Abstract: A baking oven comprises at least one hearth with a baking chamber, a heater, a vaporization device for the supply of vapor and/or fresh air, a devaporization device for the discharge of vapor and/or used air and an overpressure reduction device for overpressure in the baking chamber to be reduced. The devaporization device and the overpressure reduction device are connected to the hearth via a joint discharge duct.

Abstract: An extension assembly for use with a damper assembly and for extending the damper assembly control shaft. The extension assembly is provided for coupling of a handle to the control shaft and includes an extension member, a locking member and a securing member. The extension member includes a connecting portion having a closed end and an open end. The open end includes a bore dimensioned to operatively receive the control shaft. The extension member further includes a shaft portion extending longitudinally from the closed end of the connecting portion. The shaft portion includes two parallel flat sides merging transversely with two opposite arcuate sides and dimensioned to be received by an aperture in the handle. The locking member provides the function of locking the control shaft within bore. The securing member ensures that the handle will remain a fixed distance from duct and provides a lock tight surface for a nut to engage and hold the handle.

Abstract: A natural draft furnace has a firebox inside a water box with fire tubes containing water running through the firebox, flues from the firebox running through the water box, a front/fire door of double wall construction to preheat entering air, a damper in the fire door and a toggle-lock latching system on the fire door that provides uniform sealing pressure around the door.

Abstract: This invention provides a water heater including a water storage tank, a flue, a jacket around the tank and the flue and having a top end, a top cover which extends over the tank and the flue and which closes the jacket top end, and a flue collector within the top cover and having an exhaust opening within the top cover and in communication with the flue. The water heater further includes a flue damper mechanism comprising a damper disk pivotally mounted within the flue collector exhaust opening so that the disk can pivot between a closed position closing the exhaust opening and an open position opening the exhaust opening, and drive means for pivoting the damper disk. The drive means comprises a damper actuator exterior of the top cover, a mounting tube secured to the flue collector and secured to the damper actuator, and a damper shaft within the mounting tube and extending between the damper actuator and the damper disk.

Abstract: An integral vent damper/hood apparatus for regulating draft in a flue of a hot water heater includes a damper support having a hemispherical dome, a congruent cylindrical portion with a plurality of openings therein for passage of flue gas therethrough, and a bottom support. A coaxial faceted guide is disposed between the hemispherical dome and the bottom support with a flue gas floatable damper disposed between the hemispherical dome and the bottom support and moveable along the coaxial faceted guide in response to flue gas exiting the hot water heater flue. The damper includes a coaxial circular aperture therein for enabling the movement of the damper along the faceted guide with contact occurring only at intersections of the guide facets. A hood is provided for conducting flue gas passing through said damper support into an exhaust flue along with a fixture for coaxially attaching the hood and damper support to the hot water heater flue.

Abstract: A gas-fired, simulated log fireplace insert incorporating an automatic flue damper for controlling the operational state of a chimney vent (open/closed) in response to gas combustion, an externally mounted carbon monoxide detector for terminating or inhibiting gas combustion in response to an unsafe level of detected carbon monoxide and a temperature actuated switch, disposed within the firebox area of the fireplace proximate the flue, for terminating gas combustion in response to excessive fireplace temperatures caused by a malfunctioning damper.

Abstract: An explosion dampener fits with a pressure relief opening in a gas fireplace. The explosion dampener comprises a fireplace mounting bracket, a lever arm pivotally secured to the mounting bracket and an opening sealing member which is secured by a floating connection to the lever arm. The floating connection between the sealing member and the lever arm promotes a sealing fit of the sealing member over the pressure relief opening in the gas fireplace.

Abstract: A device for use in improving the heating efficiency of a water heater comprises a housing mounted over the heat collecting pieces of the water heater and provided with at least a set of ventilating ports, each of which is composed of a predetermined number of ventilation holes arranged in a geometric pattern. Pivoted to each of the ventilation holes is a damper, which can be triggered by a heat sensing element to turn so as to open or close automatically the ventiation holes. The heat sensing element is caused by heat to deform in order to bring about a displacement of the damper. The extent of the opening of the ventilation holes depends on the extent of the displacement of the damper.

