MChalkley
Elite Member
- Joined
- Mar 27, 2000
- Messages
- 3,198
- Location
- Eastern Virginia
- Tractor
- EarthForce EF-5 mini-TLB (2001)
Now that's more like it - if there's one thing I have to say for you guys, it's that you sure respond to a little prodding! /w3tcompact/icons/wink.gif There's some interesting comments here.
I saw several references to the brakes. That's a pretty obvious drawback, but one that doesn't have any impact on the way I use the tractor. I've found that braking is pretty worthless unless you're in 2wd and about the only time I ever used the brakes for turning was when I was trying to correct for a mistake I'd made overshooting something and that was usually because it was too hard to change speeds easily. Since I don't make the mistakes with HST, I don't need to correct for them. But I can see situations, such as mowing, where you'd normally be using 2wd and negotiating tight corners, so the brake turning could be handy. I do that kind of thing so seldom that it's not worth the trade-off to me. I'd a lot rather occasionally make a two point turn, if it really comes down to that tight a turn, than put up with the other disadvantages. Besides, as I said, most of the time I would need to make that sharp a turn, I'm in 4wd, and it doesn't work very well anyway. One post mentioned using the brakes to steer while pulling - if I'm pulling, once again I'm in 4wd, and don't need them anyway. If I'm pulling something hard enough that the load on the front tires is reduced to the point that steering is difficult, I put some weight in the bucket - I needed to do that anyway for pulling efficiency and I'm happy to be reminded of it by the overly light steering.
As for the safety issue as it pertains to reaction time, I don't see how you can get it below 100% faster stopping with the HST. Even if you assume that just pushing in on the clutch stops the tractor, which is seldom the case, the action of lifting your foot stops the HST tractor quite quickly without using the brakes, whereas with the gear tractor you have to pick your foot up off the floor board (remember - the HST would be rapidly slowing down by now), put your foot on the clutch pedal, then depress it. (Unless, you ride around with your foot resting on the clutch pedal - in which case, make sure you're putting some money in the kitty every day you use it for the clutch you're soon going to need.) Now, as I say, this assumes that merely depressing the clutch will stop the tractor. In fact, under the vast majority of circumstances, you still need to something else, like hit the brakes in order to accomplish the same thing that merely lifting your foot accomplishes with the HST. Admittedly, most of us can multi-task, so we could simultaneously depress the brake at the same time we're depressing the clutch, but it's still 100% more motion and time involved. And, again, every additional step you have to make in a panic situation increases the odds that you will be unsuccessful.
But, still regarding safety, this overlooks one of the most important aspects of the benefits of HST: immediate and perfect speed control. This allows you to go as fast as you can at any given instant, knowing you will be able to adjust this speed in an instant to match changing conditions. This has major productivity impact as well. I used to find that much of the tractor work I did involved constantly changing gears or throttle position. As I've said before, diesels don't perform the way gasoline engines do, and they're very inefficient when used that way (constantly varying throttle settings). The GST certainly makes changing gears easy, but when operating under load conditions, you frequently can't change gears without stopping first. So you find that you're in a gear too slow because you figure it would take longer to stop and switch to a faster one, knowing that in a bit the conditions will change again and you'll need the slower one again. This is not a problem with HST.
Del, I agree that going around something at creep speed isn't as fast as whipping around it with the turning brakes, but it's a whole lot safer, and with the HST you can be going full speed again in half the time you would with the GST, anyway. So slowing down and speeding up doesn't have the same negative impact with HST that it does with GST. Also, every time you hit the brakes or change gears, you're wasting efficiency much moreso than when you're changing "ratios" with HST. (BTW, my GST manual said you should never change the shift lever more than one gear at a time, which rules out shifting to neutral unless you're in first. Maybe the L35 is different...)
PaulB, as you noticed, many many people, a large percentage of them dealers, don't understand HST. They think of the HST pedal as a throttle, when nothing could be further from the truth. That's why they misinform buyers about using them and advantages or disadvantages. If you use the HST pedal like a throttle control you're not only missing the major advantages of the technology, but you're forcing it to work against physics, not with it.
Art, others have responded to your question already but, as a former owner of a GST, I can say that under constant load conditions, it's easier to go a certain speed with GST. This is because you can set the gear and throttle and forget it. Now, with varying loads, you are correct: It is more possible to maintain a constant speed with HST - within certain limitations. Often, you'll find that when the load increases, you have to increase the throttle or reduce the HST "ratio". If you choose the latter, or have to do the latter because the engine is already putting out maximum power and that's not sufficient, then you have to reduce ground speed. The same would be true with GST, of course.
