Abstract: The regenerative heater comprises the brickwork of the walls and checker of refractory materials with different coefficients of linear expansion enclosed within a jacket also included are superimposed horizontal sections corresponding to the distribution of the internal operating temperatures. Each of the horizontal sections consists of a homogeneous refractory material. Arranged between the horizontal sections are transition sections, each consisting of the refractory materials of the contiguous sections, the materials being uniformly distributed in each course and superimposed so that the content of the material in one of the contiguous section gradually diminishes from course to course toward the other section.

Abstract: Heat storage and/or cold storage are essential to effective utilization of solar energy sources, including sun and wind. Efficient auxiliary controlled heat sources are also desirable, if not essential. This invention provides a liquid heat and/or cold storage unit in radiant heat transfer relationship with the living space of a shelter for use with weather-sensitive energy sources or weather-sensitive energy harnessing mechanisms, and it includes an optional controlled heating source within the liquid storage space. Maximum heat and/or cold utilization is insured with minimal losses through transmission of heat outside living spaces. The heat storage unit may be heated or cooled and heat may be provided or withdrawn from the living space via radiation as well as convection and controlled by means of removable insulation in the form of sliding or folding doors or panels and the like.

Abstract: A motor vehicle is equipped with a heater assembly in which hot coolant from the engine is circulated through a first heat exchanger, normally called heater. The vehicle is also equipped with a refrigerating unit, i.e., an air conditioner, which has a second heat exchanger, or cooler, located in front of or behind the heater. Two separate temperature sensors are provided. One of these senses the compartment temperature while the other is located directly adjacent to the heater and senses the temperature of the air leaving the heater. The responsivity of this latter sensor is made substantially lower than that of the compartment sensor, i.e., its signal change per unit temperature change is lower, resulting in differential weighting. A control unit is so constructed that when the compartment temperature rises, the heater, which is normally cycled on and off in a quasi-continuous fashion, is shut off. If the temperature rises further, the controller activates the refrigerator unit and the air is cooled.

Abstract: Apparatus are disclosed for conditioning the air within an indoor space and include first heat transfer means for selectively heating air passing to the space and a heat pump selectively operable in a heating mode, also for heating air passing to the indoor space. Control means are provided for effecting operation of the first heat transfer means and the heat pump which include means for sensing the demand for heat within the indoor space and for distinguishing between a relatively low demand and a relatively high demand. Operation of the heat pump is effected in response to a relatively low demand for heat until such demand is satisfied. In the event that a relatively high demand for heat is sensed, operation of the heat pump is terminated and the first heat transfer means is operated until such time as both the relatively high and low demands for heat are satisfied.

Abstract: Heat exchange apparatus of the recuperator type is provided with means by which the inner tubular member can be withdrawn from a state of collapse and restrained in a position against further collapse.

Abstract: Tube support sheets fabricated from bars or machined from plates to have holes which receive a plurality of tubes. Adjacent support sheets cooperate to restrict lateral movement of the tubes without completely surrounding each tube at a tube support sheet and provide large open areas for fluid flow adjacent thereto.

Abstract: An improved heat transfer fin structure of the type normally fabricated from sheet metal and wrapped about a conduit to provide enhanced heat transfer efficiency between the conduit and a fluid in contact with the conduit, has a plurality of elongated leg portions spaced apart from each other and openings defined in the space between the leg portions. The structure provides the advantage of high efficiency combined with high peripheral stability.

Abstract: A portable refrigerator unit is cooled by a thermoelectric element of the Peltier type, having hot and cold faces adapted to be energized by an external DC source, which can be disconnected from the unit to make the unit entirely portable. The thermoelectric unit has a cold face in contact with an internal thermal sink, which in turn is in contact with a heat conducting lining, and its hot face in contact with an external thermal sink, having heat dissipating means associated therewith. The internal thermal sink has a large portion imbedded in an insulated wall of the unit, and a relatively small portion having a face free of the insulating material, which free face is in heat-transfer contact with the cold face of the thermoelectric unit. The external thermal sink with its heat dissipating means is spaced from said unit so that its surfaces are exposed to the ambient atmosphere.

