Retractable wheel system

Abstract

A retractable wheel for a ski with a fixed plate, an activation arm, a central linkage, a wheel arm, and a wheel. The activation arm pivots with the fixed plate between an engaged position and a disengaged position. The wheel arm also pivots with fixed plate and supports the wheel. The central linkage connects the activation arm and the wheel arm. When engaged, the wheel is in contact with the ground. When disengaged, the wheel is lifted from the ground. The activation arm locks into the engaged position. A biasing mechanism assists in lifting the wheel when the activation arm is disengaged. A mudguard attaches to the wheel arm to reduce debris projection. The central linkage provides a high movement ratio in the disengaged position and an increased torque in the engaged position. A secondary lock prevents disengagement when in the engaged position.

Description

TITLE OF THE INVENTIONRETRACTABLE WHEEL SYSTEMPRIORITY STATEMENT

[0001] This patent application claims priority on US patent application No. 63 / 735,644 filed on December 18, 2024.TECHNICAL FIELD

[0002] The present invention relates to snow-vehicles and, more particularly, to a retractable wheel attachment for a ski of a snow-vehicle.BACKGROUND

[0003] Vehicles equipped with skis, such as snowmobiles, are generally designed for use on snow and ice. When a snowmobile is used on hard surfaces like concrete or asphalt, it may become difficult to maneuver due to the inadequate friction and control that skis provide on such surfaces. Additionally, friction may lead to rapid wear of the skis and skegs. A retractable wheel system may allow the vehicle to move on wheels, thereby protecting the skis from damage while also enhancing control over the vehicle. Existing retractable wheel systems typically use a wheel mounted on a pivoting arm, equipped with a return spring on the pivot axis. These systems often require manual activation, which usually involves lifting the front of the ski with one hand while using the foot or the other hand to lower the wheel into position. Many of the current systems may require awkward maneuvers for activation, such as bending down and utilizing both hands and feet, which can be ergonomically challenging and inconvenient for users.

[0004] In existing systems, the wheel is held in a disengaged position by the return spring when not in use. Activation requires the wheel to pass a central point and rest against a secondary stop, with the weight of the snowmobile preventing the arm from returning to the disengaged position. Current systems often require additional components, such as rubber.

[0005] Furthermore, many systems are designed for specific ski models, necessitating unique configurations or adaptations for different vehicles. This lack of standardization can complicate inventory and installation.

[0006] Lastly, existing systems, especially those that engage from the front, may be prone to unintentional activation during extreme conditions or mechanical failures, posing safety risks to the rider.

[0007] There is a need for a safe and robust retractable wheel system for skis.SUMMARY

[0008] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0009] A first aspect of the invention described herein relates to a retractable wheel system for a ski with a wheel for engaging a ground, a fixed plate, an activation arm, and a central linkage. The fixed plate may attach the retractable wheel system to the ski. The activation arm may be pivotally connected to the fixed plate and configured to move between an engaged position and a disengaged position. The wheel arm may be pivotally connected to the fixed plate and may support the wheel. The central linkage may be pivotally connected to the activation arm and the wheel arm. The wheel arm may move the wheel into contact with the ground when the activation arm is engaged, and may lift the wheel from the ground when the activation arm is disengaged.

[0010] In embodiments, the activation arm may be positioned on a first longitudinal side of the fixed plate and the wheel is positioned on a second longitudinal side of the fixed plate.

[0011] In embodiments, the retractable wheel system may include a mount for fastening the retractable wheel system to the ski. The fixed plate may be configured to attach to the mount and the mount may be configured to attach to the ski.

[0012] In embodiments, as the activation arm pivots away from the disengaged position, the activation arm may rotate in an engagement direction and the wheel arm may rotate in an opposite direction thereby causing the wheel to move towards the ground. As the activation arm pivots into the engaged position, the activation arm and the wheel arm may rotate in the engagement direction, thereby causing the wheel to move away from the ground, and causing the activation arm to lock into the engaged position.

[0013] In embodiments, the central linkage may provide a high movement ratio to the wheel relative to the activation arm as the activation arm pivots away from the disengaged position, and provide a low movement ratio to the wheel relative to the activation arm, thereby providing an increased torque as the wheel engages the ground, as the activation arm pivots into the engaged position.

[0014] In embodiments, a biasing mechanism may be operatively connected to the activation arm to bias the activation arm towards the disengaged position, thereby assisting in lifting the wheel from the ground when the activation arm is disengaged. Optionally, the wheel may engage with the activation arm in the disengaged position, thereby causing an equilibrium between the wheel and the biasing mechanism. Alternatively, the retractable wheel system mayinclude a bumper. In the disengaged position, the activation arm may be biased by the biasing mechanism into contact with the bumper, limiting movement of the activation arm and defining a stable rest position.

[0015] In embodiments, a mudguard may be attached to the wheel arm and may cover, at least partially, the wheel. The mudguard may reduce debris projection from the wheel. Optionally, the mudguard may be made of a flexible material to absorb impacts from the debris projection. Optionally, the mudguard may include an opening at a contact point between the wheel and the activation arm to allow the wheel to engage with the activation arm in the disengaged position without damaging the mudguard.

[0016] In embodiments, the mudguard may include a deformable part, a rigid support member, and a releasable interlocking mechanism. The rigid support member may be attached to the wheel arm and disposed at an axis of the wheel. The releasable interlocking mechanism may detachably engage the deformable part with the rigid support member. In a normal configuration, the releasable interlocking mechanism may retain the mudguard in a deployed position adjacent the wheel. Upon contact between the mudguard and an obstacle, the deformable part may deform and the releasable interlocking mechanism may disengage, thereby allowing at least a portion of the mudguard to detach from the rigid support member.

[0017] In embodiments, the activation arm may include a first part pivotally connected to the fixed plate and a second part detachably attached to the first part. The first part and the second part may be attached using one or more calibrated fasteners configured to fail under excessive force to thereby protect the activation arm. Optionally, the first part may comprise a durable part and the second part may comprise a soft part. The durable part may be pivotally connected to the fixed plate and may be made of a durable material to withstand operational forces. The soft part may be detachably attached to the durable part, may be made of a replaceable material, and may act as a fusible link to protect the activation arm during excessive force.

[0018] In embodiments, the mount may include a ski axle to fasten the retractable wheel system across a width of the ski. Optionally, the ski axle may include a shoulder width to allow a lateral adjustment of the retractable wheel system on the ski. Optionally, the ski axle may have an offset fixation point and offset fixation axis (126B) relative to a main axis (126A), allowing for a vertical adjustment of the retractable wheel system relative to the ski.

[0019] In embodiments, the mount may include one or more spacers to adjust a lateral adjustment of the retractable wheel system on the ski. Optionally, at least one spacer of the one or more spacers may be a ring-shaped spacer. Optionally, the ski may have an angled surface, and at least one spacer of the one or more spacers may be a hollowed half-spherical spacer, enabling adjustment of the retractable wheel system onto the angled surface.

[0020] In embodiments, a secondary lock may prevent a disengagement of the wheel arm when in the engaged position.

[0021] In embodiments, the retractable wheel system may include an actuation mechanism. The actuation mechanism may be operatively connected to the activation arm and pivot the activation arm between the engaged position and the disengaged position. Optionally, the actuation mechanism may include at least one of a motorized actuator, a pneumatic actuator, and a hydraulic actuator.

[0022] In embodiments, the retractable wheel system may include a speed sensor to prevent transition between the engaged position and the disengaged position while the ski is in motion.

[0023] In embodiments, the retractable wheel system may include a suspension. The suspension may be operatively connected to the wheel to absorb shocks when operating over uneven surfaces.

