Abstract: A system for dispensing fluid from a container. The container is pressurized by supplying gas into the container thereby forcing the fluid out of the container through a siphon tube and an outlet valve in the container. The system utilizes a valve assembly having two valves, one for enabling the flow of the gas into the container and the second for allowing the flow of the fluid out of the container. The valve assembly is mounted in a neck member that is secured to an opening in one of the walls of the container. Arranged within the neck is a deformable seal that is compressed between a body portion of the valve assembly and an inner surface of the neck member. A non-threaded retaining ring holds the valve body portion of the valve assembly within the neck member and serves to apply the force to the valve body portion for compressing the seal.

Abstract: A filler valve for a gas tank, comprising a valve body to be mounted in the wall of the tank, to the upper end of which body a filler hose can be connected, and in the wall of which valve body outlet ports are provided, two shut-off valves being provided in the valve body, between which shut-off valves a passage is present and furthermore the space between the two valve members is in open communication with the space under the valve members, said latter space comprising a passage opening controlled by a float, and in which furthermore the valves are constructed so as to be slidable one within the other and cooperate with one and the same seat.

Abstract: For purposes of the stop of flow of water and the reduction of excess pressure in potable or sanitary water supply pipe lines, a Combination Stop and Pressure Reducing valve having one bonnet only. This combination valve, of the same size as the conventional stop valve now used in the plumbing industry, replaces the stop valve at its commonly used location and, simultaneously replaces the pressure reducing valve which is generally installed elsewhere in the pipe lines.

Abstract: A valve assembly having a cylindrical valve chamber with radially directed inlet orifices and with a circular spring leaf which resiliently seals the orifices and which may be deflected by fluid pressure within the inlet orifices to open the orifices. The spring leaf is configured so that it may deflect to open the valve inlet without deviation from its essentially oval shape.

Abstract: There is disclosed an improved check valve for operation under light pressure, as in the oral inflation of inflatable articles. The valve has a valve body and a valve element reciprocable therein, the valve element having a body which carries an annular sealing means cooperating with and selectively sealing an axially outwardly converging valve seat having the shape of part of a sphere. The valve body and the valve element are substantially shorter than those of the prior art over which it is an improvement; the means for guiding the forward or outer end of the valve element remote from the valve seat and the sealing means has pronounced clearance with respect to the axial passage through the valve body, thereby permitting appreciable tipping of the valve element relative to the valve body, the sealing means effecting a seal with the valve seat in any position of the valve element in which it may be tipped relative to the valve body.

Abstract: This invention relates to apparatus for continuously discharging liquid from a container, such as a waste water tank having a discharge pipe with an inlet located adjacent the container floor and an outlet located outwardly of the container. The liquid flow is controlled by a control unit which operates as a function of the liquid level in the container. The discharge pipe has a riser section between its inlet and its outlet which extends upwardly to an apex section to define an overflow for the liquid. The riser section is adjustable in height which is controlled by control means that always maintains the overflow at a constant elevation below the liquid level in the container.

Abstract: A multiblade damper assembly having at least three pivotally mounted blades is provided with means to interlink these blades in which a bracket is secured to each of the blades with each bracket being formed with a pair of parallel extension arms which extend beyond an end of the blades, these arms having opposed openings for receiving a cylindrical pivot at their outer ends. A cylindrical pivot is rotatably mounted in these opposed openings, this cylindrical pivot having a threaded axial bore on at least one end thereof and a cross hole extending therethrough. At least one of the brackets has a second axially bored pivot with a cross hole extending therethrough rotatably secured to the pivot between the arms of said bracket and connecting rods interconnecting pairs of blades by having the opposite ends of each rod secured within the cross holes of said pivots, including both of said rotatably interconnected pivots.

Abstract: The present invention relates to a surge absorber that may be easily custom fabricated to a particular flow line application. The surge absorber prevents "water hammer" by providing an enlarged compressible fluid chamber that is separated from the flow line by a diaphragm. When the pressure surge occurs, the greater incompressible fluid volume provided by the intermediate tubular section of the pressure vessel housing provides sufficient baffling while an internal diaphragm protector protects the diaphragm from damage by the incompressible fluid.

