Abstract: A method of crack repair for building and paving material which lowers an existing surface (S) to a new working surface (W) which is low enough to effect repairs without changing the elevation or attitude of the original surface: which fills the crack (C) with grout (1) which is in turn sealed by a bridging material (2). An initial overlay material (3) is placed over the bridging material and a reinforcing strip (4) embedded in the overlay material followed by a second layer of overlay material (5) sufficient to return the repaired area to the elevation and attitude of the original surface.

Abstract: A method for repairing eroded concrete rail ties. An abrasion resistant composition incorporating a curable binder is applied to the eroded rail seat and cured by the application of pressure and heat. A gas fired heating plate with a release surface is pressed onto the composition to force it into the eroded recess and cure it. The device incorporating the heating plate is clamped onto the rail clamp shoulders embedded in the concrete rail tie to enable pressure to be applied.

Abstract: Method and apparatus for vertically removing semiconductor integrated circuits (91) from high density multichip hybrid microcircuits without interfering with close proximity neighboring devices. An integrated circuit (91) is vertically removed by simultaneously applying tensile and torsional forces thereto. By using the present invention to transfer some of the tensile force torsionally, high density multilayer interconnect substrates (93) survive the rework process without damage. The present invention employs techniques which allow for accurate and repeatable removal of closely spaced integrated circuit devices. Removal of an integrated circuit (91) is accomplished by bonding a special thermode device (70, 70') directly to the integrated circuit (91) using a thermoset, or a thermoplastic, die attach material (90). Once the thermode (70, 70') has been attached, tensile and torsional forces are applied to the integrated circuit (91) through the attached thermode (70, 70').

Abstract: A method for injecting a chemical barrier into a surface aperture is provided. The method provides a vacuum to a work site to evacuate the air from the work site. Then, an injector head is located and retained at the work site. The injector head has a gasket that forms a seal around the work site. Pressurized fluid is conveyed to the work site through a first conduit in the injector head. Any unused fluid is conveyed away from the work site by a second conduit in the injector head.

Abstract: The invention discloses a method of repairing cracks, which is characterized in that, in injecting a repairing agent such as resin or the like into cracks occurring in an object to be repaired such as concrete, a masonry joint or the like, injection pressure of the repairing agent gradually increases after start-up of injection of the repairing agent and, further, the injection pressure is maintained substantially constant for a predetermined period of time after the injection pressure has reached a predetermined pressure, whereby the repairing agent is sufficiently spread into the cracks. Furthermore, the invention discloses a method of repairing cracks, in which the crack cavities are evacuated simultaneously with injection of the repairing agent, whereby the repairing agent is filled up in the cracks further efficiently.

Abstract: An apparatus for repairing breaks in safety glass, such as that found on automotive windshields, includes a self-contained, small fixture which can be secured to the windshield and centered on the break. The fixture includes connections for applying a vacuum source for evacuating the break, and for connecting a self-contained and self-supported measured quantity of resin to the fixture so the resin will enter the break while the break remains under a vacuum. The introduction of the resin into the break is thus enhanced, because the break is under vacuum. When vacuum is released, pressure may be applied to the resin to force it into the break to completely fill the break and provide for a visually acceptable repair. Curing of resins can then be carried out in a conventional manner.

Abstract: A method and composition for preventing a tear, hole or run in hosiery from expanding, wherein the composition comprises:(a) nitrocellulose,(b) resin,(c) dioctylphthalate, and(d) a solvent or solvent mixture.

Abstract: Sealing leaks in pressurized membranes, such as waterbeds without depressurizing. Such a membrane is gripped manually at the leak locus and vicinity, thereby folding and compressing the membrane to segregate and to seal the leak locus temporarily--and also enabling it to be dried. Next a patch is adhered over the leak locus, after which the membrane is released to return to its original shape. Apparatus for performing the steps subsequent to such manual gripping of the membrane include a base member and a first clamp member, pivoted together, between which the folded membrane is compressed; also a second clamp member, which--with the base member--compresses a patch onto the membrane, sealing off the leak locus permanently. The respective pivoted members are disengageably engageable, configured so as to maintain each such compression until completion of the desired steps, whereupon manual flexing disengages them from one another.