Abstract: A method of and apparatus for treating or completing wells to provide surface controlled subsurface safety systems in the wells, whether at the time of original completion or when the well is reworked or reequipped. A method and apparatus is provided for installing receptacles at the upper ends of one or more lower well flow conductors left in place in the well below the surface for receiving the lower ends of corresponding upper flow conductor sections having surface controlled subsurface safety valves connected therein for controlling undesired flow from the well through said lower flow conductors in the event of an emergency, disaster or accident damaging the surface flow controlling system or threatening the integrity thereof. A hanger or packer may be installed in the well casing below the surface for supporting the upper ends of the lower flow conductor or conductors therebelow and providing means for connecting receptacles at the upper ends of said lower flow conductors above such hanger or packer.

Abstract: The invention relates to a safety self-centering basket for use during tubing operations on bore holes in the mining industry and in oil fields and the like. The basket has resilient steel bars engaged at their ends with steel rings, the rings being formed from two jointed half shells. The invention is characterized in that the steel bars are held by lugs as a safeguard against them coming out of engagement with the rings. The free end of the lugs is positioned against the outer face of the steel ring.

Abstract: A method for measuring fluid advance in underground formations comprises, (1) driving bench marks into the ground over the formation spaced a predetermined distance apart, (2) measuring and recording the precise vertical displacement of each bench mark at the end of each predetermined period of time, and (3) interconnecting bench marks of similar vertical displacements to form lines, each line indicating the position of the passing of a particular amount of fluid in the formation underground at a particular time.

Abstract: An improved method is disclosed for bringing a well under control by injecting a well-controlling fluid into an adjacent well, through the subterranean formation, and thence into the out-of-control well, wherein the improvement lies in a particular sequence of steps whereby fluid communication between the boreholes is established or improved.

Abstract: An adjusted salinity and hardness, aqueous preflush containing a thickening material which can be, for example, a hydrophilic material such as polyacrylamide, polysaccharide, polyvinyl aromatic sulfonate, polyethylene oxide, methyl cellulose, etc. or colloidal silica, etc. in a concentration sufficient to increase the viscosity of the adjusted salinity aqueous preflush fluid is injected into a subterranean, petroleum-containing formation. Optionally, the preflush fluid may contain a sacrificial agent, such as sodium tripolyphosphate, etc. The high salinity formation water is efficiently displaced by viscous low salinity aqueous preflush fluid to increase the effectiveness of a subsequently injected high salinity sensitive single surfactant solution. The surfactant may be displaced by a mobility buffer solution, which then may be displaced by water.

Abstract: Nozzle having a housing with a cylindrical inner surface and with a fixed wall extending at a right angle to its axis. A movable wall is mounted in the housing adjacent the fixed wall and is rotatable about the axis, so that a pattern of apertures in the movable wall match similar apertures in the fixed wall to control flow of fluid therethrough.

Abstract: The present invention relates to a support for an earth working tool such as a chisel plow, and more particularly to a spring loaded support which permits pivoting of the earth working tool against a resilient bias force for prevention of overstress, and which includes a mounting member that distributes the stresses on the earth working tool shank itself across a substantial length of the shank to reduce stress concentration areas and lower the maximum stresses by providing a spring backing member along the shank which carries the mounting pivot tube and also carries one end of the spring assembly.

Abstract: A multi-vibro pile hammer comprising a plurality of vibro pile hammers having vibration generating units adapted to generate vibrations with different phases and in synchronism with one another, and the arrangement is made such that vibrations to be transmitted through the ground between the piles or sheet piles held by the hammers so as to be driven underground or pulled out therefrom can be counteracted thereby reducing the vibration transmitting region remarkably.

Abstract: In a system for obtaining core samples from a submerged bottom a core barrel and holder assembly attached at its upper end to a cable is dropped through the water from a floating vessel, and after the barrel has penetrated the submerged bottom a winch on the vessel is operated to raise the assembly into a guide tube carried by the vessel in an over-water position. An operator on the deck of the vessel swings the barrel through a vertical slot in the guide tube and as the cable is released slowly the barrel is guided to a near horizontal position so that the core sample can be removed from the barrel. The holder tilts within the guide tube during this operation but is prevented from passing through the slot, thereby preventing the assembly from swinging as a result of wave action on the vessel. The system can be used to take samples while the vessel is being propelled through the water and during rough weather.

