HST reverse speed adjustable?

[terra66]

Hi, This is my first post, as this looked like the most active late model tractor forum I could find. I have a JD 4700 Compact hydrostatic drive tractor. My question is this-the reverse speed is only about half that of the forward when the pedal is pressed all the way down. Is this the way they make them for safety? It is not such a problem, but I have been using the loader more lately, and it is becoming frustrating. I bought the tractor used about 3 years ago, but it has always been like this. I did look under the platform for linkage adjustment, but could not see anything obvious. Any help is greatly appreciated.

 

[LBrown59]

Welcome: Glad U joined

 

[BigE_]

Slower than normal speeds in reverse -- you probably picked up an ex-rental piece of equipment. They do this for safety reasons. I wouldn't be surprised if your loader valve was turned down as well so that you won't be able to lift as heavy of a load (also for safety reasons).

On mine, there is a bolt under the HST pedal to keep it from moving too far. This should be adjustable.

-Steve

 

[nmu98]

My 445 lawn tractor is the same way. I have been trying to change it for some time. Mine is limited by the pedal.

 

[Egon]

My Kubota B7100 has an adjustable bolt and locknut that will limit the travel of the pedal in reverse mode.

Others may be different.

 

[mwb]

I think you will find that most HST's will be a little slower in reverse; this is because of the design of the hydraulic motor. The design is optimised for best power and speed in one direction - and doesn't work as efficiently in the other.

My new Montana is slower in reverse, probably about 25% slower than forward.

Cheers,
mike

 

[john_bud]

If I need to go faster in reverse, I grab a higher gear ratio. More levers to play with, but ....

jb

 

[schmism]

ive been told that on my TC33 the only reason it doesnt go as fast in reverse as fwd as there is a limiting stop (bolt head) that keeps the pedal from moving farther backward. should you elimiate the stop, it would go just as fast backward as forward.

 

[mjncad]

I just took a look at my shop manual for the 4200 - 4400 series of tractors and the max ground speeds for each range were identical regardless of direction.

Therefore I have to assume the same is true for the 4700. Also, I seem to recall that there should be a speed decal on the fender next to the range selector lever.

As others have said, you may have gotten a unit that was originally a rental and someone messed around with the inner workings to make the lawyers happy.

 

[patrick_g]

When new, my Kubota Grand L 4610HSTC was (subjectively, I didn't use a stop watch) as fast backwards as forwards and was a true delight doing loader work.

My fuel tank developed a leak in the seam (well out of warranty) and Kubota sent my dealer a replacement for free. I paid R&R labor. Seems that when they built this little cab tractor they started with a fuel tank and built a tractor around it. They had to remove the cab and basically disassemble the tractor to change the tank. Subsequent to this fuel tank R&R my reverse speed was less than 1/2 my forward speed and slow enough to be a PITA when maneuvering. Two trips back to the dealer later and they have no clue apparently but tractor still backs slower than going forward, although not 1/2 but probably 3/4.

This is the single greatest negative factor regarding my tractor. I use my tractor hard and a slow reverse speed is a true PITA. Sure you can shift to a higher gear but first you have to come to a complete stop so that ends up taking more time that just backing slowly in many back and fill maneuvers. Having to stop to shift gears over and over and over and over when doing FEL work is totally unacceptable and stupid.

When I get to a lull in my tractor use I will take to to dealer "B" and see if their mechs can get it right.

There is nothing wrong with having equal forward and reverse speeds with a hydrostat. It is a GOOD thing.

Pat

 

[Egon]

Reverse speed control on a B7100 HST.

Parts # 90 and 100, bolt and locknut are all there is to it.

 

[dfkrug]

I think you will find that most HST's will be a little slower in reverse; this is because of the design of the hydraulic motor. The design is optimised for best power and speed in one direction - and doesn't work as efficiently in the other.

What, specifically, do you think is different about the hyd motor in the
HST, rev vs fwd?

I rebuilt my first HST this year and the HST's axial piston motor looked totally
symmetrical. HSTs DO have separate relief valves for fwd and rev, but they
had identical pressure specs (about 5000psi).

I am not saying you are wrong. I just did not find anything that indicated
that they had any differences, fwd and rev. Now pedal limiters...those
I have seen.

 

[KevPH1]

JD 4115: You must remove the right floor board for access to HST linkage.

(17 mm wrench) Remove and grind the shaft limiter linkage stop. (On reverse side only) or front facing stop surface. Grind a little, then reinstall to check. Grind a little more,than recheck. etc.

This will allow the HST shaft pivot arc to increase, hence faster reverse speed.
Hope this helps.