Abstract: A device for controlling the pitch of a helicopter's rotor blade, the device having a BLDC motor based actuator; and at least one control surface operatively connected to the BLDC motor based actuator. The actuator and the control surface are preferably fully integrated into the interior profile of the rotor blade and are capable of controlling the PFC of the helicopter and improving HHC during operation by reducing noise and vibration. The motor is preferably a high power density motor incorporating rare earth permanent magnets connected to a roller/ball screw or planetary gear set to provide the right combination of force/torque, stroke and frequency.

Abstract: Apparatus for generating electrical energy in a fluid environment, the apparatus including a wing member for disposition in the fluid and pivotally movable about an axis in response to flow of the fluid thereabout, connector rods each pivotally mounted at a first end thereof on the wing on opposite sides of the axis, a crank member attached to a second end of each of the connector rods and rotatable about a pivot axis by movement of the attached connector rod, a housing supporting the wing member, a gear system disposed in the housing, an axle interconnecting each of the crank members and the gear system, and an electrical generator disposed in the housing and driven by the gear system.

Abstract: The blade includes a current part (1) having an aerodynamic profile enclosing a spar (7) and extending from blade tip (4) to a blade root (3) provided with a pitch sleeve (21), through which twisting arm (6) passes and protrudes beyond blade root (3), and comprising a first part of a bundle (5) of superimposed and elongated metal strips, current part (1) including a block (13) based on synthetic material molded in form in a single piece around spar (7), comprising a second part of bundle (5) extending in line with the first part forming the twisting arm (6) and cooperating with the anchoring devices (14, 17) of the block (13) based on synthetic material around the spar (7).

Abstract: A water wheel with extended vanes is disclosed. The water wheel characterized in that the rotating shaft of the water wheel is supported by bearing and a hub is mounted to the rotating shaft, a plurality of vanes are provided on the rotating shaft, and one end of each vane is connected to a connection shaft, where the other end of the connection shaft is connected to A blade, the side of the tail section of the blade is provided with a pulley which contacts with a cam when the vanes are lifted up, the cam includes a section of sliding face to drive the pulley so that the vanes and blades are in a straight line, and the bottom of the cam has a linking shaft to support and secure at the body of the water wheel. The increased arm of the vanes will effectively increase the driving force of the water wheel.

Abstract: The forced air cooling fan comprises a flat disk surface having a series of circumferentially spaced apertures each including a V-shaped fan blade connected across the aperture perpendicular to the periphery of the disk-shaped surface. The V-shaped fan blade includes a pivoting device having a first blade member of one side and a second blade member of the opposing side of the pivoting device. In one position of the V-shaped fan blade, the first blade member covers a first portion of the aperture and the second blade members directs the flow of air downwardly through a second portion of the aperture. V-shaped fan blades allow the direction of the forced air to remain relatively constant when the rotational direction of the drive mechanism is reversed.

Abstract: The forced air cooling fan comprises a flat disk surface having a series of circumferentially spaced apertures each including a V-shaped fan blade connected across the aperture perpendicular to the periphery of the disk-shaped surface. The V-shaped fan blade includes a pivoting device having a first blade member of one side and a second blade member of the opposing side of the pivoting device. In one position of the V-shaped fan blade, the first blade member covers a first portion of the aperture and the second blade members directs the flow of air downwardly through a second portion of the aperture. V-shaped fan blades allow the direction of the forced air to remain relatively constant when the rotational direction of the drive mechanism is reversed.

Abstract: A variable speed helicopter tilt rotor system and method for operating such a system are provided which allow the helicopter rotor to be operated at an optimal angular velocity in revolutions per minute (RPM) minimizing the power required to turn the rotor thereby resulting in helicopter performance efficiency improvements, reduction in noise, and improvements in rotor, helicopter transmission and engine life. The system and method provide for an increase in helicopter endurance and range. The system and method also provide a substantial improvement in helicopter performance during take-off, hover and maneuver. All such improvements are valid in helicopter mode when the helicopter is supported by rotor vertical lift, in airplane mode when the helicopter is supported by wing lift and the rotor is tilted forward to provide propulsive thrust and in conversion from helicopter mode to airplane mode.

Abstract: The blade structure of a wind turbine is provided which has enough strength for sporadic large load and increased durability. The blade can be formed into a thinner blade profile, with which blade performance is improved, increased efficiency of the wind turbine is attainable, and the noise induced by Karman vortex street is reduced.

