ttr 4400 HST - moves great to backward but moves weak to forward ? some problem here

[joaorodrigues88]

hello, I'm a new owner of a 2007 antonio carraro ttr 4400 hst, this week testing the machine I observed that the tractor don't have the same power and speed when it's move to front compare when I press the pedal to rear. I have a great speed and horse power when vehicle moves backward and poor power and speed when moves forward! testing on a climb, the tractor was struggling, and had no strength to climb, I accelerated but it's like as if the clutch was slipping, testing the same climb move backward, it climb it with no problems... Why this happens? I thought it might be the clutch, but it works well in reverse gear... If someone with experience in hydrostatic transmition can help me?
I'm already search on this forum for a similar problem and looking for the service manual on the internet, with no success...

Regards
John

 

[Wagtail]

G'day Mate and welcome to TBN from Downunder./G'day Mate e bem-vindo ao TBN da Austrália.

A question first... it sounds as though the forward and reverse pedal is a single 'rocker' type, yes? (as opposed to individual forward and reverse pedals)

Seeing as your hydraulics work perfectly well in reverse (which means that all of your hydraulics works) the first thing that I would look at is the linkage from the forward 'half' of your pedal to the transmission (or wherever it goes). Something is loose and the movement of the pedal (in that direction) isn't happening.

Enjoy the site./Aproveite o site.

 

[oldnslo]

Does the engine sound like it is working while driving forward?


Do you get different noises from the HST while driving forward Vs in reverse?

I would expect this model to have relief valves for forward Vs reverse. If the forward relief is stuck partially open it will limit the drive power and cause excessive heat in the system.

Do you a service manual for this machine?

 

[LD1]

Some HST tractors allow more pedal travel going forward. Meaning a faster speed.

Limited backwards pedal travel limits backwards speed by basically forcing you to NOT push the pedal all the way.

Have you ever driven a HST before. It's backwards from conventional wisdom in that when you run out of power, the first reaction is to push the pedal more, and thats the opposite of what you want to do. Try not pushing the pedal as far and see what the power is like

 

[joaorodrigues88]

Hello Wagtail, thank you!
Yes, the pedal it's a rocker type.
I think it's important to say that all the fluids and filters were changed at the official shop. And all the hydraulics works great.
tomorrow I will check for some bad linkage, But seems that I have no access to this, because the axis of the pedal goes directly to the inside of the "box".

 

[joaorodrigues88]

Hello Oldnslo

The motor runs normally, I test the forward in low and high rpm, and the engine works well, but I hear the transmission struggling.

I can't find the manual... Will be a great help because It's the first time I drive a hst and I have no ideia how it works, usually where I can find this relief valves?

Thank you

 

[joaorodrigues88]

LD1

This tractor it's reversible, so I think there are no limit, Now I have an idea ! I will try to test this tractor with the reversible mode, so it will invert the hydraulics of the rocker pedal, and I will check if in reversible move it will moves great to forward ( backward in the normal mode) and poorly in backward.

I will try to make a movie tomorrow to show you guys !

thank you for your help

 

[oldnslo]

Hello Oldnslo

The motor runs normally, I test the forward in low and high rpm, and the engine works well, but I hear the transmission struggling.

I can't find the manual... Will be a great help because It's the first time I drive a hst and I have no ideia how it works, usually where I can find this relief valves?

Thank you

Since this tractor is reversible it should drive the same in both forward and reverse so I doubt it is your technique since it operates fine in reverse.

Relief valve location: With out a parts diagram it would be difficult to say. They are almost always located in the HST housing.

 

[joaorodrigues88]

I think there are no technique in the pedal, it's just step the pedal, and accelerate in the handle accelerator.

I will try to drive in reversible mode to see if the problem with forward maintain or change, if it's a problem in the linkage of the pedal it will reverse the problem, right?

 

[joaorodrigues88]

The "speed fix" device, seems not working on the tractor, I move it when the tractor is running and it don't block a constant speed... can it have any relation with the forward ?

 

[Spanner]

Yes, it can.
"Speed Fix" is a type of Cruise Control. It is electric operation via dashboard button and internal components. You may need dealer support for this issue.

These are versatile machines and the swiveling seat concept is very interesting.

When you tried in Reverse-Mode, did the problem reverse?

 

[oldnslo]

Since this has the swivel seat and controls it could be electro-proportional controls on the HST. If this is not getting the correct signal it could make the HST weak in one direction and operate fine in the other direction.

Like Spanner asks did this problem follow the reverse mode of operation?

 

[joaorodrigues88]

today I test in the reverse mode, and no changes... the problem is the same. The only difference in the mechanics, it's a reversible valve for the direction.
I looked under the tractor to check the linkage, and the only thing I can see it's 2 pistons that are individual pressed by the movement of the pedal, I think it's hydro valves.
I think I need to call to the local service..

 

[oldnslo]

today I test in the reverse mode, and no changes... the problem is the same. The only difference in the mechanics, it's a reversible valve for the direction.
I looked under the tractor to check the linkage, and the only thing I can see it's 2 pistons that are individual pressed by the movement of the pedal, I think it's hydro valves.
I think I need to call to the local service..

Are you saying there are two different valves the foot pedal operates? I.e. one on each side..

If yes then this sounds like the pump is hydraulic pilot operated and yes you will probably have to contact the local service company. I believe you stated all the fluids & filters were change Who changed all the fluids and filters?

 

[joaorodrigues88]

The filters and fluids was changed by the official local shop.
I will back with news soon.
thank you

 

[tonuadrian]

Did you solved? I have almost same problem