Abstract: A tensioner has a tensioner body and a plunger slidably mounted in a hollow cylindrical part of the tensioner body. A plug is screwed into a female or internal screw formed from one end of the hollow cylindrical part. A coil spring is loaded in a spring accommodating hole of the plunger and in a spring accommodating hole of the plug. The coil spring is a left hand spring. On the other hand, the direction of the plug being screwed into the tensioner body is right, which is opposite to the winding direction of the coil spring. Since the direction of the plug being screwed and the winding direction of the coil spring are different, when the plug is being screwed into the tensioner body with the coil spring held between the plug and the plunger, the coil spring slides on the bottom of the spring accommodating hole of the plunger or on the bottom of the spring accommodating hole of the plug without being caught at either end.

Abstract: A lever assembly includes a lever and a fastener for pivotally mounting the lever to a fixed support member. The lever is composed of a lever body made of a plastic and a reinforcement plate assembled with the plastic lever body. The lever body has a first groove formed in one surface of the lever body and extending from a central through-hole to a position in proximity of a mount hole formed at one end of the lever body, and a second groove formed in the opposite surface of the lever body and extending from the central through-hole to a position in proximity of the other end of the lever body. The reinforcement plate is fitted in the first and second grooves across the central through-hole of the lever body. The fastener comprised of a screw with flanged head has a portion lying over part of the reinforcement plate to prevent the reinforcement plate from displacing off the lever body.

Abstract: A ratchet tensioner has a plunger retractably mounted in a housing and urged by a spring in a direction to project outward from the housing, and a ratchet pawl pivotally mounted on the housing and having a first prong normally engaged with one of ratchet teeth formed on the plunger so as to prevent backward motion of the plunger. The ratchet pawl also has a second prong spaced a predetermined distance from the first prong in the backward direction of the plunger and engageable with a second rack tooth to release meshing engagement between the first prong and the rack tooth when the plunger is moved forward due to a slack of a timing chain used with the tensioner. In order to maintain a predetermined amount of backlash between the first prong and the rack teeth, the rack teeth have a height greater than a half pitch of the ratchet teeth.

Abstract: A silent chain comprises a link assembly including at least two inner link plates each having a pair of teeth and bushing holes and connected and fixed to each other with a pair of bushings press-fit into said respective bushing holes, an intermediate link plate including a pair of teeth and bushing holes, and a guide plate including a pair of pin holes. The members are combined and articulably connected to by other with connecting pins. A row of link assemblies is disposed in the center with respect to the width direction of the chain and extends along the longitudinal direction of the chain. The intermediate link plates are disposed on both sides of the link assembly and guide plates are disposed on outer sides of each of the intermediate link plates. Each bushing in the link assembly disposed between said intermediate link plates has a length substantially equal to the spacing space between the intermediate link plates.

Abstract: A ratchet-operated tensioner 1 is constituted by a principal plunger 4 slidably fitted into a cylinder chamber 3 formed in a tensioner body, an inner plunger 5 slidably fitted into the principal plunger, a compression spring 7 provided in an oil pressure chamber 6 and a ratchet mechanism 9. An O-ring 8 that slidably comes into contact with an inner wall of the principal plunger 4 is attached to an outer periphery of the inner plunger 5. In the ratchet-operated tensioner 1 with the pressure oil chamber according to the present invention the oil leak from the pressure oil chamber is prevented by preventing the oil leak from a gap between the principal plunger 4 and the inner plunger 7 during the engine's shutdown.

Abstract: A hydraulic tensioner includes a relief valve provided at a projecting end portion of a plunger. The relief valve has a pressure path communicating with a high pressure oil chamber, a valve body fitted for sliding movement in the pressure path, a spring for normally biasing the valve toward the high pressure oil chamber, and an outlet port communicating, when the valve body is moved back against the force of the spring, with the pressure path. The valve body is formed as a unitary member including a slidably movable portion fitted for sliding movement in the pressure path and acted upon by a hydraulic pressure of the high pressure oil chamber, and a flange portion having a cross sectional area greater than that of the slidably movable portion for being acted upon by the force of the spring.

Abstract: A hydraulic tensioner includes a relief valve mechanism assembled in a plunger and held in fluid communication with a high-pressure oil chamber defined between a housing and the plunger which is slidably inserted in a plunger accommodation bore in the housing with a tip portion projecting therefrom. The relief valve mechanism is composed of a cup-shaped orifice member having an orifice formed in an outer circumferential surface thereof, and a relief valve assembled in the cup-shaped orifice member. The relief valve includes a cup-shaped sleeve slidably received in the orifice member, a spring urging the sleeve toward the high-pressure chamber, and a discharge port normally closed by the sleeve and adapted to be opened when the sleeve is displaced against the force of the spring. The thus constructed relief valve mechanism is small in size and capable of achieving downsizing of the hydraulic tensioner.

