Kubota L4850 - Hydraulic shuttle slippage

Laurenf · Sep 16, 2019

I have a Kubota L4850 that is losing all forward power. I can run it on flat ground in a low gear, but as soon as there is any resistance (applying the brake, slight hill, etc.) the wheels stop turning while the RPMs are maintained. It does not feel to me like a slipping clutch, I suspect that it is a lack of pressure in the hydraulic shuttle.

My model does not have the Ever Clutch, instead the valve assembly is under the right foot plate.

Does my model have an adjustment similar to the Ever Clutch models where I can adjust the shuttle valve orifice? Or am I limited to whatever the factory setting is?Can anyone suggest what I should do next to try to solve the problem? I'm thinking of disassembling the shuttle valve assembly and giving it a cleaning.

More info:
- The tractor now takes a very long time to warm up in the winter before I can get the hydraulic shuttle to engage. Tried changing the hydraulic fluid, didn't help. Last winter was the first winter we had the tractor, but I swear in the beginning of the winter it took less time to warm up.
- I don't seem to have any reduced power in the front end loader.
- The rods that engage the shuttle shift seem to be tight. I can force the shuttle valve a bit further by hand, but it does not change the power to the wheels.

Thanks for your help! If someone knows where I can get the service manual for less than 150$ please let me know, otherwise I will be buying it in the next couple of days of off ebay.

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North Idaho Wolfman · Sep 17, 2019

Everything you are saying is pointing to the clutch pack seals.

How does it do in reverse?

Laurenf · Sep 17, 2019

Same story forward as reverse.

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North Idaho Wolfman · Sep 17, 2019

Now that points to a mechanical clutch issue, as forward and reverse have different clutch packs.

Laurenf · Sep 17, 2019

It was running fine and happened out of nowhere. I was running the pto with the bush hog and had been doing a fair bit of forward and backwards. The engine doesn’t stall, it just stops moving with any amount of strain. I was able to get it out of where I was working by using the bucket when it wouldn’t move.

In a small town in Northern BC... trying to avoid a 500km haul to a mechanic who may or may not be able to help. Also trying to avoid taking it apart without knowing what I’m after...

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North Idaho Wolfman · Sep 18, 2019

Laurenf said:
It was running fine and happened out of nowhere. I was running the pto with the bush hog and had been doing a fair bit of forward and backwards. The engine doesn’t stall, it just stops moving with any amount of strain. I was able to get it out of where I was working by using the bucket when it wouldn’t move.

In a small town in Northern BC... trying to avoid a 500km haul to a mechanic who may or may not be able to help. Also trying to avoid taking it apart without knowing what I’m after...

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Get the WSM and look at clutch adjustment, if it helps at all then the mechanical clutch is the issue for sure, but if adjusting doesn't work, then it still does not eliminate the mechanical clutch being the issue.

heppeone · Oct 13, 2019

North Idaho Wolfman said:
Get the WSM and look at clutch adjustment, if it helps at all then the mechanical clutch is the issue for sure, but if adjusting doesn't work, then it still does not eliminate the mechanical clutch being the issue.

Any idea if this model has a single stage clutch or dual? The single would it have an adjustment. Not referring to the hydraulic clutch operated via shuttle.

North Idaho Wolfman · Oct 13, 2019

heppeone said:
Any idea if this model has a single stage clutch or dual? The single would it have an adjustment. Not referring to the hydraulic clutch operated via shuttle.

Single clutch disk on that model, the clutch and pressure plate will not have any adjustment, but the linkage for it does.

rbargeron · Oct 14, 2019

Laurenf: Hopefully it will be an easy cure.

My WSM shows that the L4850 with Hydraulic Shuttle Shift but without Ever Clutch does indeed have the dry dual clutch for pto and travel.

It sounds like the travel clutch is just out of adjustment. With the tractor parked, engine off, push the clutch pedal by hand. There should be some free play before it gets harder. Sounds like yours may have none or very little. Adjust the turnbuckle under the left floorboard to get about 1" of play.

