Abstract: A chain tensioner comprising a housing, a plunger having racks formed on its opposite sides, a protrusion biasing spring, cams arranged in oblique guide grooves in the housing and engageable with the racks of the plunger, and a spacer supporting a cam biasing spring. The minimum backlash distance X is equal to h/tan &thgr;, where h is the height of the rack teeth, and &thgr; is the angle of the cam guide surfaces relative to the protruding direction of the plunger. The angle &thgr; is between 15° and 70°. The tensioner prevents wobbling noises produced by a timing chain on starting an engine, prevents whistling sounds due to excess tensioning of the chain, and allows backlash to be readily set to accommodate the requirements of a wide variety of engines.

Abstract: A tensioner for an endless power transmission belt, the belt being driven about a sheave. The tensioner may comprise a base, a resilient device, and first and second arms pivotally coupled for movement in an open and a closed direction. The tensioner may also comprise first and second pulleys rotatably coupled to the first and second arms, the resilient device biasing the arms in the closed direction in which the first and second pulleys apply tension to the belt. The tensioner may also comprise first and second stops positioned outside the arms on the base to limit the movement of the arms in the open direction in response to an increase in tension in the belt.

Abstract: A walk behind self-propelled crawler snowplow includes a snowplow mechanism driven by an engine via a belt drive power transmission mechanism, and an overload protection device associated with the belt drive power transmission mechanism for protecting the engine against overload. The overload protection device comprises a tension sensor for detecting the tension in an endless belt and generating an electric overload signal to disengage an electromagnetic clutch in the belt drive power transmission mechanism when a belt tension greater than a predetermined value is detected.

Abstract: A cartridge type hydraulic tensioner for a chain or belt is described comprising a cylinder (11) with an inner bore (13) and a hollow piston (12) sliding in the cylinder and biased outward by an elastic elements and by pressurized fluid fed into said bore (13), at least one rack (20) being formed on the skirt of the piston (12) and engaged by a toothed pad (21) passing through a corresponding aperture (22) formed in the wall of the cylinder and biased against the rack by an annular spring (25) housed in an annular seat (24) formed in the skirt of the cylinder (11) without protruding from the bulk of the cylinder.

Abstract: A hydraulic tensioner comprising a hollow plunger having rack teeth formed on a portion of an outer circumferential surface, slidably received in a bore of the housing, where the plunger has an inner space to form a fluid chamber with the bore. A slider housing portion, having an inclined surface, located in the housing, receives a wedge-shaped slider having a ratchet portion adapted to engage with the rack teeth of the plunger and a second side surface. The wedge-shaped slider being slidable along the inclined surface of the slider housing portion in a direction crossing an axial centerline of the plunger. The hydraulic tensioner further includes a first spring biasing the plunger in a protruding direction, and a second spring biasing the slider such that the slider moves along the inclined slide surface of the slider housing portion. A “wedge-effect” prevents the plunger from moving backwards.

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 piston rod position detecting mechanism is proposed which can detect continuously or in a multiple-point manner that the piston rod position has changed due to increase or decrease in the protruding amount of the piston rod due to aging. The protruding amount from a cylinder end wall is detected by a position detecting mechanism comprising a detecting coil housed in a bobbin provided at the cylinder end, a flange portion formed on the piston rod, and a coil spring. Also, an autotensioner and an electromagnetic valve with such a position detector are proposed. Further, a belt tension adjusting device is provided with a detector for detecting the position of a tension pulley which is pivotable with increase or decrease in the belt tension.

Abstract: A belt tension adjustment apparatus and an optical scanner using the same. The belt tension adjustment apparatus includes a plate spring and/or a tension spring. Utilizing the elasticity of the plate spring or the elastic forces provided by the plate spring and the tension spring, a section of the transmission belt bends to produce a tension in the belt. With the belt tension adjustment apparatus, belt tension in the transmission belt can be easily adjusted and hence the belt can be easily mounted or dismounted from the belt wheels during installation, maintenance or adjustment.

