GST Vs Gear drive

[computernerd]

All, I've seen a video from Messicks comparing gear drive and hydrostatic and in the video the gear drive kicked the hydro's but with pulling power.

My question is if anyone knows with regard to pulling power if a GST would be more akin to to gear drive which I would expect or hydrostatic

 

[PaulL]

I thought that video had some flaws. Yes, gear drive will put more power to the wheels than HST. If the wheels can take it. And in the smaller tractors, you run out of traction long before you run out of power - which is why they didn't do those tests in low ratio.

I believe the GST is fundamentally a gear drive with an electronic change/shifter. It's like a gear drive, not like an HST. When you're not changing gears it is a fully locked up transmission, unlike an HST which has built in slip in it (like an old school automatic without lockup).

 

[NCL4701]

Gear, GST, and HST all have their place but much as I’ve enjoyed and learned from Neal’s videos, I thought the Messick’s test was a little odd. If I’m trying to apply as much torque to the ground as possible, gear or or otherwise, it’s in the lowest available gear and it always runs out of traction before it runs out of power.

 

[computernerd]

Thanks Paul, I get that HST is preferred over gear but I do not understand for the life of me why HST is preferred over GST. IMO GST is best of both worlds. When I was growing up hydro was laughed at as inferior due to the hydraulic pressure needed

 

[computernerd]

Gear, GST, and HST all have their place but much as I’ve enjoyed and learned from Neal’s videos, I thought the Messick’s test was a little odd. If I’m trying to apply as much torque to the ground as possible, gear or or otherwise, it’s in the lowest available gear and it always runs out of traction before it runs out of power.

IMO he explained in the video he needed to "limit" power so as not to cause slip so he could get some consistent measure on the gauge. I got the impression if he did it in low the wheels would have just slipped due to the available power and would not have yielded a measurable result. Just my .02

 

[old and tired]

...but I do not understand for the life of me why HST is preferred over GST...

I drive GST like a gear tractor, using the clutch. I can not help it... when hooking up to an implement, I love the precision of HST. If I needed "X" amount of HP to pull something ground engaging, I would get a larger HST to cover the lost due to transmission.

 

[NCL4701]

IMO he explained in the video he needed to "limit" power so as not to cause slip so he could get some consistent measure on the gauge. I got the impression if he did it in low the wheels would have just slipped due to the available power and would not have yielded a measurable result. Just my .02

That kind of makes sense, but in an actual use situation pushing the loader into a pile, pulling a box scrape, skidding logs, etc. traction is the limiting factor on max pulling power for all of them. I would have liked to see what the strain gauge maxed out at for them when they broke traction to actually see if it was valid or junk data. A HST in medium or high range v a gear in 2nd or 3rd or whatever gear he had it in (been a while since I watched it) is apples to oranges. I do understand a locked up clutch and gears all the way to the wheels is more efficient transfer of power than a hydraulic pump running a hydraulic variable displacement piston motor feeding the gearbox.

I kind of think the transmission question gets to be a what oil / grease do you use kind of thing. Lots of educated valid opinions without much conclusive result. For loader work I’ll stick with HST but if I was discing a 50 acre field I’d rather have gear even with the cruise control on the HST. And yes, I’ve run a loader on a gear drive (not GST and not even with a shuttle) and loader/grapple work and mowing was most of why I bought the L so I wasn’t interested in gear. I wouldn’t suggest dismissing any of them out of hand because of how they were 30 or 50 years ago. The tractors I grew up with and used as a younger man look a lot like my L but they are VERY different machines in more ways than I can even start to list.

Bottom line, I’m happy with what I have for what I use it for but it isn’t a good match for every application. Hope the OP and others are happy with their choice as well.

 

[computernerd]

The tractors I grew up with and used as a younger man look a lot like my L but they are VERY different machines in more ways than I can even start to list.

I would like to hear more of this. I am same. I operated a MF gear drive doing loader work and when my uncle got the hydro it was night and day. loader work with gear drive is brutal at best. But that to me is why GST is superior in all ways. with hyrdo, you fwd/rev with your foot whereas GST you shuttle shift with your hand.

