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  Drive sprocket for a tracked vehicleUSPTO Application #: 20060012247Title: Drive sprocket for a tracked vehicle Abstract: A snowmobile is propelled by an endless track that is operatively connected to the snowmobile's engine by two drive sprockets. Each drive sprocket includes one set of external teeth and two sets of internal teeth that engage three corresponding sets of track teeth formed on the track. Alignment cleats are mounted on the inside of each of one of the sets of track teeth. During low-load operation, contact between the cleats (and the track teeth on which the cleats are mounted) is minimized or eliminated, which reduces or eliminates noise caused by collisions between the metal sprocket and the metal cleats. During higher load operation, the track deforms such that the set of external sprocket teeth engage the cleats and associated set of track teeth. (end of abstract) Agent: Osler, Hoskin & Harcourt LLP (brp) - Montreal, CA Inventors: Dominic Girard, David Belzile, Eric Bertrand USPTO Applicaton #: 20060012247 - Class: 305199000 (USPTO) Related Patent Categories: Wheel Substitutes For Land Vehicles, Tracks Or Treads, With Guide Means For Interfitting With Sprocket Wheel Or Roller, Sprocket And Track Engagement, Sprocket Wheel Structure, Per Se The Patent Description & Claims data below is from USPTO Patent Application 20060012247. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] The present application is a continuation of U.S. application Ser. No. 10/636,917 filed on Aug. 8, 2003. Through the '917 application, the present application claims priority to US Provisional Application No.: 60/402,088 filed on Aug. 9, 2002. The disclosure of both are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to drive sprockets for tracked vehicles, and relates more specifically to the tooth design for such drive sprockets having improved traction with reduced noise generation. [0004] 2. Description of Related Art [0005] Tracked vehicles such as snowmobiles and snow groomers drivingly engage the ground through one or more endless tracks. Endless tracks conventionally include an outer side with a pattern of projecting lugs or ribs that are designed to engage the snow or other ground surface, apply traction, and propel the vehicle. Conventional endless tracks also include an inner side that engages one or more drive sprockets, which, in turn, are operatively connected to a propulsion system of the vehicle. [0006] The drive sprockets and the inner side of the endless track typically include mating teeth that provide traction between the drive sprockets and the endless track. Conventional drive sprockets use either external or internal teeth. [0007] FIGS. 9 and 10 illustrate a drive sprocket 1010 that includes a plurality of radially-extending sprocket teeth 1020 projecting outwardly from an outer circumferential side of the sprocket 1010. An endless track 1030 includes a plurality of longitudinally spaced holes that define a plurality of track teeth 1040. Reinforcing metal bars (not shown) extend laterally across the endless track 1030 through the track teeth 1040 to reinforce the track teeth 1040 and the track 1030. The track teeth 1040 mesh with the sprocket teeth 1020 to provide traction between the drive sprocket(s) 1010 and the track(s) 1030. In the typical example where the drive sprocket 1010 is used, two such sprockets 1010 usually are provided to engage each endless track 1030. [0008] Each track tooth 1040 is surrounded by a metal alignment cleat 1050 that meshes with the sprocket 1010 to keep the endless track 1030 laterally aligned with the drive sprockets 1010. As the drive sprockets 1010 rotate to propel the vehicle, the cleats 1050 rattle against the valleys formed between adjacent sprocket teeth 1020. This metal-to-metal contact creates noise, especially when the vehicle travels quickly. [0009] FIGS. 11-13 illustrate an additional conventional drive sprocket 1060 that includes a plurality of axially-extending sprocket teeth 1070. An endless track 1080 includes a plurality of longitudinally-spaced track teeth 1090 projecting inwardly from an inner side of the endless track 1080. The sprocket teeth 1070 engage the track teeth 1090 to provide traction between the sprocket 1060 and the endless track 1080. Alignment cleats 1050 are laterally offset from the track teeth 1090 on the endless track 1080 and the sprocket teeth 1070. Consequently, the cleats 1050 do not typically rattle against the sprockets 1060 as much as in the previous example, and noise is reduced as compared to sprockets 1010 that rely on radially-extending teeth 1020. [0010] While the use of axially-extending teeth 1070 instead of