Abstract: The present invention relates to a coupling, employing a thermal sleeve, for connecting a secondary conduit to a main conduit.The coupling according to the invention connects a main conduit with a secondary conduit which opens through a lateral opening into the said main conduit and includes a tubular sleeve which is located according to the axis of the secondary conduit, in which the entry mouth of the sleeve is connected in a sealed manner to the said secondary conduit, and its end engages in the said lateral opening thus constituting an orifice, and is so designed that the said sleeve is shaped so that it converges according to the axis of the secondary conduit, in the sense directed from the outside towards the axis of the main conduit.This coupling may be used in the piping system for a nuclear reactor.

Abstract: A module for conducting each of a plurality of fluids from a source thereof to a desired delivery location along a wall comprises a horizontally elongated body having therein a plurality of lengthwise extending bores, one for each fluid, that are spaced apart vertically. On an upright front surface of the body there are a plurality of linear indicia, preferably V-grooves, one for each bore. Each indicium is contained in a horizontal plane that also contains the axis of its bore, so that an outlet from each bore can be formed anywhere along its length by drilling rearwardly into the bore from its indicium. The body has a uniform cross-section along its length to be suitable for extrusion, and it includes an attachment portion and portions that provide a dust seal between it and a wall to which it is attached.

Abstract: In hand looms a plurality of moveable parts of the loom are interconnected by means of the different loom parts.An improved attachment of tying up strings wherein the tying up string consists of a crochetted string shaped as a continuous series of loops, which are used for effecting the interconnection of said loom parts either alone, in pairs, and/or with or without separate fitting members thereby eliminating manual tying work.

Abstract: A draw hook having a bearing end, the outside circumference of which projects beyond the end of the baulk and serves simultaneously as stop against the recoil or repulsion knife and the stop rail. The drawing force for the movement of the heddle frame occurs from the draw hook directly through the bolt onto the baulk. The reaction and the holding force act directly onto the bearing end of the draw hook.

Abstract: A fabric for reinforcing elastomeric or other plastic materials comprising a steel cord warp and a steel weft wherein the warp cords are substantially sinusoidal and have an elongation of about 1-2% at 10% of the breaking load of the fabric and the weft elements are substantially straight.

Abstract: A ribbon loom has a reed drive, a weft-needle drive, an operating needle drive and a shed-forming drive. A main drive shaft carries discs and/or cam discs to which the first-mentioned three drives are directly and articulately coupled. An auxiliary drive shaft extends transverse to the main drive shaft and is connected to the shed-forming drive; it is coupled to the main shaft via a worm transmission the transmission ratio of which can be varied by replacing the worm wheel with a differently dimensioned one.

Abstract: A winding and cutting device for winding a wire on a connection pin of electrical components, and for the purpose of cutting off the excess remaining wire in one work cycle. A stationary sleeve is provided with a rotatable mandrel which has a central bore which is open at least in the direction of its one front face into which the pin is inserted during winding and which has, at least in the winding area, a diameter corresponding at least to the winding diameter. The sleeve and the mandrel have a slanted slot which is open at least in the direction of the one front face and which is aligned relative to the bore.

Abstract: Apparatus for tensioning wire, such as wire loops applied over a braided wire sleeve forming a sheath for an electrical cable splice. The tensioning apparatus comprises an jack rod and jacking mechanism of known construction, a first wire clamp fixed to the based end of the jack rod, and a second wire clamp assembly slidably mounted on the jack rod opposite the jacking mechanism from the first wire clamp whereby the jacking mechanism may be operated to spread the lapped ends of a wire loop to tighten the loop.

Abstract: A container filling device that raises a case of empty containers to be filled to engagement with a centering block and fill tube assembly. Each centering block surrounds a fill tube extending into the container and forms a seal around the neck of the container to be filled while providing communication between the interior of the container and a vacuum system. Fluid operated reciprocating piston pumps, through a system of check valves, draw measured amounts of liquid product from a bulk storage container and thereafter inject the measured amounts through the fill tubes into the containers while air is simultaneously exhausted from the containers by vacuum.

Abstract: The kit of the present invention is for use in the refilling within a survival unit of a gaseous supply tank through a filler valve having a threaded stem adjacent the free end thereof and a gripping surface on the filler valve. The gas is generally oxygen although other gas may be supplied. The kit includes an adapter to provide coupling relationship with the threaded stem of the filler valve so as to permit a flow of oxygen into the supply tank such that refilling thereof may take place without removal of the supply tank from the survival kit. The adapter includes an elongated member with an aperture extending therethrough and is adapted to mate with the filler valve in sealing engagement therewith so as to permit gas flowing through the aperture to enter the filler valve. The adapter further includes a holder with a bore extending axially therethrough and the elongated member extends axially through the aperture.