Granted my observations are theoretical but GST seems to have ease of hyrdo and advantages of drive without the disadvantage of drive with unnecessary clutch wear via clutch slipping.

Does HST ever change gear ratios or does it just drive high and higher rpm to gain more speed?

Also, what are your thoughts on Neil's video showing you have to ease on the petal on HST to "gain" torque instead of the guttural mash the petal.

 

[old and tired]

...you have to ease on the petal on HST to "gain" torque instead of the guttural mash the petal...

That's how the HST in "economical" Standard L's work. If you get into the Grand L, with "HST+", it does shift ranges (Not 100% sure how it works...)

As for driving a HST with a foot treadle pedal or use my hand with GST. I spill my beer shifting with a GST I'm used to driving for hours using my foot... so the treadle pedal is no problem for me.

 

[PaulL]

Does HST ever change gear ratios or does it just drive high and higher rpm to gain more speed?

In my mind an HST is a bit like an old automatic transmission with no torque converter. The revs on the machine are always constant. I think the treadle pedal is effectively varying the vanes in the pump somehow - it's pumping more or less (or maybe it's a valve on the pump, unclear to me). Bottom line, in behaviour it's a bit like a CVT - the harder you press the pedal the higher the effective gearing, your revs don't change. That's why it pulls harder when you press lightly, which is totally counter-intuitive.

On the Messicks video - I think Neil was looking to demonstrate that the gear driven can put more power to the wheels than the HST, which is true. And aiming to measure it. But in the real world, that only matters if you're for some reason limited to driving in medium but want to put a lot of power down - perhaps you are pulling an implement and you want a certain ground speed (hence M), but need enough power to pull it. If you can just change gears, then either tractor will run out of traction. It's not as unusual as you'd think though, I can imagine wanting to pull a plow at a certain speed - whilst both the HST and the gear driven might be able to break traction in low gear, the gear driven would probably pull that same plow faster (assuming you're not running out of traction). I guess that turns into more productivity in a given day.

 

[computernerd]

whilst both the HST and the gear driven might be able to break traction in low gear, the gear driven would probably pull that same plow faster (assuming you're not running out of traction). I guess that turns into more productivity in a given day.

To me the whole point is ease. If the GST is pulling the same load and working 70-90% less that is considerable.
There was a comment above saying to just buy more HP and go HST but to me that is the point. Neil showed the gear had 300% or so (can't remember) more pulling power so to buy the same one would need 300% more HP and to me it's not coincidental that > 60HP do not offer HST.

 

[NCL4701]

I would like to hear more of this. I am same. I operated a MF gear drive doing loader work and when my uncle got the hydro it was night and day. loader work with gear drive is brutal at best. But that to me is why GST is superior in all ways. with hyrdo, you fwd/rev with your foot whereas GST you shuttle shift with your hand.

Granted my observations are theoretical but GST seems to have ease of hyrdo and advantages of drive without the disadvantage of drive with unnecessary clutch wear via clutch slipping.

Does HST ever change gear ratios or does it just drive high and higher rpm to gain more speed?

Also, what are your thoughts on Neil's video showing you have to ease on the petal on HST to "gain" torque instead of the guttural mash the petal.

I didn’t have much real understanding of HST until I got in an hour long conversation with the service manager at my local dealership. He wanted a bit of my expertise and I wanted an expert’s explanation of how HST actually works so we traded. After that the stuff I’d read about them started to make sense.

In theory, HST is pretty simple. The diesel runs a hydraulic pump. The pump feeds a hydraulic piston motor with a swash plate (which is akin to the “block” the pistons run in). The foot pedal varies the angle of the swash plate, which determines the speed of the motor. If you angle it enough, it runs backward, and the sweet spot between forward and reverse it doesn’t turn at all. That hydraulic motor output is hooked to a rather traditional gearbox with two or three ranges, and that gearbox feeds into the transfer case, etc out to the wheels same as anything else.

