Kubota M62 Drive Disengages By Itself

[RedNeckGeek]

I've been mowing on steep uneven ground the past few days and have a problem with the tractor coming to a stop all by itself while traveling in a straight line. Engine speed isn't effected; it's as if I've taken my foot off the Speed Control Pedal causing the tractor to stop. I've also seen this behavior when turning the steering wheel near or at full lock while in four wheel drive while moving. It's almost as if there's some kind of safety cutoff that senses the drive line loading up and disabling the drive train to stop the tractor.

Taking my foot off the Speed Control Pedal and pressing back down in the former direction of travel has no effect, the tractor just sits there. Sometimes pushing the Speed Control Pedal for the opposite direction will cause the tractor to move in that direction, and then the original direction starts to work again. Other times travel in both directions is disabled. I've been able to get it going again by turning the steering wheel from side to side. Sometimes I have to turn the engine off and restart to get going again.

This is more than just a PITA, it's also a safety problem when working on steep ground. The tractor doesn't take off like it was in neutral, but it will move downhill unless I hold it back with the brake. That could be real bad news if the Speed Control Pedal or steering wheel manipulation doesn't restore motion.

I've verified that this is not the Operator Presence Control in the seat acting up by taking my weight off the seat while the PTO is running. When I do, the engine dies unless I sit back down immediately. The engine will die when I lift my butt off the seat even when I'm not using the PTO, so I don't think the PTO has anything to do with the problem. And the problem still happens even when the Bushog is replaced with the box blade.

Sorry if my description is unclear; I'm really not sure how to describe what's happening. Maybe there's a ghost in the machine?

Anybody having similar problems on an M62 or other Kubota tractor?

 

[JWR]

Well, you have a long history of experience so I must assume you have checked the hyd fluid, made sure there is plenty of that, looked at (or replaced) the hyd filters so they are not clogged or restrictive, etc. At first blush it would seem like the main HST is gasping for fluid.

I'm guessing you used to use the L3240 for mowing and, when you got rid of it, are converting to using the M62 with bush hog for mowing...

Yeah, I sure agree you cannot stand to have this driveline stoppage going on when operating on steep ground.
Several questions (which may help others to understand your problem & maybe know what is wrong...)

• You are getting no red lights or dash indictors?
• Are the rest of your hydraulics operating OK when this disease hits (like FEL and 3pt lift?)
• Hours on this tractor ? Not real high?
• An M62 is not your typical mowing tractor -- more of a backhoe comfort zone. Did you have hoses and/or control linkages apart getting the backhoe off and the mower/ 3pt hitch hardware on?
• I am ignorant of the M62 controls: Is there a safety or setting control that you are supposed to use when the machine is parked and braced in position for doing backhoe work (to make sure the machine is'nt going anywhere while you are using the backhoe) ?? Is that a manual control or automatically invoked when using the backhoe?

Good luck.

 

[mikester]

Sounds like drive by wire issue, check out my post#11

Kubota L4701 Sometimes Stalls When Moving Forward with HST Pedal

This winter I've been having a problem with the tractor where it starts fine, and then when I press the HST pedal to move forward it stalls. If I leave off the pedal quickly it will not stall and RPMs will come back up. Interestingly, when pressing the pedal for reverse it does not stall. Is...

www.tractorbynet.com

 

[RedNeckGeek]

Thanks for the replies. Good questions; here are some answers:

No red lights or dash indicators.

But I haven't yet checked for trouble codes. I'll do that.

No issues with FEL or 3PH; I've experienced the lurching that low hydraulic fluid can produce and that doesn't seem to be the problem.

Right at 600 hours.

Hydraulic fluid is at the proper level, but the tractor is due for a new HST filter.

Haven't had the backhoe on in more than a year. It uses several dedicated hydraulic ports on the rear of the tractor.

There are two valves on the back each actuated by an odd lever that gets switched between backhoe and 3PH modes. I'll check to make sure they're set properly, but my past experience is that the tractor won't start if they are set wrong.

I searched the Owner's Manual for safety switches and lock outs, and the Operator Presence Switch in the seat is the only thing I found. It works by killing the ignition when weight is removed from the seat, and as mentioned, I tested it to make sure it is working as designed. When the tractor won't move, there is no change in engine RPM. In fact, while mowing, I set the RPMs to about 2200 with the hand throttle, and that RPM is maintained while the Speed Control Pedal has no effect.

One of the posts in the linked article mentions an HST safety switch under the left hand side of the tractor. I'll see if I can locate it. I do recall that the Speed Control Pedal uses mechanical linkage and cables, but that doesn't mean that there isn't a safety switch in there somewhere. Next time I have a chance I'll try digging through the shop manual to see if there is any mention of the HST safety switch.