Abstract: Methods and apparatus are provided for enabling an instrument and a connected flexible line contained in a drill string to be left in the string while a pipe section is being added to or removed from the string, to thereby avoid the inconvenience and loss of time normally involved in removing the instrument and flexible line from the string on each such occasion. This result is preferably accomplished by initially threading the flexible line at the surface of the earth through a series of extra pipe sections positioned at a storage location adjacent the well, so that each of these sections can then be successively moved from that location to a position of connection into the upper end of the drill string with the flexible line already installed in the added section.

Abstract: An improved downhole system for operating a drill bit around a small radius of bend in the directional drilling of curved holes from a vertical well hole in an oil or gas formation. The system is comprised of a plurality of double shaft downhole motors assembled in line and their shafts are connected by a flexible coupling. A flexible assembly encloses the area between the motors and provides a means for drilling fluids to be pumped through the system to a drill bit. The system can be constructed of either electrical motors or fluid turbine motors which can operate from drilling fluids pumped down a drill pipe string.

Abstract: A drill bit having a carbide tip brazed in the drill bit shank is disclosed for use in forming cylindrical holes in both concrete and steel by rotation about a central axis. The carbide tip has two side surfaces on opposite sides of said central axis. The top surfaces are connected by a substantially V-shaped notch which extends between the side surfaces and has its vertex off-center of the central axis to more effectively cut both concrete and steel.

Abstract: An electronic weighing apparatus, is provided with a load cell which is responsive to the weight of an article being weighed. A preamplifier amplifies the analog output signal from the load cell which is representative of the weight of the article, by a predetermined amplification factor. An analog-to-digital converter converts the amplified weight representing analog output signal into a digital signal representative of the weight. The analog-to-digital converter has an enhanced resolution which may be as high as five times the resolution of a conventional A/D converter. An adder adds a first predetermined digital signal representative of the decimal value "2" to the weight representing digital signal. A divider divides the sum output from the adder by a second predetermined digital signal representative of the decimal value "5".

Abstract: A weighing apparatus for separating elongated products in bulk into quantities of a predetermined desired weight. The apparatus includes a weighing chute for receiving the elongated product, a weigher connected to the chute, and a sensor actuated by the weigher for producing control responses as the weight of product in the chute approaches the desired weight. The weigher further includes a dribbling apparatus responsive to the control responses for dribbling the product into the chute at a rate which is decreased as the desired weight is approached and for stopping when the predetermined weight is achieved.

Abstract: A load platform with multiple stress sensitive magnetic member supports is disclosed in which the frequency of an electrical output signal is proportional to the applied platform load. This device consists of multiple magnetic stress sensitive members in which mechanical stress is induced by the platform load and a magnetic multivibrator constructed so the stress sensitive magnetic characteristics of the stress members are the principal frequency determining elements of the magnetic multivibrator. Also disclosed are various stress member loading configurations, a laminated stress member, and methods for zero-load, linearity, and scale factor adjustments in the variable frequency transducers. Also disclosed is an adjustable frequency-sensitive switch which can be used as a load switch.

Abstract: This weighing scale has a platform, a load cell supporting the platform and a base supporting the load cell. The load cell utilizes electrical strain gage elements, which are connected in an electrical circuit controlling an indicator. The scale is constructed to be unaffected by the eccentricity of the load on the platform. The scale is particularly suited for use in retail or other establishments, where loads are placed on the platform casually and rapidly, so that eccentric loading is common. The load cell comprises an integral block of material divided by four transversely bored holes and two horizontal slots into two relatively rigid vertical members and three relatively flexible horizontal members connecting the vertical members. The platform is supported on one of the vertical members. The base is connected to the other vertical member. The upper and lower horizontal members transfer all bending moments due to eccentric loads from one vertical member to the other.

Abstract: A motorized skateboard having a drive axle with a drive wheel coupled to a prime mover and an idler wheel, wherein the drive wheel is made to support more weight than the idler wheel in order to improve the traction of the skateboard.