Abstract: A wind-powered turbine has vanes (2-5;36-39) that are pivoted (13;44) to radial arms (6;41) of its rotor (1;30,31) and are turned by rods (14;45) linking the vanes (2-5;36-39) individually to a common pivot (16;47) which is offset from the rotor-axis (8;42) on a crank-arm (17;48). The rods (14;45) constrain their pivots (15;46) with the vanes (2-5;36-39), to follow a circular path (B) centred on their common pivot (16;47) on the crank-arm (17;48) so that vane-pitch varies cyclically with rotor-rotation. Angular adjustment of the crank-arm (17;48) about the rotor-axis (8;42) varies the angular phasing of the pitch cycle within each revolution such that for constant wind speed and direction (W), rotor-speed changes.

Abstract: A variable edge rotor blade adapted to be driven by the rotor hub includes an airfoil section; a movable edge section coupled to the airfoil section, and an actuator device operating independently of the hub, disposed in the blade proximate the movable edge section, fixed to the airfoil section and coupled to the movable edge section for oscillating it between an increased lift and decreased lift position.

Abstract: A foldable propeller for a ship having a hub (2) for mounting on a drive shaft of the ship, and at least two skew-type blades (1), each of which is pivotably arranged in the hub (2) for configuration between a first, essentially folded together position and a second, essentially unfolded position, wherein each blade (1) presents a generator line (8). Each of the blades (1) has a skew distribution such that the leading edge of the inner and outer radii, respectively, are located substantially forward and aft of the generator line (8) of the blade (1). The mid-chord line (10) of the propeller extends substantially forward and aft of the generator line (8) of the blade (1). A foldable propeller with such blade geometry provides improved performance; in particular, ready unfolding, high reverse thrust and low noise and vibration.

Abstract: An apparatus for generating electric power using wind force which is capable of generating good quality electric power by combining the apparatus with the inventor's water wave force-based electric power generating apparatus and installing this combined apparatus in the sea.

Abstract: The invention provides a method of driving a plurality of plastic fan blades (14) integrally molded with a band (16) about and engaging a metal driving hub (12) at an interface by rotating the fan blades (14) in unison with the hub (12) up to a predetermined rotational speed at which the band (16) flows or expands radially to create a space between the band (16) and the hub (12) whereby the fan blades (14) are allowed to rotate at a slower rotational speed than the hub (12) to prevent the fan blades (14) from bursting in response to centrifugal force. The drive connection may optionally include band projections (24) and/or male projections (26) which shear before or as the separation occurs. A film may be disposed at the interface to prevent the plastic of the fan blades (14) and band (16) from bonding to the metal hub (12).

Abstract: An automatic flap that uses on each wing two adjacent fins, one of which is smaller and is located on the middle or front of the wing, the other, which is larger, on the bottom rear of the wing, with a shaft in the common eccentric zone linking the two fins, said shaft being parallel to the axis of the wing, having the fins different resistance to the ram air, creating a rotation torque as a function of the aircraft's speed, when retracted, they are shaped so that the front or top fin adapts to the upper surface of the wing and the rear or bottom fin adapts to the lower surface so that, together with the wing, they form an aerodynamic profile, there are attachment arms between the two fins, and bands or springs to assist or complement the action of the smaller fin whose resistance is such that, at low speed, the flap remains extended.

Abstract: A submersible magnetic motor having improved rotary blades comprising a magnetic motor body, a magnetic rotor and a rotary impeller wherein the rotary impeller comprises a rotary hub provided with a plurality of blades which are uniformly distributed and extend outwardly around the periphery of the hub. The rotary hub is provided with an axial hole centrally formed therethrough for positioning an end of a central shaft of the magnetic rotor. The present invention is characterized in that the blades are each provided at the outer end edge with two stoppers and a fin freely pivoted therebetween, so as to be adjacent to the inner surface of the wall of the receiving chamber of the submersible motor. When the magnetic rotor is actuated to rotate, the fins each pivots to contact one of the two stoppers due to the resistance of the water such that the submersible motor can be maintained at a constant rotation speed, and the water pumping efficacy can be substantially improved.

