With hydraulic clutches... does shifting at lower RPM help?

[will-max dairy]

So... this newfangled tractor I've had for the last five years. It has hydraulic clutches. It's how the reverser thingy works. Love it.

But, I usually try to use the reverser, or shift at a lower RPM and then rev up once the transmission is engaged in the new gear.

But... maybe that is old school thinking. Maybe I'm thinking about how that may have been better for old tractors with the clutch engagement mechanically controlled by my foot...

But with these hydraulic clutches, wouldn't higher RPMs mean more hydraulic pressure and a more definitive hydraulic clutch engagement with less slipping?

It seems that this is how the tractor was designed. If you just leave the RPMs up and, say, use the reverser, the transmission doesn't really slip at engagement or try to feather, there is a slight delay and then a very definite engagement (sometimes causing a minor spinout of the wheels on soft ground).

Maybe I'm confusing old school thought with newfangled tech?

 

[Jim.ME]

Are you talking about a hydraulic clutch reverser, hydraulic range clutches or both? It helps the tell what machine you are talking about. They may not all be the same.

What does operator's manual tell you?

 

[will-max dairy]

It's a Mahindra 6075. They call it an HST "Hydrostatic Standard Transmission"

It has three ranges, five gears each range. They all shift with a clutch pedal; but the clutch pedal isn't just a straight linkage to a throwout bearing... it's a hydraulic clutch (that they actually call an "inching pedal").

The reverser is just a lever, no pedal engagement is needed. It has Forward-Neutral-Reverse... and can be used in any gear. (although... I have yet to use reverse in Hi Range, 5th Gear...) Whenever you use the reverser, it uses a hydraulic clutch to disengage then re-engage the transmission as you go through neutral... to the other direction.

All I know is... you definitely need hydraulic pressure for the tranny to work. In very cold weather, I often have to start and let the tractor warm up for ten or fifteen minutes. Otherwise, you wait f-o-r-e-v-e-r... for it to shift...

 

[will-max dairy]

I've been through the manual, but don't remember if it had recommendations, or what they were. Should probably look through it again.

 

[used red MN]

No matter what type of clutch or engagement unit there is in use any time the driving parts and the driven parts are closer to the same speed the less wear that will occur. Most “wet clutches” such as the clutch packs these types of unit uses will withstand slipping or engaging at different speeds with less wear than a dry clutch.
Personally I wouldn’t recommend running it full throttle or at any engine speed with NO consideration to how much it abuses the clutch.

 

[will-max dairy]

No matter what type of clutch or engagement unit there is in use any time the driving parts and the driven parts are closer to the same speed the less wear that will occur. Most “wet clutches” such as the clutch packs these types of unit uses will withstand slipping or engaging at different speeds with less wear than a dry clutch.

I mostly thought about this watching a neighbor use their skid steer to move snow. They just kept the throttle at full bore...back, forth, back, forth...

Myself, when I use the Mahindra on the loader... I set the hand throttle at, say 1500... and do any shifting at those RPMs... then use the foot throttle to rev up, once the transmission is engaged.

When my brother drives the tractor, he just leaves the throttle full bore... forward, reverse... shifting gears... whatever... (of course... he stalls the tractor every once in a while like this... the hydraulic clutch does not feather... so if you pick too high of a gear, thinking that RPMs and feathering are gonna do the trick... think again)

 

[wore out]

So... this newfangled tractor I've had for the last five years. It has hydraulic clutches. It's how the reverser thingy works. Love it.

But, I usually try to use the reverser, or shift at a lower RPM and then rev up once the transmission is engaged in the new gear.

But... maybe that is old school thinking. Maybe I'm thinking about how that may have been better for old tractors with the clutch engagement mechanically controlled by my foot...

But with these hydraulic clutches, wouldn't higher RPMs mean more hydraulic pressure and a more definitive hydraulic clutch engagement with less slipping?

It seems that this is how the tractor was designed. If you just leave the RPMs up and, say, use the reverser, the transmission doesn't really slip at engagement or try to feather, there is a slight delay and then a very definite engagement (sometimes causing a minor spinout of the wheels on soft ground).

Maybe I'm confusing old school thought with newfangled tech?

Dunno, specifically about your tractor, but typically machines with wet clutches use regulated apply pressure, which is probably reached a little above slow idle, and remains pretty constant/regulated as the engine is revved up.

 

[will-max dairy]

Dunno, specifically about your tractor, but typically machines with wet clutches use regulated apply pressure, which is probably reached a little above slow idle, and remains pretty constant/regulated as the engine is revved up.

This would lean me towards thinking that the clutch engagement is independent of RPMs at most normal operating speeds;... so the engagement would be a little easier on the clutches, if you're not trying to make the tractor jump from zero ground speed to full RPM ground speed, as soon as it engages.

 

[G1000VISTA]

I mostly thought about this watching a neighbor use their skid steer to move snow. They just kept the throttle at full bore...back, forth, back, forth...

Skid loaders are a hydraulic pump and motor versus a transmission and clutch. No clutch to wear out; just a swash plate. Wont hurt a skid loader at all to run it that way. Tractor's are a different story.