Abstract: A snow vehicle suspension system including a pair of suspension struts associated one with each of the two steerable skis of the vehicle; each of the struts including a first generally tubular shaped housing fixably secured to the underside of the vehicle above the associated of the skis, a second generally tubular housing telescopically disposed within the first housing and connected at the lower end thereof to the associated ski, shock absorbing means within the second housing and including a reciprocable piston mounted on one end of a piston rod extending axially outwardly from the upper end of the first housing, the upper end of the piston rod being secured to a portion of the vehicle above the strut and having a helical coil spring extending coaxially thereof between the upper end of the strut and the aforesaid vehicle portion, a steering arm having a first portion operatively connected to the vehicle steering mechanism and a second portion rotatable about the longitudinal axis of the strut, with a secon

Abstract: An electrically operated auxiliary unit for driving a bicycle constructed to be attached to the bicycle frame and, by means of driving engagement created by the weight of the drive motor along a lever arm, propel the bicycle with a drive pulley. The unit includes a motor support frame including a horizontal bar located at one side at the top of the rear wheel of the bicycle and which is attached to the bicycle frame. A horizontal arm, pivotally mounted on the horizontal bar, extends tranversely over the rear wheel. A motor is mounted upon the horizontal arm with the center of gravity of the motor located on the opposite side of the wheel from the location of the horizontal bar. The horizontal arm acts as the lever arm, and driving engagement is created between the drive pulley and the wheel of the cycle by the weight of the motor.

Abstract: An airfoil is mounted on the exhaust pipe of a tractor trailer vehicle generally forward the exhaust pipe opening so as to be upstream of the exhaust pipe in the airflow deflected by a drag reducer mounted on the tractor roof forward the exhaust pipe. The airfoil splits the deflected airflow around the exhaust pipe. The airfoil has a pervious portion located generally below the exhaust pipe opening to allow airflow therethrough to prevent a low pressure buildup in the area generally below the exhaust pipe opening. The airfoil also has an airflow impervious portion located generally above the exhaust pipe opening to create a low pressure behind the impervious portion and generally above the exhaust opening to thereby draw the exhaust flow upwardly into the deflected airflow.

Abstract: An ornamental molding or grill for a motor vehicle body, especially for the front section of the driver's cab of a truck, which grill is provided with a ribbed surface having air passages therethrough and extending at least over the major portion of the width of the vehicle body. The air passages are provided in substantially horizontally extending flanks of the ribs, and the space between the ribs serves as channel for the impacting air.

Abstract: A hood panel support structure for a secontionalized access opening closure panel of an engine compartment in a hood assembly and the like, including a unique fabricated structure which positions the panel sections, with cross beams having means upon which the panels are secured, and side beams incorporating resilient end mounting means, the structure presenting an aesthetically clean and neat appearance.

Abstract: A pair of hand grips are clamped to a steering wheel. The grips are connected by a pair of cables extending through flexible tubes to opposite ends of a pivotable bar mounted on the steering column of the steering wheel. The opposite ends of the pivotable bar are respectively affixed to the accelerator pedal and the brake pedal of a vehicle. Pressure applied by the hands of the operator on the hand grips selectively depresses the accelerator pedal and the brake pedal. Springs mounted in the hand grips and at the distal ends of the tube maintain the cables in open position yieldable to pressure on the hand grips.

Abstract: An anti-nose-dive safety system, for a vehicle having a chassis and a pair of front and axle assemblies, includes a bumper assembly having a frame pivotably mounted on the chassis adjacent to the front end thereof, and a retractable bumper slidably mounted on the frame for movement between a normal, extended position and a retracted position, and a front end suspension assembly including an air piston arrestor pivotably coupled between each of the front end axle assemblies and the bumper assembly frame. Apparatus are coupled to the bumper assembly and chassis for raising the front end of the chassis in response to movement of the bumper from its normal position to its retracted position and apparatus are provided for arresting the air piston arrestors in a relatively rigid non-compressible state also in response to the retraction of the bumper. The safety system is especially suitable for compact cars.

Abstract: The present invention relates to a seismic transducer for generating waves in an elastic medium and is particularly applicable to the generation of low frequency shear waves. The transducer is comprised of a mass member having more than one parallel hydraulic cylinder disposed therein, a piston member disposed in each cylinder, each piston member including a piston and a pair of oppositely extending rods, and a frame interconnecting the ends of the piston rods which frame has a base surface thereon for engaging a surface of the elastic medium in energy coupling relationship. A system of hydraulic fluid bleed-back ports associated with the piston members serve to aid lubrication and keep high pressures off of the rod end seals. The present construction permits total enclosure of the mass member and plural piston member assembly.