[0024] A second aspect of the invention described herein relates to a vehicle with a ski and the retractable wheel system of the first aspect described herein. The retractable wheel system may be attached to the ski, enabling the vehicle to be lifted and moved using the wheel of the retractable wheel system when the retractable wheel system is in the engaged position.

[0025] In embodiments, the vehicle may be a snowmobile, a ski-bike, a ski-equipped airplane, a ski cart, or a sleigh.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Further features and exemplary advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the appended drawings, in which:

[0027] Figure 1 is a drawing of a front-left perspective view of an exemplary retractable wheel system attached to a ski in accordance with the teachings of the present invention;

[0028] Figure 2 is a drawing of a front-right perspective view of an exemplary retractable wheel system attached to a ski in accordance with the teachings of the present invention;

[0029] Figure 3A, Figure 3B, Figure 3C, Figure 3D, Figure 3E, Figure 3F, referred together as Figure 3, are drawings of views of an exemplary retractable wheel system in accordance with the teachings of the present invention. More specifically:- the drawings of Figure 3A depict a left view of the retractable wheel system; the drawings of Figure 3B depict a back view of the retractable wheel system;the drawings of Figure 3C depict a right view of an exemplary retractable wheel system;- the drawings of Figure 3D depict a top-left view of an exemplary retractable wheel system;- the drawings of Figure 3E depict a top view of an exemplary retractable wheel system; and- the drawings of Figure 3F depict a top-right view of an exemplary retractable wheel system;

[0030] Figure 4A is an exploded view of an exemplary retractable wheel system with a biasing mechanism and calibrated fasteners, in accordance with the teachings of the present invention;

[0031] Figure 4B is an exploded view of an exemplary retractable wheel system with a biasing mechanism and an activation arm comprising a soft part and a durable part, in accordance with the teachings of the present invention;

[0032] Figure 5A, Figure 5B, Figure 5C, and Figure 5D, referred together as Figure 5, are drawings depicting the retractable wheel system with a mudguard installed. More specifically:- the drawings of Figure 5A depict a side view of the retractable wheel system on a ski with a mudguard when the retractable wheel system is in a disengaged position;- the drawings of Figure 5B depict a side view of an exemplary retractable wheel system on a ski with a mudguard when the retractable wheel system is in the engaged position;- the drawings of Figure 5C depict a side view of an exemplary retractable wheel system with a mudguard; and- the drawings of Figure 5D depict an exploded view of an exemplary retractable wheel system with a mudguard;

[0033] Figure 6 is an exploded view of an exemplary retractable wheel system comprising a durable part and a soft part, in accordance with the teachings of the present invention;

[0034] Figure 7A and Figure 7B, referred together as Figure 7, are views of an exemplary retractable wheel system on a ski in accordance with the teachings of the present invention. More specifically:- the drawings of Figure 7A depict a view of an exemplary retractable wheel system on a ski when in the disengaged position; andthe drawings of Figure 7B depict a view of an exemplary retractable wheel system on a ski when in the engaged position;

[0035] Figure 8 is a drawing of an exemplary retractable wheel system depicting engagement of the wheel and the activation arm when in the disengaged position, in accordance with the teachings of the present invention;

[0036] Figure 9A, Figure 9B, Figure 9C and Figure 9D, referred together as Figure 9, are drawings depicting an exemplary retractable wheel system in various configurations, in accordance with the teachings of the present invention. More specifically:- the drawings of Figure 9A depict an exemplary retractable wheel system in the disengaged position;- the drawings of Figure 9B depict an exemplary retractable wheel system pivoting away from the disengaged position;- the drawings of Figure 9C depict an exemplary retractable wheel system pivoting towards the engaged position; and- the drawings of Figure 9D depict an exemplary retractable wheel system in the engaged position.

[0037] Figure 10A, Figure 10B, Figure 10C, and Figure 10D, referred together as Figure 10, are views of an exemplary retractable wheel system depicting different mount configurations in accordance with the teachings of the present invention. More specifically:- the drawings of Figure 10A depict an exemplary mount for retractable wheel system, with a large shoulder and spacers;- the drawings of Figure 10B depict an exemplary mount for retractable wheel system, with a medium shoulder and spacers;- the drawings of Figure 10C depict an exemplary mount for retractable wheel system, with a thin shoulder and spacers;- the drawings of Figure 10D depict an exemplary mount for retractable wheel system, with an offset fixation point and spacers;

[0038] Figure 11 A, Figure 11 B and Figure 11C, referred together as Figure 11 , are drawings depicting exemplary spacers for a retractable wheel system, in accordance with the teachings of the present invention. More specifically:- the drawings of Figure 11A depict an exemplary retractable wheel system attached to a ski using a thin ring-shaped spacer, a large ring-shaped spacer, and a hollowed half-spherical spacer;the drawings of Figure 11 B depict a side view of six exemplary spacer configurations using various sizes of ring-shaped spacers and a hollowed half- spherical spacer; and- the drawings of Figure 11 C depict a perspective view of six exemplary spacer configurations using various sizes of ring-shaped spacers and a hollowed half- spherical spacer;

[0039] Figure 12 is a drawing of a top-left perspective view of an exemplary retractable wheel system in an engaged position with a secondary lock in accordance with the teachings of the present invention;

[0040] Figure 13A is a drawing of a side view of an exemplary retractable wheel system with a mudguard contacting an obstacle in accordance with the teachings of the present invention, and Figure 13B and Figure 13C are drawings illustrating an exemplary mudguard retention and release mechanism;

[0041] Figure 14A and Figure 14B, referred together as Figure 14, depict an exemplary retractable wheel system with a mudguard that includes an opening in accordance with the present invention. More specifically:- the drawings of Figure 14A depict a side view of an exemplary retractable wheel system with a mudguard with an opening; and- the drawings of Figure 14B depict an exploded view of an exemplary retractable wheel system with a mudguard with an opening; and

[0042] Figure 15 is a drawing of a side view of an exemplary retractable wheel system with a bumper in accordance with the teachings of the present invention.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0043] Vehicles with skis, such as snowmobiles, are designed to slide on terrain such as snow, ice or water. When these vehicles are being transported or serviced however, they may have to navigate hard surfaces such as concrete, asphalt, or gravel. When gliding over hard surfaces, vehicles may be difficult to maneuver due to the inadequate friction while skis and skegs may suffer significant wear and damage. Wheels attachments, for skis, have been used to raise the skis and allow ski-vehicles to roll over hard surfaces, but most are either unsafe, inconvenient to use, or made of complex components. The techniques described herein relate to a retractable wheel system that may resolve, at least partially, some of these issues.

[0044] Reference is now made to the drawings in which Figure 1 depicts a front-left perspective view of an exemplary retractable wheel system 100 attached to a ski 400 in accordance with the teachings of the present invention, Figure 2 depicts a front-rightperspective view of an exemplary retractable wheel system 100 attached to a ski 400, and Figure 3A, Figure 3B, Figure 3C, Figure 3D, Figure 3E, and Figure 3F, referred together as Figure 3, depict views of an exemplary retractable wheel system 100 in accordance with the teachings of the present invention. More specifically, Figure 3A depicts a left view of the retractable wheel system 100, Figure 3B depicts a back view of the retractable wheel system 100, Figure 3C depicts a right view of the retractable wheel system 100, Figure 3D depicts a top-left view of the retractable wheel system 100, Figure 3E depicts a top view of the retractable wheel system 100, and Figure 3F depicts a top-right view of the retractable wheel system 100.

[0045] A first aspect of the techniques described herein relates to a retractable wheel system 100 for a ski 400 with a wheel 210 for engaging a ground, a fixed plate 310, an activation arm 320, and a central linkage 330. In the context of the disclosure, a ski 400 may be a structural component of a ski-vehicle 1000, such as a snowmobile or similar vehicle, designed primarily for use on water, snow and ice. The embodiments presented herein may be adapted for different types of vehicles, such as a ski-bike, a ski-equipped airplane, a ski cart, or a sleigh. Although typical embodiments may be detachably-attached to ski-vehicles as part of an after-market add-on, persons skilled in the art will readily recognize that the retractable wheel system 100 presented herein may be permanently attached to a ski 400.