Abstract: A flow control has a rotary gate residing within an internal flow space in a conduit. The gate is mounted for movement relative to the conduit between first and second positions, the gate in the first and second positions accounting for a different flow rate between first and second fluid masses between which the gate resides. The gate has an actuator with a plurality of spaced shoulders. A flexible force-applying member is connected to the actuator and bears upon the shoulders to thereby urge the gate towards the other of the first and second positions. The shoulders are situated so that the number of shoulders engaged by the force-applying member at any one time is not the same as the gate moves from the one of the first and second positions towards the other of the first and second positions.

Abstract: Flue gas is captured from an emissions stack and recirculated to a burner by an induced flue gas recirculation system comprising: a mixing assembly for mixing combustion air and recirculated flue gas into a substantially homogeneous mix; a burner assembly for mixing and combusting the combustible mix with a fuel to produce a flue gas; an injection assembly, connected to and downstream from the mixing assembly and connected to and upstream from the burner assembly, for receiving the combustible mix from the mixing assembly and injecting it with the combustible fuel into the burner assembly; a combustion chamber connected to and downstream of the burner assembly for containing the combustible mix and flue gas; an emissions stack connected to and downstream from the combustion chamber for venting the flue gas from the combustion chamber; recirculating means for recirculating a portion of the flue gas from the emissions stack to the mixing assembly; and a purge assembly connected to the recirculating means for re

Abstract: An indicator for a fireplace damper door includes a spiral wire and a contact arm that may engage the wire. The arrangement is such that upon a multiple number of rotations of the contact arm, continual contact is maintained. The arm and wire are is an electrical series circuit with an indicator lamp, which will be illuminated when the damper is opened.

Abstract: Damper position of a damper in a heating system is monitored. The damper is movable between end positions in response to movement of a motor shaft. The motor shaft moves in response to a movement request signal. A shaft position signal is received by a position detector and has a value representative of position of the motor shaft. When the damper reaches an end position, it is determined whether the value of the shaft position signal is within a predetermined tolerance. If it is outside of the tolerance, then the system is shut down as unreliable; otherwise, the shaft position signal is recalibrated to maintain accuracy.

Abstract: In a bimetal-actuated damper a loop-shaped bimetal element engages a damper element. One end of the loop is fixedly fastened while the other end of the loop is movably connected with the damper element. This improves temperature-dependent response and sensitivity of the damper and prevents damage from overheating or permanent change of operating characteristics.

Abstract: There are disclosed means and method for improving the efficiency of combustion in an automatic gas-fired furnace through retardation, without restriction of the exhaust emission of the products of combustion, which are caused to dwell longer in the combustion chamber to elevate the temperature, not only through the impoundment of what would otherwise be waste heat, but by the conversion of CO gas and excess air to CO.sub.2 gas, thus, reducing the two former, increasing the latter, along with temperature. This reduces the condensate in the exhaust chimney. An enlarged chamber in the exhaust gas conduit is incorporated within the line of exhaust flow from furnace to chimney. A baffle plate, approximately equal in area to the cross-sectional area of the conduit, is immovably secured in the chamber normal to the line of exhaust flow. The chamber is completely closed except for the exhaust flow entry and exit ports.

Abstract: A barometric damper includes a swingably mounted damper blade having a first adjustable counterweight assembly lying in a common plane with the damper blade and mounted for rotation therewith. The torque arm mass loading can be varied. A second adjustable counterweight assembly coupled to the damper shaft adjusts the static control point of the damper.

Abstract: An air vent for supplying air for combustion to a fireplace or the like inside a building, the vent comprising a duct having an inlet end outside the building and an outlet end inside the building, a cover hingedly mounted over the outlet and pivoting between an open position and a closed position covering the outlet, the cover being sufficiently light that a pressure differential caused by combustion inside the building maintains the cover open. A tab, having a portion of hook-and-loop type fastening material, depends from the cover and a patch of mating hook-and-loop type fastening material is positioned adjacent the outlet end to engage the tab. The cover is sufficiently heavy that when the pressure differential drops the cover falls with sufficient force to engage the tab and patch, locking the cover closed.

Abstract: A housing supporting a signal-controlled, power operating unit for a damper is mounted internally within a duct by a tubular supporting sleeve in an angularly and axially adjusted position projecting from an open end of the duct. A shield fixed to the external end of the sleeve backs an annular sealing flange engaged by the damper element, which is enclosed by a flow deflecting hood slidably assembled on the shield.