For now, though, I'm pretty much done with mowing, at least until we get more rain. And I'm hoping we don't. A few years ago it kept raining into June, and I had to mow twice.

 

[RedNeckGeek]

Was out on the tractor again yesterday, and I'm pretty sure the problem is triggered by me shifting my weight around in the seat. I was doing a lot of work with the box blade that involved turning around to look backwards, and pushing on the back of the seat. Several times when twisting around into that position, or twisting back forward, the tractor stopped moving and I had to dance around on the Speed Control Pedal, or turn the steering wheel from side to side, to get moving again. It was pretty repeatable. It does not kill the engine like lifting my weight off the seat does, it just stops the tractor from moving. When I get a chance I'll get the parts diagram for the tractor out and see if there's some kind of sensor in the seat or seat support structure. Maybe there's an adjustment to make it less sensitive.

 

[rbargeron]

Sounds like maybe fluctuating HST charge pressure? The HST charge pump's oil cooler has steering fluid running through it too. Do the cooler and its tubing look ok?

 

[JenniferKubotaM62]

I’m having this exact problem, did you find a resolution?

 

[oosik]

Sounds like you need to tighten up the seat belt a couple notches.

 

[oosik]

Got me to thinking. Why doesn't my 2009 M6040 have a seat safety switch and your bigger M62 does. Mine - get off the seat - a buzzer will buzz about 8 to 10 times. That's it. This is only when the PTO is in use. Nothing changes - life goes on.

 

[Smokeydog]

Bumpy hillside mowing wasn’t compatible with a well worn seat and operator present safety switch on the M59. Bottom of seat plastic was also cracking. Also I need to stand to visually see some FEL operations. So I bypassed the safety switch with a push button switch. Switch gives a thief deterrent option if needed. I accept the responsibility. Operated many a tractor without such gizmos for decades.

 

[JenniferKubotaM62]

Bumpy hillside mowing wasn’t compatible with a well worn seat and operator present safety switch on the M59. Bottom of seat plastic was also cracking. Also I need to stand to visually see some FEL operations. So I bypassed the safety switch with a push button switch. Switch gives a thief deterrent option if needed. I accept the responsibility. Operated many a tractor without such gizmos for decades.

Bummer, my situations a bit different, I deleted my seat switch long ago. It’s not my engine dying like a safety switch issue, the engine stays running all movement just stops. I can turn off the ignition and turn it back on and it’ll go forward and backwards no problem and that works fine for a while and then I’ll be racing forward and high and then all of a sudden screech the thing stops moving, engine still running but no forward or back movement so I’m not sure what’s going on. I checked the connections at the throttle position switch at the foot pedal. I checked the swashbuckling or whatever it’s called swash plate cause I had issues in the past after washing it. If I return the throttle to the center position like I was gonna start it again and wait long enough eventually it comes back and I can go forward and back or I just shut the key off and turn it back on right away, it works definitely dangerous if you’re loading something up high and you need to move all of a sudden lose you lose your movement. This one’s got me stumped.

 

[Smokeydog]

My M59 key/ignition switch has been twitchy since I bought it 6-7 years ago. On the list to be replaced.

Think Mikester experience is worthwhile to consider.

 

[mikester]

Out of curiosity does it happen when you are in 4WD?

 

[rScotty]

Some ideas from my notes.... all of these have been discussed at some time in the past. None exactly match the symtoms Geek was having. In fact, I don't think they match any of the problems here. But they did happen, so are worth knowing.

1. WHITETIGER SAID (202?) :
Next time it starts acting up, leave the hydrostat pedal in neutral and engage the PTO. If the seat switch is causing the problem, the engine will die in about 1 to 2 seconds.
If engaging the PTO does not shut the engine off, step on the hydrostat pedal leaving the PTO ON. If it dies in about 1 to 2 seconds, the failure is the hydro pedal safety switch.

MIKESTER (2022) wrote:
The engine would lug to the point of stalling in fwd or rev with auto-throttle and stall-guard active. Going to full throttle and putting the HST pedal to the floor would get past the stall point and it would drive me back to the shop.
I bought some contact cleaner spray and cleaned the harness contacts from the servos and to the HST pedal. On the M59 the servo harness clips are a SOB to get at unless you have alien long skinny hands and fingers. I could only get at the top one off with a set of 18" forceps and a straw on the contact cleaner spray.
I let everything dry thoroughly, re-assembled and am driving around without any problems for over a month now.

