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Tech Notes: Alpha One Game Changer

Will Arctic Cat’s paradigm shift set off the next wave of innovation?
RELATED TOPICS: ARCTIC CAT | SUSPENSIONS | TECH NOTES
Arctic Cat Alpha One single rail rear suspension
Every so often someone comes up with a new and better idea of how a snowmobile should work. There are lots of examples: Roger Skime’s front engine Arctic Panther with slide-rail suspension, Bobby Unser’s first IFS suspension, Yamaha’s liquid-cooled 440 SRX, Polaris’ IFS Indy sleds, Yamaha’s super-light Phazer, and lately Ski-Doo’s Rev platforms and E-TEC injection systems, to name a few. In each case, the other manufacturers got into mad scrambles to catch up.

■ Twenty years in the making
The reason we think the Arctic Cat Alpha One will result in the next mad scramble is that the trend has been to make sleds lighter, faster and easier to handle and ride. To be fair, the single-rail concept did not fall completely out of the sky; it has been used on some snow-bikes for quite some time now. Snow-bikes excited sledders with their easy handling, but only one ski out front is not the optimum setup for overall stability. The Alpha One suspension duplicates some of the snow-bike’s nimble deep-snow performance by bending and conforming the track to the surface and providing traction where regular tracks would only hook-up on part of the track surface.

The immediate thought is that Arctic Cat borrowed the technology from the snow bikes, but it actually turns out to be the other way around. The single rail concept has been in the idea stage at Arctic Cat for more than 20 years, and has been one of the pet projects of Andy Beavis, the mountain sled team manager at Arctic Cat. Before Andy took over as manager of the mountain team, he spent 15 years engineering Arctic Cat mountain sleds, and also worked with the hillclimb race team as well as competing on the circuit himself.

It turns out the single rail projects have been ongoing for at least 10 years and the actual patent work was completed in 2012. Some work was done to possibly fit a single rail to the ZR 200 youth sled that Arctic Cat and Yamaha collaborated on. When the single rail was not used on the 200, Camso asked to use the tooling for snow-bikes. As you’ll see elsewhere in this issue, AmSnow’s Western Editor Ryan Thompson has spent a fair amount of time on the new Alpha One and is impressed with the new and unique handling it offers, stating, “It takes riding to a whole new level in what is possible and can be accomplished while boondocking in the steep and deep of the mountain West. It also is a great confidence booster for anyone trying to improve their riding game.”
Arctic Cat Alpha One single rail rear suspension
Arctic Cat Alpha One single rail rear suspension
■ Simple idea, superb results
The concept itself is about as simple as you can get. Instead of two side rails holding the track flat, there is one center rail which lets the track pivot around it and conform better to off-trail surfaces. Although it is a single rail, it actually has two standard Arctic slides mounted on it with a 0.375-inch gap between them. This means the slides are mounted on a 1.5-inch center distance from each other, making it a 2.75-inch wide single rail with a gap down the middle. The gap is then used to run the side guide clips through it that otherwise would run on the outside like on the Camso snow-bike track. While the snow-bike track is 12 inches wide, the Alpha One track is a full 15 inches and comes in 154 and 165-inch lengths.

Since the track twists, Arctic Cat needed to make sure the edges were still stiff in order to get a good bite in the snow, therefore larger fiberglass cross-rods were used. The track has two distinctive lug-paddle layouts, where the center paddles actually have a negative tilt, are softer to flex and pack the snow better. The outside lugs are stiffer with an aggressive forward tilt, to give good bite in side hills. Designed specifically for the Alpha One, the track features centered windows to align with the beam. Aggressive 3-inch paddles with a 3.5-inch pitch provide phenomenal traction with the flexibility to maneuver almost effortlessly.