Abstract: A method and article for joining two substrates or repairing a substrate comprising positioning in thermal contact with and surrounding the substrate(s) a tubular article comprising conductive polymeric material. Two electrodes extending along the whole or part of the article as connected to a source of electrical power to cause current to pass through and heat the article. The conductive polymeric material is urged radially inwards towards the substrate(s). The radially inward movement may be caused by recovery of the conductive polymeric material, or by the use of elastomeric material.

Abstract: An anchoring process for use in a hydraulic electric facility turbine structure (1) includes, allowing for anchoring of a turbine liner wall (8) to a backing wall (9) while the liner wall (8) is in place and during repairs. The process includes positioning of apertures (20) within the liner wall (8). Second apertures (22) coaxial with the apertures (20) in the liner wall (20) are drilled into the backing wall (9) sufficient for purposes of embedding a reinforced steel bar (44) in a manner so as to appropriately support the liner wall (8). After the apertures (20, 22) had been formed, an adhesive material (42) in an unactive state in inserted into the aperture (20) of the liner wall (8) and into the secondary aperture (22) of the concrete backing wall (9). The steel reinforcing bar (44) is then inserted through the aperture (20) of the liner wall (8) and into the secondary aperture (22) of the backing wall (9).

Abstract: A method for permanently compacting a hollow resilient structure such as a recyclable plastic container to facilitate recycling thereof. As the structure is compressed cutting blades provided on the compressing surface perforate the walls of the container thereby cutting interlocking tabs into the surface. At the same time the interlocking tabs are forced outward and through the cavity left in the walls of the container by displacement of the tabs. The tabs straddle the cavity and become locked against the walls of the container by the separating force of the resilient plastic.

Abstract: Masking tape is disclosed for covering the gaps between adjacent panels of an automobile body and for isolating a section of a panel to be refinished. The tape includes an elongated flexible core having a cross-sectional shape of substantial thickness. At least a portion of the core's outer surface is adhesive. The core is narrow enough at one end to be inserted into a gap and wide enough in another portion to cover the gap, but not the panel edges. The outer surface of the core is angled or curved in such a way as to form an outwardly opening pocket which creates a vortex during spray painting which, in turn, causes paint to gradually diminish in thickness or feather out in the direction of the pocket's bottom.

Abstract: A method and apparatus for recycling used plastic bottles formed of a lower base cup and an upper container with a neck ring comprising in combination: a processing star wheel for supporting bottles by their neck rings and for moving the supported bottles sequentially through a plurality of processing stations; an input conveyor for sequentially feeding bottles to the processing star wheel; a first processing station for inserting pressurized air into the containers to return them to their essentially initial shape; a second processing station for inserting hot water into the containers for cleaning purposes and for effecting their contraction; a third processing station for removing the base cups from the containers; a base cup conveyor for feeding the separated base cups from the system for granulization and recycling; a fourth processing station for removing the labels from the containers; a label conveyor for feeding the separated labels from the system; a fifth processing station for removing the water f

Abstract: An apparatus for repairing cracks in a windshield is provided. The apparatus includes a mounting bracket having a plurality of arms. Each arm has a suction cup attached to it for securing the mounting bracket to the windshield to be repaired. One suction cup will be removable for attachment at a second location on its corresponding arm. An injector tube will be attached to the mounting bracket and extend through an aperture in the center of the mounting bracket. When it is desired to repair cracks near the periphery of the windshield, the removable suction cup will be attached to its second location and the injector tube will be attached to the suction cups original location.

Abstract: A method for repairing voids in a finished urethane foam product having a typical backing insert or retainer wall, the method including the steps of forming a hole through the retainer wall adjacent the void; inserting a small elastomeric sheath through the hole into the void; injecting a urethane or silicone elastomer into the sheath to fill same to conform to the void; and sealing off the hole with a suitable plug which may be sanded flush with the retainer wall outer surface.

Abstract: A barrier foam tray contains recycled reclaim of barrier foam. The tray comprises a sheet of foamed polystyrene (PS) having laminated to it a flexible barrier film. The foamed polystyrene part can have admixed therein from 0.0001% up to 30% by weight of the flexible barrier film. The barrier film contains a barrier polymer such as ethylene vinyl alcohol copolymer (EVOH). The tray is made by grinding laminate scrap and extruding reclaim therefrom with virgin polystyrene.

