Kubota L4740 PTO, Check the pressure

[moship]

According to the tech he did a serial number search to verify any service bulletins, then the went to the service manual as I did, and he gave me page numbers, the two pages in the service manual stated the same pressure for the six different L Series, and it doesn't break down gear,GST or HST. They are all the same.

Doing some research on the WSM for the Grand L40-3's.

It looks like there are several manuals:
9Y111-03691 ???
9Y111-03692 2012
9Y111-03693 Jan 2015

I often use Messick's website for reference and find they don't even list the newer version on their workshop manuals page. They list 9Y111-03692, but when you check the details it replaces -03691. It also says the a-03692 is discontinued with no reference to 9Y111-03693. Entering the part number directly (9Y111-03693) it gives the details but no reference that it replaces -03691 or -03692. My purpose of reporting this... Perhaps your dealer isn't referencing the most recent version (9Y111-03693). Could it be Kubota found a problem with the PTO pressure and it was updated in the latest manual?

I'm guessing your version of the manual is either 9Y111-03691 or 9Y111-03692. (I think the part number might be printed on the last page). What version did your tech person reference? Could it be they don't have the latest version?

Can you private message what dealer you contacted?

David_Kb7uns,

Thanks for your post concerning Newbury's response. I follow this forum on a regular basis and didn't recall PTO pressures being discussed previously. Also searched the forum prior to posting and didn't find anything related to Kubota PTO pressure. I really thought I missed something and was eager to learn more about the subject, only to find his post in poor taste. I think we're here to help and learn from each other.

 

[David_Kb7uns]

I have a Grand L3130 GST, now the GST and FST versions get their PTO flow from the steering circuit section of the pump and the GST has a regulator valve to run the transmission on and I think part is split off for the PTO.

The HST is using the charge pump, inside the transmission, to get the PTO pressure from, I would be looking at that circuit especially if you are getting variations when the HST pedal is being used, is the charge pump bad? or one of the regulating valves bad? or does the HST have too much leakage for the flow coming off the pump?

I only have the Grand Lxx30 series manual but Kubota made some changes on the Lxx40s and some were good and some bad like the front shaft seals, think you need to get some flow and pressure checks upstream of the PTO section to see what everything else is doing as you do not need problems with the HST being low on charge pressure as thus can cause problems also, tracking down the correct version manual is needed as they did do changes on the run as problems were discovered in the -1 -2 -3 versions.

David

 

[Kubota 2007]

Page from my service manual, I had it here at the house, tomorrow I'll get the part number of the manual, it at my garage.

 

[jonsstihl]

Sorry to bring back an old thread but my new to me tractor is sort of doing the same thing.

I mowed for about 3 hrs and the pto would not shut off but when it is cold it shuts off.

Checked the PTO pressure and it is at 300PSI. Tried adjusting, one turn of the threaded stem in the valve gets me to 320PSI but if I go any further I have no threads left to screw the cap back on the adjuster.

The work shop manual has been updated the manual transmission and GST versions have 334-362PSI and the HST version has 363-413PSI.

So the PTO pressure comes from the charge pump in the HST.

Mine must be just starting to seize up since it seems to only do it when the tractor is really warmed up well. I took it back out and mowed for about 30 minutes but the PTO would still shut off so it really needs to heat soak properly before seizing. I have had the tractor since february and the problem never occured with the snowblower on it.

When I get the gauge hooked up again I could do some tests and see how the pressure varies with HST load since my hose is long enough to wire the gauge to the cab door handle. I couldn't get it to repeat the stuck on PTO problem and get a pressure reading while the pto was stuck on.