Abstract: Compact, lightweight, rotating eccentric weight seismic sources and a seismic exploration method particularly suitable for use in relatively inaccessible onshore regions. The source includes an eccentric weight rotatable about an axis and a sensor to detect the instant of peak earthward force developed by the source. A coded energy signal is transmitted into the earth and the seismic waves returned from within the earth are detected. The polarity of a signal proportional to the seismic waves is periodically sampled to produce a plurality of sign-bit samples. The sign-bit samples are automatically shift-summed in response to a code signal generated by the sensor, thereby forming a plurality of shift-summed samples which are recorded to provide a correlated seismic trace.

Abstract: A driver unit for a horn type loudspeaker is disclosed. The driver unit comprises a dome-shaped diaphragm and an equalizer positioned on the concave side of the diaphragm. The equalizer has a convex surface adjacent the diaphragm and a plurality of slits extending from the convex surface to an interior, outwardly opening throat. The slits are disposed in equal angular pitch with the outermost slits being located at the edge of the convex surface of the equalizer. The outermost slits are approximately one half the width of the remaining slits, the remaining slits being of equal width.

Abstract: An improved concentric pass-type muffler construction. The muffler includes an outer generally cylindrical casing enclosed by a pair of end heads, and an inlet tube, connected to the exhaust pipe of an engine, is mounted axially on one head, while an outlet tube is mounted on the opposite head. Located centrally within the casing is an inner body having a central closure or baffle and the inlet tube communicates with the upstream end of the inner body, while the outlet tube communicates with the downstream end of the body. The upstream end of the inner body is provided with an oval configuration and the major diameter of the upstream end is secured to the inner surface of the cylindrical casing. The downstream end of the inner body is also provided with an oval configuration, with the major diameter being displaced 90.degree. from the major diameter of the upstream end of the body, and is secured to the caasing.

Abstract: This application disclosed a modular stairway system for circular structures or other structures having non-linear walls. The invention comprises a plurality of first stringer means, a plurality of first connecting means for joining the first stringers, a plurality of second stringer means horizontally spaced from and parallel to the first stringer means, and a plurality of adjustable second connecting means for adjustably joining the second stringers such that the first and second stringers conform to the curvature of the structure. A plurality of stairs are horizontally interposed between the first and second stringers, and a stair mounting means for securing the stairs to the first and second stringers are provided.

Abstract: A portable escape ladder comprises a bracket for gripping over a building window ledge, a pair of chains suspended from the bracket and supporting a series of spaced transverse rungs therebetween and optional stand-off devices attached at least to some of the rungs to hold the ladder a fixed distance from the building wall. There is provided a form of connection between the rungs and the chains in which the ends of the rungs are pressed flat and formed with an opening in which the junction of a pair of chain links is captively held. The optional stand-off devices comprise substantially flat frames with upright extensions fitting in bores formed in the respective rungs and fastened in place by snap nuts on the ends of the uprights.

Abstract: A ladder extension device for enabling a ladder to stand upright upon uneven or inclined surfaces is disclosed which is composed of a pair of diametrically opposed side members, preferably L-shaped, connected by hinges and secured about a ladder leg by bolts or other means.

Abstract: A bracket including a clamp for removable clamped engagement with a ladder is provided for support from an upstanding inclined ladder and includes a rigid support arm projecting horizontally outwardly from the clamp and the side of the ladder facing in the direction toward which theladder is inclined. The outer end of the arm includes a mount supported therefrom for angular displacement about an axis extending transversely of the support arm and an elongated clamp arm is supported from the mount for oscillation therewith relative to the arm. The clamp arm is disposed at generally right angles relative to the axis of oscillation of the mount and is swingable with the mount in a plane generally paralleling the support arm. The clamp arm includes one end portion which may be lengthwise advanced and retracted relative to the mount.

Abstract: An annular portion is provided in a friction surface of a disc brake adjacent to the circumference of the friction surface of the disc brake at least on one side thereof. This annular portion of the friction surface of the disc brake is slowly inclined along its circumference. A friction pad adapted to be forced against the friction surface of the brake disc includes a pressure bearing portion which is adapted to be forced against the aforesaid inclined surface of the annular portion, when the friction pad is worn down beyond a wear limit. When this pressure bearing portion is pressed against the annular portion, the inclined surface of a brake disc slides on the pressure bearing portion, so that the pressure bearing portion may cyclically receive reactions from the inclined surface of the annular portion at no sacrifice of a damage thereon, because of the smooth inclined surface of the annular portion of a disc brake.