Abstract: A propeller in particular for a ship has blades each of which is pivotally arranged in the hub of the propeller so that the blade is capable of pivoting to and fro in an axial plane between forward and rearward positions. The blades are constructed such that each of the blade profiles formed as the intersecting face between a cylinder face coaxial with a propeller and a blade, is symmetrical in a position between forward and rearward positions which are determined by fixed stops in the hub and/or the simultaneous actions of the centrifugal force and the hydrodynamic pressure on the blade at a predetermined speed of rotation. This imparts a high efficiency and a quiet and steady operation to the propeller, when the ship navigates forwardly and rearwardly.

Abstract: A controllable pitch propeller for application principally to sailboats employing electric auxiliary power. The design addresses a highly efficient approach to performing four basic functions desirable on sailing vessels that have electrical, or internal combustion, auxiliary power and onboard electrical systems typically employing batteries. The design employs no external nor remote actuator means; instead, blade position (nominal pitch) is inherently "controlled" by the direction of shaft rotation and whether the propeller is acting as a propulsor or a turbine. The four basic functions, or configurations, performed by the design are 1) forward propulsion, 2) reverse propulsion, 3) efficient power generation as a turbine, and 4) feathering for no-power minimum drag. The propeller includes a cambered blade configured with a cross section that would purposely act efficiently with fluid inflow impinging on either edge, depending upon the function being performed.

Abstract: A mechanical device which converts the wind energy into rotational mechanical energy has a cross-wind-axis rotor structure, having multiple, orientable blades around its periphery, mounted parallel to the rotor axis. Each blade is interconnected with an orientable stabilizer mounted on the same rotor radial line as the blade, at a smaller radius, so that during rotation, the blade and the stabilizer are able to pivot simultaneously and essentially parallel to each other, in the course of aligning themselves, into a pitch angle, where the opposing pitching moments created by the aerodynamic lift forces over the blade and the stabilizer, equilibrate each other, and where the aerodynamic lift forces are the optimum to induce the necessary torque to spin up the rotor.

Abstract: A pitch control system for a vertically launchable and recoverable winged aircraft includes a collective and cyclic pitch control system, a drive yoke and a rotor hub. The collective and cyclic pitch control system is operably connected to two proprotor blades to cyclically control the pitch of each proprotor blade, so that the aircraft is capable of controlled helicopter mode flight when the aircraft body is pointed in a generally upward direction. Proprotor blade flapping caused by applying cyclic pitch control results in teetering of the rotor hub with respect to the drive yoke. Torsion bar springs are used with suitable mechanical linkages to resist this teetering motion and generate the hub moment which is transmitted to the airframe and used to maneuver the aircraft.

Abstract: A variable pitch propeller primarily for marine use which includes a hub for mounting on a driven shaft. The hub has a plurality of blades which are mounted to bearing rings which are carried in recesses in the hub, with removable snap rings retaining the bearings therein with cap screws from the bosses extending to and engaged with the bearing rings for full 360.degree. rotation to automatic pitch positions and with cap screws which may extend into spaced holes in the hub for setting the blades to desired fixed positions.

Abstract: A stirring system for stirring contents in a laboratory flask having a round or spherical bottom and a reduced neck includes a stirrer shaft manufactured with a ring at the lower end thereof which permits attachment of a blade with a nut and bolt made of TEFLON material. The nut and bolt prevents the stirrer blade from flipping over during assembly and allows for a controlled tightening force to be applied to ensure that the blade remains in proper stirring position during use. The nut and bolt design permits use of the shaft with any stirrer blade having a keyhole cutout or circular opening. A method of stirring contents in a laboratory flask by attachment of the stirrer blade to the stirrer shaft with a nut and bolt is also disclosed.

Abstract: This invention is a paddlewheel apparatus having an epicyclic gear train in a rotatable holder at an end of a plurality of cantilevered paddles. The paddles are maintained substantially vertical throughout the rotation of the holder and they are completely unobstructed by any other part of the apparatus in all phases of operation. A housing which extends over the holder and the paddles is open at the bottom to pass the downwardly hanging paddles into the water.

Abstract: A multi-blade rotor (1), especially for a helicopter rear anti-couple propeller, includes a hub body (3) to which are connected twistable straps (11 to 17) each formed by two bundles (20) of fibers with a flattened cross section arranged radially around the hub (3), each of the bundles (20) forming at least two halves of different blades (11 to 17) and being twisted and curved in the region of its passage near the center of the hub body (2) in such a way that it forms a tangent to the circumference of the center of the hub body (3) along the greater dimension of its cross section.