That all has some implications for operation. The hydraulic motor is cooled by fluid flow so it prefers lower gear range, heavier pedal for higher flow to cool better. But, the hydraulic pump can struggle keeping up with flow if the pedal is full forward and if that happens, a full forward/reverse pedal can produce less torque than a lighter pedal (reduce flow with less pedal to keep pressure up). That also has the sometimes advantage of having full torque at very low speeds. With HST I can ease the loader into a pile without slipping a clutch, spinning tires, or hitting it with any speed. It is very easy to make very precise movements with the HST which I like for forklift and grapple work. Torque is solely dependent on hydraulic pressure. Speed is dependent on flow. Diesel engine speed pretty much remains constant with rare need for variation. Also, if your thinking HST isn’t better for loader work, check out a dedicated wheel loader or skid steer. If there’s a gear drive or GST skid steer or wheel loader made in the last couple of decades, I’d be quite surprised but never hear anyone say they wish their skid steer had a clutch or reverser lever.

I also do a LOT of back/forward in tight spaces. HST shines there. I would take it any day over even a reverser lever.

PTO on HST loses some HP due to the inefficiency of the hydraulic drive. In the case of my tractor it’s a bit over 1 HP. Yes, it’s less. Wasn’t enough to be a big deal to me but that’s just me.

Issue I would have with HST putting it in a field pulling tillage implements would primarily be heat. There’s very little heat generated by a locked clutch you rarely touch and a pile of gears in an oil bath. The fluid friction in the HST is going to generate a good bit of heat in that application and all the advantages of HST are useless in tillage work. You can pull a plow with a HST but there’s just zero advantage to doing it with HST.

And you’re correct large tractors don’t offer HST. HST is good for utility tractors doing a lot of loader work, mowing, forklifting, but not efficient for tillage so not much use in a 100 HP tractor. Same model tractor with gear drive having 300% drawbar pull of identical model with HST... that’s insane and I don’t care who said it. That’s WAY wrong. I’ve pulled a 4000lb break strength chain in half twice in 30 minutes with a HST L4701. Nobody is convincing me if it had gear drive it would pull over 12,000 lb.

I would agree with your original thought that GST may be a good compromise if you’re leaning toward gear but want an upgrade from totally manual clutch/stick setup.

I’m not an apologist for HST over everything else. I’m just suggesting really consider what you’ll be doing with it, test drive the type transmissions you’re considering if possible, and if you pick a gear or GST or HST do it because it best fits your application and no other reason.

Past that (compared to similar hp older models) higher 3 point capacity, higher loader capacity, 4WD, power steering, diff lock, options to festoon it with hydraulics front to rear with pressure and flow to run small motors and various cylinders or even a backhoe, ROPs, SSQA. It’s just a VERY different machine than tractors from even 20 years ago.

 

[PoTreeBoy]

I would like to hear more of this. I am same. I operated a MF gear drive doing loader work and when my uncle got the hydro it was night and day. loader work with gear drive is brutal at best. But that to me is why GST is superior in all ways. with hyrdo, you fwd/rev with your foot whereas GST you shuttle shift with your hand.

Granted my observations are theoretical but GST seems to have ease of hyrdo and advantages of drive without the disadvantage of drive with unnecessary clutch wear via clutch slipping.

Does HST ever change gear ratios or does it just drive high and higher rpm to gain more speed?

Also, what are your thoughts on Neil's video showing you have to ease on the petal on HST to "gain" torque instead of the guttural mash the petal.

