Abstract: A vehicular snow ski steering keel bar having a recessed surface portion extending at least partially along the length in the side surfaces of the bar. A lower side surface portion below the recessed surface portion includes lateral extensions extending beyond the recessed surface potion to collect and/or compact snow and/or material coming in contact with the steering keel bar. An upper side surface portion has lateral extensions that further direct snow into the recessed surface portion during turning and cornering of the bar. The cross-sectional shape of the bar includes a basic hourglass shape with curved and/or flat surfaces. Various cross-sectional shapes can be used along the length of the bar to fine-tune the turning characteristics of the steering keel bar. Different configurations or shapes can be utilized for the sides of the bar to vary the turning characteristics between left and right turns.

Abstract: A snowmobile ski includes an elongate ski element. The elongate ski element has a tip and a tail defining a length therebetween, top and bottom surfaces, first and second lateral edges extending longitudinally between the tip and the tail defining a width therebetween, and an attachment flange extending upwardly from the top surface. At least one lateral extension element is detachably secured to one of the lateral edges to thereby increase the lateral width of the snowmobile ski.

Abstract: An improved snowmobile steering ski attachable to the steering spindles of a snowmobile and, generally, including a frame, which may be integrally molded as part of the ski, and having multiple protruding keels that emerge from the bottom running surface of the ski proximal the ski's front end and gradually increase in protrusion with respect to the bottom running surface to a point of maximum protrusion at a point on the ski runner near to the steering spindle of the snowmobile is disclosed. The keel then gradually decreases in protrusion from its maximum protrusion to merge back into the bottom surface proximal the rear end of the ski.

Abstract: A vehicle snow ski system for creating a preload force upon a front portion of a ski in combination with a resilient preload member. The method basically comprising an elongate ski body having a front portion in a position P1, applying a force upon a front portion of the elongate ski body thereby bowing the front portion into position P2, securing a preload member to the front portion and a middle portion of the elongate ski body, and releasing the force applied to the front portion whereby the resiliency of the front portion deforms the preload member until the front portion is into position P3. Position P1 of the elongate ski body is preferably less than 20 degrees with respect to a longitudinal axis of the elongate ski body. The preload member is preferably comprised of a first segment and a second segment having an obtuse angle between one another. The first segment is preferably longer than the second segment thereby deforming an amount greater than the second segment.

Abstract: A combined flexible snowmobile ski and handle having a forward section anchored to the front of the ski and connected to longitudinal flanges of the ski with a lost motion cross head. The cross head has a longitudinal transverse slot accommodating a transverse cylindrical member amounted on the flanges of the ski. The handle retains the forward section of the ski in an upwardly curved shape.

Abstract: A ski for a snow vehicle includes a ski body, a ski mounting bracket, and a keel. The ski body includes a generally horizontal surface that contacts the snow when the ski is in use. The ski mounting bracket is located on a top side of the ski body. The keel includes a forward portion and a rearward portion. The keel depends from and is adjustable with respect to the ski body.

Abstract: A ski for a vehicle for slidably engaging a surface to be traversed. The ski includes a longitudinally extending runner having a forward portion, a rearward portion and a middle portion therebetween, the forward and rearward portions having a wider lateral width than the middle portion. The forward, rear and middle portions form an hourglass shape, generally. One or more skis may be adapted to a vehicle that includes a frame, a rear drive means for propelling the vehicle along a surface to be traversed and the one or more skis may be attached to a front portion of the frame for slidably engaging the surface to be traversed.

Abstract: A ski for a snow vehicle includes a snow contacting portion that has a generally horizontal surface and a keel depending therefrom. The keel includes a keel base, a first inclined surface, and a second inclined surface. The keel base extends laterally from a longitudinal central plane of the ski to a lateral extent. The first inclined surface extends between the keel base and an inflection line that extends longitudinally. The second inclined surface extends between the inflection line and the generally horizontal surface. The inflection line is located no farther laterally from the longitudinal central plane than is the lateral extent of the keel base.

Abstract: Wheel unit to be semi-permanently mounted on the ski of a snowmobile. Wheels are readily deployable or retractable as conditions require. The wheel unit allows the snowmobile to be driven over gravel, dirt, and hardtop surfaces, without losing its ability to be steered with the handlebars.