Abstract: A propeller blade tip path plane-inclining device which is provided with a fuselage, a propeller including a center piece rotating unitary with a rotation shaft in association therewith and a plurality of blades extending substantially horizontally from the center piece and differing the variation in pitch during the rotation thereof from one another, a motor for driving the propeller for rotation, a position detector for detecting the position of the propeller in the propeller rotation plane, and a control device for controlling the motor in accordance with an output signal of the position detector.

Abstract: A bearingless hub structure for a rotary-wing aircraft is provided, the structure including a hub body adapted to be securely connected to a rotor mast, a plurality of flexible beam members provided integrally with the hub body to extend radially outwardly, a pitch housing encircling each of the flexible beam members, and having a radially outward end portion which is rigid with a radially inward end portion of a rotor blade, a spherical bearing positioned adjacent to a radially inward end portion of the flexible beam member for supporting the pitch housing, a lead-lag damper positioned between the flexible beam member and the pitch housing, and the flexible beam members each having a flexible plate portion which is of a low bending rigidity in a flapping direction, a flexible portion provided radially outwardly of the flexible plate portion having a low bending rigidity in the lead-lag direction, and a twist-flex portion provided radially outwardly of the flexible portion.

Abstract: A wind turbine with a stationary tower and a set of turbine blades rotatably attached to the top and bottom of the tower. A set of upper and lower braces connects the turbine blades to prevent any sag or skewing of the turbine blades as they rotate about the tower. The wind turbine may also include a stationary shell attached to the tower and inside the sweep of the turbine blades, to direct the airflow toward the turbine blades at the shell periphery, thereby improving overall performance and efficiency of the turbine.

Abstract: This invention is a paddlewheel apparatus having epicyclic gear trains in rotatable holders at opposite ends of a plurality of paddles. The paddles are maintained substantially vertical throughout the rotation of the holders and they are completely unobstructed by any other part of the apparatus in all phases of operation. A housing which extends over the holders and the paddles is open at the bottom to pass the downwardly hanging paddles into the water.

Abstract: A main helicopter rotor has a number of blades, and a drift shaft supporting at its top end, a hub consisting of a rigid annular body integral and coaxial with the drive shaft. An elastically deformable torodial body surrounds and is connected to the annular body for defining, with the same, a closed-section torodial assembly. Each blade is connected to the hub by a connecting element extending at least partially through the annular body and the torodial body, and connected respectively to the same by a first and second spherical elastomeric bearing.

Abstract: A main helicopter rotor having a number of blades and wherein a drive shaft supports, at its top end, an annular hub integral with the drive shaft and in turn supporting, via a spherical elastomeric joint having its center on the axis of the drive shaft, and an elastic axial suspension, a toroidal body surrounding the drive shaft. Each blade is connected to the hub by a connecting element extending through both the hub and the toroidal body, and connected respectively to the same by a first and second spherical elastomeric bearing.

Abstract: An improved clevis joint capable of withstanding substantial pivotal motion between its joined members and loading along its axis. An improved clevis joint wherein the parts joined thereby are pivotally connected by two sets of elastomeric bearings which are free to rotate about the joint axis and which envelope and support a free floating centering pin from the joined members so that during motion between the joined members, said elastomeric bearing sets share the rotary motion due to the rotating of the connecting pin.

Abstract: A propeller or fan blade is rotatably mounted to a blade retention pitch member by a pin radially outside of a spinner. By mounting the propeller blade for rotation about the axis of the pin, the blade response to a vibratory excitation in a first mode of vibration is modified such that the twisting motion of the blade is minimized. High speed stability of the blade is enhanced thereby. Moreover a damaged blade may be easily replaced.

Abstract: A wind power plant construction includes a turbine with at least two blades, a shaft, and blade angle control apparatus. According to the wind power plant construction shown, supports are rigidly connected to the shaft substantially radially thereto, and are coordinated with the blades. At the extreme ends of the supports are flapping pivots, to which the blades are attached. The blade extends from the flapping pivot towards the shaft; that portion of the blade doing so constitutes an arm to which a control means is connected. The blade is weighted so that the centroid line and axis of rotation of the blade lie closer to the leading edge of the blade than does the buoyancy center.