Abstract: A heating appliance such as a hot-air circulating microwave oven using a shape memory alloy as the damper spring for driving the damper unit. The damper lid a capable of switching the direction of air to be supplied into the heating chamber and the damper spring, made of shape memory alloy drives the damper lid in the air path inside a duct, delivering air cooled by a cooling fan to both the heating chamber and a magnetron.

Abstract: The invention provides a fuel saving device comprising a flue damper of simple mechanical construction mounted on a support member. A hinge connects the flue damper to the support member allowing the closure of the flue damper which is counter balanced when the furnace is shut down. When the furnace is on the gas flow opens the damper.

Abstract: This invention provides an adjustable damper having a tubular duct section defining first and second diametrically opposed openings and first and second sets of detents formed radially from the material of the duct about the respective openings to define a plurality of damper settings. The first detent set is offset angularly relative to the second detent set and a valve element is provided having a circular central portion proportioned to fit within the duct section. Diametrically opposed first and second shoulders project from the periphery of the disc and aligned first and second stub axles are formed from the material of the disc and depend from the respective first and second shoulders. These shoulders are engaged with the respective first and second sets of detents such that in any one selected angular position of the valve element, the element is located by engagement of one of the shoulders in one of the detents of the detent sets.

Abstract: There is disclosed an extension apparatus for a damper assembly having an extension member for effectively extending the damper assembly control shaft and a securing member for securing the extension member onto the control shaft.

Abstract: Disclosed herein is a preferred process for making a catalyst. A catalyst such as is named in the title of this invention. The process begins with the chosing and blending the different refractories in order to necessitate the longevity of the damper. The mixing of the materials, with water, to the right consistency is very important in this process. To much moisture in the material will not provide the necessary porosity the catalyst needs. After mixing, the dampened material is placed into a two piece break away mold and pressed into the desired shape, size and density. The proper amount of curing time and the damp cool area in which the curing is to take place also adds to the longevity of the damper. The object of this invention is to provide an inexpensive process that doesn't require heat, for manufacturing a catalyst that will not become contaminated or less active with use, but by it's causing a more complete combustion, will create a higher BTU output and a decrease in fuel consumption.

Abstract: A filter assembly for an exhaust stack having a housing defining an interior chamber and an inlet and an outlet which are connected in series with the exhaust stack. A mounting frame is secured diagonally within the interior of the housing so that the mounting frame is interposed between the inlet and outlet of the housing. A plurality of filter elements are detachably secured to the mounting frame so that influent into the housing inlet passes through the filter elements prior to exhaust out through the housing outlet and to the atmosphere. The filter assembly is easily retrofitted to existing systems.

Abstract: A fireplace comprising a base adapted to support a fire grate, side walls extending from the base, a passage for the flow of combustion gases from the fire grate and a damper in the passage for controlling the flow of the combustion gases. The damper carries a shaft and is displacable about the axis of the shaft. The shaft is axially displacable to permit ready mounting of the damper in and demounting thereof from the fireplace.

Abstract: A combustor unit for a woodburning stove comprises a generally T-shaped flue assembly interiorly receiving a combustor having a catalyst to facilitate combustion of exhaust gases. The combustor is pivotal between a combustion position wherein the combustor is positioned across an exhaust passageway to an open position wherein the combustor is substantially removed from the exhaust gas stream and positioned within an access passageway.

Abstract: A chemical recovery furnace (10) having air nozzles (12) is provided with apparatus (22) for keeping the nozzles clear of combustion product deposits, and also accurately controlling the airflow through such nozzles. Each nozzle has slots (20) in the sidewalls thereof, which slots are of decreasing width, the smallest width (38) being closest to the furnace. A plug (22) is slidable within each nozzle to control airflow, and also remove deposits from within the nozzle.

Abstract: A normally energized motor maintains a counterbalanced damper closed to block air inflow in a non-combustion condition of an appliance. Deenergization of the motor by thermostat control releases a rotor for displacement through a limited angular stroke. Through a lost-motion linkage connection the damper is displaced, in lagging relation to the rotor to the open position. The open position of the damper is detected by a sensor to open a fuel valve in the appliance.

Abstract: Method and apparatus for the regulation of the flow of fuel gas in the fuel gas supply duct of a heating wall of a coke oven to assure uniform heat distribution in the oven are provided. The regulating means consists of a thin plate having a similar shape to that of a fuel gas supply duct for insertion therein. Pivotally attached to and extending perpendicularly from the outer face of the plate are twin parallel control rods with gage marks inscribed thereon. To effect the regulation of fuel gas flow, the regulating means is inserted into the fuel gas supply duct at an appropriate location and the flow rate is adjusted by pivoting the plate by the manipulation of the adjusting rods.