Abstract: A tool support device for use in a belt grinding apparatus (1), the apparatus including, a drive motor (60), a drive shaft (61) and an abrasive belt arranged to be driven by the drive motor, (60) the tool support device (10) including a primary carriage (20) including a plurality of mounting zones (22, 23, 24) thereon, each mounting zone being adapted to receive a primary working tool assembly, (40, 41, 42), one or more of the primary tool assemblies including a secondary carriage (46) operatively mounted to the primary carriage (20) at one or respective one of the mounting zones (22, 23, 24) the primary carriage (20) being mounted for rotary movement so that it can adopt a plurality of working positions, wherein in each working position one of the primary working tools can be selectively disposed at a work station in an operative position, the secondary carriage (46) having a plurality of additional working tools thereon, the secondary carriage (46) being adapted for rotary movement relative to the primary c

Abstract: A belt or chain tensioner comprises a plunger that is slidably received in a chamber of the tensioner housing. The plunger is biased by a spring to project out of the housing and into contact with a tensioning shoe by which tension is applied to the chain or belt. The chamber is supplied with hydraulic fluid to damp movement of the plunger within the housing. The spring is captively connected between the plunger and housing and located outside of the housing. The tensioner is simple to install and remove from an internal combustion engine as the plunger and housing are held together by the spring.

Abstract: To provide a hydraulic tensioner lifter which can reduce the filling time of oil pressure into an oil chamber which is in a state wherein air is present therein and can sufficiently exhibit a vibration-damping function. A hydraulic tensioner lifter for applying tension to an endless power transmission band of a power transmission mechanism includes a plunger fitted for sliding movement in an accommodation hole of a tensioner body B and cooperating with the tensioner body B to define an oil chamber therebetween. An air-bleeder mechanism is provided for exhausting air in the oil chamber to the outside of the oil chamber. The purge valve P has a check valve function of permitting the exhaustion of the air in the oil chamber to the outside of the oil chamber but blocking admission of air into the oil chamber from the outside of the oil chamber and blocking discharging of the oil pressure in the oil chamber to the outside of the oil chamber.

Abstract: A hydraulic rack-style tensioner includes two concentric pistons in the bore of a tensioner housing. The lower piston which occupies a generally lower position in the housing has conventional ratchet teeth on an outside surface. The ratchet teeth form a rack which are engaged by a pawl. An upper piston occupies a generally upper protruding position in the housing. A chamber is defined between the upper piston and the housing, or between the upper piston and lower piston. Pressurized fluid in the chamber between the upper and lower pistons act to cushion impact of the rack and pawl mechanism when high loads from an associated tensioner arm and chain cause the upper and the lower pistons to be forced back toward the tensioner housing.

Abstract: A chain tensioner, includes a housing intended for attachment to a stationary machine element of an internal combustion engine, and a piston received in the housing for axial displacement against a strand of a chain to thereby implement a tensioning of the chain. An adjusting mechanism is provided for moving the housing relative to the machine element in a direction to and away from the strand of the chain, whereby a spacer establishes a distance between the housing and the strand to thereby define an installation position of the housing.

Abstract: A hydraulic timing chain tensioner assembly includes a shoe configured to contact a timing chain, and a plunger having a distal end abutting the shoe. The plunger is movable within a cylindrical opening formed in a tensioner body. The cylindrical opening includes oil and a spring member therein to cushion chain loads transmitted through the shoe and plunger. A spring-controlled oil pressure relief structure is operatively associated with the cylindrical opening to vent the oil when the oil is pressurized above a predetermined level by the plunger, thereby enabling further movement of the plunger into the cylindrical opening to reduce maximum loads experienced by the timing chain.