Abstract: A lever assembly includes a lever and a fastener for pivotally mounting the lever to a fixed support member. The lever is composed of a lever body made of a plastic and a reinforcement plate assembled with the plastic lever body. The lever body has a first groove formed in one surface of the lever body and extending from a central through-hole to a position in proximity of a mount hole formed at one end of the lever body, and a second groove formed in the opposite surface of the lever body and extending from the central through-hole to a position in proximity of the other end of the lever body. The reinforcement plate is fitted in the first and second grooves across the central through-hole of the lever body. The fastener comprised of a screw with flanged head has a portion lying over part of the reinforcement plate to prevent the reinforcement plate from displacing off the lever body.

Abstract: A ratchet tensioner has a plunger retractably mounted in a housing and urged by a spring in a direction to project outward from the housing, and a ratchet pawl pivotally mounted on the housing and having a first prong normally engaged with one of ratchet teeth formed on the plunger so as to prevent backward motion of the plunger. The ratchet pawl also has a second prong spaced a predetermined distance from the first prong in the backward direction of the plunger and engageable with a second rack tooth to release meshing engagement between the first prong and the rack tooth when the plunger is moved forward due to a slack of a timing chain used with the tensioner. In order to maintain a predetermined amount of backlash between the first prong and the rack teeth, the rack teeth have a height greater than a half pitch of the ratchet teeth.

Abstract: The housing of a ratchet tensioner is formed of an aluminum-containing metallic material in order to decrease the weight of the tensioner. A hard alumite layer having a thickness of 5 to 50 &mgr;m is formed on the inner circumferential surface of a plunger accommodation bore formed in the housing, and a lubricant is incorporated into the alumite layer. Thus, the service life before occurrence of seizure is increased.

Abstract: A tensioner device for adjusting a tension in a chain wound around two sprockets includes a tensioner lever held in sliding contact with a slack run of the chain, an oil-filled tensioner provided on a stationary member, and a ratchet tensioner provided on the tensioner lever. The oil-filled tensioner includes a piston movable back and forth relatively to a housing attached to the stationary member, and a spring urging the piston in the forward direction. The ratchet tensioner includes a plunger movable in the forward direction relative to a housing formed integrally with the tensioner lever, and a spring urging the plunger in the forward direction. The piston and the plunger are held in face-to-face abutment with each other. The spring of the oil-filled tensioner has a larger spring coefficient than the spring of the ratchet tensioner.

Abstract: To provide a pivotal structure of an oscillating member facilitating management of parts and fixing work. The cylindrical peripheral face (11A) of a collar (11), which is fixedly secured by screwing a bolt (4) being inserted in a bolt insertion hole (11C ) into a tapped hole (13) in a fixed part (12), is rotatably fitted in a bearing hole (9) bored in a pivot guide portion (6) provided on the side of the pivotal support end of an oscillating member and, by means of collar movement restricting faces (8A, 10A) at the pivot guide portion (6), the cylindrical peripheral face (11A) is prevented from coming off the bearing hole (9). Since, the collar (11) is previously incorporated in the pivot guide portion (6) before the oscillating member is secured to the fixed part (12) and such assemblies can be arranged as a set of parts, management of parts and fixing work are made easier.

Abstract: To reduce a sliding resistance of a tensioner lever of a transmission chain and to suppress any flapping vibration in a free span portion of the transmission chain, a tensioner lever (1,11) has a tensioner sprocket (2,12) disposed in registry with a bent portion of a transmission chain C having a minimum bent radius of curvature. The tensioner sprocket is pressed by the tensioner lever against the slack run of the transmission chain to form the bent portion, and a shoe member (3,13) is mounted between the tensioner sprocket and a proximal end (1', 11') of the tensioner lever to slidably guide the free span portion of the run.

Abstract: A hydraulic tensioner device, which is compact in size, simple in construction and can be manufactured efficiently, has a shoe (4) for applying a tensioning force to a chain (3) or belt. The shoe has a plunger (5) which has a hollow portion (6) in which a valve block (7), a spring (9) and an inner sleeve (10) are slidably disposed. The upper end of the inner sleeve is supported within a cylindrical chamber (2) in a tensioner body (1). The tensioner body has an oil passage (11) communicating with an internal space of the inner sleeve. The bottom surface (6A) of the hollow portion and the valve block jointly define therebetween a high pressure chamber (8) filled with an oil supplied from the internal space of the inner sleeve via a check valve (7A) in the valve block.

