Backhoe Kubota Kx71-3 trackhoe travel speed failure

[AmberBear]

Hi All,
When I try to use trackhoe travel speed (faster than a slow walk), it is intermittent. It worked the first few years I had this equipment, but now kicks in and out, especially when traveling up any sort of incline. The tracks (rubber, not metal) are clear, properly adjusted and lubed. Any comments on what I have neglected or overlooked?
I sometimes have to travel nearly 1/4 mile to get to my worksite. Is that just too far for travel speed? Do I have to load it onto a trailer for that distance? If so, why have a travel speed at all?

Suggestions or comments would be most welcome.

 

[MHarryE]

I am not sure how yours works - this is how a Cat of that size works. The travel motors are 2 displacement. Holding down a pedal activates a switch that allows hydraulic oil flow to a piston inside the travel motors reducing the swash plate angle so it takes less flow to turn the motor one revolution. However torque is pressure X displacement so when you shift to a smaller displacement the pressure goes up. It also takes more power to propel at the higher speed which increases the pressure even more.

First thought on losing travel speed would be an intermittent electric current loss to the two speed valve; however, you say it is worse on an incline. The internal piston is pushing the swash plate to the different angle. Pressure in the propel circuit tries to push the swash plate back to the steep angle. If the shift pressure us too low the propel pressure might kick the swash plate back. That would explain an intermittent speed loss that gets worse on inclines.

1/4 mile is a long distance for a mini excavator, especially if you do it a lot. I load mine up and haul it if I need to move that far multiple times, like daily to the site and then back at the end of the day. I'm not sure how yours is though but having toured several plants where they make track motors, I'm leary about running them too long at high speed although I admit to being rough on mine. Travel speed heats my hydraulic oil much faster than digging and heat kills.

 

[AmberBear]

Thanks Harry,
My problem was indeed electrical. I had suspected as such, but everything checked out when I tested it. Your support made me recheck and discover a connector that was slightly out of spec and worked fine during test, but when bypassed and track hoe was driven the problem went away. I replaced the connector and the track hoe works normally. Sorry it took so long for me to reply, I wanted to wait until the snow melted...

Thanks again for your support.
Mike