Abstract: A mechanical thermostat for modulating the temperature of a solid fuel-burning stove, including a casing, a thermostat coil mounted in the casing to sense the stove wall plate temperature; a downwardly-spaced air admission mechanism. The air admission mechanism includes a pair of identical openable and closable orifices by way of a variable closure mechanism. A linkage connects the latter with the coil. The relation between temperature fluctuation and the effective open area of the orifices is expressed by a mathematical equation allowing for very constant desired stove temperature during burning time. A firing control for the stove is further provided.

Abstract: Apparatus for cooperation with an associated flue having a first axis extending away from a point proximate to an associated combustion chamber which includes a funnel shaped member having first and second ends. The second end is larger than the first end. A damper is disposed in the associated flue which has a generally central bore. The damper is mounted in the associated flue for rotation about a second axis which is generally perpendicular to the first axis and the funnel shaped member is mounted with the first end higher than the second end and with the second end extending into the damper. The mounting for the damper may comprise at least one rod shaped member extending through at least one wall of the associated flue. The mounting for the funnel shaped member may comprise a plurality of elongated members extending radially from the funnel shaped member to the associated flue.

Abstract: A fireplace screen arrangement is disclosed which includes a frame upon which a pair of mesh screen doors are pivotally mounted for movement between closed and open positions with respect to the fireplace. A damper assembly is provided for regulating the amount of air which is admitted to the fireplace through the screen arrangement. In order to provide convenient opening of the screen doors, a door-opening mechanism is provided which includes a door-engaging lever fulcrummed for pivoting movement with respect to the frame. An operating knob is operatively connected with the door-engaging lever so that inward movement of the knob moves the screen doors from their closed position. In the preferred embodiment, the operating knob is operatively connected with a movable damper plate for moving the damper plate laterally to regulate air admitted through the damper assembly.

Abstract: A damper for sealing and unsealing a vertical furnace exhaust flue pipe to minimize the escape of heat when the furnace is not operating is disclosed. The damper comprises a cylindrical body adapted to form a section of vertical flue pipe having inner and outer walls. The cylindrical body has a top opening and a bottom opening and at least one transverse hinge rod horizontally transversing the body carried by opposed apertures in opposing wall portions of the body, an annular rim mounted on the inner wall of the body and a pair of oppositely extending gull-wing shaped damper shutters pivotably mounted on said hinge rod. Each of the gull-wing shaped damper shutters have upper and lower surfaces, a lower section and an outer upper section, and in the closed condition the lower sections of the shutters extend upwardly and outwardly at approximately a 45.degree. angle with the outer upper sections of the shutters extending horizontally and slightly spaced from the inner walls of the damper section.

Abstract: There is disclosed an improved flue box assembly for use in conjunction with a heating plant, the flue box having a housing with an interior diametric opening substantially greater than the exhaust gas inlet to and outlet from the interior of the housing, and provided with a damper plate being pivotally mounted within the housing and movable between an open position and a closed position, the damper plate further having a flue opening positioned therein, the improvement consisting of a cap pivotally mounted on the housing adjacent the outlet opening thereof, the cap adapted to pivotally move between a closed position occluding the outlet opening of the housing and an open position leaving the outlet opening unobstructed, and adjustable counterbalancing means associated with the cap for adjusting the relative pressure necessary to move the cap into an open and closed position respectively in relation to the force exerted by flue gases escaping through the outlet opening of the housing, thus providing for impro

Abstract: A flexible disk damper which is capable of providing tight seals for a large diameter opening over a wide range of temperatures. Disks are made sufficiently flexible to compensate for inherent warpage in the damper seat by using a steel with a higher yield strength. Additionally, a varying cross-sectional thickness of the flexible disk is provided to ensure that unit stress is not exceeded along any point of the radius of the flexible disk for the deformation required to provide a tight seal. A pneumatic cylinder is utilized to provide a constant pressure to the flexible disks. A damper seat is fabricated from a cut plate or flat bar which is formed in an annulus. A deflection cone is utilized to deflect flue gases. The flexible disk is coupled together by bolts which are disposed in holes sufficiently large to allow independent movement of the disks to maximize deflection.

