Kubota M62 Drive Disengages By Itself

[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.