rScotty (2014)
I was pushing a load of flood debris - rock and dirt - when the HS foot pedal suddenly felt different and the engine dropped to an idle. The foot pedal would move and HST worked, but only at an idle. It wouldn't auto-rev. Looking underneath, I found that the wire cable running from the engine governor to the auto-throttle lever had broken. The cable parted inside the housing, so the only was to find it was to se that one end of that cable moved and the other end didn't .
Actually I was glad to see that. My fear was that it was going to be something in the transmission or the magical software/electronic controls. A broken cable is something I can deal with....it being a typical control cable about like a motorcycle throttle cable or bicycle gear shift cable.
Luckily - or maybe just possibly due to good design - the M-59 auto-throttle cable runs in parallel with the hand throttle cable. So when the auto-throttle cable broke, the tractor continued to work in manual throttle mode until the $30 part arrived from Messicks. Not a whole lot of difference really, and none at all as a backhoe.
I had some years before had to replace the cable that allows the seat to spin around. It stretched and had no provisions for adjustment. Messicks said that was a known problem.

rScotty (2022)
Some years later, the seat safety switch was giving fits and the hand brake switch too. I could never tell when I could restart with the seat in the backhoe position. Sometimes pulling the hand brake lever allowed it to start, but eventually not. I bypassed both. In fact, removed the hand brake lever for more foot clearance. Someday I may reinstall it in a different location. Or not.

Hope everyone find the solution on theirs. When you do, please post what you tried and results for all of us.

Is anyone keeping a list of Kubota TLB owners?

rScotty

 

[RedNeckGeek]

I’m having this exact problem, did you find a resolution?

At this point, I've pretty much concluded it's a combination of the seat switch and something in the hydrostatic system that reacts to the differential torque between the wheels front to back and side to side when the steering is at or near full turn in 4WD.

I think the seat problem is exacerbated by the plastic cover getting stiff and cracking, so if I'm not centering my weight in the seat the engine has a tendency to cut out when I hit the go pedal.

I haven't found any reference in either the user manual or shop manual to anything in the hydrostatic system that would stop forward or rearward movement based on torque, but I can eliminate the problem by dropping out of 4WD on high traction surfaces like hard dirt, asphalt, or concrete.

Not a very satisfying answer, but I'm not sure where else to look.

 

[mikester]

The only time motion stops and no lugging occurs is when I'm in 2WD and my rear wheels are spinning...it's only happened when I'm using the 3PH and the rear end is light, usually when I have a load on my forks and I'm on a slope.

Are the people experiencing issues using auto-throttle or have you throttled up when it happens?

The other thing that pops into mind is if the LO-MED-HI range selector isn't fully in gear. I've shifted ranges and had no motion after because the shifter wasn't fully in the correct position. Shifting with the clutch in makes shifts easier and more reliable when switching ranges. I haven't had it pop out of gear on me while driving.

 

[rScotty]

Sounds like maybe fluctuating HST charge pressure? The HST charge pump's oil cooler has steering fluid running through it too. Do the cooler and its tubing look ok?

Yes, I'm wondered around along the same thoughts rbargeron is having....

Anytime the larger Kubotas have a problem that shows symptoms in which the power steering is connected to a HST problem, the first thing that comes to my mind is that the HST and steering share an oil supply. So I'd suspect the HST charge pump, charge relief valve, the cooler.... and also that smaller heavy special HST filter that Kubota sells - the rather expensive HHTA0-5990 filter.

That is an unusual filter in that it is an pressure type instead of a suction type, and it has a very small micron passing. So it really cleans the oil but can plug. There may be an aftermarket filter that fits the mounting, but I wonder if a less expensive filter is functionally close to the OEM part. Anyway, I'd suspect that particular filter first - and especially if a non-OEM filter or cheapo trans/hydraulic fluid was ever used there.

As a side benefit, that filter also provides ultra-fine by-pass filtration for the entire hydraulic system....which is probably part of the reason the HST+ is so durable.

And while a new filter was on the way, I'd look in the shop manual to see if the power steering and HST have pressure test ports. Amazon sells universal hydraulic test gauge kits for a few hundred bucks - or half that if you put a "Kubota-only" set of gauges together from parts.

rScotty

 

[Drstrangeglove]

I have banged a tree or two with the bucket a few times and lose the ability to go. An engine restart was the only was to get it going. The pedal went to mush each time like the linkage broke.

 

[rScotty]

I have banged a tree or two with the bucket a few times and lose the ability to go. An engine restart was the only was to get it going. The pedal went to mush each time like the linkage broke.

Tractor AI

 

[mikester]

I have banged a tree or two with the bucket a few times and lose the ability to go. An engine restart was the only was to get it going. The pedal went to mush each time like the linkage broke.

It's throttle by wire with mechanical linkage to the creeper lever for operating the HST pedal from the BH position.