Peter - excellent summation of a number of the safety aspects of HST, in my opinion. There's far fewer things to keep track of and, consequently, far less opportunity for mistakes. And mistakes, as we all know, breed accidents.
In my tractor work, I am frequently around lots of people. But this is a crucial point, as I see it: extenuating circumstances do not change the relative safety of one system vs. another. They do change the potential consequences of a mistake drastically. For example, just because you don't kill anybody when you let your foot off the clutch thinking you were in neutral when you weren't doesn't mean it was safe - it only means you didn't kill anybody. In other words, you got away with it. This time. What about the next? Next time, will you be backing up to a three point implement with your child standing there? Or if you don't allow him or her to do that, will he or she just happen to choose that moment to walk behind the tractor? When I'm working around lots of people, there is often absolutely positively no room for a mistake. But that doesn't mean that HST's are safer in that situation and they aren't if there aren't lots of people around; it only means that if there is no one else around, you aren't likely to kill anyone. But you can't always control who or what is around - that's why they call them accidents. Another factor is that no matter what you do with an HST, you start out slowly and build up speed if you keep depressing the pedal. If you let out the clutch with a gear transmission, you take off at whatever speed the gear and rpm combination amounts to - and I mean right now. If it turns out that you shouldn't have, well, by the time you figure that out, you've probably done whatever damage there was to be done.
Another point to think about is that with HST the infinite and immediate speed control works in both directions. If you're going down a hill and need to slow down, if you downshift to accomplish this, you have an instant where you have no slowing effect while the gears are changing, then, when they do change, you get a lurch which could cause a loss of traction or, worse, a loss of tractor stability. So, instead, you have to use the brakes, a proposition that's at least 100% slower than taking your foot off the HST pedal.
As has been intimated by several posters, the biggest factor governing safety is the operator, not the tractor. But, given the fact that we're all going to make mistakes from time, minimizing the impact of them should be everybody's concern. I don't know how many times I've seen experienced operators take their foot off the clutch pedal as they were standing up to get off the tractor, only to be thrown back into the seat or across the steering wheel because the tractor was in gear. Why didn't they kill somebody? Only because there was no one there to kill. Pure luck. In my case, on a job with lots of people around, I may not have a single chance to do that without causing a fatality or a critical injury. That's not a something I could live with, knowing it was easily preventable by changing my tractor technology. So that's what I did. I realize my circumstances are very different from most, but I still believe that only increases my chances of paying dearly for a safety mishap - it does not change the relative safety of one technology over the other.
Mark
I saw several references to the brakes. That's a pretty obvious drawback, but one that doesn't have any impact on the way I use the tractor. I've found that braking is pretty worthless unless you're in 2wd and about the only time I ever used the brakes for turning was when I was trying to correct for a mistake I'd made overshooting something and that was usually because it was too hard to change speeds easily. Since I don't make the mistakes with HST, I don't need to correct for them. But I can see situations, such as mowing, where you'd normally be using 2wd and negotiating tight corners, so the brake turning could be handy. I do that kind of thing so seldom that it's not worth the trade-off to me. I'd a lot rather occasionally make a two point turn, if it really comes down to that tight a turn, than put up with the other disadvantages. Besides, as I said, most of the time I would need to make that sharp a turn, I'm in 4wd, and it doesn't work very well anyway. One post mentioned using the brakes to steer while pulling - if I'm pulling, once again I'm in 4wd, and don't need them anyway. If I'm pulling something hard enough that the load on the front tires is reduced to the point that steering is difficult, I put some weight in the bucket - I needed to do that anyway for pulling efficiency and I'm happy to be reminded of it by the overly light steering.
As for the safety issue as it pertains to reaction time, I don't see how you can get it below 100% faster stopping with the HST. Even if you assume that just pushing in on the clutch stops the tractor, which is seldom the case, the action of lifting your foot stops the HST tractor quite quickly without using the brakes, whereas with the gear tractor you have to pick your foot up off the floor board (remember - the HST would be rapidly slowing down by now), put your foot on the clutch pedal, then depress it. (Unless, you ride around with your foot resting on the clutch pedal - in which case, make sure you're putting some money in the kitty every day you use it for the clutch you're soon going to need.) Now, as I say, this assumes that merely depressing the clutch will stop the tractor. In fact, under the vast majority of circumstances, you still need to something else, like hit the brakes in order to accomplish the same thing that merely lifting your foot accomplishes with the HST. Admittedly, most of us can multi-task, so we could simultaneously depress the brake at the same time we're depressing the clutch, but it's still 100% more motion and time involved. And, again, every additional step you have to make in a panic situation increases the odds that you will be unsuccessful.
