To get the inside scoop about Arctic Cat’s new Rapid Response CVT System, we sat down with Troy Halvorson, now the snowmobile product manager for Arctic Cat, but formerly the lead engineer for the company’s M Series development team. He talked about how engineers fulfilled goals to develop a more durable drive system and shared details about working with TEAM Industries. For the complete story about new technology on 2016 snowmobiles, pick up the October 2015 issue of Snow Goer magazine.
1. Why were the new clutches and drive system developed? What were the goals with the program?
“We’ve worked with TEAM Industries in the past in different components. On our clutch systems now for 2016 we decided a few years ago that we wanted to look at a company that would help us with the design of our clutches that’s close by in the United States. We’re always trying to improve on our clutches and any part of our snowmobiles. So some of the areas, like, for instance, the primary clutch, we were looking at having a clutch that was lighter than our current one and then also more durable, and smoother shifting.
“We felt that our current clutch was a good clutch. We had a couple issues with it in the past where we’ve had to send out some service bulletins; it’s a pretty key component [that affects] how the sled works so we wanted to make sure that it worked properly, so we had to do that on the first year [of ProCross and ProClimb]. We had some issues we took care of with our customers. Going down the road we wanted to find a partner working with our clutches that would help us not only in development in regards to getting a lighter weight clutch and better performing but just to make sure we were always improving on our durability. TEAM Industries has a good record when working on those types of components so we started working with them with the mindset that in the mountains, the clutch is a very important part of the snowmobile and how it works when you’re in the deep snow and because you’re at a low ground speed and high RPM way more often than when you’re on the trail side of things you tend to be pretty hard on the clutches, and we’ve seen the first thing that goes on a mountain sled in the clutches is roller bearing wear on the spider.
“What happens there is when that roller bearing starts going out, your RPMs become erratic and a lot of times people even have a hard time diagnosing what’s going on there. And, I wouldn’t call it premature failure but it’s a failure that happens sooner than what you’d see on a trail sled and so we felt ‘OK, if we’re going to work on a new clutch we want to improve that area’ so that roller bearing lasts longer.
“We feel we’re experts on snowmobiles and how we design them. TEAM Industries, they’re experts when it comes to making clutches and those kinds of components so we wanted to align ourselves with a company that was very good at that. On the secondary side of things we felt that some of the things that we wanted to focus on was getting a secondary that was a little easier to work on, more serviceable and [more] durable because if you have a problem with durability on your driven clutches it kind of screws up the whole system. Not that we had a big problem with our driven clutches because I don’t think we did based on our warranty and feedback from our customers, but we did feel that there was areas that we wanted to improve. An example would have been the fastener that’s used to hold the driven clutch on the shaft. We heard some cases where guys weren’t getting them tight enough when they go to put the driven back on and then they’d start backing out and then lose their bolt. So when we were doing the new secondary we said, ‘Hey, we need a bigger bolt so that we can get more torque on the bolt to keep everything tight.’
“Even the aesthetics of the clutch itself. You look at the new clutch vs. the old, and most people may not even pick up on it. The cool thing about the snowmobile customer is they buy a sled and they’ll bring it in their shop and they’ll take the side panels off and the hood and they’ll just look at it, and they look at the engineering that’s gone into the parts and it means something. You buy a new car and you open the hood and all you see is a big cover. On a snowmobile you can open the hood and see the actual working components and you can see the craftsmanship that’s gone into something like the clutch. You look to see how it’s engineered and you say, ‘OK, it looks good and it performs well.’ A lot of thought goes into each one of those components. I think that’s a lot of value in working with a company like TEAM. They’re not designing snowmobiles. They’re designing clutches or drive systems. So they focus their attention on those minute details.”
2. When did project start?
[Three seasons ago] “They would come to the table and say, ‘We have the design. This is kind of what it looks like.’ And then we’ll start off, before you even start tooling any parts [they will] machine out of billet material and they’ll send us these protos and we’ll start running them and look for the values in them. Is it working better? Does it feel like it’s working better? Are the belts staying cooler? [Are the] clutches themselves staying cooler? And then you take a lot of measurements in regards to, is the sled vibrating? Or is it vibrating more than the other clutches? Trying to look at the data to see how well that power is getting to the ground. And then from that point when we did quite a bit of testing with the billet parts and felt that there was good value there.
“And the next step is obviously you get to more tooled parts and you start working through the things you’ll see with tooled parts. There are always things that you learn in the field that you may not have learned with a dyno or even from the proto part, so you work through those issues and by the time you’re done you feel pretty comfortable going through that process that you’re going to have a pretty durable product when the customer gets it.
3. In your words, describe what driving a sled with the new systems feels like.
“From the perspective of the customer, when you get on the snowmobile; when you’re getting into a situation where you need to get immediate power to the track, you don’t want any hiccups. You don’t want any stumbles. You don’t want the belt slipping. When you’re trying to get out of a hole and get back up on the snow you don’t want it to stumble at all. So, the idea is in a well working system that the power just seems fluid. It’s just right there as you squeeze the throttle. So with the new clutches we felt that as you get into the throttle that power is going into the clutches, into the drive system immediately. It isn’t like there’s any delay or any kind of hiccup going through the system. When I think of that, I think smooth. It’s a smooth transition from idle all the way up to open throttle.