Abstract: A woodworking fixture for positioning and guiding a workpiece under a stationary routing head, whereby the workpiece is subject to a composite movement as it progresses under the routing head. The fixture comprises an indexing table having a clamp for securing the workpiece thereon, mounted on a moveable carriage. The indexing table can be slanted at an adjustable angle and may be rotated as the carriage progresses under the routing head in order to create designs of varying depth into the workpiece.

Abstract: The specification describes a cutting tool comprising a cylindrical support having a series of cavities arranged in helicoidal rows on its outer surface; in each cavity, a tool-carrier and a chip-breaker are secured by means of a set-screw; means are provided for adjusting the height of the tool-carrier and the chip-breaker, for the purpose of adjusting the position of the blades of these elements within the cavity.

Abstract: A rotating arbor in a sawing machine such as a table saw or radial saw or in a milling machine is provided with a pair of pressing members that are mounted on the arbor so as to be rotated in unison therewith, and a bearing sleeve which is provided on the arbor between the pressing members so as to be rotatable in unison therewith. A rotary blade for forming a groove is clamped from both sides thereof by a pair of clamping members which are mounted on the bearing sleeve in a tilted orientation for holding the rotary blade at an inclined angle with respect to the arbor, the clamping members being pressed between, and hence secured by the pair of pressing members. Turning both clamping members relative to the pressing members allows the clamping members to be tilted together with the rotary blade with respect to the central axis of the arbor.

Abstract: A saw handle adapted to have a blade engaged therewith and further including a gripping area to allow a user to firmly hold the saw handle, the saw further including a flexible guard member which is movably secured to the saw handle adjacent to the blade such that the flexible guard is movable to extend along the toothed edge of the saw blade to be attachable thereto for protection of the teeth of the saw blade as well as for protection of the surrounding environment from the teeth of the saw blade, the flexible guard being secured to the handle by way of a resilient retaining member such as a spirally wound recoil spring which will wind the flexible guard means automatically in a circular fashion within the handle whenever the guard itself is not being pulled outwardly for placement adjacent the toothed edge of the blade, the handle defining a recess into which the flexible guard and the resilient retaining member are located, the flexible guard possibly further including a hook eye adapted to slide into a s

Abstract: An openable seal member for a container includes a tube extending across the sealed area of the container for flow communication between the interior and exterior thereof. A flexible plastic pocket member seals and encloses the outer end of the tube. Tear means are provided for opening the pocket member, comprising a circumferential line of tearing weakness positioned about the pocket member in transverse relation to the longitudinal axis of the tube. In accordance with this invention, a flexible generally conical portion is positioned between the outer end of the tube and the tear means, with the conical portion diverging outwardly and constituting an inner portion of the pocket member, to define upon opening of the seal member, an enlarged, protective area surrounding the outer end of the bore of the tube.

Abstract: A pneumatic tire and rim combination wherein the tire is captivated about the rim and a chamber is defined between the tire and the rim and a portion of the tire extends into the chamber within the carcass of the tire and serves as an annular support structure upon deflation of air within the tire, so that if it collapses, as by a blowout, a vehicle on which it is installed will continue to be supported by the tire as the interiorly extending annular portion of the tire engages the confronting surface of the rim.

Abstract: A large-sized pneumatic radial tire is disclosed. The tire comprises a tread including grooves, a belt composed of a plurality of rubberized layers each containing steel cords, and a carcass of a substantially radial construction. The tread includes two half regions divided with respect to a crown center, one a region in a direction of plysteer due to the tire construction and the ground contact reaction force acting on steel cords of at least one rubberized layer disposed near the tread, and the other being a region opposite to the direction of plysteer. A row of small holes are formed in an island part along its edge near the kicking-out side of the groove in the region opposite to the direction of plysteer.

Abstract: An annular hollow tire with an inner surface having a generally positive radius of curvature and at least one circumferentially extending rib portion on the inner surface with a negative radius of curvature located at an area of the tire subject to high stresses to mitigate the stress concentrations in that area of the tire. The method of making the tire includes the steps of providing a tire mold with a core having a selected circumferentially extending portion on the outer surface with a negative radius of curvature for forming the rib portion, filling the space between the core and mold surface with an elastomeric precursor, heating to set the precursor and form the tire and removing the tire from the mold and the core from the tire.

