Abstract: End mounts are used to secure a helical tension spring to end fixtures with various shapes and sizes. These end mounts contain an inner hole to encase the inner spring end mount and secure the end mount making it like a cap. There is also a keyhole created in the top surface that goes through the end mount allowing it to fit over the fixtures but not over the inner end mount, holding it in place. Grooves are machined in a helical pattern on the cylindrical side wall of the end mount. The spring is wound onto the grooves of the end mount.

Abstract: Compression springs, such as helical compression springs, include end portions with selectively contoured inner contact surfaces. The selective contours of the inner contact surfaces may take the form of planar, grooved, concave, or other shaped, non-circular surfaces. In addition, enough of the inner contact surface is contoured to reduce the contact stress and/or stress concentration effects on the adjacent coils when the compression spring is placed under load and the adjacent coil engages or contacts the respective end portion. The selective contouring of the end portions may be accomplished by holding the spring in a holder and moving a cutter relative to the end portion of the spring to remove the desired amount of material from the end portion.

Abstract: An improved torsion type rear suspension system for a snowmobile. The suspension includes a pair of rails movable with respect to the snowmobile body and a pair of torsion springs disposed between the body and the rails for biasing the suspension toward its extended position. Also included is a cam block having a contoured cam surface which engages a leg of the torsion spring at a variable point of contact. As the suspension moves from the extended to the collapsed position, the effective length of the spring leg is reduced, resulting in a nonlinear change in spring force as a function of deflection. The cam block may be adjusted with respect to the suspension rails with an eccentric to permit additional adjustment of the spring force function to compensate for varying terrain, vehicle speed, and operator weight.