Abstract: This invention relates to a mulch having a preprogrammed biodegradability comprising at least two different layers of biodegradable polymer coated onto a sheet of a cellulosic material, one of these layers being a layer of polylactide. The mulch is particularly useful to control weeds in agriculture, horticulture, and forestry industries. The biodegradability of the mulch can further be preprogrammed according to the type of soil, the climatological zone, and the specific applications wherefore it is intended to be used. The present invention is also directed to methods for preparing and using the multilayer coated mulch.

Abstract: An above-grade trafficway barrier adapted to arrest heavy vehicles, with an obstruction member extending between opposite sides of the trafficway, and controlled by its known mass deposed upon the grade level and preferably by spaced inertia blocks deposed at opposite sides of the trafficway, the known mass not to exceed the strength of the obstruction member and coupling thereof regardless of the vehicle mass. Impact force being gradually applied and dissipated by the known mass through a lever system with simultaneous roll, turn and sliding movements of said spaced masses; whereby the obstruction member is not subjected to greater force exerted by the impacting vehicle.

Abstract: A flexible gate is disclosed which comprises a plurality of segments. The segments may be connected by at least one coupling. When the flexible gate is acted on by a force, the flexible gate may flex. When the force is no longer present, the flexible gate may return to a substantially straight position. The segments may be removed or added as needed to repair broken segments or to adjust the length of the flexible gate.

Abstract: A resilient, insulated door panel for a sliding door includes a resilient core protected by a compliant outer covering with a seal disposed about the perimeter of the panel. The panel has sufficient resilience to recover from an impact that temporarily deforms it, yet has sufficient rigidity to transmit a compressive force needed for effectively setting the seals. Much of the core is filled with air to not only provide effective insulation and resilience, but to also provide an extremely lightweight door panel that can be operated to travel rapidly along an overhead track. Some embodiments include relatively rigid backup plates that provide a solid foundation to which the perimeter seals can be attached. The backup plates are segmented so as not to completely restrict the flexibility of the door panel.

Abstract: There is disclosed a device and associated method for impeding the motion of a land vehicle travelling along a pathway on a terrain surface. First and second supports are positioned at first and second sides of the pathway, respectively, each capable of being actuated from a compressed condition to an extended condition. A propulsion system is effective to actuate the supports. A barrier extends between the supports at a mean first height that is effective to permit passage of a vehicle when the supports are compressed and supported by each support at a mean second height effective to impede passage of the vehicle when the supports are extended. When the supports are compressed, vehicles pass over the barrier unimpeded. When the supports are extended, the barrier impedes the motion of a vehicle travelling along the pathway. At least one deceleration cable mechanically couples the barrier to a brake system.

Abstract: A protective system for overhead doors on loading dock platforms for use in connection with a pair of pipe bollards permanently erected at each of the sides and in front of the door. The system includes a pair of net securing devices each having a mounting bracket allowing the assembly to be attached to the door, a variable linkage, and a bollard collar for fitting over the existing pipe bollard when the door comes down. A spring loaded bracket in connection with the bollard collar and variable linkage allows a netting connected between the bollard collars to move for a distance until the bollard collar abuts the pipe bollard to preclude damage to the door.

Abstract: An apparatus and method for protecting an occupant of a building from flying debris from a frangible structure of the building, such as a window or the like, in the event of an explosion or other blast. A protective barrier is positioned adjacent the building structure and is constructed to be deployed by inflation of at least a portion thereof. The protective barrier is movable from a stored position adjacent the building structure to a deployed position in which it covers the building structure. A gas generating device is connected to the protective barrier and is operable to generate gas to inflate the protective barrier and move it to the deployed position in response to the sensing of an explosion or other blast by a sensing device located remote from the building.

Abstract: There is described a profiled sash section for a window sash holding a window pane and intended for being installed in an outer frame of a blast resistant window. The sash section includes a main member enabling inter-engagement between the profiled sash member and the outer frame; a window pane holding member for accommodating and securing an end portion of said window pane in the profiled sash member, and a reinforcing member designed to support the end portion of the window pane and to transmit blast pressure, if incidentally applied to the window pane, to the main member. For at least partially absorbing blast pressure energy applied to the window pane, the sash section is provided with damping means for deforming up to a predetermined limit. Also described is a blast-resistant framework for a casement window, including the window sash assembled from the mentioned profiled sash sections and adapted for rigidly and air-tightly securing the window pane in the holders of the profiled sash members.

