crossed for a simple solution
 

elektro21

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OK, let's back up. Someone may have removed the levers from the shafts. Disconnect all the linkage but the levers. Start it up. Does it start tracking? Exercise the lever through its range. What you are looking for is something that feels ridiculously loose compared to the other side. Pay attention to where neutral is and where travel begins. Is it repeatable? Does the neutral point move around? If it's consistent, pump should be fine. Now adjust your control linkage to work, which may require repositioning the lever on the shaft. If not go deeper.
More often than not, the swash plate is broken vs a roll pin. Fingers crossed for a simple solution
I see what you're trying to say and I tried this exercise the other day and it was not repeatable. Perhaps I was not flipping the levers hard enough forward and backward to get it to 'move' around. (ie a broken pin inside the swashplate) I drew up a diagram of where i can get it to go to neutral using the dampers on the pump. I fear as you have stated that there is a broken roll pin or swash plate. Time for a tandem pump tear down lesson!
933470e6aa.jpg
 

funwithfuel

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I think you have it on the run. Was hoping for the simple fix. The fact that neutral moves around, says it's hurt internally. That sucks. It sounds like you're up for a challenge, most shy away. Best of luck
 

elektro21

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Okay so I have removed the pump and inspected. Good news is that the pump appears to be in very good condition with nothing broke. I did find the problem as to why this thing crept all over the place on the left side. The spool controlling the left wheels was majorly worn out from many hours of vibration and hard use. So i managed to repair the worn spool. A new problem has arisen with the pump. I reinstalled it and now I cannot seem to get the charge pump to prime. Does anyone have any ideas of how to get this thing to prime? (I have blown air in the hydraulic reservoir still no dice)
 

funwithfuel

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According to the service manual, you should be able to remove a plug and flood the case drain cavity with clean oil. Disable engine from starting and have no control linkage hooked up. Crank the engine for 10 seconds at a time. Perform this several times. This should purge air from system. You should be able to gauge and see when you achieve charge pressure.
Glad to hear your rotating assembly wasn't damaged.
 

funwithfuel

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1. Ensure the machine hydraulic oil and system components (reservoir, hoses, valves, fittings, and heat
exchanger) are clean and free of any foreign material.
2. Install new system filter element(s) if necessary. Check that inlet line fittings are properly tightened
and there are no air leaks.
3. Install the pump. Install a 50 bar [1000 psi] gauge in the charge pressure gauge port M
4. Fill the housing by adding filtered oil in the upper case drain port. Replace plug.
5. Fill the reservoir with hydraulic fluid of the recommended type and viscosity. Use a 10-micron
reservoir filler filter. Ensure inlet line from reservoir to pump is filled.
6. Disconnect the pump from all control input signals.
After start-up the oil level in the reservoir may drop due to filling of the system components. Check
the level in the reservoir to maintain a full oil level throughout start-up.
W Warning
Damage to hydraulic components may occur if you fail to maintain the oil supply.
7. Use a common method to disable the engine to prevent it from starting. Crank the starter for several
seconds. Do not to exceed the engine manufacturer’s recommendation. Wait 30 seconds and then
crank the engine a second time as stated above. This operation helps remove air from the system
lines. Refill the reservoir to recommended full oil level.
8. Check the pressure gauge at M3. When charge pressure begins to build, enable and start engine. Let
the engine run for a minimum of 30 seconds at low idle to allow the air to work itself out of the
system. Check for leaks at all line connections and listen for cavitation. Check for proper fluid level in
reservoir.
C Caution
Air entrapment in oil under high pressure may damage hydraulic components. Do not run at
maximum pressure until system is free of air and fluid has been thoroughly filtered.
9. When the pump estabishes adequate charge pressure (as shown in model code), increase engine
speed to normal operating rpm to further purge residual air from the system.
10. Shut off engine. Connect pump control signal. Start engine, checking to be certain pump remains in
neutral. Run engine at normal operating speed and carefully check for forward and reverse control
operation.
11. Continue to cycle between forward and reverse for at least five minutes to bleed all air and flush
system contaminants out of loop.
Normal charge pressure fluctuation may occur during forward and reverse operation.
12. Check that the reservoir is full. Remove charge pressure gauge. Re-intall charge pressure plug. The
pump is now ready for operation.
Straight up copy and paste from service manual
 

elektro21

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" remove a plug and flood the case drain cavity with clean oil" This is what I was trying...probably ran about 3-4 quarts in through the top plug that comes out of the top center section....it seems to be sucking it down and putting it back in the reservoir...as the level in my reservoir went up :) Maybe I need to keep repeating this process....I did install a new Hydraulic filter...and probably should have filled the new hydraulic filter with clean oil before installing it. I removed the small plug over top of the hyd oil filter and I can see hyd fluid in that area...it run out pretty liberally. I will see if running a few more quarts of oil into the top plug of the charge pump will help to prime it. This process seems very long and painful, can someone attest to the time and effort it takes to prime the charging system? I just want to make sure I am experiencing something that is 'normal' for putting one of these pumps back in service.
funwithfuel - thanks for the manual snippet, this is much more descriptive than the priming procedure in the manual that I currently have for the machine
 

funwithfuel

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It's big but here's the manual I have. It is available free on line and has unrestricted rights to share.
 

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  • danfoss pump manual.pdf
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funwithfuel

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When you get the file check page 8. It shows the charge pump feeding the passage that the bypass is on. If that fails, you'd have flow and no pressure. The same could be said if your Co tool spools are not centered.
 

elektro21

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funwithfuel - thanks for the manual, any additional reference for this hydraulic black magic is welcome! I have not fiddled with the bypass...but definitely the control spools...maybe that is why my charge pump is not priming. Back to working on the machine...hopefully in the next few days time permitting. Thanks again for all of the excellent advice!!
 

elektro21

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OK, finally a Success! So i involved a friend who is a heavy equipment mechanic and helped me retrace all my steps through the troubleshooting matrix. Final conclusion was that the new hydraulic filter was causing some sort of restriction. So I put the old filter back on and attempted to prime up the system and there it was...pressure finally ready on the gauge! Once I got her all fired up and running...creep has largely gone away(due to previous spool repair). I will now need to fine tune the 'neutral' position with the information in the manual on this procedure. Thanks again 'funwithfuel' for all your input!!
 

funwithfuel

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Glad to hear you got her handled. Moving forward, take care of your investment. Restricted cooler flow , poor maintenance etc, are real killers of hydrostat systems.
That said, I'm sure you'll be fine from here on out. Hydrostatic pumps are not the easiest thing in the world to jump into and your getting it done. So congrats on a job well done.
 
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