Abstract: A holder for pulling-up wire in a center pull type caliper brake for a bicycle. The holder has an upper portion with a wire screw and a hook portion at the lower portion for hooking a pulling-up wire. A pair of finger members projecting from the holder member on both sides of the hook portion and a guide member serve to pull up wire from the hook portion.

Abstract: A hand reel is disclosed herein particularly for use in winding electrical extension cords. The hand reel is a spool with flanges, with the cord adapted to be wrapped around the spool between the flanges. The spool has a central bore that is large enough to accommodate the user's hand. A supporting member is slidingly attached to the spool inside the bore, allowing the spool to be rotated while holding the supporting member. The arcuate length of the supporting member is much less than the diameter of the bore, minimizing friction and allowing cleaning.

Abstract: A drive for a wheeled vehicle including a hub adapted to receive the driving wheel of such vehicle. The hub receives and rotatably supports an axle having a worm screw thereon and positioned within such hub. The worm in turn supports an eccentrically weighted driver of drum-like configuration so that rotational force transmitted to the axle in either direction traverses the weighted driver back and forth within the hub in a generally upright position. The driver resists rotation with the axle by reason of its eccentrically weighted configuration. Driving contact is made between the outer face of the driver and the inner face of the hub ends at opposite sides thereof so that rotation of the axle will cause driving force to be imparted to the hub in either direction dependent on which end of the hub the driver is contacting.

Abstract: Disengaging device for a clutch includes support means, an anti-friction bearing having one bearing race predisposed to act upon and co-rotate with disengaging means of the clutch and another bearing race predisposed not to co-rotate with the clutch disengaging means and being actable upon by the support means through a contact surface so as to effect a disengaging movement, and means providing a resistance to displacement in radial direction effective between the support means and the antifriction bearing, the means providing a resistance to displacement comprising at least one bracing or holding member elastic in axial direction, the bracing member being clamped, on one hand, by bracing profile means formed in one of the non-rotating bearing race and the support means so as to be braced directionally neutral in axial direction, the bracing member effectively engaging, on the other hand, the other of the non-rotating bearing race and the support means so as to hold the non-rotating bearing race and the suppo

Abstract: A totalizer for recording the income of a multiprice vending machine, the totalizer including a device to determine the value of the item selected, the fact that a sale was made, and a counter to total the value of all items selected. The totalizer preferably verifies the correctness of the value of the item selected to prevent erroneous counts and also preferably generates a coded output signal representing the price line of the vending machine providing information.

Abstract: The selector assembly includes a support plate and a rail that directs a coin into a coin serration detector assembly. The serration detector assembly includes a body pivotally mounted to the support plate, and a wire feeler attached to the body and providing a wire portion disposed with its side transverse to and engageable with the edge of a coin moving in a predetermined trajectory from the rail. The wire portion side engages the serrations of a serrated coin to rotate the wire feeler into the path of the serrated coin to change the trajectory and direct the serrated coin in one direction, and engages a substantially nonserrated coin to rotate the wire feeler away from the trajectory and permit movement of the nonserrated coin in another direction.

Abstract: An improved circular sorter includes an integral, rotatable, circular ring on which tiltable tray carriages are mounted. The ring is driven by a peripheral drive to convey the tiltable trays past loading stations, where articles are placed thereon, and then to sort locations where articles are selectively discharged by tray tilting, to either the inside or outside of the ring. Both loading and sort locations can be disposed interiorly or exteriorly of the ring. Yieldable rollers support the ring and operatively accommodate variations in vertical disposition, while a combination of fixed and yieldable rollers guide the ring in a horizontal path and accommodate ring pitch inaccuracies.

Abstract: A conveyor system adapted to receive a random flow of discrete items from a plurality of sources at its infeed end and to discharge an evenly distributed flow of items to a multiplicity of stations at an output end. Provision is made for skipping one of the multiplicity of stations if it is not capable of accepting additional items. Provision is also made for avoiding interruptions of the flow of distributed items when the inflow of items from one of the plurality of sources is interrupted.

Abstract: This invention pertains to an arrangement for conveying, handling and storing of solid bodies, bulk material, jelly products or liquids, which arrangement characterized by a plurality of rotary shafts arranged at a distance apart from each other, each of said shafts being equipped with one or more cams, the distance between adjacent shafts being approximately equal to or greater than the length of the cams.