Abstract: A shade roller latch comprises a latch member in a bore in a stationary stem. This latch member can fall by gravity into a notch in the inside circumferential surface of a shell rotatable with the shade roller to be received in part by this notch and lock the roller against rotation in relation to the stem.

Abstract: A servo control mechanism for controlling the reciprocal movement of a piston member along the length of a curtain rod. The curtain rod is composed of a fluid pressure-tight tubular member made of a nonmagnetic material and having pressurized fluid supply ports therein adapted to supply pressure to opposite sides of the reciprocal piston member. A plurality of ring members, certain ones of which are made of magnetizable material, surround the curtain rod and are capable of movement along the length of the rod. A plurality of permanent magnets are reciprocally mounted inside the curtain rod and are magnetically coupled to certain ones of the curtain rings which are made of a magnetizable material. An elongated strand extends between the piston member and at least one of the permanent magnet members inside of the curtain rod so that a driven movement of the piston member will cause a forced movement of the permanent magnet therewith.

Abstract: Lightweight filament reinforced composite metal matrix structures is provided. The preferred process for producing tubing comprises wrapping alternate layers of metal and filament material to be molded around a mandrel. The mandrel is removed and in its place a test tube-shaped hollow glass cylinder is inserted. The wrapped cylinder is next placed in a cylindrical shaped mold and the entire assembly placed in an oven which is capable of heating the unit to the liquidus temperature of the metal matrix. The glass, which is of a type which softens at about the melting point of the matrix material, is pressurized to a medium high pressure. Under the influence of this pressure, the glass expands, forcing the composite metal matrix against the interior surface of the mold. The consolidated tubing is then cooled to a completely solidified state and removed from the mold.

Abstract: Apparatus for continuous casting has pairs of rolls defining a path for the solidifying slab of steel. Between the rolls on each side are rows of spray nozzles. To check the operation of the sprays and thus achieve uniform cooling, checking apparatus carrying detectors for the sprayed water is passed through the path. To achieve a useful measure of the spraying efficiency the detectors must be highly sensitive and robust. Each detector has a metal diaphragm which is set in vibration by the sprayed water and a piezo-electric element fixed to the diaphragm so as to emit a signal whose amplitude is dependent on the amplitude of the vibration of the diaphragm.

Abstract: An electroslag remelting and surfacing apparatus having a cooled mould comprising a plurality of superimposed sleeves which are electrically insulated from one another. The top sleeve of the mould, being substantially a non-consumable electrode, has a current lead and a lining of electrically conducting material. If provided with a radial electrically insulating layer, it may also serve as a single-coil inductor adapted to impart a rotary motion to the slag pool.

Abstract: A method of pre-heating feed water for boilers is disclosed which utilizes the exchange of heat between the tube side of a heat-exchanger which contains de-salinated and de-ionized water and the shell side which contains hydrocarbon vapors boiling in the range of 90.degree. to 150.degree. C. The tubes are made of carbon steel with their outer surfaces aluminized.

Abstract: A slide guide 22 for a tube-type heat exchanger has a tubular geometry and comprises saddle 28 and slots 26 interposed one each between fingers 24. Saddle 28 positions slide guide 22 within tube support sheet port 30 while fingers 24 are biased so as to conform to the ovality of tube 12 and dissipate dynamic loads across a relatively large tube surface area.

Abstract: A heat exchanger wherein an upright insulated outer jacket contains a body of relatively cold liquid and spacedly surrounds an upright hollow cylindrical heat conducting body which, in turn, spacedly surrounds a helical heating body confining a flowing heating medium. The upper and lower ends of the heat conducting body are open so that cold liquid can enter the heat conducting body from below to exchange heat with the medium in the helical heating body, to thereby rise in the heat conducting body, and to issue at the upper end of the heat conducting body. The upper end of the heat conducting body has a flow restrictor which defines an outlet opening for the heated liquid. An electric heater can be installed in the outer jacket to heat the liquid when the supply of warmer medium is insufficient.