[0046] Reference is now also made to the drawings in which Figure 4A depicts an exploded view of an exemplary retractable wheel system with a biasing mechanism and calibrated fasteners, in accordance with the teachings of the present invention, and Figure 4B depicts an exploded view of an exemplary retractable wheel system with a biasing mechanism and an activation arm comprising a soft part and a durable part, in accordance with the teachings of the present invention.

[0047] The activation arm 320 may include a first part 322 pivotally connected to the fixed plate 310 and a second part 324 detachably attached to the first part 322. A two-part detachably attachable configuration may protect the activation arm 320 from transferring forces to the fixed plate 310 beyond an operational threshold. In one embodiment, the first part 322 and the second part 324 may be attached using one or more calibrated fasteners 326 configured to fail under excessive force. Examples of calibrated fasteners 326 may include shear bolts, shear screws, waisted fasteners having a reduced cross-section defining a controlled failure point, necked fasteners having a reduced cross-section defining a controlled failure point, fasteners made of a selected material and / or heat treatment to obtain a desired failure load, and fasteners having a scored or notched portion to promote failure at a predetermined location. Upon application of an excessive force, the calibrated fasteners 326 may fail to allow relative movement or separation between the first part 322 and the second part 324, thereby limiting transfer of forces to the fixed plate 310 and reducing risk of damage to other components ofthe retractable wheel system 100. In other embodiments, the calibrated fasteners 326 may be replaceable to allow restoration of the activation arm 320 after failure.

[0048] Alternatively, the first part 322 and the second part 324 may be configured such that at least a portion of the activation arm 320 acts as a fusible link. In one embodiment, the first part 322 may comprise a durable part made of a durable material configured to withstand operational forces, and the second part 324 may comprise a soft part made of a replaceable material. The soft part may be detachably attached to the durable part and configured to deform, disengage, or break under excessive force before the durable part, thereby reducing transfer of forces to the fixed plate 310 and other components of the retractable wheel system 100. The soft part may be replaceable to restore functionality after an overload event. In embodiments, fusible-link behavior of the soft part may be obtained through one or more of a reduced-thickness region, a localized weakened region, a shear feature, ora frangible interface between the soft part and the durable part. The second part 324 and the first part 322 may be attached by one or more calibrated fasteners configured to fail under excessive force, thereby protecting the activation arm 320.

[0049] Use of calibrated fasteners may allow the first part 322 and the second part 324 to comprise durable materials while providing a fusible function upon excessive force. A configuration using calibrated fasteners may improve mechanical strength under normal operating conditions and may allow the activation arm 320 to have a reduced overall thickness profile, for example by reducing material bulk otherwise required to form a deformable or frangible soft portion. In embodiments, the activation arm 320 may comprise a metal core, such as steel, optionally with a polymer overmold, to provide durability and reduce thickness.

[0050] The ski 400 may be constructed from durable materials configured to withstand friction and impact, such as metal or reinforced composites. Skegs or runners may be attached to an underside of the skis 400 to prevent sideways sliding of a vehicle and enhance handling and control of the vehicle. When navigating over hard surfaces such as gravel, concrete, or asphalt, a retractable wheel system 100 may be used to protect the ski 400 and a skeg and enhance control of the vehicle.

[0051] The wheel 210 for engaging the ground may comprise materials or structures configured to provide traction, including rubber or reinforced synthetics, to support the weight of the vehicle 1000 and provide stability during operation across various terrains. Dimensions of the wheel 210 may be influenced by factors balancing ground engagement and requirements for compactness and ease of retraction during non-use. In embodiments, a diameter of the wheel 210 may range from approximately 5 to 20 centimeters, providing ground clearance and traversal over hard surfaces; variations beyond this range may be selected according to circumstance. A larger diameter of the wheel 210 may facilitate navigation of obstacles anduneven surfaces encountered on non-snow terrains. In embodiments, a width of the wheel 210 may be approximately 1 to 3 centimeters, providing stability and load-bearing capacity for supporting the weight of the vehicle 1000 and providing traction without increasing rolling resistance or a physical footprint of the wheel 210 when retracted. Narrower or wider widths of the wheel 210 may be selected based on variables including weight of the vehicle 1000, typical load, and positioning of the wheel 210 relative to a center of gravity of the vehicle 1000. Dimensions of the wheel 210 may also permit integration of tread or gripping patterns to enhance contact and traction capabilities of the wheel 210, facilitating transitions across diverse surfaces.

[0052] The fixed plate 310 may be configured to attach the retractable wheel system 100 to the ski 400 of the vehicle 1000. The fixed plate 310 may serve as an interface between the retractable wheel system 100 and the ski 400 and may maintain a mechanical attachment of the retractable wheel system 100 and withstand dynamic forces exerted during use. The construction materials forthe fixed plate 310 may include metals, including steel and aluminum, or reinforced composites. The fixed plate 310 may feature customized mounting attributes to ensure alignment with the ski 400 and provide protection against operational stresses. The fixed plate 310 may include mounting holes or brackets to facilitate a secure and precise attachment to the ski 400, thereby ensuring alignment and stability.

[0053] The activation arm 320 may be configured to function as a mechanical control lever, thereby facilitating transition between an engaged position and a disengaged position of the wheel 210 during operation. The activation arm 320 may be pivotally connected to the fixed plate 310 and may be configured to move between an engaged position and a disengaged position. The activation arm 320 may be configured to function as a lever or control mechanism and may be operatively linked to the fixed plate 310, wherewith pivoting movement may be permitted.

[0054] The activation arm 320 may be configured to accommodate foot activation, thereby enabling ergonomic operation where users may activate the retractable wheel system 100 without adopting uncomfortable positions. The pivotal connection between the activation arm 320 and the fixed plate 310 may be achieved through use of a pin or axle extending through aligned holes in the activation arm 320 and a corresponding bracket or support structure on the fixed plate 310. The pin or axle and the aligned holes may permit rotational movement around a pivot axis.

[0055] In an engaged position, the activation arm 320 may extend in an orientation causing the wheel 210 to be lowered, thereby engaging the ground for operation over non-snow surfaces. In a disengaged position, the activation arm 320 may retract or transition to analternate orientation, thereby allowing the wheel 210 to be lifted from the ground and permitting the ski 400 to glide on snow or ice.

[0056] The central linkage 330 may be described as a coordinating structural component that may transmit torque from the activation arm 320 to the wheel arm 340. The central linkage 330 may be pivotally connected to the activation arm 320 and the wheel arm 340. The central linkage 330 may comprise one or more arms, each arm pivotally connected to the activation arm 320 at one end and pivotally connected to the wheel arm 340 at another end. In one embodiment, two activation arms 320 may be employed on opposite lateral ends of the fixed plate 310, thereby providing a clearance space therebetween, allowing for the wheel arm 340 to pivot therewithin. In another embodiment, the activation arms 320 may be partially or fully hollowed to provide clearance space for the wheel arm 340.

[0057] The wheel arm 340 may be pivotally connected to the fixed plate 310 and may support the wheel 210. The wheel arm 340 may move the wheel 210 into contact with the ground when the activation arm 320 is engaged, and may lift the wheel 210 from the ground when the activation arm 320 is disengaged. A pivotal connection of the wheel arm 340 with the fixed plate 310 may be established, potentially through a pin or axle extending through aligned openings on the wheel arm 340 and the fixed plate 310. The relationship between the wheel arm 340 and the fixed plate 310 may allow pivoting of the wheel arm 340 relative to the fixed plate 310, thereby contributing to movement of the wheel 210 between engagement with the ground and retraction away from the ground. In supporting the wheel 210, the wheel arm 340 may serve as a structural element for bearing load of the wheel 210 and for facilitating positioning thereof during transitions between an engaged state and a disengaged state. Construction of the wheel arm 340 may involve materials providing sufficient rigidity and strength, wherewith the wheel 210 may support weight of the vehicle 1000 as needed.