Abstract: A shock attenuation barrier including a plurality of layers successively arranged including a first layer, a second layer having a plurality of molded geometric shapes, a third layer including foam, a fourth layer having a plurality of molded geometric shapes and a fifth layer. Cavities defined by inside surfaces of the geometric shapes and a surface of the foam layer preferably are filled with a shock absorbing filler material.

Abstract: A crossing guard is disclosed which comprises an operator positioned on one side of a thoroughfare for raising and lowering an arm, a gate connected to the arm, a first lock positioned on the opposite side of the thoroughfare, a plurality of cables supported within the gate, joined together at fixed points intermediate the ends of the cables, and a first end assembly connectable with the cables and the gate at the end of the gate opposite the operator with the first end assembly engagable with the first lock. The device further comprises a second lock positioned on the side of the thoroughfare nearer said operator engagable with a second end assembly positioned on the end of the gate nearer said operator.

Abstract: The present invention to provides a rapidly deployable system and method for arresting the movement of a vehicle with minimal injury to the vehicle or its occupants. The invention provides a system which applies a braking force which varies according to vehicle weight and speed by utilizing a series of frangible rods for dissipating the energy.

Abstract: There is disclosed a transportable device and associated method for impeding the motion of a land vehicle travelling along a pathway on a terrain surface. First and second supports are positioned at first and second sides of the pathway, respectively, each capable of being actuated from a compressed condition to an extended condition. A propulsion system is effective to actuate the supports. A barrier extends between the supports at a mean first height that is effective to permit passage of a vehicle when the supports are compressed and supported by each support at a mean second height effective to impede passage of the vehicle when the supports are extended. When the supports are compressed, vehicles pass over the barrier unimpeded. When the supports are extended, the barrier impedes the motion of a vehicle travelling along the pathway. At least one deceleration cable mechanically couples the barrier to a brake system.

Abstract: A fortified gate system and locking mechanism which utilizes spring loaded locking mechanisms, triggered by the impact of an object such as a vehicle, to interlock a gate, a brace, and fortified anchoring devices. This interconnected structure forms an energy absorbing, impenetrable barrier. Because the gate system functions as a normal gate until an instance of attempted crashing entry, it provides reasonable accessibility while maintaining a high level of security. The present device also includes a gate anchor and locking system which is operable independent of the direction in which the gate is impacted.

Abstract: A new composite damping material is presented which exhibits an enhanced ability to dampen mechanical oscillations. The enhanced damping properties of this material are achieved through the entrapment of highly viscous damping fluids within the pores of a porous material (such as: an expanded polymer, felt, foam, fabric, metal, etc.). The entrapment of the fluid within the porous scaffold prevents flow, providing a stable composite which may be shaped into useful articles. Such a construct allows utilization of the high performance damping properties of fluids which, in pure form, are too fluid-like for most practical applications (which typically require a solid, stable, material). This composite, possessing damping performance approaching that of certain fluids, combined with stability in a solid form, can be used in many applications where materials are needed to damp the vibration of mechanical systems.

Abstract: There is disclosed a transportable device for non-destructively impeding the motion of a land vehicle travelling along a pathway. First and second telescoping devices located on either side of the pathway support a barrier. When the telescoping supports are compressed, the vehicles pass over the barrier unimpeded. When the telescoping supports are extended, the barrier impedes the motion of a land vehicle. At least one deceleration cable mechanically couples the barrier to a braking system. The braking system applies a continuous deceleration force to the vehicle of typically less than 2 g, bringing the vehicle to a stop without damaging either the vehicle or vehicle occupants.

Abstract: A restraining barrier is positionable across a roadway in a deployed position to define a restraining zone and may be moved vertically to a passive position by first and second transport components. Opposite ends of the barrier are coupled to the first and second transport components, respectively, and also couple the barrier to first and second energy absorbers of differing restraintive force in order stop vehicles of varying weight. A support cable is coupled to an indicator for providing a signal indicating vehicle impact. Additionally, a series of restraining barriers and energy absorbers may provide a series of sequentially differing restraintive forces to stop lightweight and heavier vehicles. The barrier may be a net and include a lower wire below the net assuring effective trapping of autos and trucks of a variety of heights.

