I'm working on a jd 550G direct drive transmission customer complaint is will not move at low rpms in any gear. Dozer needed to have 1600-1800 rpms to pull on any gear. I pulled suction screen and cleaned, installed new transmission filter checked filter relif was not stuck open. Installed P2 gauge, cooler pressure and lubes pressure gauges also installed steering gauges. When first looking at pressures P2 pressure is 0 at idle ,cooler pressure 70psi lube pressure is 50psi flow meter 23gpm at 250psi wide open throttle at idle 18 gpm and around 180psi Things I have done added shims to cooler relif after inspecting the spring valve was free in bore. Added shims to trans pressure control valve in efforts to raise P2 & cooler pressures. I turned shift speed screw out 9 and 11 turns from bottom trying to improve engagement of transmission.on steering control valve I have at idle 100 to 170 at wide open throttle depending on RPM P2 and Steering valve pressures increase according to RPM. lube and cooler do not change. The brakes do charge and release from park to neutral The deceleration pedal kills P2 and steering clutch pressure but clutch pedal does not have the same effect as decel pedal but clutch pedal will stop engagement and disengage when pedal is pressed and released. Oh and I do not hear any high pressure leaks inside transmission Sometimes I do hear a wine like a drive clutch has pressure and turning it must be missing the second pack to engage or loosing the 4th pack that keeps everything still Idk just giving all information I can remember. This is my first john deere dozer transmission repair in a little over my head but I can definitely swim in deep waters so to speak. Thank you Lex Carter
Adding there are a couple things I dont understand how the decellerator stops the transmission from working I cant find the solenoid presuming there is one to energize and how does it seem to do more than the left clutch pedal that will not totally stop the transmission from moving unless I press the brakes then it will set still and not creep both pedals will engage transmission when released. I guess is the same valve being moved by these two pedals only one stroking a little more than the other because I have not found an electrical solenoid on the valve body that resembles other commonly used in transmissions. Hope it's not a stupid question I've been messing with this 550G for two full days and only presenting my suspesion about what seems out of place...
When the Deere experts show up the first thing they will ask you for is a Serial Number.
Thank you I'm an hour away from equipment but will get it and post.
Ok serial number is T0550G 1768884 It a plain LGP, Dirict drive transmission with no wrench or ripper.
Will out of adjustment power control pedal 1. cause low P2 pressure 2 cause low cooler system pressure 3 cause P2 pressure to rise with rpm only reaching 180 psi @ fast idle when cold What test or tests will identify and or isolate these problems. If it's the control valve body I would rather take it out and service it but I can not do that and still have the same problem. Any help will be greatly appreciated
Welcome to HEF Lex ! Must have fat finger syndrome, your serial number is actually T0550GL768884. My first question is, you said P2 was 0 psi at idle, what is P1 at idle? If you have no pressure at idle and pressure when revved up, then there is leakage in the pump supply pressure circuit. First place I would check would be the filter relief valve. That is not a bypass valve like on most filters, that dumps to sump if there is an issue which could drop trans P2 pressure. I'll have more questions after I absorb your text and digest it.
Mg2361. Thank you for your help Mechanics all have fat fingers for cell phone key boards? Dont we? My case please overlook my typos... P1 pressure I have not checked I am at the point where manual testing procedures make me address the lack of pressure on L2 ,cooler and lube circuits. When I did the flow test the pump had 250 psi I didnt want to close off pump flow any more than that. I removed filter relif it was not hung up but I did remove the plug from top of filter housing along with spring and valve i used sand paper the valve to clean up minor scratches and reinstalled it with no change. The decellerator pedal are they using the same valve as power control pedal because owner informed me he never used PC pedal when operating his equipment. And when I performed the operations testing symptoms got worse as in needing more RPMS TO move and watching P2 pressure increase with idle and stay at 180 psi until I change gears.. it's raining today and dozer is an hour drive so tomorrow I will put gauges in P1, fwd, rev, 1 I can also hook flow meter to cooler supply if you think I should... I need a plan and your advice will be taken to impelment further testing. It sounds like I need to back up in the testing to things that effect fluid supply pressure? Mabey I need to start with external control like decellerator and power control pedal.i did notice the decell linkage looked to be out of adjustment with the slider all the way up to throttle lever so to have no free travel in pedal before changing the idle position photos in the manual has it adjusted differently that may be unrelated adjustment needed before I leave. IDK IM TRYING to do a crash course on 550G Transmissions diognistc and repairs at night any help will be greatly appreciated. With 30 years in the field I will surely have some help to offer someone in the future.
First lets ignore both the PC and Decel pedals, neither of which affect P2 pressure. We need to find out why P2 is low. You said you pulled the suction screen and cleaned. Was there anything in it? Pictures if there was? Lets eliminate the filter relief completely. Connect to two cooler hoses from the filter head relief port together and cap the filter head and recheck your P2 pressure. You said you have 0 psi at P2 at idle, in all gears? Fwd and Rev? Does the pressure steadily rise with the rpm increase or does it suddenly jump up to pressure? What do you have with the park lever down? Park lever up? Answers to theses will direct where to go next. If the cooler pressure is 70 psi at idle then you should have 70 psi minimum at P2. The cooler relief and lube relief get there oil downstream of the main pressure regulator. Either way, the low cooler and low lube pressures with the low system pressure are all indicative of excessive leakage somewhere.
Answers are in reverse order lube pressure 50psi at idle and fast idle it is normal and steady but does not fluctuate any at all cooler pressure is 70 at 1500 rpm it does not fluctuate like L2 with rpm I will look today and see cooler psi at idle L2 pressure is 0 psi at idle jumps up @ 1500 to 100-120 hot . When cold it jumps up after rpm reaches fast idle 180 psi at fast idle lube and cooler never will raise above 70 psi I put a couple shims in cooler relif and it didnt change much. I will answer the park/neutral pressures today The screen is brand new and filter new no metal in screen housing. No pics but a little trash was in screen and looked like rag or paper towel fibers just not much of it... I will cut old filter open today and look. Pump is good get up 17gmp at idle and 23 at fast idle Explain bypassing filter head. Do I need to connect the small hoses together and plug the filter head port where the tee was connected? I will do this today. The machine pulls great when it has 180 psi on L2 also the breaks release good pedals pop up quick
MG2361 I HAVE A HAPPY CUSTOMER THANK YOU FOR THE HELP...... I isolated filter housing from the return and everything works now like it should...thank you sir for the help. Hope I can return the favor one day and help someone else.
Glad to hear it and thanks for posting the result.
I know this is an old post, but maybe someone can answer. I have a similar problem. Was the fix to replace the filter housing?