[0058] In embodiments, the activation arm 320 may be positioned on a first longitudinal side of the fixed plate 310 and the wheel 210 may be positioned on a second longitudinal side of the fixed plate 310 such that the activation arm 320 and the wheel 210 may be located on opposite sides of the fixed plate 310. In embodiments, the activation arm 320 may be positioned toward a forward-facing side of the ski 400, wherewith access and operation by a user may be facilitated. Placement of the activation arm 320 in a forward position may enable engagement or disengagement of the retractable wheel system 100 without a need to maneuver around or under the vehicle 1000. Positioning of the wheel 210 on the second longitudinal side may provide a configuration allowing the wheel 210 to be deployed or retracted without interference from the activation arm 320. Opposite placement of the activation arm 320 and the wheel 210 may allow an engagement process to remain unobstructed and may maintain structural stability of the retractable wheel system 100.

[0059] In another embodiment, the retractable wheel system 100 may be configured such that both the activation arm 320 and the wheel 210 may be positioned on a same longitudinal side of the fixed plate 310, with the activation arm 320 and the wheel 210 being either forward facing or rear facing. In such a configuration, the activation arm 320 may be configured to manipulate pivoting motion thereof differently. When the activation arm 320 and the wheel 210 may be positioned on the same longitudinal side of the fixed plate 310, the activation arm 320 may, for example, be lifted upward to engage the wheel 210 with the ground, and the activation arm 320 may be lowered to disengage the wheel 210 from the ground.

[0060] In embodiments, as the activation arm 320 may be pivoted away from the disengaged position, the activation arm 320 may be rotated in an engagement direction and the wheel arm 340 may be rotated in an opposite direction, thereby causing the wheel 210 to be moved towards the ground. As the activation arm 320 may be pivoted into the engaged position, the activation arm 320 and the wheel arm 340 may be rotated in the engagement direction, thereby causing the wheel 210 to be moved away from the ground, and thereby causing the activation arm 320 to be locked into the engaged position.

[0061] Reference is now made to the drawings in which Figure 7A and Figure 7B, referred together as Figure 7, depict views of an exemplary retractable wheel system 100 on a ski 400 in accordance with the teachings of the present invention. More specifically, Figure 7A depicts a view of an exemplary retractable wheel system 100 on a ski 400 when in the disengaged position, and Figure 7B depicts a view of an exemplary retractable wheel system 100 on a ski 400 when in the engaged position. Figure 9A, Figure 9B, Figure 9C and Figure 9D, referred together as Figure 9, depict drawings of an exemplary retractable wheel system 100 in various configurations. More specifically, Figure 9A depicts an exemplary retractable wheel system 100 in the disengaged position, Figure 9B depicts an exemplary retractable wheel system 100 pivoting away from the disengaged position, Figure 9C depicts an exemplary retractable wheel system 100 pivoting towards the engaged position, and Figure 9D depicts an exemplary retractable wheel system 100 in the engaged position.

[0062] In embodiments, as the activation arm 320 may be pivoted away from the disengaged position and toward an engagement direction, the wheel arm 340 may be rotated in an opposite direction, thereby causing the wheel 210 to be moved toward the ground. For clarity, when the activation arm 320 and the wheel arm 340 face opposite directions (for example, the activation arm 320 faces a forward direction while the wheel arm 340 faces a rear direction), rotation of both arms in opposite directions may cause both arms to travel together in an upward direction or a downward direction, wherewith lowering of the activation arm 320 may cause the wheel arm 340 to also be moved downward. By contrast, in embodiments where the activation arm 320 and the wheel arm 340 face the same direction, lifting of the activationarm 320 may cause the wheel arm 340 to also be moved downward. The movement sequence may be guided by mechanical interplay between the activation arm 320, the central linkage 330, and the wheel arm 340, wherewith the activation arm 320, the central linkage 330, and the wheel arm 340 may collectively form a kinematic chain designed to translate operator input into controlled mechanical motion.

[0063] From the disengaged position, an external force may be applied to the activation arm 320, thereby prompting pivoting of the activation arm 320 toward the engagement direction. The central linkage 330 may transmit movement of the activation arm 320 to the wheel arm 340. In embodiments, the central linkage 330 may provide a high movement ratio to the wheel 210 relative to the activation arm 320 as the activation arm 320 pivots away from the disengaged position, and may provide a low movement ratio to the wheel 210 relative to the activation arm 320, thereby providing increased torque as the wheel 210 engages the ground as the activation arm 320 pivots into the engaged position.

[0064] The central linkage 330 may be configured to provide a low reduction ratio at a beginning of an engagement process, thereby allowing the wheel 210 to be lowered quickly from an initial clearance from the ground. The low reduction ratio and the initial clearance may ensure transitioning of the wheel 210 from a retracted position without causing drag or obstruction during deployment. As the activation arm 320 continues movement of the activation arm 320 towards the engagement position, linkage geometry of the central linkage 330 may transition past an over-center position, wherewith the over-center position may constitute a mechanical state where a line of action of forces aligns with a pivotal axis, thereby resulting in temporary equilibrium with minimal force needed to maintain the over-center position.

[0065] As the retractable wheel system 100 approaches an over-center position and moves towards an engagement position, mechanical interplay between the activation arm 320, the central linkage 330, and the wheel arm 340 may cause transition to a high reduction ratio. The high reduction ratio may provide torque to an operator as the wheel 210 is lowered below the ski 400, thereby lifting the vehicle 1000. Upon movement beyond the over-center position, motion of the wheel arm 340 may begin to reverse, wherewith the wheel arm 340 rotating upward as the retractable wheel system 100 reaches full engagement. In one embodiment, the wheel 210 may travel upward by about 10 mm before reaching a final engagement position. Once engaged, operational forces including weight of the vehicle 1000 and terrain resistance may stabilize the wheel 210 against unintended retraction, thereby ensuring deployment of the retractable wheel system 100 across diverse terrains.

[0066] The high reduction ratio and high torque around an engagement position may be advantageous when disengaging the activation arm 320, as transition of the activation arm 320 away from the engagement position may require downward rotation of the wheel arm 340 andslight lifting of the vehicle 1000 against the weight of the vehicle 1000. The high reduction ratio and high torque may allow an operator to exert less effort while overcoming gravitational forces associated with lifting the wheel 210 and transitioning the retractable wheel system 100 back to a disengaged position.

[0067] Reference is now made to the drawings in which Figure 4A and Figure 4B depict exploded views of exemplary retractable wheel systems 100 with a biasing mechanism 230 in accordance with the teachings of the present invention.

[0068] In embodiments, a biasing mechanism 230 may be operatively connected to the activation arm 320 to bias the activation arm 320 towards the disengaged position, thereby assisting in lifting the wheel 210 from the ground when the activation arm 320 is disengaged. The biasing mechanism 230 may include mechanical springs, pneumatic actuators, hydraulic actuators, electromagnetic devices, elastic cords, torsion bars, or gas springs. A mechanical spring may include a coil spring or a torsion spring and may provide mechanical force. Pneumatic actuators may utilize compressed air to provide an adjustable biasing force. Hydraulic actuators may apply force using incompressible fluids. Electromagnetic devices may include solenoids and may provide control through magnetic fields. Elastic cords may provide tension. Torsion bars may provide rotational energy storage. Gas springs may provide a controlled force output. Selection of the biasing mechanism 230 may depend on operational requirements including load, environmental conditions, and system integration needs. Biasing by the biasing mechanism 230 may contribute to minimizing risk of unintended grounding of the wheel 210.