Abstract: A safety stovepipe damper assembly designed for use with a conventional type stovepipe and damper as used on coal, wood, or waste burning stoves. Provisions are made for presetting the damper to a specific low fire or closed position. A latch is also provided to hold the damper at an open position when desired. A heat activated means of releasing the damper from an open damper position is contained within the safety assembly. When activated by abnormally high stovepipe temperatures, the damper returns by gravity to its preset or closed position. The safety assembly can be used on vertically or horizontally installed stovepipe and damper assemblies in all sizes.

Abstract: An oil burner shutter to block off an oil burner from a wood/coal boiler when not in use having a movable shutter with an aperture therein and means to move said shutter to an open or closed position including means to operate said shutter automatically in conjunction with said oil burner and the boiler's aquastat and damper.

Abstract: An add-on catalytic damper assembly is provided which is adapted to be positioned between the flue outlet pipe of a wood burning stove and the chimney pipe, and which provides catalytic combustion of the normally unburned portions of the flue gas. The assembly is of a very simple five part construction comprising upper and lower housing members adapted to be connected to the chimney and stove pipes, respectively; a plate nestingly mounted within the lower housing member and including a pair of side by side openings therein providing two paths for the flue gas; a catalytic converter mounted in one of the openings; and a damper plate mounted over the other opening and movable by means of an integral handle between blocking and unblocking positions.

Abstract: A wafer damper assembly formed of a thin, flat, polymeric annulus with a central opening receiving a polymeric wafer baffle. The baffle has a non-circular transverse passage receiving a cooperative shaft pivoted in the flat annulus, with a lockable quadrant handle on one end of this shaft.

Abstract: A fireplace having one or more conduits for directing outside combustion air into the firebox with a movable member adjacent a conduit outlet for normally closing said conduit and having either open or closed positions dependent upon the existence of a pressure difference across said member. A pressure difference caused by a fire in the firebox results in a higher pressure on the side of the member opposite the firebox to cause the member to move to open position. Operating structure is provided for positively closing the member and with the operating structure being operable from the front of the fireplace.

Abstract: A damper for sealing and unsealing a vertical furnace flue pipe to minimize the escape of heat when the furnace is not operating, the damper comprising a cylindrical body adapted to form a section of vertical flue pipe, the cylindrical body having a top opening and a bottom opening at least one transverse rod horizontally transversing the body and carried by opposed apertures in opposing wall portion of the body, a pair of oppositely extending gull-wing shaped damper shutters pivotally mounted on the rod and in the closed condition extending upwardly and outwardly to the inner surfaces of the cylindrical walls of the damper section, the lower edges of the wing sections engaging an annular rim mounted on the inner walls, the wings opening to a vertical position when the furnace is operating and closing by gravity when the furnace is not operating.

Abstract: A combined microwave and electric heater oven includes a fan system for cooling a magnetron, and a damper for selectively introducing a forced air flow generated by the fan system into an oven cavity. A damper cam is secured to a drive shaft of a damper motor, and a damper link is disposed between the damper cam and the damper to drive the damper. A microswitch is disposed near the damper cam so that the microswitch develops a first detection signal when the damper is tightly closed. In response to the first detection signal, the rotation of the damper motor is terminated to hold the damper in the tightly closed state. The microswitch develops a second detection signal when the damper is placed in the full-open state. In response to the second detection signal, the rotation of the damper motor is terminated to hold the damper in the full-open state.

Abstract: A thermally actuated damper for insertion in the flue pipe of furnaces consists of a cylindrical section of pipe having a diametrically extending bar fixed across its interior. The bar supports a pair of identical, semi-circular vanes formed of a bi-metallic laminate which project in a common direction from the bar. When the furnace is operating the hot flue gases cause the vanes to bend into abutment with one another so that they extend longitudinally along the flue pipe and allow substantially unrestricted flow of vent gases. When the furnace is off the cooling blades bend outwardly, toward the walls of the flue pipe, substantially blocking the flow of gases through the flue so that the warm air from the heated space is not drawn up the flue.