Abstract: The present invention teaches a runner or blade for an ice skate having a novel configuration and structure, such as a blade having greater width at the edge at both the anterior end and posterior end relative to the middle, or alternately, a blade having greater width at the edge at the anterior end relative to the middle and posterior end. Further, a runner or blade for an ice skate can include a thermoplastic material, fiber fillers, metal fillers, and a hydrophobic material. In addition, the present invention teaches a hinged blade for a hockey skate.

Abstract: A snowmobile ski built from strips of plastic to selectively form the bottom contour on the ski body of the snowmobile ski. The strips of plastic may be used to build a new ski or rebuild/reconstruct an existing snowmobile ski that has a center keel. The snowmobile ski comprises mounting shoe for mounting the snowmobile ski to the snowmobile and a longitudinally extending plastic ski body having an upwardly curved front tip toward the front end. The strips of plastic include a pair of plastic side pads. The side pads are removably secured to the bottom surface of the ski body and extend longitudinally along the ski body. The strips of plastic may also include a removable center keel. A wear bar or wear rod assembly may be fastened to the center keel.

Abstract: A stabilizer made of metal or plastic, fit on snow vehicle ski. It comprises a vertical fin forming a wing of a U-shaped section of a length sufficient to cover the bearing surface of the ski. A central channel is placed longitudinally in the centre of the U-shaped section to form with the wings a series of three parallel guides, digging a track on a surface to stabilize the direction of the ski in motion. When applied to a snowmobile ski the central channel is a bar such as used currently to protect the ski in asphalt crossings. Its wings are of steel and have a wall 19 mm high and 2 to 3 mm thick. The web is 56 to 58 mm wide and supports a corrector 6 mm thick and 56 mm wide and stretches on all the ski length. The bar is 6 mm higher than the wings.

Abstract: A vehicular snow ski steering keel bar is disclosed having a recessed surface portion extending at least partially along the length in the side surfaces of the bar. A lower side surface portion below the recessed surface portion includes lateral extensions extending beyond the recessed surface potion to collect and/or compact snow and/or material coming in contact with the steering keel bar. An upper side surface portion has lateral extensions that further direct snow into the recessed surface portion during turning and cornering of the bar. The cross-sectional shape of the bar includes a basic hourglass shape with curved and/or flat surfaces. Various cross-sectional shapes can be used along the length of the bar to fine-tune the turning characteristics of the steering keel bar. Different configurations or shapes can be utilized for the sides of the bar to vary the turning characteristics between left and right turns.

Abstract: A sports board with an expanded foam core that has a density adapted so the core will receive a solid sheet skin laminated directly thereto without an adhesive layer. The sports board includes a bottom solid sheet skin laminated directly to a bottom surface of the expanded foam core, and a foam top skin laminated to a top surface and heeled to side surfaces of the expanded foam core.

Abstract: Wheel unit to be semi-permanently mounted on the ski of a snowmobile. Wheels are readily deployable or retractable as conditions require. The wheel unit allows the snowmobile to be driven over gravel, dirt, and hardtop surfaces, without losing its ability to be steered with the handlebars.

Abstract: The board assembly for sliding on grass slopes comprises a board, a retaining means attached to the board and a locking means for clamping an ice block to the retaining means. The board has, essentially, a rectangular shape with longitudinal and transversal axes of symmetry, upper and lower surfaces, a front and rear end and a pair of lateral ends. The retaining means is attached to the lower surface, has an axis of symmetry coinciding with the longitudinal axis of symmetry and is adaptable to capture an ice block. The locking means actuates on the retaining means for closing it and, thereby, clamping the ice block in place.

Abstract: A snowmobile having asymmetrical, high floatation skis. The snowmobile includes left and right steerable skis carried by a front suspension system that in turn is mounted to the snowmobile's chassis. Each ski has a downwardly extending longitudinal keel, and inner and outer floatation portions extending laterally from the keel. The inner floatation portion of each ski is wider than the outer floatation portion of such ski, making the ski asymmetrical with respect to the keel and giving the ski greater floatation without increasing the overall width of the snowmobile. Preferably the front suspension system includes left and right generally downwardly and forwardly extending spindles, each spindle carrying at its lower end the corresponding ski. The spindles define the steering axes for their respective skis. Preferably the steering axis of the spindle passes through the keel.