My L35 has the 8x8 GST - to correct an earlier post, this model is all manual/hydraulic, no electrical at all. The later 12x8 has some electrical, I think.
You may be aware, but there are 3 sections in the tranny: gears 1 - 4, hi-low range, and for-rev with a hydraulic clutch between two of the sections (not at the main input, the foot clutch is in the usual place). All the gears are synchronized. The 1-8 gearshift lever by the seat selects 1L to 4H via hydraulics and the for-n-rev lever on the steering column is mechanically connected to the shuttle while hydraulically controlling the clutch.
I like the setup, but nothing's perfect.
1. Your feet can stay on the floor, but I find my left hand and arm stay busy shifting from the shifter to shuttle. Which means it's not available to steer, and I use the foot throttle a lot since my right hand has to leave the steering wheel to reach the throttle by the right side of the seat (good location when turned around on the backhoe, but not so good for forward facing).
2. When shuttling, unlike HST, you're not 'downshifting' to slow down. You can either move your hand to the shifter and downshift, then shuttle; coast down in neutral; or use the brakes to slow down in neutral before finishing the shuttle shift. If you're in 4F and shuttle, you'll be in 4R as fast as the hydraulic clutch allows. This works well as long as you use the throttle to ease things. You can also do it any gear, but I'd hate to experience a 6th gear full throttle shuttle .
3. Whereas the HST has smooth, continuous power ratio change, the GST has finite ratios and when you shift from one to another there is a noticeable delay. This can be very 'noticeable' if you start up a hill in too high a gear and need to downshift. Under some situations you need to be ready with the brakes to keep from rolling back while the shift is happening (like you would with a manual gear set-up).
The newer GSTs may have different driving traits.
BTW most, if not all, HSTs have 2 or 3 range gearboxes. These are usually not synchronized, so you have to stop to change ranges.

 

[computernerd]

Also, if your thinking HST isn’t better for loader work, check out a dedicated wheel loader or skid steer. If there’s a gear drive or GST skid steer or wheel loader made in the last couple of decades, I’d be quite surprised but never hear anyone say they wish their skid steer had a clutch or reverser lever.

That was a very good explanation of Hydro transmissions, Thank you.

I hadn't thought about skid steers being hydro but it makes sense for them given their joystick controls and constant back and forth. If I had to pull a lever 400 times a day I would probably feel differently but then again as you say a skid steer doesn't do laps around a field.

This is kind of the essence of my query. Kubota does not put the GST in their full line and you are somewhat limited on tractors you can get so I wanted to see if I am missing something or it is just sales based on perceived ease.

When I get ready to buy I'll have to drive a gear (since they likely won't have a GST) but as I remember throttle controls speed pretty well (even as a cruise control?) and as long you can with shuttle shift control quick back and forth I don't see a down side other than the limitations of available units and horsepower.

 

[NCL4701]

My L35 has the 8x8 GST - to correct an earlier post, this model is all manual/hydraulic, no electrical at all. The later 12x8 has some electrical, I think.
You may be aware, but there are 3 sections in the tranny: gears 1 - 4, hi-low range, and for-rev with a hydraulic clutch between two of the sections (not at the main input, the foot clutch is in the usual place). All the gears are synchronized. The 1-8 gearshift lever by the seat selects 1L to 4H via hydraulics and the for-n-rev lever on the steering column is mechanically connected to the shuttle while hydraulically controlling the clutch.
I like the setup, but nothing's perfect.
1. Your feet can stay on the floor, but I find my left hand and arm stay busy shifting from the shifter to shuttle. Which means it's not available to steer, and I use the foot throttle a lot since my right hand has to leave the steering wheel to reach the throttle by the right side of the seat (good location when turned around on the backhoe, but not so good for forward facing).
2. When shuttling, unlike HST, you're not 'downshifting' to slow down. You can either move your hand to the shifter and downshift, then shuttle; coast down in neutral; or use the brakes to slow down in neutral before finishing the shuttle shift. If you're in 4F and shuttle, you'll be in 4R as fast as the hydraulic clutch allows. This works well as long as you use the throttle to ease things. You can also do it any gear, but I'd hate to experience a 6th gear full throttle shuttle .
3. Whereas the HST has smooth, continuous power ratio change, the GST has finite ratios and when you shift from one to another there is a noticeable delay. This can be very 'noticeable' if you start up a hill in too high a gear and need to downshift. Under some situations you need to be ready with the brakes to keep from rolling back while the shift is happening (like you would with a manual gear set-up).
The newer GSTs may have different driving traits.
BTW most, if not all, HSTs have 2 or 3 range gearboxes. These are usually not synchronized, so you have to stop to change ranges.

Now I know why the salesman didn’t talk to me about GST. He obviously recognized pretty quickly I ain’t smart enough to handle all that!

