M7040 Problem

[r40kh]

I have a two year old M7040 power shuttle. I noticed this week when I started the unit the tractor would rock back and forth during warm up with the idle rpm set at 1400 rpm. Both the main transmission and shuttle were in neutral at the time.When the tractor is warm this does not occur. I have advised my dealer and they agree that shouldn't/can't happen but advised that I should keep the parking brake on while sitting unattended. That doesn't solve anything. What's funny is that if I take the idle rpm to 2000 rpm or lower it to 1000rpm the rocking stops. I did a search on this forum and found a thread called "jerky hydraulics" that mirrors my problem exactly. Unfortunately the thread was never updated as to what was found to be causing the problem. Anyone else ever experience this? and if so what was the solution. I have one month of warranty remaining and I would hate to have a problem with these symptons that may lead to a more serious problem after the expiration of the warranty..although because I have reported the problem to the dealer I would expect them to look after me..I hope

 

[Tx Jim]

Which hyd oil do you use? If main trans is in neutral then it appears to me this must be "cold oil" related. I don't ever lock my M7040 brakes down for parking because Kubota was "too tight to install a warning light/buzzer" and I don't want my employees driving around with brakes applied.

 

[unclebilly]

Take it in and get the dealer to sort it under warranty while you still can. It could be crap in your shuttle or a bad seal so.

 

[TripleR]

If you can't get them to fix it, document everything, we had an engine replaced on a John Deere after the warranty had expired because it was reported well in advance of the expiration, had a really good dealer too.

 

[r40kh]

I have a good dealer and I expect that he will look after me..but what he's saying is that they never heard of this problem. I'm assuming that if someone else had the problem as indicated in a thread on this forum that the issue would have been reported to Kubota and there should exist some information on the cause and solution in their data base. The dealer wants me to try it again to see if the problem repeats...of course its +15 here today and I only have the problem when cold so I'll have to wait.

 

[TripleR]

No argument there, but some problems may be so rare records are hard to find, who knows. I remember an issue with a "clunking noise" on a M7040 owned by NICOT that was not resolved. I kept in touch with him for a while and he finally traded his off.

 

[r40kh]

Tx Jim...The dealer did my last service so Kubota oil all around. That service was done at 60 hours and I have just over 100 now. I agree not having a warning alarm/light when the brake is on sucks. Like you I seldom use the brake

 

[Tx Jim]

I should have been more explicit on type of oil UDT or SUDT?

 

[r40kh]

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

 

[Tx Jim]

I'm glad I live where the temperature doesn't get low enough so that my M7040 sits still when engine is started.

 

[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.