621B drive problem

One of our mechanics is working on a Case 621B loader that has problems with the powershift transmission, the converter will not load the engine and the unit will not spin the tires in any range, we looked at the charge pump and converter relief, all seems to be in order, pressures are uniform across all the clutch test points but slightly low. Do these machines have any history of internal converter failure that would cause high stall speed, what should we be looking for. I am sure there are techs on this forum with experience in this area, or customers who have had similar failures, thanks in advance, Mel

I would cut open the filter for the transmission and inspect for metal debris, usually when something like a converter fails there will be some metal particles in the oil. If your converter has a one way clutch (sprag) for the stator, it may be free-wheeling both directions, that would cause the problem you are talking about, but probably with no debris in filter. A faulty one way clutch wouldn't cause any low pressures either. At any rate a transmission overhaul may be in your near future.

the b series case run the zf transmission?

I am not sure of the mfgr of the transmissin in question, I am not assigned to the job, just looking for info as to the likelyhood of failures that would cause the symptoms described. Question for the other gentelman who responded, generally when a sprag fails in a 580E or others useing the BW reverser a extremely slow stall speed will be experienced. While I am leaning toward a failed converter myself as the condition of the charge pump (only one minor scratch on the pump gear, otherwise absolutely perfect) practically rules out a problem in that area. I posted because there are many of these units out there and problems generally are predictable as to their cause, ie, broken bellville springs in the BW forward clutch pacs in the 580 series hoes. That is the type info I am looking for. I will post the info of the mfgr when I get it as I know that may be vital to the diagnosis. I can tell you that the charge pump had to be pulled out of the front of the unit with a homemade puller made of flat plates and jackscrewsto put against the tranny case. also the converter stub is carried by a needle type bearing in the pump rather than a bushing as is common in smaller units, hope this helps, Mel

melben i have not worked on the case scraper but looking at a break down of the parts. the first thing i would do is check the filter for metal and the case also. then the control valve has solinoids and i would adjust all the control spools and linkages to factory specs and check power and operation of the solinoids. this tranny should have a spec for inlet and outlet pressure for the torque the inlet is always higher to keep it charged with oil. relief valvs would be next. case might let you study thier service manual and copy differnt sections someone there could save you a lot of time

Steve, cutting the filter apart and checking for metal is a good idea and one thing that we havn't done as of yet, We have the factory service manual for the 621B but it is vague in certain areas such as where system relief is located in the valve body. Another post suggested the sprag in the converter as the problem but we are experiencing high stall speed with a lack of torque transfer, in other units I have repaired the sprag failure caused extremely low stall figures, down around 1000-1200 rpm on 580e- early k size machines, however I am leaning toward the converter as I mentioned previously in the other post, thank you for posting to this thread , the more info I gain the easier it will be to put my finger on the problem

Melben,

I work for ZF Precision Transmission Inc. out of Colmar, PA. The Case 621B runs our
4WG-150 transmission. If you are having any trouble with the transmission, please feel free to give me a call @ (215) 822-8300 and I would be more then happy to assist you with any troubleshooting etc.

-Nicholas MacFarland

Welcome to Heavy Equipment Forums ZFPTrans! :drinkup

zfptrans, thank you for your reply, the unit in question is up and running as of today, we installed a new torque converter, charge pump and an updated charge relief cartridge. The results were excellent, the unit has good power up hills where it would not go before without shifting to the lower gears to get up. The engine high idle was a bit slow today so we did some work on the injection pump throttle linkage to get the lever against the high idle stop, also cured some throttle linkage binding to make a smoother throttle action. It was obvious from the start of my post that there was not a whole lot of info out there which speaks well of the unit. While all responses were good diagnostic steps there was not any hard info to go with. That means failures must be rare. I have a feeling that the converter must have failed internally causing the high stall condition. Upon inspection and getting down in the converter stub and trying to find sprag action and not being able to and not knowing for sure if the converter even had one we decided to replace the converter as the work to redo the job if we guessed wrong would be prohibitive. What are your thoughts. melben

Melben,


Unfortunately, changing the torque converter is not always the solution to the problem. I have seen many transmissions with internal failures such as a burned clutch packs, broken piston rings, etc. In most cases, swapping torque converters only delays the inevitable. I am not saying this is the problem in your case, but I think it's something you should have looked a bit more in to.

Also, I am just curious as to where you bought the pump and converter from? In the future, send me an email before you purchase any ZF parts. As a ZF distributor I can offer you the lowest prices on all ZF parts as well as remanufactured converters. Please keep me informed on the status of your equipment

Thanks for your prompt reply, the high stall problem is cured, the unit now delivers good torque to the wheels, We purchased the parts through Case so I'm sure that we could have bought better direct from you. If we can use you in the future we will get hold of you. mel.

Melben,

I am glad to hear everything is working now. We take great pride in our product, so this is good news to us.

Take care,

Melban How do you like 621b and how much was the trans fix? I know were I can buy one for $7500 first gear is gone motrors been rebuild machine has 8000 hours on it motor I don't know hours sense rebuild.

need help please... 621b trans will not move

wzntme, give me a shout at (215) 822-8300

i have a case 621b it will shift good and then just stop moving if you let it sit for an hour it will move agian then just go into nuatral....need help

I fought the same problem, when the loader stops check the ohms on the 5 solenoids under the valve body cover. I had one that would open when the machine was warm after a hour of cooling off the solenoid would close again.

That is what was wrong we got it going now
thanks for your help

Does anybody know where i can get a ecu or transmission computer for a 621b case.
with a zf box Vin JEE0055870?

I bought one from Bowers, phone# 1-866-792-8220, $2000.00 I think, but $1000.00 less than CNH.
There should be a ZF part # on your ecu.