Abstract: A kit (150) of parts from which tools may be assembled for the repair of glass cracks by insertion of resin having an index of refraction substantially that of the glass. The tools are a repair bridge (160) and a repair bar (180) which may be placed on an automobile windshield and used to inject resin into a glass crack and a crack spreader (170) which may be placed on the inside of a windshield and used to spread the crack to facilitate entry of the resin. Methods of use of the tools are disclosed.

Abstract: Cavities, such as manholes of differing sizes and shapes are repaired by an apparaatus that includes an inflatable bladder enveloped by a carrier formed of a resin-impregnated fiberglass fabric. A hoist lowers the bladder and fabric into the manhole and an air blower inflates the bladder until the fabric tightly overlies the inner walls of the manhole. The resin then cures in situ. The liner so created forms a monolithic whole that is impervious to water and silt and prevents further crumbling and deterioration of the inner surfaces of the manhole. The bladder is deflated and retracted after the resin in the fabric has cured.

Abstract: An apparatus and method for repairing cracks and chips in automobile windshields provides two or more injectors mounted on a bridge element that heats repair chemical prior to inserting the repair chemical into at least two holes or chips in the windshield and a crack between the two chips, and also heats the windshield prior to inserting the repair chemical into the chips and crack.

Abstract: A method for drying the cavity in a shatter crack of a multi-layer laminated safety glass prior to repair of the crack utilizes a hand-held radiant heating device. The device includes a housing made of a metallic heat dissipating material and which carries an electrically energized radiant heating coil sized to approximate the diameter of the shatter crack cavity. The housing is affixed to a handle provided with a switch for controlling energization of the coil. In use the device is manually positioned in spaced proximate relationship to the cavity on the same side of the glass as the cavity and the switch is activated to energize the radiant heating coil for a period sufficient to remove water or other liquid resident in the shatter crack cavity.

Abstract: A method of seaming polymeric composite pieces to form a unitary cover which is impervious to the weather is disclosed. The method comprises assembling one or more pieces of a fused composite covering having a weatherable side and a non-weatherable, fusible, side to form a narrow seamable opening; fusing a tape over the seamable opening, and then filling the narrow seamable opening with a weatherable caulk to cover any remaining exposed non-weatherable material.

Abstract: In a construction material comprising a flexible carrier substrate impregnated or coated with a water-hardening resin, the resin contains as an additive polyether polysiloxane polyurethanes of the formula ##STR1## in which R.sup.1 is lower alkyl,m is the average number of siloxane groups in the range from 5 to 25,R is ##STR2## in which X is lower alkylene,Y is an aliphatic, cycloaliphatic, aromatic or araliphatic moiety, which is unsubstituted or substituted by further ##STR3## Z is a polyether moiety based on ethylene oxide units propylene oxide units, or both with the average number of ethylene oxide and propylene oxide units being in the range fro 10 to 100 andR.sup.2 is lower alkyl.

Abstract: A self-adhesive stocking patch for mending a nylon stocking. In its broadest aspects, the stocking patch comprises a thin resilient element of a shape and size to approximate typical tears occurring in nylon stockings. Adhesive attachment means is affixed to the element for securely attaching the element to portions of the nylon stocking adjacent to such a tear. The adhesive attachment means includes at least one piece of synthetic material of the type that adheres when pressed together with nylon (i.e. VELCRO.TM.). When applied to the stocking the patch provides an expedient means for temporary repair.

Abstract: A barrier injection apparatus for injecting a barrier at a site characterized by a holder for holding the apparatus in place against the force of injection; at least one injector for injecting a medium for a barrier at the injections site when in place; respective conduit system extending from the storage unit, and including a pump for inducing pressure onto the medium, to the injection site for injecting the medium at the injection site under pressure; storage unit for storing the medium at atmospheric pressure and being connected with a suction side of a pump that will introduce pressure; a second conduit connected with the barrier injection apparatus and adapted to remove unused medium from the site, an adjusting mechanism for adjusting the injectors to a correct distance; and a gasket sealingly surrounding the injection site for constraining the medium to flow into the site under pressure and insulate the medium from a holding mechanism. Also disclosed are specific preferred embodiments.

Abstract: In a method of constructing a reinforced pail from an existing pail having a covered top, an annular ring is formed from a top portion of the side wall by removing the top cover and cutting the side wall around a periphery parallel to the top end of the existing pail, thereby forming a modified pail. The annular ring is then slid as a concentric sleeve over the modified pail to a position where it snugly engages and reinforces the modified pail. The ring is then secured to the pail in such position.