Abstract: An improved snowmobile steering ski attachable to the steering spindles of a snowmobile and, generally, including a frame, which may be integrally molded as part of the ski, and having multiple protruding keels that emerge from the bottom running surface of the ski proximal the ski's front end and gradually increase in protrusion with respect to the bottom running surface to a point of maximum protrusion at a point on the ski runner near to the steering spindle of the snowmobile is disclosed. The keel then gradually decreases in protrusion from its maximum protrusion to merge back into the bottom surface proximal the rear end of the ski.

Abstract: A steering ski for a snowmobile is disclosed. The steering ski comprises a ski body and a wear bar connected to a ski bracket. The ski bracket is used to attach the ski to the balance of the snowmobile. The ski body also receives a reinforcing member that reinforces a portion of the ski body which is curved upwardly. Reinforcing ribs travel along the length of the ski body on an upper portion of the ski body. The sole of the ski body or lower surface includes a keel that expand in width from a forward-most portion and then decreases in width rearward of a juncture between a snow contacting portion of the ski body and the upwardly-extending portion of the ski body. A wear bar is positioned along the keel and depends below a lowermost portion of the keel rearward of the widest portion of the keel. The wear bar extends into the ski body through a forward aperture and a rearward aperture.

Abstract: A snowmobile ski includes a bridge adapted to connect to a ski leg of a snowmobile, a ski body having an inner lateral edge, an outer lateral edge, a top surface adapted to be connected the bridge, and a bottom surface adapted for moving over snow, a keel running lengthwise along the bottom surface of the ski body in such a manner that a centerline of the keel is offset from a centerline of the bridge in a direction toward the outer lateral edge of the ski body, and a runner connected to the keel.

Abstract: A sled (24) traversing a surface is provided. The sled includes a shell (22) having an upper surface, a lower surface, and spaced first and second ends. The sled also includes a steering assembly (24) coupled to at least the shell, elongate first and second runners (26a) and (26b), and a pivot assembly (60) extending between the shell and at least one of the first and second runners. The pivot assembly permits pivoting motion of the first or second runner relative to the shell. The sled also includes a first attachment assembly (58a-58c) extending between the shell and at least one of the first and second runners, such that the first attachment assembly permits sliding and pivoting motion of the first and second runners relative to the shell.

Abstract: A suspension for a vehicle includes an upper A-arm and a lower A-arm. A leg with an axis is rotatably connected to both the upper A-arm and the lower A-arm. A mechanical link is rotatably connected to the leg so that movement of the mechanical link applies rotational force to the leg to cause the leg to rotate about the axis.

Abstract: A steering ski for a snowmobile comprises a ski body and a reinforcing member. The steering ski has a flat portion for contacting the surface of the ground and an upturned leading portion. The reinforcing member is connected to the upturned leading portion at multiple connection points. The ski and the reinforcing member are coupled to transmit forces in a way that reduces the pressure in the upturned leading portion. The forces are applied to the ski when the snowmobile strikes obstructions in its path and when it lands after becoming airborne. A stopper is provided to transmit the forces.

Abstract: A mechanism that improves the steering characteristics of molded plastic skis is provided that employs the use of a flexible carbide steering cleat. This flexible carbide steering cleat is made up of a plurality of carbide tipped steering members that are attached individually to the lower surface of a plastic one piece snowmobile ski. Each of the individual cleat members is equipped with a mounting plate that has indentations on either side which, when a series of the cleats have been placed in the keel in succession, creates a space between them. This space allows the cleat members to flex independently of one another in response to the flexing of the ski without binding on one another. Therefore, the flexing ability of the present invention allows the individual cleat members to maintain the maximum contact with the snow surface, regardless of how much the ski itself flexes during its use.

Abstract: A ski for a snowmobile or other snow machine is provided with a central channel for increasing the flow of snow under a gliding surface at the bottom of the ski. The increased flow of snow enhances flotation of the ski. The channel may be formed by two keels, one disposed to either side of a gliding surface of the ski. A series of longitudinal grooves may also be formed within the contoured gliding surface, alternately interspersed with lands. The grooves and lands increase a shear force exerted against the snow over which the ski travels, when the orientation of the ski is altered out of the line of travel. The increased shear force causes the snowmobile to consistently follow the course of the ski, improving tracking and handling of the ski.