Abstract: A heavy duty shock absorber system for resisting large forces as may be encountered, for example, in a restraining barrier for a railroad crossing. A concrete bunker with an upstanding concrete-filled steel pipe has a hydraulic, compressive shock absorber mounted on the steel pipe for rotational, axial, and orthogonal movement. Forces applied to the shock absorber always pass through the axis of the steel pipe, thereby maximizing the resistance to the force while minimizing the necessary size of the system. A net is stored in a pit transverse the roadway parallel to the railroad tracks and is raised and lowered as appropriate. Each end of the net is attached to shock absorbing systems of the type described above.

Abstract: A fortified gate system and locking mechanism is disclosed which utilizes spring loaded locking mechanisms, triggered by the impact of an object such as a vehicle, to interlock a gate, a brace, and fortified anchoring devices. This interconnected structure forms an energy absorbing, impenetrable barrier. Because the gate system functions as a normal gate until an instance of attempted crashing entry, it provides reasonable accessibility while maintaining a high level of security.

Abstract: A rotating guard rail assembly formed preferably of steel tubing and sheathed in a polymerized material such as plastic. The assembly generally comprises a vertical stanchion sheathed in plastic and having a rotating jacket assembly mounted about the exterior of the stanchion. The jacket is free to rotate about the stanchion thereby acting as a cornering or pivoting device to redirect a moving object upon impact of the guard rail assembly.

Abstract: A restraining barrier assembly is positionable across a roadway in a deployed position to define a restraining zone and may be moved vertically to a passive position. The barrier may be a rectangular net with wires (or cable) (21, 22, 23) spanning the net and a lower wire 24 below the net assuring effective trapping of autos and trucks of a variety of heights (of the vehicles and of their forward bumpers, hood and driver compartment sections) and a variety of spans between their bumpers and their forward wheels. Vertical strips (25, 26) are provided at intervals along the span of the barrier to maintain spacing of the wires from each other and relative to ground level. The lowest wire (24) is set back from the plane of the barrier that includes the mid-height and upper wires.

Abstract: A restraining barrier (30) is positionable across a roadway in a deployed position to define a restraining zone and may be moved vertically to a passive position by first and second transport members (13, 14) slideably mounted to first and second towers (3, 4) on either side of the roadway. The barrier may be a rectangular net. First and second cables (34, 35) each support an opposite end of the barrier to the said first and second transport means respectively and also couple the barrier to an energy absorber (known per se). The cable includes a support cable which also responds to the impact of a vehicle as by breaking. The cable is coupled to an operate indicator for producing a signal indicating the vehicle impact.

Abstract: A security barrier apparatus suitable for use in residential, farm and industrial settings includes a motor, a chain and a brake mechanism for engaging the chain. The apparatus is mounted to a first support such as a post. The chain extends from the first support to a second spaced support and is raised and lowered relative to the ground by operation of the motor. The motor may be remotely actuated by an electronic transmitter. The apparatus further includes protective features to prevent damage to the motor in the event that a vehicle collides with the chain.

Abstract: An energy absorbing motor vehicle barrier includes a collapsible energy absorption assembly which is stored in a vault in the ground. Upon deployment, the energy absorption apparatus is lifted out of its vault, where it thereby expands and deploys. The energy absorption apparatus includes four stages of pairs of elastomeric torsion springs configured into scissors arrangements, with each stage having a progressively higher effective spring rate, to thereby decelerate a vehicle which strikes the apparatus.

Abstract: A security barrier apparatus suitable for use in residential, farm and industrial settings. The apparatus includes a motor, a cable, a chain secured to the cable and a brake mechanism for engaging the chain. The apparatus is adapted to be mounted to a first support such as a post. The chain extends from the first support to a second spaced support and is raised and lowered relative to the ground by operation of the motor. The motor may be remotely actuated by an electronic transmitter. The apparatus further includes protective features to prevent damage to the motor in the event that a vehicle collides with the chain.

Abstract: A gate bar for a toll gate apparatus includes a tubular member surrounded by a sleeve of resilient material. The sleeve is protected by a sheath which may be painted to improve the visibility of the bar.