[0069] Reference is now made to the drawings in which Figure 15 depicts a side view of an exemplary retractable wheel system 100 comprising a bumper 328 in accordance with the teachings of the present invention. In embodiments, the retractable wheel system 100 may comprise the bumper 328 configured to prevent over-disengagement of the activation arm 320. The bumper 328 may be positioned to be contacted by the activation arm 320 when the retractable wheel system 100 reaches the disengaged position, thereby limiting further movement of the activation arm 320 beyond an intended range.

[0070] The bumper 328 may be constructed from a durable yet resilient material such as rubber, an elastomer, high-impact plastic, or a composite configured to withstand repeated impacts. Upon reaching the disengaged position, the activation arm 320 may pivot into contact with the bumper 328, thereby reducing shock loading, noise, and wear and preventing overdisengagement. In embodiments, the bumper 328 may be received in a cavity of the activation arm 320 and may be removable and replaceable.

[0071] Reference is now made to the drawings in which Figure 8 depicts an exemplary retractable wheel system 100 depicting engagement of the wheel 210 and the activation arm 320 when in the disengaged position, in accordance with the teachings of the present invention.

[0072] In an alternative embodiment, when the wheel 210 is disengaged, a disengaging motion M1 of the activation arm 320 may be accompanied by a motion M2 of the wheel arm 340 and, incidentally, the wheel 210. The wheel 210 may contact and engage the activation arm 320, thereby creating a physical and dynamic equilibrium state between the wheel 210 and the biasing mechanism 230. In such a configuration, the wheel 210 may physically contact the activation arm 320, thereby functioning as a mechanical stop configured to limit further movement and secure the retractable wheel system 100 in the disengaged position. Contact between the activation arm 320 and the wheel 210 may be complemented by equilibrium of forces, where weight of the wheel 210 is balanced by a counteracting force from the biasing mechanism 230, thereby maintaining positional stability. Use of the wheel 210 as a stop for the activation arm 320 may reduce complexity of the retractable wheel system 100 and improve robustness of the retractable wheel system 100.

[0073] Reference is now made to the drawings in which Figure 5A, Figure 5B, Figure 5C, and Figure 5D, referred together as Figure 5, depict the retractable wheel system 100 with a mudguard 240 installed. More specifically, Figure 5A depicts a side view of the retractable wheel system 100 on a ski 400 with a mudguard 240 when the retractable wheel system 100 is in the disengaged position, Figure 5B depicts a side view of the retractable wheel system 100 on a ski 400 with a mudguard 240 when the retractable wheel system 100 is in the engaged position, Figure 5C depicts a side view of the retractable wheel system 100 with a mudguard 240, and Figure 5D depicts an exploded view of the retractable wheel system 100 with a mudguard 240.

[0074] In embodiments, a mudguard 240 may be attached to the wheel arm 340 and may cover, at least partially, the wheel 210. Debris projection from the wheel 210 may be reduced by the mudguard 240. The mudguard 240 may act as a shield, wherewith debris such as rocks, mud, or snow may be prevented from being thrown by the wheel 210, thereby protecting the vehicle 1000 and surroundings thereof from damage or hazards.

[0075] In embodiments, the mudguard 240 may be made from a flexible material, such as rubber, thermoplastic elastomers, or impact-resistant plastics. Flexibility may allow the mudguard 240 to absorb impacts from debris projections, thereby reducing wear and tear on the mudguard 240 and mitigating potential damage to the wheel arm 340 or other components. Flexible materials may accommodate movement or deformation due to environmental conditions without compromising the protective function.

[0076] In embodiments, the mudguard 240 may comprise a flexible portion and a retainer portion. The retainer portion may comprise a metal piece mounted at the wheel axis, for example as a replacement for a washer of a wheel fastener assembly. The flexible portion may be slid into a cavity defined by the retainer portion, the cavity having a geometry that is circular around the wheel axis to allow the flexible portion to withdraw in the event the mudguard 240 becomes caught between the wheel 210 and an obstacle during reverse movement. In embodiments, the retainer portion may further include a groove, slot, or channel configured to retain the flexible portion in place during normal operation.

[0077] Reference is now made to the drawings in which Figure 14A and Figure 14B depict an exemplary retractable wheel system 100 with a mudguard 240 that includes an opening 222. In an alternative embodiment, the mudguard 240 may include an opening 222 at a contact point between the wheel 210 and the activation arm 320. The opening 222 may allow the wheel 210 to engage with the activation arm 320 in a disengaged position, thereby preventing damage to the mudguard 240 while ensuring smooth operation of the retractable wheel system 100.

[0078] Reference is now made to the drawings in which Figure 13A, Figure 13B and Figure 13C, referred together as Figure 13, depict an exemplary retractable wheel system 100 with a mudguard 240, including a configuration in which the mudguard 240 contacts an obstacle O.

[0079] In embodiments, the mudguard 240 may comprise a deformable part and may be mounted adjacent the wheel 210 by a rigid support member 242 disposed at an axis of the wheel 210. In embodiments, the rigid support member 242 may be attached to the wheel arm 340 at the wheel axis. In typical embodiments, the rigid support member 242 may be fixed relative to the wheel arm 340 such that the rigid support member 242 and the wheel arm 340 may move together during operation, although other arrangements may be used, including mounting the rigid support member 242 to a component at the wheel axis that is distinct from the wheel arm 340. In embodiments, the rigid support member 242 may be captured by a wheel fastener assembly, and the rigid support member 242 may optionally function as, or replace, a washer or spacer at the wheel axis. The deformable part of the mudguard 240 may be made of a material selected to deform under impact, including rubber, thermoplastic elastomers, thermoplastic polyurethane, flexible polyolefins, silicone, or other flexible polymers, and the deformable part may optionally include reinforcing ribs, variable thickness regions, or locally thinned regions configured to promote controlled deformation. The rigid support member 242 may be made of a rigid and durable material, including steel, aluminum, titanium, or reinforced composites, to withstand operational forces at the wheel axis.

[0080] In embodiments, the mudguard 240 may further comprise a releasable interlocking mechanism configured to detachably engage a deformable part with the rigid support member 242. In a normal configuration, the releasable interlocking mechanism may retain the mudguard240 in a deployed position adjacent the wheel 210, for example to reduce debris projection from the wheel 210. Upon contact between the mudguard 240 and an obstacle O, for example during reverse movement, the deformable part may deform and the releasable interlocking mechanism may disengage, thereby allowing at least a portion of the mudguard 240 to detach from the rigid support member 242. Such detachment may function as a fusible interface to protect the mudguard 240 and / or adjacent components by reducing a likelihood that the mudguard 240 becomes caught between the obstacle O and the wheel 210, which may otherwise cause tearing, bending, or braking forces on the mudguard 240 and associated structure. After detachment, the mudguard 240 may be reattached by re-engaging the releasable interlocking mechanism.

[0081] In embodiments, the releasable interlocking mechanism may be implemented in various ways. For example, and as illustrated in Figure 13A, Figure 13B and Figure 13C, the releasable interlocking mechanism may comprise complementary interengaging protrusions or nudges, including first protrusions 246 on the rigid support member 242 and complementary second protrusions 244 on the mudguard 240, configured to snap together in a normal configuration and to separate when a deformable part deforms upon obstacle contact. In other embodiments, the releasable interlocking mechanism may comprise one or more of: an interference fit; a snap-fit using tabs, hooks, barbs, or detents; a tongue-and-groove arrangement, a dovetail arrangement, a slot arrangement, or a channel arrangement configured to retain a deformable part during normal operation while permitting withdrawal upon obstacle contact; or a clamp, a clip, a ring, or a strap configured to release under a selected load. In embodiments, a release force of the releasable interlocking mechanism may be selected by one or more of a geometry of interengaging features, material stiffness, hardness, number of engagement points, engagement depth, and surface finish, whereby the mudguard 240 may preferentially release before permanent damage occurs.