Abstract: An fuel-fired hot water furnace includes the use of an improved combustion chamber, heat exchanger and breaching damper, and further includes utilizing the water heated in the furnace as the means of heating a separate domestic supply of water directed through a side car hot water heater in fluid communication with the furnace. The improved combustion chamber includes a primary combustion cylinder which is orthogonally attached to a secondary combustion cylinder, and the secondary combustion cylinder is provided with a necked-down discharge so as to facilitate a thorough burning of a fuel and air mixture. The heat exchanger includes a primary rise and fall arrangement for the combustion gases so as to provide for maximum heating of the water within the heat exchanger prior to the gases being emitted outwardly from the furnace through a breaching tube, and the breaching damper is provided within the breaching tube so as to regulate the rate of combustion gas flow.

Abstract: A heating device for consuming a combustionable fuel, having an internal combustion chamber with top, sides, ends, and a grate forming the bottom; an outer shell, having a top, sides, ends, and a bottom in spaced relation below the grate; a primary air supply adapted to distribute the air beneath the grate; a secondary air supply adapted to preheat the secondary air prior to entering the combustion chamber at a location above the grate; an axis door in one end suitable to pass fuel within the combustion chamber; an exhaust chamber between the combustion chamber and the outer shell adapted to extend across the top and at least partially down a side in fluid communication with the combustion chamber; an exhaust port adapted to exhaust the combustion gases from the exhaust chamber externally of the device; a damper adapted to selectively divert exhausting gases in the exhaust chamber at least partially down one side, to extend the distance travelled by the exhausting gases to improve secondary combustion and the

Abstract: An elongated air manifold is provided to be positioned with the manifold extending across the opening of a fireplace closed by conventional glass doors. The manifold is disposed inward of the glass doors and includes outlet openings spaced longitudinally therealong and a shiftable damper plate for variably opening and closing the outlet openings. The opposite ends of the manifold include air inlet openings with which air ducts opening to the exterior of an associated building are communicated and the air inlet openings of the manifold have valve structures operatively associated therewith for variably opening and closing the air inlet openings. The valve structures and the damper plate may be operated from within the fireplace.

Abstract: The invention relates to a bearing assembly adapted to be connected to a damper blade, and particularly a damper blade intended to be disposed within the duct of an air conduit used in a heating or cooling system. The assembly is characterized in that the bearing pin is supplied in a first position, from which it may be partially retracted, and after installation may be shifted to an extended position from which, if necessary, it may likewise be retracted, making it particularly suitable for installations wherein the duct interior is provided with an insulating lining.

Abstract: For a damper, an improved damper operator including a bimetallic element connected at one end to the frame of the damper, and at the other end to a pivotal linkage which is also pivotally connected to the blade or blades of the damper.

Abstract: An energy-saving closure system is provided for use in preventing needless energy loss. The system employs a pivotal closure adapted to alternately move between the fully open and fully closed portion in a conduit for conveying gases relative to a combustion zone. The closure requires pressure diffentials only for being urged into the open and closed positions such as normally occur in the heating cycle. No energy-consuming, auxiliary apparatus is needed.

Abstract: A wood furnace permits controlled combustion of sectors or segments of wood-type fuels for a high turn down ratio. The primary combustion chamber comprises a refractory base portion for high temperature combustion and an upper portion with a water jacket in heat exchange relationship with the upper portions of the fuel for quenching combustion. A plurality of refractory secondary combustion channels or a single laterally extending or distributed secondary channel leads away from the refractory base portion of the primary combustion chamber. The secondary channels or distributed channel conduct flue gases from different sectors of the fuel, and permit completion of combustion in a high temperature environment. A plurality of flue draft pathways lead from the secondary combustion channels or distributed channel for transfer of heat from the end products of combustion to a heat transfer medium. Separate dampers are provided for controlling the draft in the separate flue draft heat exchange pathways.

Abstract: A mounting pin for a pivoted damper blade is disclosed which comprises a cylindrical shaft having a cenrtrally positioned hole extending therethrough, this hole being surrounded on one side of the pin with an upstanding flat seat. This hole is longer than it is wide so that it extends longitudinally of the pin. Also, the pin at one side of the seat is formed to include longitudinal depressions which provide a plurality of circumferentially spaced arc segments which form an interrupted circle. This pin is mounted on a blade at a side margin thereof by means of a bolt extending through a hole in the blade and through the hole in the pin, and a nut is associated with the bolt, the nut locking against the flat seat of the pin. A resilient gasket is interposed between the head of the bolt and the rear face of the blade so that the bolt need not be held while the nut is tightened. Also, a locking washer is desirably interposed between the nut and the seat.