M7040 Problem

[SDT]

I'm using UDT

I just received an email from my dealer with the response from Kubota which basically states that this a a normal occurrence for this tractor

Here is what they say:

"The scenario as described sounds like a normal condition for tractors equipped with Hydraulic shuttle type transmissions. Basically the drag applied to the clutch plates within the clutch packs during cold temperatures is enough to simulate some partial drive. Because tractor is so easy to roll it may in some cases provide a minimal amount of movement if brake is not applied.

Please assure customer that we have not seen any failures related to this and if all procedures related to service and operation are followed as described in OPS manual, that there should be no concern of a problem to arise.

Hope this helps
Thanks
Henry

Sounds line a put off.

What is described is not possible with the gear transmission in neutral. Be sure to specify that this was the case. Too often, those responsible for answering queries grasp at straws to get things off of their desk.

Dean

 

[MHarryE]

Kubota's response was what I had in mind might be the cause. My M135GX recommends Super UDT, one reason being lower viscosity at low temperatures. That would likely improve the situation but may not completely cure it. You're talking my kind of weather when you say it is 15 degrees and isn't cold.

 

[r40kh]

Just for kicks I fired the tractor up today and even with the +15C temp I was still experiencing the jerky movement. I communicated this to Kubota and also asked for a a more retailed explanation of how drag on the clutch plates was causing my problem even though both main and shuttle were in neutral...they haven't responded. Being so warm it was a good day to get the snow blade installed and all greased up for the first storm. I'll update this thread if I hear from Kubota

 

[jcummins]

I bought a new M7040 in Texas, sold it after putting 450+ hours on it, in a move to Illinois. I just recently bought another used M7040. Neither of these tractors have that trait. UDT in both. Now, having said that it doesn't get real cold in Texas, and I haven't gone through a winter with this one yet.

 

[MHarryE]

I haven't seen this tractor's specific clutch pack arrangement for the power shuttle, but in general the transmission in neutral has a forward and reverse clutch pack - a series of friction discs ithe flat driving plates between. The power from the engine is always being transmitted and the friction plates are turning but there is no hydraulic pressure clamping the drive discs to the driven disks so nothing turns. Move the direction control to forward and hydraulic pressure presses the friction plates against the driven plates and away you go. Now have a more viscous fluid in the clutch pack. The viscous fluid is now working as a friction material between the drive discs and driven discs so a little torque is transmitted, when viscous enough it transmits enough torque to slightly move the tractor but not enough to really rotate the tire so it breaks free. Static friction turns to dynamic friction which is lower and the tractor rocks back. Then this repeats until the oil warms enough to where it cannot provide enough friction to even slightly move the tractor. Dry clutches won't do this - friction coefficient of air is too low to transmit any significant torque. Wet clutches have this to some extent as long as one set of discs is rotating. Colder fluid = more tendency to transmit torque. Wider disc spacing (possibly from clutch wear) = less ability to transmit torque. Once inherited a machine where the friction between these plates was so great due to very high speed that it actually burned the paint off the housing. Does your transmission not have a neutral gear position where this will no longer happen? Does this phenomena happen only when the transmission is in gear but the shuttle is in neutral?

 

[r40kh]

MHarrryE

Great explanation and makes sense even to me although I'm dumb as a stump mechanically. To answer your question this is happening with both the main transmission and the shuttle in the neutral position ...I don't understand how this is possible. I've asked Kubota this question..but as yet no reply. Even worse this happened yesterday on start up with the ambient air temp at +15 C and the tractor sitting inside my garage although unheated. So if I'm correct in reading your post the explanation from Kubota is not possible as previously communicated by SDT?

 

[Tx Jim]

MHarryE
I agree with you. That's the reason I asked r40kh which hyd oil was in his tractor. To me rather than relying on dealer to solve the problem I would change hyd oil to SUDT and see if problem went away.

 

[Chilly807]

Unless he wants to make a trip to the US, we can't get SUDT in Canada. Instead, what we get is called Premium UDT, which as far as I can tell is simply UDT with a cold-weather additive package. I called several Canadian dealers right across the country a couple of years ago to see if SUDT was available in Canada, and it wasn't at that time. My local dealer thought he MIGHT be able to order it in from the US if I really wanted it badly enough, but the minimum quantity was 45-55 gallons (drum), if I remember correctly.

The part that would bother me would be the gremlin on my shoulder wondering if the tractor would ever do more than just rock back and forth and simply start moving. Unnerving if you're behind it trying to hook up an implement and the thing keeps moving slightly. Easy way to lose a finger or two..

Sean

 

[bigbull338]

i use kubota hydro oil in my tractors.on the mx5100hst i used caseih motor oil.i may use DELO oil in the 7040 when i change it but havent decided yet.

 

[Tx Jim]

Chilly807
Thanks for correcting me as I was unaware that SUDT was unavailable in Canada. I agree problems on a nearly new tractor makes one uneasy about the tractors future reliability.