Abstract: A method for repairing breaks in safety glass, such as that found on automotive windshields, includes as an apparatus a self-contained, small fixture which can be secured to the windshield and centered on the break. The fixture includes connections for applying a vacuum source for evacuating the break, and for connecting a self-contained and self-supported measured quantity of resin to the fixture so that resin will enter the break while the break remains under a vacuum. The introduction of the resin into the break is thus enhanced, because the break is under vacuum. When vacuum is released, pressure may be applied to the resin to force it into the break to completely fill the break and provide for a visually acceptable repair. Curing of resins can then be carried out in a conventional manner.

Abstract: Colloidal polymer dispersion for internal sealing of pipe connections containing 1-40% by weight of a water-soluble polyol and 99-60% by weight of an aqueous colloidal polymer dispersion.

Abstract: For replacement of a rear window pan (2), which has become unusable, in the folding hood (1) of a convertible a replacement pane (6) is provided of which the encircling frame (7) is provided at its inner side with a hot-melt adhesive (9). Worked into the encircling frame (7) are electrical resistance heating wires (10) which can be subjected to current to soften the hot-melt adhesive (9) to enter an adhesive bond with a remaining edge region (5) of the old pane (2). Another pane replacement can be carried out simply in that the hot-melt adhesive (9) is again softened, the fitted replacement pane removed and replaced by a new one of the same type.

Abstract: The invention relates to a multi-ply wood product. The supply of wood suited e.g. for the production of plywood has considerably decreased. Consequently, attempts have been made to compensate the deterioration in the quality of the surface finish and in other wood qualities e.g. by means of various coating methods, with varying success. The most important problem has been the insufficient adhesion between the coating and the wood. For the elimination of these problems, a multi-ply wood product has been developed in which at least one layer is formed by a crude fiber ply blank comprising haphazardly oriented fiber material as well as bonding agents, additives and filler materials.

Abstract: A method of repairing a damaged portion of a glass layer of glass-lined steel equipment by repeated steps of applying a repair agent to a damaged area of the glass layer and then heating the repair agent for solidification and adherence to the glass by the use of a sol-gel process, until a thickness of a repair glass layer becomes almost equal to the existing glass layer adjacent thereto without generating cracks or exfoliations in the glass.

Abstract: A plug of deformable material such as wood or plastic, for tightly sealing a cylindrical recess provided in wood, in which recess a crushable ampule with a wood attack combating agent can be accommodated, said ampule being attachable in a cavity of said plug by means of spring lugs, said plug being provided with a conical drive-in surface, and at least one deformable sealing clamping means being provided on said plug; the plug, at the end facing away from the drive-in end, containing a separate clamping sealing means for engaging the inner circumference of the recess, the outer radial dimensions of the sealing means and of the plug being such that complete sealing is acquired and maintained without damaging the wood after the plug has been driven into the recess, even in the event of high pressure build up in said recess.

Abstract: A method for installing an electrical heat sensor in a heatable laminate to function as a substitute for a defective heat sensor originally installed in the laminate during the manufacture thereof, comprising the steps of drilling a blind hole in an edge of the laminate, inserting a heat sensor into the hole, and filling the hole with a material to seal the hole and the heat sensor from contamination.

Abstract: To facilitate the repair of short sections of pipe by providing a lining in situ, a repair carrier containing the repair lining is moved into position adjacent the pipe length to be lined, the lining is forced out of the carrier into position in the pipe where it is fixed in position and the carrier is then removed from the pipe leaving the lining in place. A flexible tube forming a part of the carrier is used to initially position the lining in the carrier and then to force the lining out from the carrier and urge it against the interior of the pipe, preferably by eversion.

Abstract: In a concrete column supporting an overhead load and having a base end resting on a surface, a process of strengthening the column to increase its ability to withstand atypical physical loading accompanying an earthquake, involving the steps of defining a work area about the surface of the column to which the strengthening is to be applied, the work area defined by circumferential marginal edges arranged in spaced-apart relation; overwrapping the work area with at least one layer of high-strength, stretchable fibers wherein the fibers are oriented at an angle to the vertical axis of the column; applying a coat of hardenable material, having a modulus at least as great as that of the fibers, over the layer of fibers to form a hard outer shell thereover; and, injecting a quantity of a hardenable, low-shrink liquid under the layer of fibers and over the surface of the work area in an amount sufficient to cause the fibers to undergo stretching from about 1/2% to about 4% of their elongation.

