Abstract: In a ratchet-type tensioner having a plunger with rack teeth formed thereon and a piston with ratchet teeth that engage the rack teeth, the ratchet teeth can be disengaged from the rack teeth by insertion of a tool through a tool insertion hole in the tensioner housing and exerting a prying action on the toothed end of the piston to move the piston away from the plunger. Alternatively if an oblique camming surface is formed on the toothed end of the piston, the ratchet teeth can be disengaged from the rack teeth by pushing the tool inward against the oblique camming surface. The piston and the hole in which it slides are shaped to prevent rotation of the piston. The ratchet teeth on the piston and the rack teeth on the plunger can be oblique to allow setback of the plunger when excessive force is exerted on the plunger.

Abstract: In a ring-type tensioner, an expansible elastic ring disposed in a groove formed in the wall of a plunger-accommodating hole cooperates with teeth formed on the plunger to restrict axial movement of the plunger. The ring and the groove in the wall of the plunger-accommodating hole have flat radial surfaces for mutual engagement. However the ring also has oblique plunger-tooth engaging surfaces. The ring has manipulable end parts that can be locked in fixed relation to each other by a tool to secure the plunger against axial movement. The tool can also be inserted into a gap between the manipulable end parts to expand the ring and thereby release the plunger.

Abstract: A ratchet-type tensioner capable of restricting setback of a plunger includes a ratchet mechanism that allows setback of the plunger by sliding a ratchet element in a disengaging direction to disengage ratchet teeth from rack teeth when a reaction force acts on the plunger as a result of excessive chain tension. The ratchet element is slidable in a ratchet-receiving hole, and an inclination suppressing structure that prevents the ratchet element from becoming skewed in the ratchet receiving hole to an extent such that its forward end contacts one side of the hole while its rearward end contacts the opposite sides of the hole.

Abstract: In a ratchet-type tensioner having a plunger with rack teeth formed thereon and a piston with ratchet teeth that engage the rack teeth, the ratchet teeth can be disengaged from the rack teeth by insertion of a tool through a tool insertion hole in the tensioner housing and exerting a prying action on the toothed end of the piston to move the piston away from the plunger. Alternatively if an oblique camming surface is formed on the toothed end of the piston, the ratchet teeth can be disengaged from the rack teeth by pushing the tool inward against the oblique camming surface. The piston and the hole in which it slides are shaped to prevent rotation of the piston. The ratchet teeth on the piston and the rack teeth on the plunger can be oblique to allow setback of the plunger when excessive force is exerted on the plunger.

Abstract: Deaeration of the high pressure oil chamber of a hydraulic tensioner takes place though a helical orifice formed by opposed flanks of the threads of a threaded hole in the tensioner housing and the threads of a screw inserted into the hole. The opposed flanks are maintained in spaced relationship by a force exerted by a spring washer disposed between the head of the screw and a surface of the tensioner housing surrounding the opening of the threaded hole. The flank of the thread of the hole that forms part of the boundary of the helical orifice can have a concave curvature in order to increase the aperture of the air flow path. A groove in the surface surrounding the opening of the threaded hole prevents the washer from sealing off the flow of air. This groove is disposed with its exit end at a level above its entry end.

Abstract: In a ring-type tensioner, an expansible elastic ring disposed in a groove formed in the wall of a plunger-accommodating hole cooperates with teeth formed on the plunger to restrict axial movement of the plunger. The ring and the groove in the wall of the plunger-accommodating hole have flat radial surfaces for mutual engagement. However the ring also has oblique plunger-tooth engaging surfaces. The ring has manipulable end parts that can be locked in fixed relation to each other by a tool to secure the plunger against axial movement. The tool can also be inserted into a gap between the manipulable end parts to expand the ring and thereby release the plunger.

Abstract: A ratchet mechanism of the ratchet tensioner comprises a toothed ratchet element slidable in a housing and movable in a sliding direction, a plunger movable in an advance/setback direction and having rack teeth engageable by the teeth of the ratchet element, and a ratchet-biasing spring for biasing the ratchet element so that its teeth engage the rack teeth. The rack teeth have stop surfaces facing in the setback direction and sliding surfaces facing the advancing direction. The sliding surfaces are curved surfaces bulging in the advancing direction and in the direction of disengagement of the ratchet element from the rack teeth, the bulge being in an area extending from an entry starting location to an entry ending location.

Abstract: A ratchet-type tensioner capable of restricting setback of a plunger includes a ratchet mechanism that allows setback of the plunger by sliding a ratchet element in a disengaging direction to disengage ratchet teeth from rack teeth when a reaction force acts on the plunger as a result of excessive chain tension. The ratchet element is slidable in a ratchet-receiving hole, and an inclination suppressing structure that prevents the ratchet element from becoming skewed in the ratchet receiving hole to an extent such that its forward end contacts one side of the hole while its rearward end contacts the opposite sides of the hole.

Abstract: There is provided a ratchet-type tensioner whose spring stopping washer for seating a ratchet biasing spring is rigidly and readily assembled to a ratchet-receiving hole so as not to fall out of the ratchet-receiving hole and which reduces flapping noise and prevents seizure of the plunger by securely and stably operating a ratchet mechanism in operating an engine. The ratchet-type tensioner 100 is arranged so that the spring stopping washer has a C-ring anchored in the rear-end area of the ratchet-receiving hole by fitting in a diameter-reduced state and by enlarging its diameter within an anchoring circumferential groove of the ratchet-receiving hole and a spring stopping piece extended from the C-ring to a ring center area to seat the ratchet biasing spring.

Abstract: In a ratchet tensioner, rack teeth on a plunger are engaged by ratchet teeth on one end of a movable plug that slides in a hole in the tensioner housing along a direction orthogonal of the direction of movement of the plunger. The movable plug is prevented from rotating in the hole in which it slides so that the ratchet teeth engage the rack teeth on the plunger smoothly and reliably.

Abstract: A self-expanding endovascular stent formed of stainless steel wire which is bent into an elongated zigzag pattern. The zigzag pattern has a plurality of substantially straight wire sections of various lengths separating a plurality of bends. The zigzag pattern is helically wound about a central axis to define a tubular shape such that a majority of the bends are disposed in a helix. Adjacent bends in the helix are interconnected with a filament. The stent is capable of being radially compressed such that the straight wire sections and the bends are tightly packed around a central axis. The stent resiliently self-expands to assume a tubular shape when released from the compressed state. Depending on the pattern of the lengths of the straight wire sections in the zigzag pattern, the final tubular shape can be made irregular to match a patient's vascular system. In other words, the diameter of the tube which is defined by the stent can be made to vary along the length of the stent.

Abstract: A self-expanding endovascular stent formed of stainless steel wire which is bent into an elongated zigzag pattern. The zigzag pattern has a plurality of substantially straight wire sections of various lengths separating a plurality of bends. The zigzag pattern is helically wound about a central axis to define a tubular shape such that a majority of the bends are disposed in a helix. Adjacent bends in the helix are interconnected with a filament. The stent is capable of being radially compressed such that the straight wire sections and the bends are tightly packed around a central axis. The stent resiliently self-expands to assume a tubular shape when released from the compressed state. Depending on the pattern of the lengths of the straight wire sections in the zigzag pattern, the final tubular shape can be made irregular to match a patient's vascular system. In other words, the diameter of the tube which is defined by the stent can be made to vary along the length of the stent.