John Deere 4600 MFWD will not engage

[pctwst]

Hi All,
I have a JD 4600. I can not get it to go into 4WD. The linkage is intact and the handle rotates the shaft on the side of the trans. The roll pin is in place and the shaft moves in both directions when the handle is raised or pushed down. I am going to jack up the front wheel and see if it will spin and I am going to check the fluid level in the front axel in a few minutes. I have the Power reverser gear model. I bought this used. I don't know when it stopped working. I do know I needed the 4wd the other day when I got stuck in a ditch, LOL.. Had to pull it out with a pick up truck. LOL

Anyway, typically what is the most common failure on the MF4WD that causes it not to engage? Or where is the first place to look. I looked at the parts breakdown and everything else is internal. No sure that I want to split the tractor but will if I have to.

Thank you!

 

[pctwst]

Well, I lifted the wheel. It free spins. I checked the fluid in the axel, It was low. I changed the fluid and filled to correct level. It still does not engage. I tried bumping it into 4wd in reverse. Still nothing. I took it for a long ride and stopping and pulling lever. Still nothing. With the tractor moving the gear will grind when the handle is pulled. I know that isn't the correct way to engage but wanted to hear or feel it. I did it slow and stopped. the linkage seems to be working. Now what? LOL.

 

[DanMc77]

I also have a 4600, with the loader and backhoe. The loader can lift the front and the backhoe stabilizers will lift the rear. This makes it easy to run the drive train. So do you have just the bare tractor? I'm at about 3200 hours and the machine runs great. I keep it in 4wd full time due to a steep driveway.

 

[DanMc77]

Post a pic of your machine.

 

[Hoss710]

there is a wear block in their that slides the splined shaft to engage the 4wd. I have a picture of it somewhere. mine had worn down pretty bad. replaces it when the tractor was split when we rebuilt the hydrostatic transmission. you can see the paw / plate on the cross shaft on the bottom. mine had worn all the way threw the mounting bolt. that slide the shaft forward to engage the front wheel drive.

 

[pctwst]

there is a wear block in their that slides the splined shaft to engage the 4wd. I have a picture of it somewhere. mine had worn down pretty bad. replaces it when the tractor was split when we rebuilt the hydrostatic transmission. you can see the paw / plate on the cross shaft on the bottom. mine had worn all the way threw the mounting bolt. that slide the shaft forward to engage the front wheel drive.

Thanks. So, since it is all mechanical and internal, it looks as if the only way to determine the cause of failure is to split the rear. I saw that block on the parts breakdown and in the service manual. Do you know if the fluid level in the front axel has any impact on the 4wd engaging on the geared/power reverse trans?

Did you split the tractor? Or have Deere do it? If you did it, How long did it take you?

 

[pctwst]

Post a pic of your machine.

Will do. Any particular part you want to see? Thanks!

 

[pctwst]

I also have a 4600, with the loader and backhoe. The loader can lift the front and the backhoe stabilizers will lift the rear. This makes it easy to run the drive train. So do you have just the bare tractor? I'm at about 3200 hours and the machine runs great. I keep it in 4wd full time due to a steep driveway.

Thanks. No, I have a 400CX loader on the front. No backhoe yet. I am looking for a 48 backhoe with the correct mounting brackets. So far no luck. I can put the rear up on stands and lift the front with bucket or put on stands. The front wheels just free spin in both directions with one wheel or both wheels off the ground. They spin independently of each other meaning that one has no impact on the other. I thought that if engaged that if both wheels off ground they should spin in opposite directions if rotated.

 

[Hoss710]

the front axle shouldn't have anything to do with the engagement part. shouldn't be the linkage, that block. and the drive shaft which is spring loaded to return to off.

I had deere split the tractor to rebuild the hst . And while it was split they noticed that. The last time the tractor was split. ( long story) I had to Sr techs do the work. they had the tractor split and transmission out in just over 4 hrs. Those guys knew how to get it done !!

 

[pctwst]

the front axle shouldn't have anything to do with the engagement part. shouldn't be the linkage, that block. and the drive shaft which is spring loaded to return to off.

I had deere split the tractor to rebuild the hst . And while it was split they noticed that. The last time the tractor was split. ( long story) I had to Sr techs do the work. they had the tractor split and transmission out in just over 4 hrs. Those guys knew how to get it done !!

Thanks. Do you know a way to troubleshoot further without splitting the machine? Would bad spring loaded ball bearing detents cause this? To me it seems that the linkage is moving and the collar is moving over the splines when the handle is pulled.