But, still regarding safety, this overlooks one of the most important aspects of the benefits of HST: immediate and perfect speed control. This allows you to go as fast as you can at any given instant, knowing you will be able to adjust this speed in an instant to match changing conditions. This has major productivity impact as well. I used to find that much of the tractor work I did involved constantly changing gears or throttle position. As I've said before, diesels don't perform the way gasoline engines do, and they're very inefficient when used that way (constantly varying throttle settings). The GST certainly makes changing gears easy, but when operating under load conditions, you frequently can't change gears without stopping first. So you find that you're in a gear too slow because you figure it would take longer to stop and switch to a faster one, knowing that in a bit the conditions will change again and you'll need the slower one again. This is not a problem with HST.
Del, I agree that going around something at creep speed isn't as fast as whipping around it with the turning brakes, but it's a whole lot safer, and with the HST you can be going full speed again in half the time you would with the GST, anyway. So slowing down and speeding up doesn't have the same negative impact with HST that it does with GST. Also, every time you hit the brakes or change gears, you're wasting efficiency much moreso than when you're changing "ratios" with HST. (BTW, my GST manual said you should never change the shift lever more than one gear at a time, which rules out shifting to neutral unless you're in first. Maybe the L35 is different...)
PaulB, as you noticed, many many people, a large percentage of them dealers, don't understand HST. They think of the HST pedal as a throttle, when nothing could be further from the truth. That's why they misinform buyers about using them and advantages or disadvantages. If you use the HST pedal like a throttle control you're not only missing the major advantages of the technology, but you're forcing it to work against physics, not with it.
Art, others have responded to your question already but, as a former owner of a GST, I can say that under constant load conditions, it's easier to go a certain speed with GST. This is because you can set the gear and throttle and forget it. Now, with varying loads, you are correct: It is more possible to maintain a constant speed with HST - within certain limitations. Often, you'll find that when the load increases, you have to increase the throttle or reduce the HST "ratio". If you choose the latter, or have to do the latter because the engine is already putting out maximum power and that's not sufficient, then you have to reduce ground speed. The same would be true with GST, of course.
Peter - excellent summation of a number of the safety aspects of HST, in my opinion. There's far fewer things to keep track of and, consequently, far less opportunity for mistakes. And mistakes, as we all know, breed accidents.
In my tractor work, I am frequently around lots of people. But this is a crucial point, as I see it: extenuating circumstances do not change the relative safety of one system vs. another. They do change the potential consequences of a mistake drastically. For example, just because you don't kill anybody when you let your foot off the clutch thinking you were in neutral when you weren't doesn't mean it was safe - it only means you didn't kill anybody. In other words, you got away with it. This time. What about the next? Next time, will you be backing up to a three point implement with your child standing there? Or if you don't allow him or her to do that, will he or she just happen to choose that moment to walk behind the tractor? When I'm working around lots of people, there is often absolutely positively no room for a mistake. But that doesn't mean that HST's are safer in that situation and they aren't if there aren't lots of people around; it only means that if there is no one else around, you aren't likely to kill anyone. But you can't always control who or what is around - that's why they call them accidents. Another factor is that no matter what you do with an HST, you start out slowly and build up speed if you keep depressing the pedal. If you let out the clutch with a gear transmission, you take off at whatever speed the gear and rpm combination amounts to - and I mean right now. If it turns out that you shouldn't have, well, by the time you figure that out, you've probably done whatever damage there was to be done.
Another point to think about is that with HST the infinite and immediate speed control works in both directions. If you're going down a hill and need to slow down, if you downshift to accomplish this, you have an instant where you have no slowing effect while the gears are changing, then, when they do change, you get a lurch which could cause a loss of traction or, worse, a loss of tractor stability. So, instead, you have to use the brakes, a proposition that's at least 100% slower than taking your foot off the HST pedal.
As has been intimated by several posters, the biggest factor governing safety is the operator, not the tractor. But, given the fact that we're all going to make mistakes from time, minimizing the impact of them should be everybody's concern. I don't know how many times I've seen experienced operators take their foot off the clutch pedal as they were standing up to get off the tractor, only to be thrown back into the seat or across the steering wheel because the tractor was in gear. Why didn't they kill somebody? Only because there was no one there to kill. Pure luck. In my case, on a job with lots of people around, I may not have a single chance to do that without causing a fatality or a critical injury. That's not a something I could live with, knowing it was easily preventable by changing my tractor technology. So that's what I did. I realize my circumstances are very different from most, but I still believe that only increases my chances of paying dearly for a safety mishap - it does not change the relative safety of one technology over the other.
Mark
says it all, ".....operators take their foot off the clutch pedal as they were standing up to get off the tractor, only to be thrown back into the seat or across the steering wheel because the tractor was in gear. Why didn't they kill somebody? Only because there was no one there to kill. Pure luck." 