Abstract: In an air heater, an initial group of passes on the airside is arranged in the form of a package wherein the passes consisting of banks of tubes are connected in parallel with the uptake gases.The passes of the package are located predominantly at the same horizontal level, are made of tubes of the same length and run in a zone of the same gas temperatures which is dangerous insofar as corrosion can be provoked therein.The width of the packaged passes progressively increases directly with the increase in the rates of air flow through the passes, and a feeding air duct admitting the last inflow of cold air is connected downstream of the last and widest pass to the connecting air duct serving the rest of the passes of the air heater.In an apparatus like this one, assembled from standard components, minimum overall dimensions and low weight are combined with high thermal efficiency.

Abstract: This invention relates to a hot water system which utilizes heat from the refrigerant of a refrigeration system to produce hot water. The utilized heat consists of the superheat of the refrigerant vapor, the latent heat of condensation, and part of the sensible heat of the liquid refrigerant. The water passing through a water-cooled condenser, which is part of the refrigeration system, is heated to a selected temperature by removal of both the superheat of refrigerant vapor, the latent heat of condensation, and part of the sensible heat of the liquid refrigerant as it passes through the condenser. The condenser has a water inlet and an outlet between which is connected to a hot water storage tank. As the water in the condenser is heated by absorption of the superheat of the refrigerant vapor, the latent heat of condensation, and part of the sensible heat of the liquid refrigerant passing therethrough, the heated water rises and flows by convection into the storage tank.

Abstract: A fin strip of the kind used as secondary heat transfer surface in heat exchangers. Convolutions in the strip are formed to increase the developed length of a fin strip and thereby to increase the surface area which can be accommodated in a given space, particularly an annular space, without obstruction to flow. In a strip corrugated to provide alternating peaks and valleys, peaks are depressed to form spaced apart peak portions interconnected by intermediately positioning valley portions which add to the developed length of the strip without reducing the space between strip valleys. In an annular space occupied by a fin strip made in accordance with the invention fin density is substantially uniform throughout.

Abstract: Intermediate exchanger comprising a vertically axed cylindrical internal ferrule, an external ferrule coaxial to the internal ferrule, two plates with annular horizontal tubes located in the vicinity of the upper and lower ends of said ferrules, a bundle of straight tubes extending between the tubed plates in the form of cylindrical layers coaxial to the ferrules, said layers being mutually reinforced by transverse belts formed by horizontal bands carrying hollow members located between the tubes of the layers and in contact with the latter, collectors for the admission and discharge of the secondary fluid circulating within the said tubes being respectively provided beneath the lower plate and above the upper plate, the inner ferrule forming a pipe for the supply of the secondary fluid to the admission collector, while the outer ferrule is upwardly extended by a pipe for the discharge of the same secondary fluid collected in the discharge collector after passing through the tubes, and inlet and outlet ports

Abstract: A passage is provided in a heat exchanger water compartment to permit extension of a tube therethrough and at the same time assist in sealing the tube and passage interface. The distance between the intersection of the lower bottom edge of the water compartment bottom part with the inner edge of the passage and the intersection of the horizontal extension of the upper edge of the bottom part in the direction of the passage extension has a positive value.

Abstract: A spirally fluted metallic heat transfer tube is disclosed wherein the finished tube has improved heat transfer performance through the provision of a predetermined number range of multiple start continuous helical flutes formed along its longitudinal length, the flutes having specific helix angle relation and flute height to tube hydraulic diameter ratio so as to establish a ratio of thermal diffusivity to momentum diffusivity greater than 1.

Abstract: A pumping apparatus that may be used with a well in which a sucker rod is connected with the well so as to remain in axial alignment with the same during shifting of the well and the sucker rod is supported clear of the well and the structure for operating the same.

Abstract: A deflection wedge is positioned in a long horizontal drill hole by securing it with a shear pin to an extension on a drill string. The extension is turned independently of the drill string to enable a droparm mechanism to actuate a trigger which stops rotation at a predetermined orientation. Rotation is effected by means of a rifle bar mechanism. The rifle bar presses against the bottom of the hole to cause rotation and the trigger declutches the rifle nut when the droparm drops.