Abstract: In a chain tensioner having a plunger biased to protrude from a housing by a spring, a pair of wedge-shaped cams are received in tapered recesses in the end of the housing, cooperate with racks formed on opposite sides of the plunger, and are urged against oblique seats formed by the tapered recesses by a biasing spring. The cams and racks produce a ratcheting action maintaining chain tension by preventing retracting movement of the plunger. The cams and racks disperse the load imparted to the plunger by the chain, and reduce localized wear, allowing the housing to be made from a light weight material such as aluminum. Accuracy requirements associated with conventional pawl-type ratcheting tensioners are avoided.

Abstract: In a ratchet-type hydraulic tensioner for use with a timing chain of an internal combustion engine, two or more oil reservoirs gradually receive oil fed under pressure from an external source, and supply the oil through a hydraulic valve mechanism to a high pressure oil chamber formed by a plunger and a housing in which the plunger is slidable. Throttle holes, formed in partition walls separating the reservoirs, control the flow of oil from one reservoir to another. An excess oil discharge hole is optionally provided in one of the reservoirs. The invention prevents abnormal protrusion of the plunger, reduces chain noise and component damage due to wear, and rapidly re-establishes proper tension on engine start-up.

Abstract: A tensioner is formed with components having improved wear resistance. At least one component of the tensioner is covered with a diamond-like amorphous carbon coating (DLC). The coating is applied to the tensioner without causing hydrogen brittleness in metallic members. In addition, the coating may be formed on tensioner components formed with resin. In one embodiment of the invention, a metal element is dispersed into the diamond-like amorphous carbon coating.

Abstract: A hydraulic tensioner includes a piston that is pivotally mounted to a tensioner arm. The piston is slidably received within a hollow body that is pivotally mounted to a mounting block or engine. In different embodiments, the body is mounted to the tensioner arm while the piston is biased against the mounting block or pivotally connected to the mounting block or engine.

Abstract: A chain tensioner apparatus includes a mounting bracket adapted for connection to an associated engine block. The mounting bracket defines a pivot point and a support surface. A blade is connected to the bracket and includes: (i) first and second opposite end portions joined together by a central portion; (ii) a hub defined by the first end portion; and, (iii) a first end wall connecting the hub to the central portion. The hub of the blade is pivotably connected to the bracket at the pivot point and the second end of the blade abuts the support surface. The blade defines an exterior chain guide surface adapted for slidingly abutting an associated chain of an associated chain drive system. The chain tensioner apparatus further includes a tensioning spring connected to the blade, the spring having opposite first and second ends located respectively adjacent the first and second opposite end portions of the blade. The spring contacts and exerts a biasing force on the central portion of the blade.

Abstract: A hydraulic automatic tensioner for adjusting the tension of an endless belt in a power transmitting mechanism for transmitting power to engine accessories of an internal combustion engine through the belt comprises: a fixed first member (11), a piston (PS) formed integrally with the first member (11), a movable second member (12) coaxially combined with the first member (11) so as to be axially movable relative to the first member (11), a cylinder (CY) formed integrally with the second member (12), defining a fluid-reservoir chamber (R) for storing a hydraulic fluid together with the first member (11), and provided with a leak passage (20), axially slidably receiving the piston (PS), a spring (S) pushing the first and the second member (11, 12) away from each other. The piston (PS) and the cylinder (CY) form a pressure chamber (P) filled with the hydraulic fluid.

Abstract: A cartridge tensioner (10) for drive transmission belts and chains comprises a cylinder (12) with a cylinder bore, a piston (14) slidably received in the cylinder bore and provided with a piston bore (40), a vent device (16) housed in the piston bore and comprising an end part and a stem integral with each other, a pressure spring (18) acting between a shoulder of the cylinder and the vent device, and a retaining device (20), accessible from the outside of the cylinder. The retaining device, in a position engaged with the stem of the vent device, retains the vent device preventing the action of the spring on the piston, and, in a position of disengagement from the stem of the vent device, allows the spring to bias the device against the piston and to act consequently on the piston.