radially-extending teeth 1020 reduces noise, the axially-extending teeth 1070 are not as effective at generating traction with the track 1080 as the radially-extending teeth 1020. The reduction in traction may be caused, in part, by the fact that the internal track teeth 1090 are typically not reinforced and therefore deform under high loads. Accordingly, a greater number of sprockets 1060 must be used to generate sufficient traction with the endless track 1080. As illustrated in FIGS. 8 and 9, four internally toothed sprockets 1060 (two inner sprockets 1060 with two sets of sprocket teeth 1070 and two outer sprockets 1060 with one set of sprocket teeth 1070) are typically used. [0011] As a result of this, a need has developed for a sprocket construction that provides the superior traction of the drive sprocket 1010 while also minimizing the generation of noise as does the drive sprocket 1030. [0012] Others have attempted to solve these problems. FIGS. 14-16 illustrate an additional conventional drive sprocket 1110 that includes a plurality of axially-extending sprocket teeth 1120. The sprocket teeth 1120 engage the track teeth 1090 of the endless track 1080, as shown, for example, in FIGS. 12 and 13. The drive sprocket 1110 further includes a plurality of radially-extending sprocket teeth 1130 projecting outwardly from the an outer circumferential side of the sprocket 1110. The radially-extending sprocket teeth 1 130 mesh with track teeth 1040, as shown, for example in FIGS. 9 and 10 to provide traction between the drive sprocket 1110 and the endless track. The radially-extending sprocket teeth 1130 extend directly from the outer circumference of the sprocket 1110 and have a width substantially the same as the sprocket teeth 1120. The drive sprocket 1110 exhibits many of the drawbacks identified above. SUMMARY OF THE INVENTION [0013] Accordingly, one aspect of embodiments of the present invention provides a drive sprocket that generates more traction than conventional drive sprockets. [0014] An additional aspect of embodiments of the present invention provides an improved drive sprocket that reduces noise. [0015] A further aspect of embodiments of the present invention provides an improved drive sprocket that includes at least two sets of teeth. [0016] A further aspect of embodiments of the present invention provides a drive sprocket with both radially-extending and axially-extending teeth. [0017] A further aspect of embodiments of the present invention provides a sprocket for a vehicle having an endless track and a power plant. The sprocket includes a sprocket wheel that is engagable with the power plant of the vehicle. The sprocket wheel has a rotational axis, a perimetrical surface, and first and second axial surfaces. The sprocket also includes a first plurality of teeth extending radially outwardly from the perimetrical surface in spaced-apart relation, and at least a second plurality of teeth extending axially outwardly from the first axial surface in spaced-apart relation. A third plurality of teeth can extend axially outwardly from the second axial surface in spaced-apart relation. [0018] The sprocket wheel, the first plurality of teeth, and the second plurality of teeth may be integrally formed. The sprocket may also include a third plurality of teeth extending axially outwardly from the second axial surface in spaced-apart relation. Each of the first plurality of teeth, each of the second plurality of teeth, and each of the third plurality of teeth may be radially aligned. [0019] The perimetrical surface defines valleys between adjacent ones of the first plurality of teeth. The perimetrical surface may be generally cylindrically shaped such that each valley comprises an arc-shaped surface. [0020] Each of the second plurality of teeth define an outward surface that may be disposed radially farther from the rotational axis than adjacent valleys. [0021] Each of the second plurality of teeth may have two notches therein. Each of the second plurality of teeth has a base portion and a tip portion. The notches may be formed in the base portion. Continue reading... Full patent description for Drive sprocket for a tracked vehicle Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Drive sprocket for a tracked vehicle patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Drive sprocket for a tracked vehicle or other areas of interest. ### Previous Patent Application: Graduated train braking Next Patent Application: Electric power control device for watercraft Industry Class: Wheel substitutes for land vehicles ### FreshPatents.com Support Thank you for viewing the Drive sprocket for a tracked vehicle patent info. 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