Abstract: A flexible ski which is molded in one piece entirely of UHMW plastic. The adjustable flex ski is made up of a ski body which forms the majority of the invention and provides the base from which the other components are formed. This ski body is molded in a flat configuration. The front portion of this ski is given a pre-load function by bending the forward most portion of the ski body in an upward fashion. It is then held in this position by the use of pre-load bar which extends pivotally rearward from the tip of the ski to a ski saddle located on the upper center surface of the ski body. This saddle provides various attachment points for the pre-load bar and can thus, vary the amount of pre-load on ski. The saddle is also supplied with an attachment point for mounting the ski on the vehicle. This configuration allows the tip of the adjustable flex ski to flex in an upwardly fashion when confronting obstacles which provides the operator with a greater degree of control in rough terrain.

Abstract: An improved snowmobile steering ski attachable to the steering spindles of a snowmobile and, generally, including a frame, which may be integrally molded as part of the ski, and having multiple protruding keels that emerge from the bottom running surface of the ski proximal the ski's front end and gradually increase in protrusion with respect to the bottom running surface to a point of maximum protrusion at a point on the ski runner near to the steering spindle of the snowmobile is disclosed. The keel then gradually decreases in protrusion from its maximum protrusion to merge back into the bottom surface proximal the rear end of the ski.

Abstract: A tote-sled assembly includes spaced runners adapted to slide along malleable and hardened surfaces and having separate parts that are assembled in an end to end relationship and are overlapped by a detachable connector. The tote-sled assembly further includes a plurality of toothed wheels and detachable vertical struts adapted to reduce the overall size of a partially disassembled assembly.

Abstract: A ski is disclosed for efficiently sailing on snow or ice. The ski has greater thickness than a conventional downhill ski. The substantially triangular shape of the cross-section of the ski is longitudinally constant so as to generate simultaneously both lift and lateral forces with minimum drag. The surface of the ski in contact with the snow or ice is made from or treated with a low friction material. The ski has a longitudinally upward concave curvature to facilitate turning. The ski tip is formed with deadrise like the bow of a boat or, in the alternative, may be a thin shovel like the tip of a conventional ski. The ski incorporates an edge or blade extending downwardly below the central part of the ski to enhance the lateral to drag force ratio on ice.

Abstract: In a snowmobile ski suspension having two parallel front mounted steerable skis, each ski is steerable by rotation of the trailing suspension arms about a frame mounted bearing forward of the center of the ski. Steering input from the handlebar rotates the suspension and the ski. The ski moves laterally towards the outside of a turn during rotation to provide increased cornering stability. The ski has a keel mounted forward of its center for ease of turning. The dual support steering column provides a forward offset for the handlebar which leans the driver toward the inside of a corner for better balance and provides crash protection.

Abstract: The invention provides an improved ski for a snow vehicle such as a snowmobile, the ski having a snow contacting surface thereof which has a greater width proximate the front portion of the ski compared to a width rearwardly thereof. The snow contacting surface may be a portion of the keel or the ski itself although preferably both utilize this arrangement. An adaptor for converting existing skis to this configuration is also disclosed. Better directional stability is imparted to the snow vehicle using this type of ski.

Abstract: A snowmobile steering ski has an elongated one-piece blow molded body formed of polyethylene, preferably ultra high molecular weight polyethylene. The top wall of the body has raised portions defining hollow sections with the bottom wall and displays a central recessed area adapted to receive the lower end of a snowmobile steering component. A pair of fixation holes are provided in lateral sides of the recessed area for fixing the steering component to the ski while further fixation holes are provided in the bottom of the recessed area for fixing a wear bar to the under face of the body.

Abstract: An improved snowmobile steering ski attachable to the steering spindles of a snowmobile and, generally, including a frame, which may be integrally molded as part of the ski, and having multiple protruding keels that emerge from the bottom running surface of the ski proximal the ski's front end and gradually increase in protrusion with respect to the bottom running surface to a point of maximum protrusion at a point on the ski runner near to the steering spindle of the snowmobile is disclosed. The keel then gradually decreases in protrusion from its maximum protrusion to merge back into the bottom surface proximal the rear end of the ski.