Abstract: A ratchet tensioner includes a mechanism for selectively locking and releasing a plunger with respect to a ratchet pawl. The plunger locking and releasing mechanism has an actuator plate secured to the shaft of a ratchet pawl body for co-rotation therewith above the outside surface of a housing shaft in which a pin-accommodating hole is formed. The actuator plate has a pin-insertion hole smaller in diameter than the pin-accommodating hole and is manually movable about the axis of the shaft in opposite directions between a locking position in which the pin-insertion hole is in substantial alignment with the pin-accommodating hole and the engagement between a ratchet pawl and ratchet teeth on the plunger is maintained, and a releasing position in which the pin-insertion hole is out of alignment with the pin-accommodating hole, and the ratchet pawl is released from interlocking engagement with the ratchet teeth against the force of a ratchet pawl spring.

Abstract: To provide a hydraulic tensioner, which can prevent the bottoming out or over-stressing of a spring in an incorporated check valve, can reduce the contact surface pressure between a check ball and a retainer, and can reduce the production cost, a hydraulic tensioner comprises a check valve incorporated in the housing which causes oil to flow into a high pressure chamber to block the back flow of oil. The check valve comprises a ball seat, a check ball facing the ball seat, a spring, which biases the check ball against the ball seat and a retainer, which retains the spring and limits the movement of the check ball. The spring comprises a conical coil spring, and the surface of the retainer, which retains the conical coil spring and limits the movement of the check ball, is formed in a flat surface.

Abstract: A blade-type chain tensioner (10, 110) is provided including a shoe (30, 130) adapted to impart tension to a chain (16), a blade spring (28, 128) engaging the shoe (30, 130), a piezoelectric strain element (35, 135) coupled to the blade spring (28, 128) or the shoe (30, 130), and a circuit (34, 137) adapted to receive a voltage or voltage data signal generated by a sensor (33, 133) coupled to the blade spring and shoe assembly (28/30, 128/130) in response to a vibration having a predetermined frequency or frequency band occurring in the blade spring and shoe assembly (28/30, 128/130), wherein the circuit (34, 137) is adapted to operably interact with the piezoelectric strain actuator element (35, 135) to induce a vibratory moment therein effective to reduce the vibration of the chain tensioner (10, 110).

Abstract: A belt tensioner for a power transmission belt may be provided that operates on an endless path and that utilizes asymmetric motion control. The belt tensioner may have an arm with a belt engaging section and a drum section, a support member for securing the tensioner relative to the belt, where the arm pivots on the support member, and a tension spring that urges the arm to pivot about the support member in a first direction and urges the belt engaging section against the belt with a force to tension the belt. The tensioner also may have a fluid filled chamber inside a portion of the drum section of the arm and a valve pivotally attached to the tensioner so that the valve extends across the fluid containing chamber.

Abstract: This invention provides a chain tensioner that is compact, excellent in operation, easy to maintain and handle and low in manufacturing cost. This chain tensioner has a tubular housing 1 having a bottom, a plunger 3 installed in the inner periphery 1a of the housing so as to smoothly slide inside the housing, a return spring 5 providing the plunger 3 with a force pushing outward, a plurality of latching grooves 33a-33d formed on the outer periphery of the plunger 3, a resister ring 7 capable of locking in the latching grooves, and a check valve 6 that is mounted on the bottom of the housing inner periphery 1a, provides the housing inner periphery 1a with operating oil and prevents its reverse flow. The range of backward movement of the plunger 3 is limited by mating the resister ring 7 locked in the latching grooves 33a-33d with a first stopper 21 formed on the housing inner periphery 1a.

Abstract: In a ratchet-type hydraulic tensioner for a chain transmission, having a plunger and a housing forming a high pressure oil chamber, an excess supply oil discharge passage is provided. The discharge passage communicates with an oil supply passage leading from an oil supply opening, which receives oil under pressure from a oil pump, to a hydraulic check valve mechanism in the housing, which delivers oil to the high pressure oil chamber. Excess oil is discharged to the exterior of the tensioner housing and directed toward the chain. Excessive chain tension is avoided, and smooth and reliable chain travel, and suppression of whistling sounds, are achieved.