Abstract: A repair patch for damaged sections of panels made of composite materials, wherein the damaged section of the panel has been cut out by, for example, a hole cutting saw, includes a bolt which is inserted through the hole and a rigid washer on the bolt, of about the same diameter as the hole. A flexible washer, substantially larger than the hole, is pushed through the hole and the rigid washer bears against it. The flexible washer has radiating flukes, extending from a central hub region, which can bend when the flexible washer is pushed through the hole, and then spring back to about their original shape on the blind-side. One edge of the flukes is curved which causes the flukes to twist and present only one edge to the edge of the hole as the flexible washer is pushed through, to facilitate passage of the flexible washer through the hole.

Abstract: A high-strength patching material made of a cloth woven from continuous filament fiberglass warp and filling yarns and impregnated between the yarns with a resinous pliabile-plastic material which hardens spontaneously upon exposure to aqueous moisture is disclosed for use in leakproof patching of pipes and other containers of fluids under elevated pressures.

Abstract: A process for restoring imaging members, which comprises (1) providing, subsequent to its utilization and removal from an electrophotographic imaging device, an amorphous silicon photoconductive imaging member with a protective overcoating; (2) contacting this member with a fluorine containing composition for an effective time period enabling the removal of the protective layer; (3) washing and drying the surface of the resulting imaging member; and (4) subsequently depositing a protective layer thereover.

Abstract: A support device for use in repairing laminated glass having an exterior portion having a magnetic device and an attachment adapted to hold an arm with an aperture therein adapted to hold a resin injection device in position over a damaged portion of a windshield and an inner portion which includes a magnetic device adapted to be aligned with the magnetic device on the outer portion, the opposite magnetic device holding the arm and resin injection device in position for repair of the damaged portion of the laminated glass.

Abstract: A process for integrating and permanently conserving an oil painting on canvas first eliminates stresses in the paint film induced by the original canvas by breaking down the weave of the canvas through physical abrasion or other means for severing the loops without damaging the paint film. The stress relieving step is followed by integrating the paint film, the original ground layer, remnants of old canvas, and a new dimensionally stable backing layer of material having an estimated life comparable to the expected life of the paint film. Integration is accomplished by means of a liquid coherant that cures to a permanent flexible material that provides a continuous bond between the paint film and the new backing layer. The coherant has a life expectancy comparable to that of the backing layer, with no deleterious physical or chemical effects on the paint film.

Abstract: A thin wall liner is positioned within the circular bowl of a sand muller to overlay the interior mulling surface upon which foundry sand is placed and is mulled by a plow blade that rotates within the bowl over its mulling surface. The bowl surface is annular and ring-like in shape. The liner is formed of a number of similar segments which are arranged together in edge to edge relationship to form an annular, ring-like cover over the bowl surface. The liner segments are secured to the bowl by bolts which extend through aligned holes in the segments and in the bowl. Most of the outer surface of the liner is spaced a short distance from the bowl surface by means of thin pads formed on the outer surface of the liner, around the area of the bolt holes. The pads contact the bowl surface, to provide a space between the remainder of the liner and the bowl surface. This space is filled with a grout-like material for bonding the liner to the bowl and for shock absorbing and load distribution.

Abstract: An apparatus and method for repairing a knot hole in a piece of lumber includes a rod of compressible polyethylene material and an adhesive caulk. The caulk is applied to the knot hole. The rod is forcibly inserted into the knot hole being secured by a force fit and the adhesive caulk. The rod is cut flush with the surface of the wood being repaired. The surface can be stained or painted along with the remainder of the structure.

Abstract: A method of resetting a separated portion of a tile floor from a base flooring, such as a concrete slab, by drilling a hole through the tile floor into the slab, forcing an adhesive into the hole and separated portion, monitoring the flow controlling upward force on the tiles and controlling the leveling of the titles and resetting.