Abstract: The invention relates to a flapping restrainer device for the blades of a rotorcraft main rotor, and a rotor head comprising the same. The lower restrainers comprise a reciprocal star-shaped plate (32), having as many radial branches (33) as blades, and each one of the branches being engaged into a radial opening (6) of the hub (3). Outside the latter, the star-shaped plate (32) cooperates with supporting runners (47) integral with the blades. The upper restrainers comprise, for each blade, a stop which is retractable by the effect of the centrifugal force and which is composed of a lever (52), pivoting on a pivot (53) carried by the hub (3), and a first arm (55) of which constitutes a stop finger directed towards an upper supporting component (60) integral with the blade, while a second arm (56) carries a governor weight (57) and a nose (58) for support against a shoulder (59) integral with the hub (3).

Abstract: A fluid apparatus comprising a motor, a blade wheel connected to the motor shaft, plural moving blades disposed along the outer circumference of the blade wheel with each moving blade shaft extending into the blade wheel and being rotatable relative to the blade wheel, small gears attached to the moving blade shaft inside the blade wheel, a large gear disposed to be level with the blade wheel so as to be geared with the small gears, an impeller connected to the large gear and housed in a casing with oil so that there may be produced a relative angle difference between the blade wheel and the large gear upon starting of the blower, and stoppers for stopping the large gear at predetermined positions with respect to the blade wheel at normal and reverse modes of the blower respectively.

Abstract: The present invention relates to a heat exchange machine for removing the excess of the heat during the summer period and the excess of humidity during the cold period. The machine comprises two tubes, one inside the other, an intermediate frame with two sets of blades attached to the frame from inside and outside thereof and driven by a common reversible motor in the same direction. One of these sets is the set of blades rigidly fixed to and the other one is swingingly mounted in the frame, so that the change of the direction of the fixed set of blades induces the change of the direction of the air flow in one of the tubes, meanwhile the direction of the air flow along the other tube induced by the other set of swingable blades remains the same regardless of the direction of rotation of this set.

Abstract: A controllable lifting rotary wing for an aircraft wherein each rotor blade is mounted in such a manner that it has freedom to oscillate in pitch about its feathering axis. The aerodynamic center on each rotor blade is displaced forward of this feathering axis over at least a portion of the span. Cyclic aerodynamic forces on this spanwise portion cause the blade to change pitch sinusoidally once-per-revolution of the rotor whenever the rotary wing aircraft experiences a change in flight attitude or velocity. The result is that the rotor blades automatically and continuously change pitch to cancel out cyclic lateral flapping moments which are normally produced on a helicopter rotor blade by such a flight disturbance. This rotary wing has greatly improved stability by virtue of this self-feathering action. Cyclic pitch control moments are applied to the rotor blades by indirect means which do not interfere with automatic blade feathering. Means for control of collective pitch of the blades are also provided.

Abstract: A one piece fan blade for a wind machine is sandwiched between a hub and a plate, the fan blade and the hub and is secured thereto by a teeter pin extending through the bore from opposed passageways in the hub. The shaft is centered in the bore of the hub to permit tilting of the hub about an axis coincident with the teeter pin to an angle commensurate with the spacing intermediate the shaft and the bore. Apparatus at the extremities of the teeter pin reduce wear on the teeter pin retaining plates and contribute to lubrication of the opposed journals.

Abstract: A self-adjusting propeller device having a control blade and a thrust blade connected together in nondiametrical relation and pivotally mounted on a hub for rotation about a hub axis. In response to a change in load on the device, the control blade pivots in relation to the hub axis at generally constant pitch, and, by virtue of the manner in which the pitch and thrust blades are interconnected and disposed on the hub, the thrust blade pivots at a changing pitch so that the device applies a substantially constant torque. Structure is provided for chaning the pitch of the control blade independently of the load from a remote location during operation of the device. The selection of control blade pitch positions provides for transmission of forces in either axial direction and at selected magnitudes including a neutral or non-force-transmitting mode.

Abstract: A low vibration helicopter rotor including a four-bar linkage arrangement which permits the straight line connecting the center of gravity of each pair of diametrically opposed rotor blades to intersect the rotor hub geometrical center at all cyclic conditions.

