B7500 hydro only goes in reverse

teach · Jan 4, 2018

I have a question I am hoping someone out there in Kubota land might be able help with. I used my hydro B7500 about two weeks ago during 25-35 degree weather with no issues. Then, after not using it for a week, I took it out again, but the temps were now in the single digits here in RI. It will only move forward in 2WD on level ground, either in high or low gear. As soon as I start up the slightest incline, it simply stops moving. It will continue moving forward if I step on the pedal to engage the post-rear traction, or if I put in 4WD. Also, it moves in reverse in 2WD just fine, even up a an incline. Any ideas where to start looking before I take it to my dealer/mechanic? I did have all the hydro fluid and filters changed at the end this past summer and have not put a lot of hours on it since, but I do use it every weekend for brief periods of time.

Any suggestions or ideas are much appreciated. Thanks!
Teach

Mendonsy · Jan 5, 2018

I don't have any answers other than possibly something interfering with the foot pedal movement. I will definitely be interested in what you find out so it never happens to my B7500.

Volfandt · Jan 5, 2018

Three things to check.
1) While the problem is occurring check and make sure the wheel isn't spinning in the the tire. Low tire pressure coupled with slippery conditions can cause this.
2) I believe the B7500 series tractors have some kind of wedges used to secure the wheel to the axle. IIRC they are designed to make moving the wheel in/out easier. In any case make sure all bolts associated with the wheel/axle assembly are good and tight.
3) Make sure your hydraulic fluid level is correct. Are you using SUDT or UDT. SUDT or SUDT2 is better in cold weather conditions as they are multigrades. UDT is a single weight.

Good luck

Jeff F. · Jan 5, 2018

Please check that the parking brake isn't set

s219 · Jan 5, 2018

Wheel spinning inside tire is my guess.

aczlan · Jan 5, 2018

s219 said:
Wheel spinning inside tire is my guess.

Mine as well, on our B7500 even if you took the wedges completely out you would not be able to spin the axle inside the hub for the wheel so that's not it.
If the wheel rotates when you put it into 4 wheel drive or hit the differential lock that to me would say that either the rim is spinning inside the tire or else something is broken inside and it's going to be very expensive.
Bringing the rear tire pressure up to the sidewall rating is probably the fastest and easiest way to stop the rim from spinning inside the tire.
I would also take a crayon or something and draw a mark from the rim to the tire so you can see if the rim rotates in relation to the tire.
Aaron Z

robertm · Jan 6, 2018

aczlan said:
Mine as well, on our B7500 even if you took the wedges completely out you would not be able to spin the axle inside the hub for the wheel so that's not it.

On my past B7500, the axle couldn't spin in the hub if it wanted. The rear axle shafts were hexagonal, allowing you to pull pins and slide the rim in/out, or reverse the wheels for different tracking widths.

teach · Jan 6, 2018

Well everyone, as it turns out, the rim was spinning inside the tire! I would never have guessed that this could happen. It has been extremely cold here in Little Rhody lately, and that combined with a faulty valve stem, allowed the tire pressure to drop off just enough to let a little beat juice leak out, thus making he rim/tire seal slick enough to make the rim spin. It was a messy fix, but a relatively easy one once I got the shop up to a comfy 50 degrees (supposed to go down near zero tonight!). I was concerned that it was something internal and expensive. Thank you all for your suggestions and ideas.
Teach