“[When] you hit a crossing and you land, you expect when you get on the throttle again you don’t have that – you may have felt on some sleds if they’re not clutched properly – you don’t get good backshift. So, you’re always making sure that power is always there. If it’s on the trail, in the mountains or on the tourings, you get off the throttle and you get back on the throttle that it’s very quick and smooth. There isn’t any delay.
“When clutches start binding, it transfers into belt heat. The belt’s wanting to do one thing and the clutches are doing another thing and when you get belt heat you get premature belt failure. That’s a key part of why the tolerances need to be tighter. It’s like a well-oiled machine or a watch. All of the parts are working together they’re smooth, and if they’re smooth it keeps the heat down and it lasts longer.
4. Could tightening the tolerances on the old clutches have been a solution?
“Let’s say you take a drive clutch and you have different components of the drive clutch. You machine one sheave here, then you machine another sheave and you machine a cover. Even with our other clutches, it was important to match the clutch cover up with the moveable sheave because they work together and they’re kind of a matched set. The tighter the tolerances, the more something costs.”
5. Regarding the process for the primary clutch’s spider, do you know other things in the world that are Melonite processed?
“It’s a fairly common surface treatment resulting in a harder outer case. You see it in shock shafts, anything where there is higher heat.”
6. Was there research involved to find the correct secondary clutch fin angle? What interesting things did you learn?
“We’ve learned stuff on that, as well as TEAM has learned it. The fins that they designed, I go back to fins that we’ve had on our other clutches where we did a lot of different testing in regards to simulations. The thing with the fins, you have to be careful. You know it’s going to improve the cooling effect of the driven clutch but it also can be a detriment in that it can rob horsepower.
“You look at some of the older sleds and we used to put actually covers on those fins and so when designing the fins, you can design a fin where all it’s doing is maybe robbing horsepower and it may not be doing a very good cooling effect to the driven clutch. So there’s been work where guys have tried different heights of fins. I’ve heard clutching guys say that it can take a mile to a mile-and-a-half off the top end. And that can mean something to some people. Two guys going across a big lake and his buddy’s ahead of him, a mile-an-hour can feel like a lot.”
7. In your testing, how much cooler does the system run compared to the old?
“We saw that when our sleds were geared a little higher that maybe we were having more belt issues than what we wanted. You understand that there [are] certain conditions that a snowmobile goes in and you’re still going to get higher belt temperatures so you try to get it so everything’s working properly so it isn’t a matter of a part that’s not right. You’d rather have conditions dictate whether you’re going to have a warm belt more than the system itself. If you’re geared too high and you like to crawl around in deep snow, you’re going to have higher belt temperatures.
“Geared optimally and you’re in deep snow, you’re going to have higher belt temperatures than if you were just driving on a trail with no load on the system, so we want the system to work properly so that the maximum belt temperature will be as low as possible for the conditions you’re running in. We saw that in a well-calibrated system, the belt temperatures would probably be anywhere from 5 to 20 degrees [F cooler]. We saw more of a consistent basis that the clutches ran a little bit cooler than what the other clutches would have been running, but it’s hard to put a direct correlation to it because there’s so many variables when it comes to clutch and belt temperature. But I’d say for the most part they ran a bit cooler.”
8. Related to controlling variables:
“It’s difficult to duplicate the exact conditions so all you do is you just test a lot. You need to get a good sampling. Some days it might be hard to see any difference. They both might be running cool. [We] never saw a case where the TEAM clutches were running hotter than the clutches we had on before but there were cases where they were running the same temperature.
“We never really saw big outliers. If one sled was running really hot or warm belt temperatures or clutch temperatures, generally it had to do with there was something not right with that system. For example, if your clutch offset was not set properly. You’re going to get high belt temperatures. So it wouldn’t matter if you were running TEAM clutches or the other clutches, your belt temperature is going to be affected by something that’s not right.
“Or, let’s say if you’re running too tall of gears in a system, you’re going to get high belt temperatures regardless of which clutches are on there. So, if you’re going to compare clutches you need to compare both running systems. Are both systems calibrated properly? Apples to apples, you’ll see slightly cooler temperatures, but not drastic. They’re not way cooler, because they’re both running cool.”
9. Can you talk about some of the difficulties in designing the BOSS setup?
“When we first started there were certain designs that we were going for that were maybe a little lighter, but then when got them on the sled we learned some were not quite making our durability targets. We’re very cognizant of not having a drive or driven clutch that would be perceived as not durable so we almost err to the side of durability. Make it durable so that there’s absolutely no way that the consumer’s going to have a problem with it.
“You could look at the other end of it that if we make it lighter, but after a certain amount of miles then the clutch is going to go bad and people are just going to have to deal with it. We’re under the mindset that it’s got to be durable always, for the life of the product. And so there’s always some give and take there. Maybe TEAM might come to us and say ‘we’re going [with] this design’ and we’ll say ‘No, we tested it. We found this issue, we need this issue corrected.’ So there’s a lot of back and forth in regard to that.
“But we’ve had a good relationship with them and they understand the importance of the durability but I think that maybe we might be a little more. They do clutches for not just us, and I think we came across as we don’t want to skimp at all on the durability. It’s got to be, if anything, more durable. Like I said, err to the side of durability even if that means adding a little bit of weight in it. When you start looking into the whole design of the driven clutch and how it works with the driven shaft there was some stuff going back and forth on that, but otherwise it wasn’t drama-filled by any means. It was a pretty good design process with them.”