Abstract: A parking space barrier comprises a stationary base for anchoring to the ground of a parking space and a moveable pylon attached to the base member by an extensible cable. The pylon comprises a cushioned peripheral portion upstanding from a carriage containing a spring motor attached to one end of the cable. A wirelessly operated lock remotely controlled by the car driver secures the carriage to the base adjacent the entrance to the parking space. A car entering the parking space engages the cushioned peripheral portion and pushes the pylon before it across the parking space to a vehicle admitting position, the cable extending under the car and winding the spring motor so that the pylon will be drawn back by the spring motor and cable with the car when reversing out of the parking space. A manually operable arresting device is provided to maintain the pylon in the vehicle admitting position remote from the base member, if required.

Abstract: An apparatus wherein a barricade structure is positioned in a first orientation below ground level and raised to a second position in above ground level orientation to provide a barricade relative to various railroad crossings and the like. The apparatus includes spaced parallel posts mounting a plurality of equally spaced bars therebetween, the bars include shock-absorbing plates equally spaced orthogonally relative to the bars and parallel to the posts. An individual or plurality of spools effects raising and lowering of the organization.

Abstract: A vehicle security barrier which can be conveniently placed across a gate opening as well as readily removed from the gate opening to allow for easy passage. The security barrier includes a barrier gate in the form of a cable/gate member in combination with laterally attached pipe sections fixed by way of the cable to the gate member and lateral, security fixed vertical pipe posts. The security barrier of the present invention provides for the use of cable restraints across gate openings to provide necessary security while at the same time allowing for quick opening and closing of the gate areas without compromising security.

Abstract: There is provided a collapsible barrel-shaped barricade which telescopes within itself for compact storage. Particularly, a solid and heavy base is provided for stability and a series of telescoping ring members are mounted thereon; the lowest ring being mounted to the base and upper rings being concentric with the lower ring. The concentric rings are arranged to interlock by placement of a tab from an inner ring into a horizontal slot on the inside of an outer ring. This interlock operates to hold the rings in an extended position when the barricade is in use.

Abstract: A terrorist vehicle arresting system includes a rigid immovable crash barrier postioned at one side of a driveway and a turnstile having a circular sector positioned at the other side of the driveway in such a manner that upon entrance of an unauthorized vehicle through a corresponding gate across the entrance of the driveway, means are provided to rotate the turnstile such that the turnstile deflects the vehicle into the crash barrier. In a further embodiment, two opposing turnstiles are used to wedge an oncoming vehicle therebetween. In one embodiment, the terrorist vehicle arresting system includes a rope-barrier attached to an elevating and lowering mechanism on one side of the driveway and is attached at its other end to the turnstile, such that upon the unauthorized attempted entrance and the striking of the rope-barrier, the turnstile is rotated by the rope-barrier into the driveway, diverting the vehicle into the crash-barrier.

Abstract: An assault-resistant gate is intended to bar passage, through an opening, of large vehicles moving at high velocity. The gate has a relatively strong hinge-post. A beam extends from the hinge-post across the opening. The beam is relatively rigid in a horizontal plane. The beam is attached to the hinge-post by a breakaway mounting. The attachment is weaker than the hinge-post. Energy absorbing material is disposed behind the beam on either side of the opening.

Abstract: A semaphore type trafficway barrier for arresting vehicles, and comprised of spaced posts at opposite sides of the trafficway, one a pivot post disposed on a vertical axis and with a yieldable mounting rotatable plate on the post to carry a beam to swing between an open ineffective position to a closed effective position as well as to yield to impact, and characterized by a cable anchored to the pivot post and carried by the beam with an end engaged over a bit on the other post at the opposite side of the trafficway.

Abstract: A barrier system is provided for blocking a roadway to prevent passage of a vehicle. The barrier system comprises a series of inflatable bags connected to a flexible net, and energy dissipating units connected to ends of the net. The system is normally located in a subterranean chamber when deactivated. When activated, the air bags are inflated and rise above the ground surface while pulling the net upwardly therewith. A vehicle which impacts the barrier is rapidly decelerated under the energy dissipating action of the air bags, energy dissipating units, and net.

Abstract: A device for inhibiting parking or travel on pavement, comprising an elongated barrier member that is hingedly affixed to a support bolted or otherwise securely attached to the pavement. The barrier member can be oriented in two positions, one which the barrier member is prone to allow traffic to pass thereover, and a second which the barrier member is essentially upright to inhibit travel. A brace extends between the barrier member and the support and resiliently retains the barrier member in the upright orientation to absorb the impact of a vehicle.