Abstract: Disclosed are systems for removing hydrocarbons from subterranean deposits thereof. A fluid-impervious barrier screen is formed to isolate parts of the deposit or to isolate the deposit from adjacent fluid-permeable earth formations. The barrier screens are formed by fracturing a vertical zone in the formation by micropercussive fracturing or detonation of microexplosive charges in a series of closely-spaced bore-holes to form a vertically extending fractured plane. The fractured plane is sealed with a sealing medium to form a fluid-impervious screen.Hydrocarbons trapped in the enclosed deposit zone are flushed from the formation by recirculating a fluid medium such as superheated brine and/or hot gases through the enclosed deposit zone under sufficient pressure to cause turbulent flow through the pore formations and to relieve the overburden pressure. The flushing medium may be injected in a series of pressure pulses to force the fluid through the pores by hydraulic ramming.

Abstract: Methane is recovered from an underground coal seam via a borehole which extends from the earth's surface through the overburden to a cavity that is in, partly in or proximate to the coal seam. The cavity is constructed and arranged to be collapsible. Coal from the coal seam moves toward the coal seam under the influence of triaxial compression converting adsorbed methane to free form methane that is recovered.

Abstract: A hanger and stinger assembly includes an expandable joint therebetween for the stinger to be telescoped with the hanger between extended and collapsed positions. An actuating spool for use in conjunction with a wireline tool mechanism is provided for hydraulically actuating the slips on the hanger and a releasable catch is connected between the stinger and a tubular receptacle mounted on the hanger to normally limit upward movement of the stinger to its extended position. A latch at the upper end of the stinger is utilized to hold the catch in a release position enabling the stinger to be withdrawn from the receptacle by a straight pull and a locking mechanism normally positions the latch to keep from holding the catch in its release position and the locking mechanism is hydraulically actuated.

Abstract: An improved offshore platform, the platform including three decks in the wellbay area; a first lower deck adapted to provide a workspace for the positioning of equipment to be lowered to the ocean floor, a second middle deck, said middle deck being the main production deck from which production conduits from said wellbores are supported and from which production operations are conducted after completion of said wellbores and a third upper deck said third deck being adapted to support drilling, completion and workover equipment and to provide a protective barrier between said equipment and said second deck.

Abstract: An apparatus for lifting a blow-out preventer during oil or gas drilling operations includes a base frame which can be manually positioned atop the rotary table of the drilling platform of the drilling rig used to drill the well. The apparatus further includes a pair of winches which can be lowered to preselected positions on the base frame, after positioning the base frame on the rotary table, and secured to the base frame via pins that extend through clevises that are welded to the base frame and through apertured lugs that are welded to the winches and extend into the clevises. The blow-out preventer is lifted by the winches via cables that are wrapped on reels of the winches and passed through the base frame and rotary table to the blow-out preventer to which the cables are attached.

Abstract: A method for drilling wellbores from an offshore platform to penetrate a subterranean formation using a combination of surface drilling techniques and subsea drilling techniques to achieve an improved effectiveness by avoiding the necessity for large conduits communicating the ocean floor and the offshore platform.

Abstract: A fire protection system including a discharge valve for discharging a pressurized extinguishing agent from a storage container into a distribution manifold. Discharge of the agent is induced by a pneumatic release mechanism that responds to the application of fluid pressure. Mounted in predetermined protection zones are a plurality of discharge nozzle arrays, each connected to the outlet of a distribution valve, the inlet of which is connected to the distribution manifold. Each distribution valve comprises a valve closure movable between a closed position that seals the valve inlet from the valve outlet and an open position that permits fluid flow therebetween, a pneumatic actuator for moving the valve closure to the open position in response to the presence of fluid pressure and a fluid pressure transfer mechanism that transmits fluid pressure from the actuator to the discharge valve release mechanism in response to movement of the valve closure to its open position.

Abstract: A power hoe for working soil. The power hoe includes a drive shaft contained inside a housing and driven by an electric hand drill. A drive pin mounted to a drive plate at the end of the drive shaft is inserted into a piston housed in a sleeve. The piston is allowed to slide back and forth within the sleeve thus allowing the rotational motion of the drive pin to be translated to harmonic reciprocating motion at the sleeve in a direction perpendicular to the path of the moving piston. The sleeve is attached to a cutting head, thus causing the cutting head also to reciprocate. The cutting head can be adjusted so as to change the length of the stroke; the speed of the stroke varies with the speed of the hand drill. A curved cutting edge on the blade of the cutting head compensates for the arc of the blade as it reciprocates, allowing for more efficient working of the soil.