Abstract: A Multi-functional foldable sled including a body portion with a front section, a rear section and a middle section. The front section and the middle section have a front hinge therebetween for pivotal coupling. The rear section and the middle section have a rear hinge therebetween for pivotal coupling. Provided are a pair of rear runners with each rear runner having a rear pole support exteriorly mounted thereon. A pair of front runners are included and each of the pair of front runners having a front pole support exteriorly mounted thereon. Finally, a pair of elongated pole members are provided. Each one of the pair of pole members is positioned within one of the rear pole supports and one of the front pole supports for allowing the body member to transport the pair of pole members.

Abstract: Variation in steering force is reduced by providing side edges attached to the right and the left side surfaces of a steering ski. The side edges have a continuously curved lower surface. A vertical plane including the axis of a pivot shaft crosses a middle portion of each side edge. Dislocation of contact centers from a pivot point, and the distances between the pivot point and the contact centers are small when the steering ski swings on the pivot shaft.

Abstract: A snowmobile ski having a front portion the bottom of which is slightly concave. On each side of the middle portion of the snowmobile ski there is a downwardly extending longitudinal side portion. At the front of each downwardly extending longitudinal side portion are located a forward-facing horizontal wedge and a forward-facing vertical wedge. At the rear of each downwardly extending longitudinal side portion are placed a rear-facing horizontal wedge and a rear-facing vertical wedge. A flexible loop is attached to, and mounted flush with, the bottom of the front portion of the snowmobile ski. The flexible loop curves in front of, and above, the front portion of the snowmobile ski, before being slidably attached to the top of the front portion of the snowmobile ski. The middle portion of the snowmobile ski is thicker than either the front portion or the rear portion of the snowmobile ski.

Abstract: An improved snowmobile steering ski attaches to the steering spindles of a snowmobile and generally includes a frame and an elongated ski having a protruding keel that emerges from the bottom running surface of the ski proximal a front end and gradually increases in protrusion with respect to the bottom running surface to a point of maximum protrusion at a point on the ski runner directly below the steering spindles of the snowmobile. The keel then gradually decreases in protrusion and merges back into the bottom surface proximal a rear end of the ski runner.

Abstract: A wear rod for skis of snowmobiles and similar vehicles, comprising a horizontal base for engaging an underside of a ski and a vertical wear element projecting downwardly from the horizontal base. The base provides firm support for the wear element and good protection for the ski against bending, whereas the wear element provides good penetration into the snow and good steering control. By making the wear element shorter than the base in the longitudinal direction of the ski, the ratio of the length of the wear element in front of the pivoting point of the ski to the ratio of the length behind this point can be varied to provide favorable steering control characteristics without affecting the support for the ski.

Abstract: A composition for treating skate blades has a polytetrafluoroethylene (PTFE) resin and a carrier. The carrier includes a wetting agent for dispersing the PTFE resin and an inert agent for reducing any volatility of the wetting agent and which will not contaminate ice. The composition is applied to the skate blade and burnished thereon for presenting a blade surface impregnated with PTFE resin and having a reduced coefficient of friction.

Abstract: A luge sled having features which enhance performance and safety characteristics of the sled. The sled generally comprises a support structure for supporting a sled rider, at least two runners, a cavity, a mounting boss, and an elastomeric bushing positioned between the cavity and the mounting boss and including a body portion which substantially encloses the side surfaces of the mounting boss around the perimeter thereof. The elastomeric bushing may further include an end portion which substantially encloses the end surface of the mounting boss. The runners are molded from glass-reinforced plastic and are formed into an I-beam section. The runners also include a plurality of reinforcing ribs protruding from a side surface thereof. The runners include a front segment having a front surface which is generally vertically disposed. The sled includes front and rear bridge supports which are molded from glass-reinforced plastic and also include reinforcing ribs in a lower surface thereof.

Abstract: A snowmobile steering ski or skis, which may be equipped with a ski liner to prevent undue drag on a snowmobile snow, includes a integral fin that enhances steering control in turning or resisting sidehill slippage of the snowmobile particularly in traversing powder or hard packed. The ski liner fin is integral, or replaceable, and extends outwardly along the outer edge and downwardly over a central portion of the ski. The fin contacts the snow on the inner side of either a flat turn, or the uphill slope of a sidehill run, because the forward end of the snowmobile ski is cambered so as to tip downwardly toward the steered direction of a turn.

Abstract: The ski supports of a snowmobile are each provided with a plurality of wheel assemblies, with each wheel assembly arranged for pivoting relative to the ski support from a first position elevating the wheels above a top surface of each ski support to a second locked position wherein the wheels are directed below the ski supports.

