Advantages of a gear/synchro over HST?

[Heywood Jannockitov]

Are any of these really infinate? or do they all have ranges like my old ford three of them you still had to stop to change ranges

Exactly, they are infinite only to a point. Personally, I would rather "infinitely" vary my working speed in an appropriately selected gear/range using the throttle pedal to vary engine rpm, thus speed, between idle and whatever, as opposed to listening to the engine drone away at a constant high pto rpm, still varying the speed with a foot pedal.

Sure, you can reverse without clutching but that involves pivoting your foot which I have trouble doing, or moving your foot between two pedals, something I didn't like when testing a 4720. With power reverser, I shuttle forward reverse with a steering column lever that is always at my fingertips because the shuttle stalk moves with the telescoping steering column.

If I want an additional 20 percent increase in ground speed, I have a HI/LO button on the shifter. It is close to having the best of both worlds.

You have to remember not all gear/HST trannies are created equal. Some, like Massey's Dyna-6 transmission, you can clutchless powershift between gears on the fly. The 24x24 trans in my 5425 can't, but I can use the power reverser to shift to neutral (clutch in) with my fingertip (my lefthand holding the steering wheel) and shifting gears with my right hand. I get very smooth shifts this way and my foot hasn't touched the clutch pedal.

If you were comparing your HST to a older non-shuttle gear tractor with an H pattern shifter between your legs, then that would definitely become tedious real fast when doing loader work, and an upgrade to a new modern HST would seem like heaven.

 

[woodyacres]

I do believe the HST is safer and more convenient. It's safer because it's easier for a mistake to get you into trouble with gear. Well when you are operating a gear shifter, range selector, shuttle lever, clutch, joystick, and and possibly even a 3PH lever, it's easy to forget one or the other. This doesn't happen with HST because you always have infinite speed control from your foot. No fooling with all that other stuff.

Gittyup... That's exactly why I purchased the HST. I didn't mind the shuttle shift, but being this is my first tractor (besides lawn mowers) that I have ever driven, I wanted it simple and easy. HST had one less thing to worry about while driving. I absolutely LOVE my HST and would NEVER trade for a gear. However, I am not plowing or harvesting field either. It seems everyone is saying how great geared tractors are ( and I am not arguing with them), but they mostly all have 30 years on tractor. I don't miss the gear tractor at all. If I had a gear, I may not miss the HST at all.

 

[patrick_g]

Uh, yaw... Typical HST CUT has three geared ranges. The HST pedal gives you essentially 0-100% of each range. Typically you do have to stop to change ranges. Typically high range is for transiting/roading and not terribly useful for any HD work. You can run a brush hog on nearly flat land if the cutting isn't too thick while in high range or do pasture spraying. You can transit on nearly level ground carrying a FEL bucket of stuff. It may be difficult to start the tractor moving while stopped facing up much of a grade in high range.

I typically use the middle range (when not transiting) and trying to do fairly heavy work. If I'm doing really HD work like pulling a 1300 lb box blade full of dirt up a fairly steep hill with a full FEL bucket then Low range will git 'er done. I'm guessing that I work the tractor in mid range probably close to 90% of the time, low range less than 5% of the time and the rest in high range.

There is no requirement to run the tractor engine at PTO speed to do useful work. My manual says to not lug the little diesel trying to get it to do hard work below about 1700 RPM. I typically run about 2000-2200 RPM and only when I NEED the extra umph do I go to 2400 or up to 2650 (PTO speed) I rarely run PTO speed or higher unless roading or really working the devil out of the little machine. EXCEPTION: When I am eating trees 4-5 inches in diameter with my 6 ft brush hog I run it up to the max for just a little while as I use the TNT to lower the cutter down on a tree that I have backed up to.

Again, regarding the infinite variability of the HST and the three ranges... The ranges are not ad seriatum You do not shift up through the gears like a manual transmission car or truck. You select the best match of range to your activity and then the pedal gives you 0-100% of that range plus nearly 0-100% reverse as well. Some HST trannys do not give you as much reverse as forward speed.

When you take your foot off the HST pedal the tractor stops pretty quickly. In low or mid range it is nearly impossible for me to get my foot off the HST pedal and on the brake before the tractor is stopped or very nearly so. In high range from full speed (over 2650RPM, 15-18 MPH)) I can get my foot on the brake before the tractor stops. Generally I DO NOT use the brakes as with just a little forethought you can reduce the throttle or feather the HST pedal and not need the friction brakes. MY tractor uses a brake hold feature for a parking brake and I do use that quite a lot.

The only times I use the clutch pedal are: 1. to get the engine to start as the clutch switch must be satisfied before you can crank the engine, 2. to change gear ranges, and 3. to engage/disengage the PTO.

I hope this clarifies some of the obviously mistaken ideas, impressions, and erroneous conjecture regarding HST in a CUT. NOt all HST are created equal or behave exactly alike. Mine is a Kubota Grand L4610HSTC.

Pat

 

[big bubba]

I make no value judgment of gear vs hst, only a question. Why are the higher end, larger ag series tractors geared (albeit with some options like swing shift, etc) rather than hst? Is this to imply that in higher HP ag application the geared tranny is mechanically a more sound design leaving the hst to the compact applications? no sides, just a question

 

[Slackdaddy]

Big B,
Look at like this - If a machine is pulling a plow across a field for up to a mile in a straight line, gear is simple and hard to hurt, therefore the big farm rigs are gear.

If a machine is constantly starting stopping, twisting turning, inching, pushing, etc - hydro is the way to go, that is why all the track loaders (big and small) are hydro.

If I was plowing with my CUT, gear would have been an option.
But since my wife and kids are using it around our 20 acre wooded lot, hydro was the only option.

As far as a hydro creeping up on you while you are off it, they know never to get off a running tractor.

Slack

 

[greenmule]

You hit a nail right on its head there.
Lawnmowers/hst,they move up to a small tractor,gotta make it so's they can use it.

 

[IslandTractor]

Big B,
Look at like this - If a machine is pulling a plow across a field for up to a mile in a straight line, gear is simple and hard to hurt, therefore the big farm rigs are gear.

If a machine is constantly starting stopping, twisting turning, inching, pushing, etc - hydro is the way to go, that is why all the track loaders (big and small) are hydro.Slack

I think that sums it up pretty well.

 

[big bubba]

Okay thanks on this, glad the question brought some consensus. On a slight tangent, no one had brought up the use of a hydraulic shuttle with a gear transmission. Granted, it's no hst, but it offers the advantage of a clutchless F&R action (eg FEL & hogging) that the hst people often brag about. I choose no sides, just that I feel that in my own case (Kub 8540) I have the advantages of both. The DK90 seems like an awesome machine and I would have gone with it over the M8540 but the hydraulic shuttle (along with the very safe and reliable transmission lock e brake & limited slip differential) sold me on the Kubota. This IS NOT a reference of one tractor company over the other, just wish Kioti had offered a hydraulic shuttle which is a convenient way of offering some advantages of an semi auto tranny in a heavy duty ag geared application. my 2 cents. hope you all have many more hours on you machines, auto or manual. bb

 

[Heywood Jannockitov]

no one had brought up the use of a hydraulic shuttle with a gear transmission

I knew it, I must be on everybodys ignore list or something

Granted, it's no hst,

Thankfully

 

[Slackdaddy]

When I 1st started looking at CUTS, I was driving around looking for one with a true clutchless Shuttle like My Case 580, they do not exist.

The power train is like this:

Engine > Torque Converter > Shuttle > 4sp gearbox

Problem with this is no way to get the 3PH PTO back to the rear.