Geared trannys-more low end torque than hydro ?

[dirtwhisperer]

I don't want to start another war on hydro versus geared - but I do have some questions regarding the two. At low Rpm's - will a geared synchro shuttled tranny have more torque than a hydro tranny since the hydro wouldn't be flowing as many GPM at lower rpm ranges ?
Second question - if you are using a FEL to load stones - how can you "speed up" to ram hard into the stone pile with a syncro tranny ? I would think this would be easier with a hydro tranny or is there a technique to use with geared synchro shuttle trannys to do this - I'm thinking you use a high speed gear then clutch in and out to give you that ability to ram the bucket into the stone ? Any help from some of you with some seat time ? Thanks.

 

[Bob_Skurka]

<font color="red"> At low Rpm's - will a geared synchro shuttled tranny have more torque than a hydro tranny since the hydro wouldn't be flowing as many GPM at lower rpm ranges ?
</font>

I'm under the impression that torque is a function of the engine, not of the transmission. There is a point in the RPM range of the engine that allows for peak torque (which may actually be different than when the engine hits peak hp).

As for using a hydro for loader work, most industrial applications use loaders with hydro transmissions because hydro makes for faster work with a FEL and since time is money, businesses buy the equipment that works the fastest.

 

[cowboydoc]

<font color="green">will a geared synchro shuttled tranny have more torque than a hydro tranny since the hydro wouldn't be flowing as many GPM at lower rpm ranges ?
</font>

It all depends on the transmission. The newer deere's have the load transfer on the hydro. This is what the bigger and more expensive hydros do. Basically when you go into a pile on a non-load transfer hydro you will stall out. My skidsteer does this. On the higher end hydros you have the load transfer and the hydro will step down to match the load you are trying to do. Instead of stalling you transfer more power to the wheels and motors. If you have this option, like alot of backhoes and front end loaders, you have a superior transmission to the gear. If this is your primary use for the tractor then it's definitely smarter to go with the hydro.

As far as having the rpms up to cycle the pump you need to just change gears. If I'm running in say B range doing loader work I'll shift down into 1st or 2nd to go into the pile, at this range I won't stall and will spin the tires before a stall, and back up to 4th coming out of the pile. On the power reverser I'll shift and flip the reverser at the same time. Once you get proficient at doing it it doesn't take any time at all. This lets you keep your rpms up. Myself I like the extra work. If you don't then a hydro would be the way to go. Not many of us that can't stand to lose a few extra pounds though. /forums/images/graemlins/wink.gif

 

[rambler]

A grear train loses about 10-15% efficiency, while a hydraulic power setup loses more like 25-30% of it's efficiency. I'm not sure torque is the proper term? But there is power loss.

As the other person said, time is money, so construction firms spend more on a properly sized hydro unit, to get the fastest throughput from workers.

As a one-man homeowner operation, the cost/ output/ ease of use relationship is much more difficult to determine - only you can judge for yourself.

Me, I'm real uncomfortable & clumbsy with & cringe at the power loss & wasted $$$ of a hydraulic tranny. I'd rather save some money & get a good solid gear tranny that is easier for me to control. But, that is just me - I've been driving gear tractors since I was 7 on the farm, and prefer manual trannies on my pickup as well. Others can & do feel differently. No problems with that. /forums/images/graemlins/smile.gif

--->Paul

 

[MicroPilot]

</font><font color="blue" class="small">( ...Second question - if you are using a FEL to load stones - how can you "speed up" to ram hard into the stone pile with a syncro tranny ?)</font>

I was under the ipression that ramming was a no-no. I just gear down low, and move into the pile while working the FEL curl and lift to get a full bucket. Never had any problems getting a good load everytime.


</font><font color="blue" class="small">( ...I'm thinking you use a high speed gear then clutch in and out to give you that ability to ram the bucket into the stone ?)</font>

Clutching like this is another no-no.

 

[Bob_Skurka]

<font color="green"> A grear train loses about 10-15% efficiency, while a hydraulic power setup loses more like 25-30% of it's efficiency. I'm not sure torque is the proper term? But there is power loss.
</font>

Rambler, I am under the impression that the difference between gear versus hydro is only about 5% of the total. Seems to me there was a thread on this topic awhile back, provided some documentation on the loss to a hydro transmission. I might be wrong, but I think it has been pretty well established the hydro loss is far less than many think, but it does exist.