Abstract: A backlashless ratchet-type tensioner includes a tensioner housing, a plunger slidably fitted into a plunger accommodation bore formed in the tensioner housing and urged by a spring such that a tip portion of the plunger is projected to the exterior of the plunger accommodation bore, and a ratchet pivotally supported on a ratchet pin provided on the tensioner housing. At least one ratchet pawl formed on the ratchet is meshed with rack teeth formed on an outer surface of the plunger so as to prevent the plunger from receding into the plunger accommodation bore. A front face of the ratchet pawl is formed substantially perpendicular to a straight line which passes through a tip of the ratchet pawl and the center of the ratchet pin. The angle between a plane perpendicular to the axis of the plunger and the front face of the ratchet pawl meshed with a rack tooth is slightly smaller than the angle between the plane perpendicular to the axis of the plunger and a rear face of the rack tooth.

Abstract: A ratchet tensioner comprising a ratchet (1) having a first ratchet prong (6) engageable with one of ratchet teeth (T) at a position displaced from the axis (O) of a ratchet shaft (3) toward the free end of a plunger (5), and a second ratchet prong (7) receivable between two adjacent ones of the ratchet teeth (T) at a position located on a line (N) extending through the axis (O) of the ratchet shaft (3) perpendicular to an axis of the plunger (5) when the first ratchet prong (6) is in mesh with the one ratchet tooth (T). A projecting length (S2) of the second prong (7), which is measured from the axis (O) of the ratchet shaft (3) to the top of the second ratchet prong (7) in a direction parallel to the perpendicular line (N), is made smaller than a corresponding projecting length (S1) of the first ratchet prong (6) at least by an amount equal to the given manufacturing tolerance in the production of the ratchet.

Abstract: A chain tension relieving device which prevents excessive tension being applied to a tension run of a chain. A shoe (5C) engages a tension run (3B) of a chain (3) stretched between a driving sprocket (1) and a driven sprocket (2) from another side of the chain in a bowed portion of the chain (3). When the tension acting on the tension run (3B) is of a prescribed value or less, the shoe surface of the shoe (5C) is held to a given advanced position so as to bow the tension run of the chain (3) by a biasing force of mechanical tensioner (15D). When the tension exceeds the prescribed value, the tension side (3B) of the chain (3) is straightened against the biasing force of the mechanical tensioner and the shoe surface of the shoe (5C) retreats from the given advanced position.

Abstract: A ratchet type tensioner with a hydraulic buffer mechanism, which is simple in construction, low in manufacturing cost, easy in securing an oil path, and large in durability. A plunger (8) is slidably inserted into a plunger insert bore (9A) which axially extends through a plunger sleeve (9) restricted to advancing displacement by an anti-retrograde mechanism. A plunger spring (10) for biasing the plunger (8) forward is provided along with a sleeve spring (14) between a plunger housing (7) and the plunger sleeve (9) for biasing the plunger sleeve (8) forward. The sleeve spring (14) has a smaller spring constant than the plunger spring (10). A high pressure chamber (H) communicates with an oil pressure supply portion through a check valve (15). The chamber is formed in a space between a bottom portion of a plunger receiving bore (7B) in which the plunger (8) is inserted and a rear end surface (7C) of the plunger.

Abstract: A tooth profile for a roller chain sprocket, is provided, which is capable of making the rollers of a chain come into engagement with the teeth of the roller chain sprocket without generating a large noise, and which is capable of making the rollers disengage smoothly from the teeth of the roller chain sprocket. The tooth profile has a first section between a first working point on a clearance flank on the back side with respect to the direction of a movement chain and the tip of a tooth, having a circular profile conforming to a moving path along which the outer circumference of a succeeding roller turns about the center of a preceding roller. The tooth profile has a second section between the first working point to the bottom of the tooth, which is continuous with the first section having a circular profile conforming to the outer circumference of the roller.

Abstract: A ratchet type tensioner with a buffer mechanism is capable of buffering an impact force applied from a chain side to a plunger, irrespective of the amount of backlash in a ratchet mechanism, and is capable of exhibiting an excellent effect of suppressing vibration of the chain. An inner plunger is inserted in a protrudable and retractable manner into an outer plunger whose backward movement is restricted by a ratchet mechanism. The inner plunger is urged in its protruding direction by means of an inner plunger spring more powerful than a plunger spring which urges the outer plunger in the protruding direction. At one end of inner plunger is an oil storage chamber in communication with a high pressure chamber at the opposite end of the inner plunger through a check valve. A clearance path is provided between the two chambers to allow oil in the high pressure chamber to bypass the check valve and flow through the clearance path.