 

[computernerd]

1. Your feet can stay on the floor, but I find my left hand and arm stay busy shifting from the shifter to shuttle. Which means it's not available to steer, and I use the foot throttle a lot since my right hand has to leave the steering wheel to reach the throttle by the right side of the seat (good location when turned around on the backhoe, but not so good for forward facing).

This is great input I really appreciate it.
Can you explain more why you are having to use the shifter? This is a hole in my thinking process. I had envisioned that the activity would dictate the gear and so once selected would not need changed until the activity changed like you're finished and time to head for the house. The shuttle I get obviously between fwd and reverse.
Also, do you wish you had HST instead? if so why?

 

[NCL4701]

That was a very good explanation of Hydro transmissions, Thank you.

I hadn't thought about skid steers being hydro but it makes sense for them given their joystick controls and constant back and forth. If I had to pull a lever 400 times a day I would probably feel differently but then again as you say a skid steer doesn't do laps around a field.

This is kind of the essence of my query. Kubota does not put the GST in their full line and you are somewhat limited on tractors you can get so I wanted to see if I am missing something or it is just sales based on perceived ease.

When I get ready to buy I'll have to drive a gear (since they likely won't have a GST) but as I remember throttle controls speed pretty well (even as a cruise control?) and as long you can with shuttle shift control quick back and forth I don't see a down side other than the limitations of available units and horsepower.

I got no clue what best fits your needs and preferences. I don’t even know what you plan to do with it. Whatever you end up with, hope you’re as happy with it as I’ve been with mine.

Even though it’s just an economy grade LXX01, retiring the antique tractors in favor of a modern tractor with loader and SSQA has been a game changer for our property maintenance.

 

[PaulL]

To me the whole point is ease. If the GST is pulling the same load and working 70-90% less that is considerable.
There was a comment above saying to just buy more HP and go HST but to me that is the point. Neil showed the gear had 300% or so (can't remember) more pulling power so to buy the same one would need 300% more HP and to me it's not coincidental that > 60HP do not offer HST.

I don't think it was anything like 300% - my recollection of the video was 3-5%. I'd go back and check, I think you're working off a wrong data point.

Issue I would have with HST putting it in a field pulling tillage implements would primarily be heat. There’s very little heat generated by a locked clutch you rarely touch and a pile of gears in an oil bath. The fluid friction in the HST is going to generate a good bit of heat in that application and all the advantages of HST are useless in tillage work. You can pull a plow with a HST but there’s just zero advantage to doing it with HST.

I would agree with your original thought that GST may be a good compromise if you’re leaning toward gear but want an upgrade from totally manual clutch/stick setup.

I’m not an apologist for HST over everything else. I’m just suggesting really consider what you’ll be doing with it, test drive the type transmissions you’re considering if possible, and if you pick a gear or GST or HST do it because it best fits your application and no other reason.

Agree with all that. The heat buildup is an interesting point. All of these options have some compromise - gear is good for long periods of steady state running, HST good for lots of back and forth, and creeping/variable speed, some of the shuttles and flasher transmissions do a fair job of both but cost a lot of money. My view would be:

• Some guys just get hung up on the numbers - they're losing HP and we all know HP is good. Losing HP that you didn't need isn't material - so if it's just about the number but not about a specific task, get the HST. Back in the day in my part of the world everyone wanted a stick shift in their car, because with an automatic you lost power. Newer transmissions not so much, and actually most new cars have plenty of power, you can afford to "waste" a bit of it on convenience. HST is a bit like that - a B size machine with 26HP has plenty of power, they sized the engine knowing you'd have an HST
• If you're doing a lot of loader work, landscaping work, general to and fro plus a bit of mowing, get the HST. It'll be fine for occasional pulling work, and it'll more than make it up in those other tasks
• If you're mostly a guy going out (with his dog) to mow the meadow, then look at a gear shift, and live with annoyance when you occasionally use the loader
• If you do a lot of both (enough that either compromise is annoying and worth spending money to avoid), buy a tractor with a better transmission - like a Grand L with the HST+, or something with a shuttle shift.