[0082] Reference is now made to the drawings in which Figure 6 depicts an exploded view of an exemplary retractable wheel system 100 comprising a durable part 322 and a soft part 324. In embodiments, the activation arm 320 may include a durable part 322 and a soft part 324. The durable part 322 may be pivotally connected to the fixed plate 310 and may be constructed from a durable material, such as steel or reinforced composite, to withstand operational forces typically encountered during deployment and retraction of the retractable wheel system 100. Such construction may ensure that a primary structural component of the activation arm 320 remains reliable and effective under standard operating conditions.

[0083] In one embodiment, the second part 324 may be detachably attached to the first part 322 using one or more calibrated fasteners configured to fail under excessive force, thereby limiting the transfer of ferees to the fixed plate 310 and protecting the activation arm 320 andother components of the retractable wheel system 100. The calibrated fasteners may be replaceable such that, following a failure event, the activation arm 320 may be restored by replacing the calibrated fasteners.

[0084] Alternatively, the second part 324 may be detachably attached to the first part 322 and may comprise a replaceable portion configured to act as a fusible link. In such embodiments, the second part 324 may comprise a replaceable material, such as plastic, rubber, or other suitable polymers, and may yield, deform, disengage, or break before the first part 322 in the event of excessive force, thereby protecting the general integrity of the remaining components of the activation arm 320 and potentially preventing system-wide damage. The replaceability of the second part 324 may facilitate maintenance and repair, allowing damage resulting from overload or unforeseen impact to be addressed without replacement of the entire retractable wheel system 100. In embodiments, the second part 324 may be partly, mostly, or fully made of a durable material, with only a segment thereof being configured to act as the fusible link. The fusible-link behavior may be achieved through one or more design strategies, including shear or fracture points configured to promote controlled failure under stress, reduced-thickness regions defining a failure location, detachable joints configured to disengage under excessive force, and / or deformable features such as tabs or protrusions configured to absorb energy through deformation.

[0085] Reference is now made to the drawings in which Figure 10A, Figure 10B, Figure 10C, and Figure 10D, referred together as Figure 10, depict an exemplary retractable wheel system 100 depicting different mount configurations in accordance with the teachings of the present invention. More specifically, Figure 10A depicts an exemplary mount for retractable wheel system 100, with a large shoulder width 122 and spacers 130, Figure 10B depicts an exemplary mount for retractable wheel system 100, with a medium shoulder width 122 and spacers 130, Figure 10C depicts an exemplary mount for retractable wheel system 100, with a thin shoulder width 122 and spacers 130, and Figure 10D depicts an exemplary mount for retractable wheel system 100, with an offset fixation point 124 and spacers 130. Figure 11A, Figure 11 B, and Figure 11C, referred together as Figure 11 , depict exemplary spacers for a retractable wheel system 100, in accordance with the teachings of the present invention. More specifically, Figure 11A depicts an exemplary retractable wheel system 100 attached to a ski 400 using a thin ring-shaped spacer 132, a large ring-shaped spacer 132, and a hollowed half- spherical spacer 134, Figure 11 B depicts a side view of six exemplary spacer configurations using various sizes of ring-shaped spacers 132 and a hollowed half-spherical spacer 134, and Figure 11 C depicts a perspective view of six exemplary spacer configurations using various sizes of ring-shaped spacers 132 and a hollowed half-spherical spacer 134.

[0086] In embodiments, the retractable wheel system 100 may include a mount 110 for fastening the retractable wheel system 100 to the ski 400. The mount 110 may function as an intermediary component, establishing a secure connection between the retractable wheel system 100 and the ski 400. The fixed plate 310 may be configured to attach to the mount 110, thereby providing a stable platform for the operational components of the retractable wheel system 100. The mount 110 may be configured to attach to the ski 400, thereby enabling integration of the retractable wheel system 100 into a structure of the ski 400. An attachment mechanism involving the mount 110 may ensure that the retractable wheel system 100 is held securely in place, potentially allowing deployment and retraction of the wheel 210 based on terrain conditions.

[0087] The mount 110 may be designed to be attached across the width of the ski 400. The transversal attachment may involve use of components such as a ski axle 120 or connecting bars, wherewith the ski axle 120 or the connecting bars may span the width of the ski 400 to provide a balanced and stable connection. By being fastened across the width of the ski 400, the mount 110 may distribute load and stresses exerted by the retractable wheel system 100, thereby enhancing structural integrity of an attachment of the mount 110 to the ski 400. The design of the mount 110 may also permit lateral adjustments, wherewith the lateral adjustments may allow customization or alignment of the retractable wheel system 100 to conform to diverse ski designs.

[0088] In embodiments, when the mount 110 includes a ski axle 120 to fasten the retractable wheel system 100 across a width of the ski 400, the ski axle 120 may serve as a structural component designed to span the width of the ski 400, thereby providing a stable and balanced base for attachment of the retractable wheel system 100. The ski axle 120 may include a shoulder width 122, wherewith the shoulder width 122 may allow lateral adjustment of the retractable wheel system 100 on the ski 400. The shoulder width 122 may provide an adjustable mechanism to align the retractable wheel system 100 with respect to the width of the ski 400, thereby enabling positioning of the retractable wheel system 100 for balance, handling, and performance.

[0089] The ski axle 120 may have an offset fixation point 124 and an offset fixation axis 126B relative to a main axis 126A. The offset fixation point 124 may allow for vertical adjustment of the retractable wheel system 100 relative to the ski 400, accommodating variations in ski design or preference in height of the retractable wheel system 100 above the ground. Vertical adjustment may provide flexibility to tailor orientation and drop of the retractable wheel system 100 to optimize contact with the ground or performance of the ski 400 across different operating conditions.

[0090] In embodiments, the mount 110 may include one or more spacers 130, whereby a gap between the ski 400 and the fixed plate 310 of the retractable wheel system 100 may be filled. A shoulder as a structural feature of the mount 110 may be utilized to determine initial spacing between the ski 400 and the fixed plate 310. The spacers 130 may act as adjustable components wherewith space between the ski 400 and the fixed plate 310 may be occupied, thereby permitting fine-tuning of positioning and alignment of the retractable wheel system 100 relative to the ski 400. By insertion or modification of the spacers 130, adaptability of the retractable wheel system 100 to varying ski designs may be ensured, whereby operation across different skiing environments may be achieved.

[0091] In embodiments, one or more spacers from the spacers 130 may take the form of a ring-shaped spacer 132. A ring-shaped spacer 132 may be used to provide uniform spacing and alignment around a central axis, thereby facilitating consistent support and even force distribution across the mounting interface. A ring shape may maintain a secure fit while allowing ease of installation and removal, as needed for adjustment. In embodiments, the spacers 130 may be constructed from metals such as aluminum or steel. Alternatively, the spacers 130 may be constructed from engineering plastics such as nylon, polyoxymethylene (POM), or polypropylene. Additional materials such as high-density polyethylene (HDPE), polycarbonate, or thermoplastic elastomers (TPE) may also be used for the spacers 130. Rubber or elastomerbased spacers 130 may also be used to provide vibration dampening or flexibility where required.

[0092] For angular adjustments, when the ski 400 may have an angled surface 410, one or more spacers of the one or more spacers 130 may be a hollowed half-spherical spacer 134. The hollowed half-spherical spacer 134 may enable adjustment of the retractable wheel system 100 onto the angled surface 410 by conforming to a contour of the ski 400 and by providing a stable anchor point.