Abstract: A terrorist vehicle arresting system includes a rigid immovable crash barrier positioned at one side of a driveway and a turnstile having a circular sector positioned at the other side of the driveway in such a manner that upon entrance of an unauthorized vehicle through a corresponding gate across the entrance of the driveway, means are provided to rotate the turnstile such that the turnstile deflects the vehicle into the crash barrier. In a further embodiment, two opposing turnstiles are used to wedge an oncoming vehicle therebetween. In one embodiment, the terrorist vehicle arresting system includes a rope-barrier attached to an elevating and lowering mechanism on one side of the driveway and is attached at its other end to the turnstile, such that upon the unauthorized attempted entrance and the striking of the rope-barrier, the turnstile is rotated by the rope-barrier into the driveway, diverting the vehicle into the crash-barrier.

Abstract: A terrorist vehicle barrier is disclosed that is an improvement on the barrier shown in U.S. Pat. No. 4,576,507. The barrier consists of two vertical I-beams having cable passed between them to provide a barrier. An expanded aluminum honeycomb is provided between the I-beam and the cable passing around the I-beam to provide an effective shock absorbing structure. The barrier can be employed as an actuatable gate or as a fence-like structure around the perimeter of a installation to provide an esthetic and cost effective barrier strong enough to stop a high speed vehicle with minimum damage to the barrier.

Abstract: A terrorist vehicle arresting system includes a crash barrier positioned at a side of a driveway instead of across the driveway; a gate across the entranceway which is dislodged by a vehicle coming through the closed gate; a net pulled out by the dislodged gate which captures the vehicle; a capstan to pivot a captured vehicle into the barrier; and cables from the net looped around the capstan, such that the netted vehicle is swung into the barrier where it comes to rest blocking the driveway. The impact-force is therefore redirected from the direction of the driveway, and the kinetic energy is dissipated upon impact with the offset, rigid barrier, thereby permitting the gate structure to be made light, aesthetically attractive, and quickly closed since the gate does not have to bear any substantial load.

Abstract: Electromechanically actuated bifolding closure apparatus including a vertical support post; a pair of generally C-shaped frame members disposed in facing relationship and pivotally joined together at their distal extremities such that in a closed disposition the two C-shaped members lie in a single plane and form a rectangularly configured super-structure, and in an opened disposition lie in different, spaced apart parallel planes rotated either 90 degrees relative to or parallel to the closed plane; hinge apparatus pivotally connecting one of said C-shaped units to the vertical post; a motive power source carried by one of the C-shaped members at a position proximate the support post; a gear drive mechanism associated with the hinging apparatus at the post and at the pivotal connection of at least one set of the distal ends of the C-shaped members; and a mechanical drive linkage coupling the motive power source to each of the gear mechanisms, such that when the motor caused the associated drive linkage to be

Abstract: A door construction includes first and second panels which are thermally bonded together at their peripheral edges. A hinge receiving pocket is defined between these panels. A door supporting hinge section is insertable into this pocket for supporting the door in place. An adjustment mechanism on the door supporting hinge section tilts the outer edge of the door relative to the inner edge of the door for adjusting the alignment of the door within a door opening after the hinge is installed.

Abstract: To prevent breakage, an end section that can be positioned across a roadway is connected through a slanting pivot to a supporting section, the raised and lowered positions of the supporting section being under control of a usual standard. The pintle of a hinge for the pivot lies along slanting abutting ends of the supporting section and the end section such that the end section while the sections are horizontal is maintained in position by gravity. An L-shaped latching device has a weight at one end, an intermediate pivot, and a latch at the other end to latch the sections together by gravity while the sections are raised from a horizontal position, the latch retaining said end section upright while the supporting section is fully raised.

Abstract: A terrorist vehicle barrier is disclosed having high strength cables stretched between two vertical I-beams. The cables are attached to the I-beams in a unique shock absorbing arrangement. The barrier is actuatable from a position below ground to effectively arrest the motion of a high speed terrorist vehicle. Various means are disclosed for actuating the gate. The barrier is designed to solve esthetic problems encountered in making a building secure from terrorist attack as well as to be strong enough to stop a high speed vehicle with minimum damage to the barrier, the vehicle, or the vehicle driver.