BTW, this model's shuttle control valve (under the right floorboard) does not have an adjustable flow orifice.

As always, prompt cheerful refund if info is bogus. Dick B

rbargeron · Oct 14, 2019

heppeone: Hi

I just found a PM from you saying you'd sent me an email about your L3750 -from heppeone@gmail.com - but I've gone thru my emails and haven't been able to find it. The address doesn't seem to work for sending to either.

You asked a very good question above. I've had several Kubotas with the Ever Clutch - (actually a newer somewhat more beefy hydraulic shuttle with a fancy name). These tractors have a single dry clutch for the pto only. Travel is all by wet hydraulic clutch packs

I didn't know that Kubota still offered the Hydraulic Shuttle but without the EC. I looked it up in my WSM and sure enough there are L4850s without EC but that have hydraulic shuttle and dual dry clutches.

Confused yet? I seem to be getting that way easier these days........

Take care, Dick B

North Idaho Wolfman · Oct 14, 2019

rbargeron said:
heppeone: Hi

I just found a PM from you saying you'd sent me an email about your L3750 -from heppeone@gmail.com - but I've gone thru my emails and haven't been able to find it. The address doesn't seem to work for sending to either.

You asked a very good question above. I've had several Kubotas with the Ever Clutch - (actually a newer somewhat more beefy hydraulic shuttle with a fancy name). These tractors have a single dry clutch for the pto only. Travel is all by wet hydraulic clutch packs

I didn't know that Kubota still offered the Hydraulic Shuttle but without the EC. I looked it up in my WSM and sure enough there are L4850s without EC but that have hydraulic shuttle and dual dry clutches.

Confused yet? I seem to be getting that way easier these days........

Take care, Dick B

Looking at the Kubota prints, it looked to me like the Hyd, shuttle shift models came with singe clutches and the mechanical shuttles came with dual disk.
Am I wrong in what I'm reading?

You are a lot more knowledgeable about this class/series than I am.

rbargeron · Oct 14, 2019

North Idaho Wolfman said:
Looking at the Kubota prints, it looked to me like the Hyd, shuttle shift models came with singe clutches and the mechanical shuttles came with dual disk.
Am I wrong in what I'm reading?

You are a lot more knowledgeable about this class/series than I am.

Sean, you're exactly right - the mechanical shuttle is the only L4850 version with the dual dry disc clutch.

There are actually THREE clutch arrangements in L4350 and L4850 tractors. I'd post the diagrams from my WSM but OTT won't allow large enough PDF files.

(1) The Manual Shuttle option tractor has a full dual stage dry clutch assembly where pto and travel are turned on and off one after the other. (no hydraulic clutch packs)

(2) The Hydraulic Shuttle option uses a variation of the dual disc setup with a dry disc for the pto and with a travel disc bolted to the back of the pto pressure plate and turning with it. With this setup the pto and travel are turned on and off together,. The travel disc drives two clutch packs controlling forward and reverse motion.

3) The Ever Clutch option tractor has a single dry disc for the pto with an independent thru-shaft bringing power to a larger set of clutch packs (named the Ever Clutch) to control travel.

Since Travel and pto are tied together on the Hydraulic Shuttle tractor, they can indeed be adjusted by the outside pedal linkage. Take care, Dick B

rbargeron · Oct 14, 2019

Laurenf: I found this page in the L4850 section of the WSM showing the clutch pedal adjustment for the hydraulic shuttle tractor (non EC).

It describes it as a single plate clutch, and it is - but there's a second disk bolted to it inside. If you ever split the machine the clutch assembly looks like a dual at first glance.

Hope you cure the slipping without disassembling it. Dick B

jmiddeler · Jul 3, 2022

I know this was a couple years ago but was the problem ever figured out. I have a L4850 with the ever clutch doing something very similar. It moves in all gears but with any resistance it stops. However if the steering is moving it gains some power back.

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Kubota L4850 - Hydraulic shuttle slippage

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