Abstract: A snowmobile ski flexing apparatus comprises a flexible snowmobile ski with a curved front portion and a flexible elongate loop attached at a first end to the front portion of the ski and bending upward and rearward and then down upon the ski to abut it at a second end at approximately its midpoint. A retainer comprising a chain is secured at one end to the ski at its front portion, while its other end is slidably engaged to the loop, allowing the latter to move lengthwise relative to the ski. A tubular sleeve with rectangular cross-section circumscribes the loop near the second end thereof and allows sliding movement of the loop when the ski is flexed, allowing flexing of a large portion of the ski and acting as a shock absorber.

Abstract: A snowmobile ski comprising a longitudinally extending runner having a bottom surface, a generally flat elongate bar having a top and bottom surface, and a steering skag extending longitudinally of the runner on the bottom side of the bar. The flat bar is generally contoured to abut the bottom surface of the runner, and furthermore extends forwardly beyond the skag and laterally and longitudinally beyond the skag so that a skag track in the snow encountered by the ski and the skag track left by the skag in the snow will be at least partially filled in by the bar.

Abstract: A machine or board for sliding over snow, such as a ski, monoski, snow surfer, sledge, sleigh, . . ., has a sole provided with longitudinal scores. The scores are not rectilinear, but present an undulated form, typically of sinusoidal appearance, which gives this machine or board a much improved slide characteristic.

Abstract: A sailboard for sailing on snow or ice with a conventional articulated hand held sail mounted on the sailboard. Two runners underneath the sailboard are located to provide balanced gliding and to permit the sailboard to be rolled laterally on the outermost portion of the runners. Each runner glides longitudinally and has low resistance to lateral slippage. However, the rear of each runner is shaped to resist lateral slippage. A blade is provided on the runner for sailing on ice. As the sailboard pitches fore and aft, the blade pivots to remain flat on the ice.

Abstract: Wear protectors for snowmobile skis are provided which comprise a relatively narrow strip composed of a wear resistant material, and wherein the strip is provided with one or more holes which are aligned with and accommodate the passage of bolts extending from a wear rod, whereby the strip may be secured to the bottom of a snowmobile ski by the wear rod.

Abstract: An improved sled for recreational use. The sled comprises a support member which is formed in the shape of a seat to accommodate a rider in an upright position. The support member has handholds at either edge for the rider to grasp. A block of ice is coupled to the bottom side of the support member. The ice is held in place by an adjustable retention member. The retention member is made up of two support blocks which are rigidly attached to the support member. A compression block is adjustably connected to each of the support blocks by means of a locking screw disposed through the support blocks. As the screw is turned, the compression blocks move inwardly clamping the ice. In alternative embodiments of the retention member, the locking screws are replaced by springs which automatically force the support blocks inward and pieces of flexible foam rubber are used to hold the ice block in place.

Abstract: A snowmobile ski is made of two main parts, namely a steel stiffener and a sole made of ultra high molecular weight polyethylene (UHMW-PE) to which a friction reducing additive has been added. The front handle is molded integrally with the ski sole and then bent back and secured to the sole and stiffener. The sole has upstanding projections on which the stiffener rests so that spaces are provided which allow the sole to deflect when impacted thereby reducing transmission of impacts to the stiffener. The stiffener is formed with a main stiffener and secondary stiffeners provided only when the ski is to be attached to the suspension assembly. The secondary stiffeners coact with the main stiffener to increase the strength and rigidity while minimizing the weight increase.

Abstract: An ice skateboard comprising an elongated platform having secured to the front and rear portions of the underside conventional skateboard trucks, with transverse axles supported by a structure facilitating slight controllable swinging movement of the axle in response to the shifting of weight on the platform, wherein each of the front and rear axles rotatably supports at opposed ends thereof elongated skate blade mounting units in a manner to be parallel to the center line of the platform, and each of the mounting units bearing a skate blade protruding in a direction away from the platform, the exposed edge of each blade having a front to rear contour of slightly convex curvature and a transverse contour of markedly concave curvature providing closely spaced ice gripping edges, and the mounting units for said blades being so fashioned as to provide a cant to the blades of at least 5.degree., thereby convergently orientating the mounted blades.