 

[Tx Jim]

Lowering engine rpm's/mph lowers stress applied to drive components when changing directions of tractor.

Most hyd shuttle(reverser) tractors have a spring loaded damper clutch to help absorb shock of tractor direction changes & depressing foot pedal is just opening a hyd valve.

IMHO full hydrostatic drives are designed better to handle tractor direction changes than a hydraulic engaged clutch such as in shuttle shift tractors but hyd shuttle is much better than sync shuttle which requires a manually operated clutch plate.

 

[Jim.ME]

I found a Mahindra 6075 Operator's manual online. I don't know if it is right for yours or not. From that one it sounds Like there is no clutch just a hydraulic valve that works to disengage the gear train to shift the range and speed gear boxes. It does not have to be used to shift the reverser. I also found a chart of recommended warm up times for the transmission/hydraulic oil based on temperature.

A study of your tractor's Operator's manual might yield more detailed information.

 

[Tx Jim]

Hyd valve that clutch pedal is attached to when pedal is depressed stops pressure hyd oil flow to forward or reverse clutch pack depending on location of reverser control handle location.

In other words forward or reverse hydraulic clutch pack takes the place IE performs the task of regular traction clutch disk.

 

[will-max dairy]

I found a Mahindra 6075 Operator's manual online. I don't know if it is right for yours or not. From that one it sounds Like there is no clutch just a hydraulic valve that works to disengage the gear train to shift the range and speed gear boxes. It does not have to be used to shift the reverser. I also found a chart of recommended warm up times for the transmission/hydraulic oil based on temperature.

A study of your tractor's Operator's manual might yield more detailed information.

indeed... welcome to my ADHD world... thanks!

That must be why they call it a "Hydrostatic Standard Transmission"... sounds like there is no actual "clutch" in a classic sense. It was ... an oxymoron to me why they would put "Hydrostatic" and "Standard" in the same sentence...

 

[Bob Bancroft]

So... this newfangled tractor I've had for the last five years. It has hydraulic clutches. It's how the reverser thingy works. Love it.

But, I usually try to use the reverser, or shift at a lower RPM and then rev up once the transmission is engaged in the new gear.

But... maybe that is old school thinking. Maybe I'm thinking about how that may have been better for old tractors with the clutch engagement mechanically controlled by my foot...

But with these hydraulic clutches, wouldn't higher RPMs mean more hydraulic pressure and a more definitive hydraulic clutch engagement with less slipping?

It seems that this is how the tractor was designed. If you just leave the RPMs up and, say, use the reverser, the transmission doesn't really slip at engagement or try to feather, there is a slight delay and then a very definite engagement (sometimes causing a minor spinout of the wheels on soft ground).

Maybe I'm confusing old school thought with newfangled tech?

My backhoe and dozer both have a hydraulic reverser. One is manual shift, one is power shift. Even though both have torque converter drives which will cushion things a bit, I idle them down when changing direction, one with an accelerator pedal, one with a de-accelerator pedal.
My compact track loader is hydrostatic drive, so speed and direction changes can occur at any engine speed without issue.
On any of my power shift farm tractors, I always use the "clutch" when changing direction.

 

[used red MN]

When my brother drives the tractor, he just leaves the throttle full bore...

If it were my tractor either the brother would change his method of operation or he would no longer operate the tractor even if he was doing work for me the tractor owner.

 

[will-max dairy]

I found a Mahindra 6075 Operator's manual online. I don't know if it is right for yours or not. From that one it sounds Like there is no clutch just a hydraulic valve that works to disengage the gear train to shift the range and speed gear boxes. It does not have to be used to shift the reverser. I also found a chart of recommended warm up times for the transmission/hydraulic oil based on temperature.

A study of your tractor's Operator's manual might yield more detailed information.

Where did you find the chart of warm up time vs temperature.

I went front to back in my print manual when I got home tonight, and didn't find anything like that.

 

[will-max dairy]

So... with an "inching pedal" and a hydraulic valve... what are the wear items?

By the way, thanks for the replies... this has been a gold mine of comments about all of the various mechanisms that could be found nowadays...

 

[Jim.ME]

Where did you find the chart of warm up time vs temperature.

I went front to back in my print manual when I got home tonight, and didn't find anything like that.

As I said, I don't know that is the correct manual for your 6075. The warmup info is on page 102 of this manual.

 

[will-max dairy]

As I said, I don't know that is the correct manual for your 6075. The warmup info is on page 102 of this manual.

Interesting. Page 102 of my print manual is "Troubleshooting"... with nothing about this particular subject. I downloaded a shop manual a couple of years ago, for the wiring diagram... I'm going to check that, to see what it says...

Thanks

 

[Tx Jim]

So... with an "inching pedal" and a hydraulic valve... what are the wear items?

By the way, thanks for the replies... this has been a gold mine of comments about all of the various mechanisms that could be found nowadays...

Inching pedal only controls a hyd valve. The mechanism that acts the same as a traction clutch on a hyd operated trans is the forward or reverse clutch plates in hyd reverser type forward or reverse clutch packs. JD rowcrop tractors with a Powershift trans also have an inching pedal that controls a hyd valve that when depressed stops hyd pressure applied to clutch packs.