Abstract: A ceiling fan with adjustable blades and equipped with a motor including a centrifugally controlled motor speed control. The motor speed control includes an adjustable, centrifugally controlled electronic switch.

Abstract: A one piece fan blade for a wind machine is sandwiched between a hub and a plate. A rotatable shaft penetrably engages a bore extending through the plate, the fan blade and the hub and is secured thereto by a teeter pin extending through the bore from opposed passageways in the hub. The shaft is centered radially inwardly in the bore of the hub between opposed journals extending radially inwardly into the bore from the opposed passageways to permit tilting of the hub about an axis coincident with the teeter pin to an angle commensurate with the spacing intermediate the shaft and the bore.

Abstract: The invention relates to an axial fan with blades that automatically adjust to the direction of rotation. The fan blades are mounted with freedom to swivel on the fan wheel and are limited in their swiveling motion by stops which are provided on the fan wheel. In order to reduce the manufacturing cost of such an axial fan, spokes, to which the fan blades are fastened by means of film hinges are mounted on the fan wheel. The fan wheel is made from a single piece of plastic.

Abstract: A windmill including a hub, at least a pair of rotor roots rotatably coupled to the hub and rotor blades mounted on respective rotor roots, wherein wind forces produce rotation of the blades, the roots and the hub around an axis of rotation passing through the hub and the hub defines a plane of rotation perpendicular to the axis of rotation. Each rotor root is mounted in an initial position at a predetermined compound angle with respect to the axis of rotation and the plane of rotation. The rotor roots are spring biased in an initial position and are coupled to each other and to the hub by means of a spring and linkage members disposed in the hub. Upon rotation of the rotors, centrifugal force acts on the rotors in opposition to the spring biasing and produces synchronous rotation of the blade roots relative to the axis of rotation and the plane of rotation thereby decreasing the pitch of the blades with respect to the wind direction and correspondingly controlling the speed of rotation of the rotors.

Abstract: The invention relates to a radial fanwheel, wherein the fan blades are connected to a hub by spokes. Each fan blade is connected by connecting elements to the adjacent fan blades in the vicinity of their ends. Specifically, the spokes and connecting elements, as well as the fan blades themselves, are elastically deformable by the loads which develop.

Abstract: Yaw trimming in large wind turbines is achieved by laterally offsetting the turbine yaw axis from the axis of rotation of the hub.

Abstract: A variable-pitch marine propeller comprises helicoidal blades 6 each mounted on a hub 1 to freely pivot about radial axis 25 spaced in front, in the direction of rotation, of the center of pressure of the blade 6 whereby water pressure acting on the blade exerts a torque which tends to turn it about its axis in a direction to bring the surfaces of the blade into line with the flow of water over it. The axis 25 is also spaced behind, with respect to the direction of movement of the propeller through the water, a major portion of the pressure surface of the blade whereby, the resultant of the drag of the water exerts a torque which tends to turn the blade in an opposite direction. The shape and mass distribution of the blades relative to their pivot axes are also such that centrifugal effects tend to move the blades, in the absence of hydrodynamic forces, into a pitch equal to that of the helicoid.

Abstract: A system is provided to adjust the operating angle of attack of a variable pitch impeller blade in response to different conditions. The impeller blade is pivotally mounted around a pivot axis and a small control surface attached to the blade provides a turning moment around the pivot axis to oppose a similar moment provided by the lift component of the blade. The operating angle of attack of the blade is determined by the angle at which the moment from the control surface tapers off as it approaches stall range, thus equalizing the moment from the impeller blade.

Abstract: In combination with a lawn edger device which is used to cut vegetation along the edge of a sidewalk or other similar hard surface, the edger having a housing which has mounted thereon a motor, the housing and motor being mounted on a wheel assembly for movement along the sidewalk or lawn, the motor causing rotation of a cutting blade, the improvement comprising the including of a fan device located adjacent to the cutting blade for the purpose of blowing shredded vegetation created by the cutting blades, the fan device to be rotatably driven by means of the motor, the fan device comprising a series of fan blades which are flexibly attached to a fan hub, the fan device comprising a series of fan blades which are flexibly attached to a fan hub, the fan hub being mounted on a driving shaft and capable of being moved in respect thereto, whereby because of the flexible mounting of the fan blades and the non-rigid connection between the fan hub and the fan driving shaft the fan is not capable of causing injury to