Abstract: Apparatus for repairing laminated glass including a resin injector member engagable with a support member attachable to a laminated glass surface while in a vertically installed position. The resin injector member includes (1) a tubular body portion having a openings at each opposed end, a tubular tip portion positioned in one of the ends and a tubular vacuum stem extending outwardly perpendicular to the body portion, (2) a tubular mid-portion having openings at each opposed end disposed to fit snugly within the body portion, and (3) a cylindrical plunger portion, one end having cross hatches for gripping action and an opposed end disposed to fit snugly within the mid-portion. The support member includes (1) a planar base member, (2) at least one leg member for supporting the base member, (3) a suction cup attachable to the base member, and (4) an aperture extending through the base member for the engagement of the resin injector member.

Abstract: The present invention relates to a method of mending runs, snags, holes or the like in hosiery by the application of adhesive material. A single application applicator may be used. The preferred adhesive is biocompatible so that the adhesive may be applied while the hosiery is being worn; and the preferred adhesive is a cyanoacrylic adhesive. Decorative material such as dyes, glitter or other decorative material may be added to the adhesive to match or to decorate the hosiery.

Abstract: The present invention is a method of sealant injection and the apparatus to be used therefor. The method is comprises the steps of injecting the sealant into a bellows-like injection container through a check valve and compressing the container resiliently by the spring means to inject the sealant into the cracks of the structures of such as concrete at a low velocity and under a low pressure constantly. The apparatus comprises an injection pipe to be adhered to the surface of the crack, a bellows-like injection container to be connected the pipe, a check valve provided between the injection container and the injection inlet and resilient means to compress the container.

Abstract: A process for increasing resistance to penetration of glass in a glazed opening, including removing the glass from the glazed opening; and replacing the glass by laminated glazing consisting of the glass removed to which is fastened, by cementing with the aid of at least one intermediate layer of thermoplastic material, a sheet of thinner glass which has dimensions substantially equal to those of the glass removed except for having a thickness which is less than that of the glass removed, and which has been subjected to a chemical tempering treatment.

Abstract: The process provides for the structural reinforcement of manufactured articles made of stone or, in general, agglomerates by means of a sequence of steps which comprise the following: (a) the article to be treated is heated; (b) spraying on one surface of the article a particular adhesive called primer; (c) spraying on the same surface a resin preferably containing glass fibers or fibers of another material; (d) spraying on the same surface grit of stone having a constant and defined granulometry; (e) applying an action of vibration or compression on the article in order to facilitate the cohesion of the grit with the resin; (f) letting the resin undergo a catalytic reaction which eventually may require application of heat; (g) levelling the surface by mechanical operations. The same process may be repeated on the other surface of the article if one desires to cut the article along its thickness for the purpose of obtaining a very thin product.

Abstract: In order to line a pipeline or passageway active in conveying effluent without interrupting the flow of effluent therethrough, a first bypass conduit is passed through the section to be lined before the lining is inserted and the effluent is pumped therethrough, a second bypass conduit is passed through the lining after it has been inserted but before is has been fixed in position, the effluent is then pumped through that second conduit, the lining is fixed in position, normal effluent flow resumes, and the second conduit can be removed for future use.

Abstract: A hole (12) in a panel (10) of composite material is cut by a router or the like to dress it into a rounded hole (12'). A cavity is routed or otherwise formed in the panel (10) to extend across the dressed hole (12') in the direction of maximum tension loads in the panel (10). An insert (16) is secured in the cavity (18). The insert (16) and the cavity (18) have matching plan forms and each has a relatively narrow central portion and enlarged end portions (42, 44). The end portions (42, 44) of the insert interlock with end portions of the cavity (18) such that tension loads will be carried by the insert (16) from a region of the wall (10) on one side of the hole (12') across the hole (12') to a region of the wall (10) on the opposite side of the hole (12').

Abstract: A device for injecting a liquid repair material into a crack in glass such as a windshield has a central body portion including a rigid frame that is supported by three legs in a triangular configuration. A suction cup with a single adjustment knob holds the device against the windshield. One of the legs is an injector assembly comprising a cylinder and pressure screw assembly. Vacuum is applied to the cylinder by a nipple through the cylinder sidewall. An O-ring at the bottom of the cylinder sidewall seals between the bottom of the cylinder sidewall and the windshield. The pressure screw assembly includes a piston slidable within the internal passage. The lower end of the piston includes a seal for sealing engagement with the sidewall. In the preferred embodiment the piston seal is a sealing cap completely covering the bottom end of the piston and completely blocking the passage and sealing against said sidewall.