 

[PaulL]

This is great input I really appreciate it.
Can you explain more why you are having to use the shifter? This is a hole in my thinking process. I had envisioned that the activity would dictate the gear and so once selected would not need changed until the activity changed like you're finished and time to head for the house. The shuttle I get obviously between fwd and reverse.

I'm assuming it's about controlling speed. If you're using a loader you want a reasonably low ratio into the pile, but then once you back away from the pile to go somewhere, you need to decide whether you're going to roar along (slowly) at high revs, or change to a higher ratio to get somewhere quickly.

An HST lets you drive your tractor a bit like a car (even better really) by just pushing on the pedal to go faster or slower, and you can tolerate a lot of variation in speed without shifting ratio. All the gear driven transmissions you'll need to shift gear or adjust the throttle. Dad's tractor has a foot throttle for this purpose, which is sort of like using the HST, but the range of speeds you can get aren't as wide as the HST - it mostly runs between about 800rpm and 2000 rpm - so your range of speed with the throttle isn't that wide. While you could run in a high ratio then slip the clutch to get a creeping speed, it's a pain to do that.

Again, it's all tradeoffs. Can you do it - yes. When I drive Dad's tractor (admittedly a much larger machine with way more capability than my B) I do miss the HST. But an HST wouldn't really be ideal in his machine, it's an 80HP tractor and he spends a lot of time mowing his paddocks, plus a fair bit of time hauling stuff around the farm. A gear shift+shuttle is great for that, and he really doesn't use his loader as much as I do. When we're trimming trees with one of us in the bucket, or when we were skidding logs last time I visited, the clutch and shuttle were a bit of a pain. In the bucket the person in the bucket gets a bit of a jolt when you let the clutch out (the clutch is heavy), unless you're right down in one of the creeper gears. Skidding logs you couldn't creep on the throttle, you had to drop the clutch and put up with a bit of wheel spin. I guess we were ruining the turf pulling logs over it anyway, but I wouldn't want to be doing that at my place.

 

[PoTreeBoy]

This is great input I really appreciate it.
Can you explain more why you are having to use the shifter? This is a hole in my thinking process. I had envisioned that the activity would dictate the gear and so once selected would not need changed until the activity changed like you're finished and time to head for the house. The shuttle I get obviously between fwd and reverse.
Also, do you wish you had HST instead? if so why?

Like PaulL said, if I'm using the loader I may load in 4F, then back out in 4R, but if I'm carrying the load very far I want to go faster than 4th gear will go. Yeah, if you're making short shuttles, you don't need to shift.
HST? For me, the GST is fine. Besides, it's all that was offered on the L35. Plus, when I'm using the backhoe, I can leave the shuttle in F or R and shift from N to 1 (the shift lever is at my right hand) to creep, as long as I don't need brakes. I'm usually loading up saplings or pushing small trees over, so not purely loading. I can see HST if primarily loading with a small (<40hp say) tractor. The larger tractors have enough excess power/torque that a gear tractor works ok by loading at low RPM and revving up to travel. I've used an M7040 with hydraulic shuttle some mowing and moving hay, and it works good for that. It has synchronized 1 - 4, un-synchronized hi-low, and for-rev on the column. The reverser uses two hydraulic clutches, one forward and one reverse. The foot clutch just regulates the clutch pressure, there is no dry clutch.
For your future tractor, we don't know what you'll be doing or what size you're talking about. The smallest Kubotas are HST only and the largest are gear-shuttle only (I think). The transition zone is where you have a decision to make. If you're serious about a gear drive there are 2 things to watch out for: 1. They may not be synchronized and may not have shuttle. This may mean the reverse speeds are limited* 2. They may not have independent PTO - when you disengage the wheel clutch, you're also disengaging whatever's on the PTO. This is a real PITA when mowing and you need an over-running clutch to keep the spinning mower from continuing to drive the wheels.

* My dad bought a Ford 3930 8x2 gear tractor. It's a good utility tractor, but 1. It's not synchronized, the gears are constant mesh but the shift dogs don't have synchronizers so it's stop to shift, at least to reverse 2. The reverse gears are limited. "It has too reverses, too slow and too fast." Shuttle would be nice. It does have independent PTO, which would be a must have for me.