[0093] Reference is now made to the drawings in which Figure 12 depicts a top-left perspective view of an exemplary retractable wheel system 100 in an engaged position with a secondary lock 220 in accordance with the teachings of the present invention.

[0094] In embodiments, a secondary lock 220 may prevent accidental disengagement of a wheel arm 340 when in an engaged position. The secondary lock 220 may serve as an optional safety feature by maintaining stability and engagement of the wheel arm 340, whereby a wheel 210 may remain in contact with ground during operation over non-snow surfaces.

[0095] In one embodiment, the secondary lock 220 may be pivoted and engaged with a secondary lock anchor point 221 located on the activation arm 320. When used in conjunction with a biasing mechanism 230, force exerted by the biasing mechanism 230 may contribute to engagement of the secondary lock 220 into the secondary lock anchor point 221 of theactivation arm 320. The secondary lock 220 may be pivoted into a locked position and interfaced directly with the secondary lock anchor point 221 of the activation arm 320, thereby preventing reverse movement. Alternatively, the secondary lock 220 may be configured to engage with the wheel arm 340. In other embodiments, engagement may be achieved using latches, hooks, or pins that may physically bind the secondary lock 220 and the wheel arm 340 together, thereby securing the wheel arm 340 against unintentional retraction.

[0096] The selection of an arm with which the secondary lock 220 may engage may depend on factors including mechanical design preferences, space constraints, and ease of operation. When the secondary lock 220 engages with the activation arm 320 or when the secondary lock 220 engages with the wheel arm 340, the secondary lock 220 may be configured to be operable while preventing accidental disengagement due to terrain-induced shocks or vibrations. A locking mechanism may be configured to engage automatically when the retractable wheel system 100 transitions to a full engaged position, wherewith deliberate action may be required for disengagement, thereby providing user safety and system reliability.

[0097] In embodiments, the retractable wheel system 100 may include an actuation mechanism 250. The actuation mechanism 250 may be operatively connected to the activation arm 320 and may pivot the activation arm 320 between the engaged position and the disengaged position. The actuation mechanism 250 may transform manual operation of transitioning between positions into an automated process.

[0098] The actuation mechanism 250 may be realized through several types of actuators, each offering unique benefits depending on specific requirements and constraints of system design. A motorized actuator, such as an electric motor, may convert electrical energy into mechanical movement, thereby providing precise control over motion of the activation arm 320. A pneumatic actuator, using compressed air to produce movement, may provide a quick response and straightforward integration. A pneumatic actuator may be suitable for environments where electrical systems may be less effective or where a lightweight option may be preferred. A hydraulic actuator, utilizing pressurized fluid to achieve movement, may exert significant force and may provide smooth, controlled movement, especially for applications requiring high power output relative to size. Although more complex than pneumatic systems, hydraulic actuators may offer superior precision and consistency under various load conditions.

[0099] In embodiments, the actuation mechanism 250 may include a flexible linkage, such as a cable, to facilitate movement of the activation arm 320. The flexible linkage may be similar to systems used in bicycle brakes or gears, where a cable transmits force from a remote actuator, such as a lever or pedal, to the activation arm 320. In embodiments where a flexible linkage is used, the flexible linkage may be routed along the vehicle to a convenient control point for manual actuation or to a convenient location for engagement with a remote actuator.

[0100] In embodiments, the retractable wheel system 100 may include a speed sensor 252 configured to prevent transition between an engaged position and a disengaged position while the ski 400 is in motion. The speed sensor 252 may be used to ensure that the activation arm 320 and the wheel 210 remain stable during movement and to permit transition between the engaged position and the disengaged position when safe conditions are met. The speed sensor 252 may utilize various sensing technologies to determine speed of the ski 400, including Hall Effect sensors, rotary encoders converting rotational movement into digital signals, and GPSbased systems using satellite data to calculate ground speed. Accelerometers may also be used to determine speed by analyzing acceleration patterns, while optical sensors may measure speed by detecting interruptions in a light beam caused by rotating elements. In embodiments, speed may be provided by the vehicle 1000 and communicated through a communication channel. In some configurations, the speed sensor 252 may work in tandem with a control mechanism to inhibit engagement or disengagement when the ski 400 exceeds a predetermined speed threshold, whereby transitions may occur under safe and controlled conditions.

[0101] In embodiments, the retractable wheel system 100 may include a suspension 260, wherewith the suspension 260 may be operatively connected to the wheel 210 to absorb shocks when operating over uneven surfaces. The suspension 260 may be realized through various types of suspension technologies, including coil spring suspensions, air suspensions, and hydraulic suspensions. Dampening of shocks may also be achieved by using a soft material as a spacing layer of the fixed plate 310. A layer of rubber or reinforced synthetics material, for example, between the fixed plate 310 and the ski 400, or between the fixed plate 310 and the activation arm 320 and the wheel arm 340, may absorb vibration from terrain and may provide a smoother riding experience. The suspension 260 may also be integrated with the wheel arm 340 or similar structural elements, ensuring that dynamic loads on the wheel 210 may be managed to prevent undue wear or mechanical stress on other components of the retractable wheel system 100. By reducing vibrations and shocks, the suspension 260 may contribute to ride quality, may prolong a lifespan of the wheel 210, and may protect structural integrity of the vehicle 1000 to which the retractable wheel system 100 may be attached.

[0102] A second aspect of the techniques described herein relates to a vehicle 1000 incorporating both a ski 400 and the retractable wheel system 100 as described in the first aspect. Integration of the retractable wheel system 100 with the vehicle 1000 featuring skis 400 may enhance versatility of the vehicle 1000 and functionality thereof. In typical applications, the vehicle 1000, such as snowmobiles, ski-equipped airplanes, or ski-carts, is primarily designed for use on snow or icy terrains.

[0103] By incorporation of the retractable wheel system 100, improved adaptability of the vehicle 1000 may be achieved, thereby allowing traversal of non-snow surfaces without causing undue wear or damage to the skis 400 and skegs. The retractable wheel system 100 may be attached to the ski 400, thereby enabling the vehicle 1000 to be lifted and transported using the wheel 210 when the wheel 210 is in an engaged position. A vehicle 1000 incorporating both a ski 400 and the retractable wheel system 100 may be capable of navigating over hard surfaces like gravel, asphalt or concrete, where direct ski contact traditionally results in rapid degradation and inefficiency.

[0104] When engaged, the wheel 210 may support the weight of the vehicle 1000, thereby facilitating movement and maneuverability of the vehicle 1000 over various terrains while the ski 400 may be lifted off the ground. In embodiments, the vehicle 1000 may be a snowmobile, a ski-bike, a ski-equipped airplane, a ski cart, or a sleigh. For a snowmobile, the retractable wheel system 100 may be used when crossing bare patches of land or when loading onto a trailer for transport, whereby the skis may be protected from abrasion on hard surfaces like gravel or pavement. A ski-bike may be operated with the retractable wheel system 100 when navigating transitions from snowy trails to asphalt bike paths, thereby allowing a switch to wheeled operation without risking damage to the skis during off-season rides or mixed terrain events. A ski-equipped airplane may utilize the retractable wheel system 100 when taking off from or landing on cleared runways, whereby taxiing over tarmac or other non-snow surfaces may be enabled, thereby eliminating the need for dedicated airport equipment to assist in such movements. Ski carts may be operated with the retractable wheel system 100 when moving indoors, to storage areas, or across mixed-terrain paths, whereby cargo stability may be maintained and the structure of a ski cart may be preserved. A sleigh may be operated with the retractable wheel system 100 when entering cleared urban or commercial zones, or when transitioning across areas. Other types of ski- vehicles, including vehicles designed to glide over water, may be used in conjunction with the retractable wheel system 100.