 

[_RaT_]

Bob, I must agree with you. After driving gears and hydro's and then testing JD's, NH's and Kubotas gears and hydro, there is no possible way the hydro loss is anywhere near that compared to a gear as Rambler eluded too. No way. I think this whole thing was very well explained in the recent past by someone quite familiar with the whole thing. I just put it this way. I drive it, I use it and it works beautifully. There is little more I could want short of free petrol for life! /forums/images/graemlins/grin.gif

 

[cowboydoc]

No Rambler is right. Depending on which tractor they lose anywhere from 20-30% of total power while a gear tractor loses 10-15%. Depending on what tractor you look at that 5% # is the DIFFERENCE of total between the two. These tests were also on heavy duty hydros and not the cheaper hydros put in CUTS. So it's hard to say what the CUT's are. It would be really nice if the CUT's were put to the test like the Ag tractors are. But you're never going to see independent tests.

 

[slowrev]

Just a question or two on this subject. The Hydro CUT's I have been around recommend to run the engine at PTO speed all the time. Do Hydro tranny losses increase as the RPM is decreased ? Are the Hydro tranny losses the same at all RPM ranges or is the spec given only for WOT ? Where it might be the most efficient ?

 

[cowboydoc]

Hyrdos are best run at higher rpms because they run off of a hydraulic pump. The motor has to run to operate the pump. On my skidsteer, hydro, the manual recommends running at full throttle. This is also common on dozers, front end loaders, and backhoes.

As far as being more efficient you are going to be more efficient at higher rpms, but this is true for a gear tractor too. The higher the rpms the more power it is going to have. It's the same when you test on a dyno, you run it wide open. It's just a different transfer of power. As far measuring they are measured at their peak power which is usually at pto speed or full throttle depending on the unit. Your manual recommends pto speed, my skidsteer is full throttle.

 

[dirtwhisperer]

</font><font color="blue" class="small">( Hyrdos are best run at higher rpms because they run off of a hydraulic pump. The motor has to run to operate the pump. )</font>

So - does this mean that a geared shuttle shift could be more durable as far as the longevity of the engine over time since it doesn't need to run near full throttle all the time like a hydro ?

 

[cowboydoc]

That would certainly be my opinion but others will not agree. The problem is there is no testing on any of this. Pretty much you just have to go by what you feel from reading everyone else's opinions. If you talk to most farmers/ranchers that do any kind of serious farming/ranching they will not have one if you gave it to them. If you talk to homeowners that have an acreage of from 1-40 they will tell you there is nothing better.

 

[slowrev]

" The higher the rpms the more power it is going to have. " Yes the more power overall, but I am talking about transmission losses not just how much power the engine is cranking out.
One thing when you stall out a gear tranny, the engine dies...well usually the tires spin first /forums/images/graemlins/smile.gif Does a Hydro act this way ? or just quit pulling and load the engine down ? If the tranny will stall out before the engine then to me it would appear that the loss can go up much higher than the manufacturer states. At least to my way of thinking. I suspect that the manufacturers % power loss in the hydro trannys is the minumim power loss and the loss is much higher at lower RPM's.

 

[BillyP]

<font color="blue"> One thing when you stall out a gear tranny, the engine dies...well usually the tires spin first Does a Hydro act this way ? or just quit pulling and load the engine down ? </font>

Slowrev, I have the JD 4610 with hydro. I've tried to stall the tractor, just for my own curiosity, but it won't stall. This was done by easing the FEL up to a tree and MFWD engaged. All it does is spin the tires.

I also tried climbing a really steep hill. Set the range to C (high) and RPM at idle and it climbed it with no problem. I did have a 616 brush cutter on the back but it was up.

 

[slowrev]

Some in here have spoken of driving into a dirtpile and stalling the drive out with hydro tranny CUT's.

 

[_RaT_]

Unless I am racing another tractor, I never use full throttle or even PTO RPM. Typical RPM is around 1900 to 2300 RPM depending on application. The same applies to my shuttles.

 

[slowrev]

Rat,
That is full throttle for larger and older tractors /forums/images/graemlins/smile.gif

 

[_RaT_]

My old International has a PTO RPM of 2200, that is not full throttle. Todays shuttles with which we are comparing the HST RPM's to are the same PTO RPM wise within a given model. Typical seems to be from 2500 RPM and up. I was recently at a train museum where with some diesels the full RPM was 450 RPM.

 

[dirtwhisperer]

here's a question - how does the manufacturer determine what sets a tractors PTO rpm - is it the peak HP rpm for the given engine ?

 

[_RaT_]

When the engine RPM turns the PTO at 540 RPM.