RTV900---Is there an interlock between brake and transmission?

[chilibit]

Let me describe the issue and I did try searching.

I descend a long grade to my farm gate, hang a U-turn and yank the hand brake and kill the motor. Gate closed I shift to neutral, start the motor and feed the accelerator and simultaneously release the hand brake. It does not want to move off up the hill. I have owned two 900s and this is not what I think is normal.

Let the foot off accelerator, mash the foot brake (first push is spongy and goes 3/4 to floor and second push is hard and high) then move foot from brake to feed the accelerator and it will engage normally and I motor back up to the top of the ridge.

There are likely two separate issues. A leaking master cylinder perhaps on the mushy pedal side but why does the foot brake activation seem to disengage some kind of transmission lock (loosely used term I know)? How the leaking MC could lose fluid in less than a minute puzzles me. Frankly, I seem to recall that starting off after only using the hand brake was a non-issue in the past.

Any insights appreciated.

Vince

 

[texasjohn]

Yes, they are interrelated.

See this thread. http://www.tractorbynet.com/forums/atvs-utility-vehicles/154987-kubota-rtv-900-problems.html

See post 11...copied below.

I am a kubota tech at a dealer, so I dont have anything for you to read about it, but what I know is from experience. I have to say, 90% of the shifting problems that I have run into are due to operator error. If you dont know how to shift the trans properly, you will have a problem. It all comes down to taking the pressure off the driveline so you can shift the transmission which is done two ways. The early models did not have the pressure release knob on the dash, so if you stopped for a second with your foot on the brake pedal, and then push hard before you shift, it will just slide out of gear and into the next. The brake linkage is also tied into the hst pressure release valve. The newer ones had the knob you could pull to do the same thing, but still had the brake pedal tied into it like the earlier ones. Now on the new ones, there is no knob anymore, just the brake pedal again. If there is one thing I always tell rtv owners and operators, it is to just have a little patience with the shifting. With a little less speed, they shift perfectly every time.

 

[MHarryE]

If I understand you correctly your problem is not shifting into gear but it not propelling once you shift it back into gear after having restarted. I tried this on mine and didn't have any problem going but maybe I didn't stop on as steep grade as you are referring to. Is it normal practice for you to stop the engine when closing the gate? Normally I just apply the hand brake or at most shift to neutral, then applying the handbrake. Mine is a 2012 model and from reading back it looks like they made several changes over the years so it could be a difference between our models.

 

[chilibit]

If I understand you correctly your problem is not shifting into gear but it not propelling once you shift it back into gear after having restarted.

Yes, it has to do with the HST engaging and moving forward. I agree with the Kubota tech about pace and drive line bind-up. Those are different but real quirks. Yes, I could leave it run and in gear and dodge the problem except..... And naturally it bugs me not to understand why.

This comment "The brake linkage is also tied into the hst pressure release valve." matches my observation. I still think the soft pedal is related to this somehow.

Thanks for the comments and insights. Much appreciated.

 

[Gator6x4]

Let me describe the issue and I did try searching.

I descend a long grade to my farm gate, hang a U-turn and yank the hand brake and kill the motor. Gate closed I shift to neutral, start the motor and feed the accelerator and simultaneously release the hand brake. It does not want to move off up the hill. I have owned two 900s and this is not what I think is normal.

Are you stopping the forward motion of the unit by using the brake pedal to stop and then applying the hand brake and turning the ignition off, or "Yanking the hand brake to stop the unit and kill the engine"? If, yanking the hand brake to stop the unit and simultaneously kill the engine, you might trying using the foot brakes to stop, place unit in neutral, set the hand brake and dismount.

 

[chilibit]

Yes, this happens when I do not use the foot brake to stop but merely yank the hand brake and jump. Forward motion is drained by the incline. I would be nervous about leaving it in neutral on my grades. Using the foot brake is the key thing I guess but in eight years it has never raised its head. Now it is. I will try not killing the motor tonight when I go for the mail and see if that changes things. Thanks.

 

[texasjohn]

hmmmmm.....if you have had the machine for numerous years and operated it the same way all this time, and this behavior is new....then I think something has changed in the vehicle. I don't know if it is a problem, or "just different."

By the way, you do exactly what I do at a gate, for the same reason...slope. I don't recall ever having a "soft" brake pedal followed by a hard one...may happen one of these days

 

[chilibit]

Rather than leave this hanging which seems rude, let me just say that I will pursue the soft brake pedal and plan to use the foot brake routinely as opposed to not. Likely a good habit regardless. Thanks for the thoughts and time.