The single rail is suspended by the usual and proven linkage designs, with a front swing arm controlled by a Fox Float 3 QS3 air spring shock with a piggyback reservoir. This shock takes most of the punishment and needs the extra oil volume of the larger reservoir, but it also has the new and simple adjustable dampening with three settings: soft, medium and hard. The rear arm is a floating link and is also controlled by a Fox Float 3 QSL air spring shock. The rear shock has a lockout feature which gives very hard compression dampening. This feature helps keep the sled from rotating backwards on really steep hills, and allows for greater control while climbing steep mountains. The single rail has a much wider slide, but because it is in the center, further away from the track edges, the suspension also has two ice scrapers mounted on the front arm to throw more snow for lubrication into the center rail.
Arctic Cat Alpha One single rail rear suspension
Arctic Cat Alpha One single rail rear suspension
There are a number of obvious advantages with the single rail. First, the suspension is lighter by 11 pounds, compared to a twin rail design. Twin rail designs also hold more snow between the rails and crossbars, which adds to the overall weight when riding in loose snow. With the single rail, Ryan Thompson and his crew could report hardly any extra snow building up during hard use, which could easily mean 30-50 pounds less for the suspension to control, therefore a much quicker response from the air shocks as well as much less rider fatigue from the added weight. The original prototype monorail was fabricated and welded together from aluminum extrusions.

The production version is much more advanced. To save an additional 2 pounds the front is a magnesium casting that incorporates the front arm mount, front shock mount, limiter strap mount, idler wheel mount, and front anti-stab wheel mounts. The rest of the rail is extruded aluminum, but the two pieces are joined together by a space-age adhesive process. Welding the two pieces together would be dangerous, since magnesium is a fire hazard that is used in fireworks to give off nice glowing sparks. Since adhesive was used up front, it is also used for the brackets on the aluminum rail as part of the complete assembly procedure, eliminating all welding.

The suspension is mounted in the new Ascender platform. In this design the front drive axle is lowered 1.125 inches, which provides a larger tunnel clearance for the 3-inch lugged PowerClaw track. With the lower driveshaft, it gains a 9.7-degree flatter approach angle with the large 8-inch drive sprockets. The flatter approach angle not only reduces friction when the track hits the rail, but tests have shown that it more effectively compresses and packs the snow for better grip by the paddles. This allows the sled to come up on top of the snow faster than steeper angles that tend to churn the snow and sometimes, in loose conditions, actually promote track spin rather than gradually gripping the snow, leading to trenching.

■ Alpha dog?
There are obviously many questions about the new design: Will the components hold up, will the drive sprockets be strong enough, will the tracks derail and break and so on? Naysayers are left standing on the sidelines, just as racers did when they first saw Bobby Unser’s IFS design, and most predicted it would break. Five years later they all had to have one to be competitive. The verdict is still out on just how well the Alpha One will perform in the spring when the snow goes from soft during the day to hard over night. Would the track bend and slide-out during these morning conditions and a stiffer twin-rail fair better? The AmSnow test crew felt this was an unfair question because on hard ice, nothing bites. Most riders wait until later in the day when the surface is softer again. The Western Mountain test crew all felt that the Alpha One performed better than twin rails in a lot of conditions, but a verdict will have to wait until a full season of testing in all conditions has been done.
Arctic Cat Alpha One single rail rear suspension
■ Kickoff to creativity
Is the Alpha One suspension going to be a game changer? Much depends on mechanical performance. If there are no major defects, the competition will have to match Arctic Cat’s new technology and that may result in drastic design changes in the future. Personally, I think that’s a good thing. The industry needs a swift kick every now and then to get those creative juices flowing. For years now, I have seen snowmobile designs treading water with small refinements to established driver-forward designs that all start to look like clones of each other. The Alpha One isn’t like that, so it’s a leap in the right direction.

As a development engineer, I would like to see a light mono rail on a 128-inch 1.375 Ripper track in a low center of gravity, 400-pound trail sled that leans in corners like a motorcycle and offers a new and exciting handling experience, like the Phazers and the Indys did when they set new standards.

A single slide rail in a light and affordable trail sled may just do that and it would be a welcome game-changer. Maybe with Textron now aboard, Arctic Cat engineers will have enough resources to carry these innovative designs to new levels of excitement.
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