Abstract: A self-closing door hinge for a curtain door mounted within a frame consisting of a channel having a double helical track and a roller on said helical track which is returned to a pre-selected position after movement in either direction by compression of a spring thereby moving an arm carrying a curtain door connected to said channel to a preselected position.

Abstract: A traffic door biased to the closed position and adapted to be swung to the open position when pushed manually or engaged by material handling equipment. The door includes an inverted L-shaped frame and a spring loaded cam mechanism is associated with the upper horizontal frame section of the frame and acts to bias the door to the closed position. The door is pre-hung on a vertical rail which is offset from the plane of the door. At the time of installation, the rail is plumbed and secured to the doorway jamb. The pre-assembled unit facilitates proper installation of the door, and the offset rail eliminates the need for rubber flaps to seal the gap between the door and the jamb. The traffic door assembly also includes an upper trim panel attached to the horizontal frame section which can be trimmed to size to fit the doorway.

Abstract: A multi-panel closure is disclosed in which a fastening member comprising a pair of integral back-to-back channels is positioned between the facing pair of edges of adjacent panels. The facing side sections of each channel grip the aforesaid edges between them. The panels are positioned so as to have at least one edge in alignment with each other. A split sleeve which is fastened to a rotatably supported closure post includes a pair of parallel flanges which receive the aligned panel edges therebetween and which are riveted to each panel along its aligned edge.

Abstract: A band comprising continuous glass fibers provides intrusion resistance for a plastic door mounted between two vertical posts in an automobile. The continuous fibers of the band are disposed horizontally and may be separate from the door or form an integral part thereof.

Abstract: A parking lot gate is provided with a flexible connector between the elongated gate arm and the arm drive mechanism to prevent breakage of the gate arm or the arm drive mechanism. The flexible connector includes a first connection plate connected to the arm drive mechanism, a second connection plate connected to the gate arm, and first and second coil springs connected between the first and second connection plates. The first and second coil springs are positioned essentially parallel to one another and in an essentially vertical plane.

Abstract: In a preferred embodiment of the invention, there is provided an air-lock tunnel composed of side and top panels forming a tunnel and swing-hinge-mounted panel doors at each of opposite ends of the tunnel, all panels being refrigeration insulation flexible panels, of which the panel doors are typical in general structure, each panel door being closed-cell rubber sheet sandwiched between sandwiching Nylon sheets each surface-coated with a rubber layer and each rubber-coated Nylon sheet being flexible, having a lower half of the exposed (exterior) surface of the sandwiching flexible sheets covered by an attached bumper or kick guard sheet of thick Nylon fabric having a polyvinylchloride composition plastic coating and having a cut-out groove spaced-from and following the curcumscribing edge thereof in which twisted Nylon thread follows and is recessed within the cut-out groove in the sewn attachment of the bumper sheet to the exposed surface of the flexible sheet, the door having the sandwiching fabric sheets e

Abstract: A barrier for separating the passenger compartment of a vehicle from the compartment occupied by the vehicle operator. This barrier is comprised of a stiffly flexible, firm but not hard, frame made of a material such as polyvinyl chloride tubing, the size of the frame being expandable to allow for press fit installation. The frame is traversed by flexible bands which perform the barrier function.

Abstract: Apparatus is disclosed for use with an automatic closure of the type wherein the closure member, such as a door, returns to a home position when displaced therefrom. The closure member is at least partially supported by a hanger arm secured to a cam follower that rides on a cam track. The cam track forms part of a stationary structure which provides a bearing for a rotatable post. The post may carry further support means for the closure member.

Abstract: In a preferred embodiment of the invention, there is provided an air-lock tunnel composed of side and top panels forming a tunnel and swing-hinge-mounted panel doors at each of opposite ends of the tunnel, all panels being refrigeration insulation flexible panels, of which the panel doors are typical in general structure, each panel door being closed-cell rubber sheet sandwiched between sandwiching Nylon sheets each surface-coated with a rubber layer and each rubber-coated Nylon sheet being flexible, having a lower half of the exposed (exterior) surfce of the sandwiching flexible sheets covered by an attached bumper or kick guard sheet of thick Nylon fabric having a polyvinylchloride composition plastic coating and having a cut-out groove spaced-from and following the curcumscribing edge thereof in which twisted Nylon thread follows and is recessed within the cut-out groove in the sewn attachment of the bumper sheet to the exposed surface of the flexible sheet, the door having the sandwiching fabric sheets ex