[0105] In the present description, unless defined otherwise, all technical and scientific terms as used herein may have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure pertains. Use of the word “a” or “an” when used in conjunction with the term “comprising” or “include” in the claims and / or the specification may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one”. Similarly, the word “another” may mean at least a second or more. Use of the expression “at least one of” followed by a set of elements may suggest that any combination of the elements from the set is being considered, including a single element from the set, and all elements from the set. For clarity, “at least one of’ followed by a set is not limited to having at least the whole set once, and possibly multiple times (although these embodiments are included in the meaning of the expression). As used in this specification and claim(s), the words“comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “include” and “includes”) or “containing” (and any form of containing, such as “contain” and “contains”), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0106] The invention described herein is not to be limited to the particular embodiments described hereinabove, as variations of these embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments; and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims. As will be understood by a skilled person, other variations and combinations may be made to the various embodiments of the invention as described herein above. The scope of the claims should not be limited by the preferred embodiments set forth; but should be given the broadest interpretation consistent with the description as a whole.

Claims

CLAIMS1 . A retractable wheel system (100) for a ski (400) comprising: a wheel (210) for engaging a ground; a fixed plate (310) for attaching the retractable wheel system (100) to the ski (400); an activation arm (320) pivotally connected to the fixed plate (310) and configured to move between an engaged position and a disengaged position; a wheel arm (340) pivotally connected to the fixed plate (310) and supporting the wheel (210); a central linkage (330) pivotally connected to the activation arm (320) and the wheel arm (340); and wherein the wheel arm (340) is configured to move the wheel (210) into contact with the ground when the activation arm (320) is engaged and lift the wheel (210) from the ground when the activation arm (320) is disengaged.

2. The retractable wheel system (100) for a ski (400) of claim 1 , wherein the activation arm (320) is positioned on a first longitudinal side of the fixed plate (310) and the wheel (210) is positioned on a second longitudinal side of the fixed plate (310).

3. The retractable wheel system (100) of claim 1 or claim 2, further comprising a mount (110) for fastening the retractable wheel system (100) to the ski (400), wherein the fixed plate (310) is configured to attach to the mount (110) and the mount (110) is configured to attach to the ski (400).

4. The retractable wheel system (100) of any one of claims 1 to 3, wherein:- as the activation arm (320) pivots away from the disengaged position:- the activation arm (320) rotates in an engagement direction and the wheel arm (340) rotates in an opposite direction thereby causing the wheel (210) to move towards the ground; and- as the activation arm (320) pivots into the engaged position:- the activation arm (320) and the wheel arm (340) rotate in the engagement direction, thereby causing the wheel (210) to move away from the ground, and causing the activation arm (320) to lock into the engaged position.

5. The retractable wheel system (100) of any one of claims 1 to 4, wherein the central linkage (330) is configured to:- as the activation arm (320) pivots away from the disengaged position:- provide a high movement ratio to the wheel (210) relative to the activation arm (320); and- as the activation arm (320) pivots into the engaged position:- provide a low movement ratio to the wheel (210) relative to the activation arm (320), thereby providing an increased torque as the wheel (210) engages the ground.

6. The retractable wheel system (100) of any one of claims 1 to 5, further comprising a biasing mechanism (230) operatively connected to the activation arm (320) and configured to bias the activation arm (320) towards the disengaged position, thereby assisting in lifting the wheel (210) from the ground when the activation arm (320) is disengaged.

7. The retractable wheel system (100) of claim 6, further comprising a bumper (328), wherein, in the disengaged position, the activation arm (320) is biased by the biasing mechanism (230) into contact with the bumper (328), thereby limiting movement of the activation arm (320) and defining a stable rest position.

8. The retractable wheel system (100) of any one of claims 1 to 7, further comprising a mudguard (240) attached to the wheel arm (340) and covering, at least partially, the wheel (210), wherein the mudguard (240) is configured to reduce debris projection from the wheel (210).

9. The retractable wheel system (100) of claim 8, wherein the mudguard (240) is made of a flexible material to absorb impacts from the debris projection.

10. The retractable wheel system (100) of claim 8 or claim 9, wherein the mudguard (240) comprises:- a deformable part;- a rigid support member (242) attached to the wheel arm (340) and disposed at an axis of the wheel (210); and a releasable interlocking mechanism configured to detachably engage the deformable part with the rigid support member (242);wherein:- in a normal configuration, the releasable interlocking mechanism retains the mudguard (240) in a deployed position adjacent the wheel (210); and- upon contact between the mudguard (240) and an obstacle (O), the deformable part is configured to deform and the releasable interlocking mechanism is configured to disengage, thereby allowing at least a portion of the mudguard (240) to detach from the rigid support member (242).11 . The retractable wheel system (100) of any one of claims 1 to 10, wherein the activation arm (320) comprises:- a first part (322) pivotally connected to the fixed plate (310); and- a second part (324) detachably attached to the first part (322); wherein the second part (324) and the first part (322) are attached by one or more calibrated fasteners (326) configured to fail under excessive force to thereby protect the activation arm (320).

12. The retractable wheel system (100) of claim 3, wherein the mount (110) comprises a ski axle (120), configured to fasten the retractable wheel system (100) across a width of the ski (400).

13. The retractable wheel system (100) of claim 12, wherein the ski axle (120) comprises a shoulder width (122) configured to allow a lateral adjustment of the retractable wheel system (100) on the ski (400).

14. The retractable wheel system (100) of claim 12 or claim 13, wherein the ski axle (120) comprises an offset fixation point (124) and an offset fixation axis (126B) relative to a main axis (126A), allowing for a vertical adjustment of the retractable wheel system (100) relative to the ski (400).

15. The retractable wheel system (100) of claim 3, wherein the mount (110) comprises one or more spacers (130) configured to adjust a lateral adjustment of the retractable wheel system (100) on the ski (400).

16. The retractable wheel system (100) of claim 15, wherein at least one spacer of the one or more spacers (130) is a ring-shaped spacer (132).

17. The retractable wheel system (100) of claim 15 or claim 16, wherein the ski (400) comprises an angled surface (410), and wherein at least one spacer of the one or more spacers (130) is a hollowed half-spherical spacer (134), thereby enabling adjustment of the retractable wheel system (100) onto the angled surface (410).

18. The retractable wheel system (100) of any one of claims 1 to 17, further comprising a secondary lock (220) configured to prevent a disengagement of the wheel arm (340) when in the engaged position.

19. The retractable wheel system (100) of any one of claims 1 to 18, further comprising an actuation mechanism (250) operatively connected to the activation arm (320), wherein the actuation mechanism (250) is configured to pivot the activation arm (320) between the engaged position and the disengaged position.

20. The retractable wheel system (100) of claim 19, wherein the actuation mechanism (250) comprises at least one of a motorized actuator, a pneumatic actuator, and a hydraulic actuator.

21. The retractable wheel system (100) of any one of claims 1 to 20, further comprising a speed sensor (252) configured to prevent transition between the engaged position and the disengaged position while the ski is in motion.

22. The retractable wheel system (100) of any one of claims 1 to 21 , further comprising a suspension (260) operatively connected to the wheel (210), and configured to absorb shocks when operating over uneven surfaces.

23. A vehicle (1000) comprising:- a ski (400);- the retractable wheel system (100) of any one of claims 1 to 22; and wherein the retractable wheel system (100) is attached to the ski (400), thereby enabling the vehicle (1000) to be lifted and moved using the wheel (210) of the retractable wheel system (100) when the retractable wheel system (100) is in the engaged position.

24. The vehicle (1000) of claim 23, wherein the vehicle (1000) is any one of a snowmobile, a ski-bike, a ski-equipped airplane, a ski cart, and a sleigh.

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