Abstract: A plunger equipped with a relief valve mechanism is slidably mounted in a tensioner housing. The relief valve mechanism has a valve spring disposed between a valve and a spring retainer plug in a compressed condition. The spring retainer plug has a stopper surface formed on the side which opposes the valve. The maximum displacement of the valve and the maximum amount of compression of the valve spring are defined by the stopper surface so that the maximum shear stress acting in a wire of the valve spring is less than a fatigue limit of the valve spring wire.

Abstract: In a tensioner for a timing belt or chain in an engine, a plunger, which is spring-biased in a protruding direction, is temporarily held in a retracted condition by a pivoted U-shaped or L-shaped wire spring. The spring has a locking portion engageable with a pin or groove on the plunger, and two arms having ends remote from the locking portion. The ends are pivoted to the housing on laterally displaced pivot axes. The lateral displacement of the pivot axes causes the wire spring to be under stress when its locking portion is engaged with the plunger, and the stress urges the locking portion toward a disengaged position. Thus, the plunger is held in its retracted condition during assembly by the locking portion of the wire spring, but is automatically released by disengagement of the locking portion from the plunger when the plunger is moved farther in the retracting direction.

Abstract: The present invention provides a hydraulic tensioner with a ratchet mechanism simple in structure. The hydraulic tensioner (1) includes a hollow plunger (3) that is slidably received in a bore (2a) of the housing (2) that has an inner space (3a) defining a fluid chamber (20) with the bore (2a) and a rack member (7) provided slidably in axial direction in a groove (3b) on an outer circumference of the plunger (3).

Abstract: A belt tensioner for a power transmission belt is provided that operates on an endless path and that utilizes asymmetric motion control. The belt tensioner has an arm with a belt engaging section and a drum section, a support member for securing the tensioner relative to the belt, where the arm pivots about the support member, and a tension spring that urges the arm to pivot about the support member in a first direction and urges the belt engaging section against the belt with a force to tension the belt. The tensioner also has a stator inside the drum section utilized to form arcuate spaces circumferentially spaced around the stator between the stator and the drum section and arcuate shaped wedges in the arcuate spaces. The tensioner further has a Bellville spring coupled to the arm and a friction device positioned between the wedges and Bellville spring.

Abstract: A belt tensioner for a power transmission belt is provided that operates on an endless path and that utilizes asymmetric motion control. The belt tensioner has an arm with a belt engaging section and a drum section, a support member for securing the tensioner relative to the belt, where the arm pivots about the support member, and a tension spring that urges the arm to pivot about the support member in a first direction and urges the belt engaging section against the belt with a force to tension the belt. The tensioner also has a stator inside the drum section utilized to form arcuate spaces circumferentially spaced around the stator between the stator and the drum section and arcuate shaped wedges in the arcuate spaces.

Abstract: A damping mechanism used in a tensioner for tensioning a power transmission belt including a damping plate having a friction surface, at least one ramp surface and first and second contact points for operatively connecting a spring whereby the spring torque applied to damping mechanism in combination with a reactive force at the pivot surface generates a normal force.

Abstract: A hydraulic tensioner that decreases the number of components, secures an adequate backlash, and prevents backward movement of a plunger. The hydraulic tensioner includes a hollow plunger having rack teeth formed on a portion of an outer circumferential surface, slidably received in a bore of the housing, where the plunger has an inner space to form a fluid chamber with the bore. A slider housing portion, having an inclined surface, located in the housing, receives a wedge-shaped slider having a ratchet portion adapted to engage with the rack teeth of the plunger and a second side surface. The wedge-shaped slider being slidable along the inclined surface of the slider housing portion in a direction crossing an axial centerline of the plunger. The hydraulic tensioner further includes a first spring biasing the plunger in a protruding direction, and a second spring biasing the slider such that the slider moves along the inclined slide surface of the slider housing portion.

Abstract: A ratchet tensioner includes a plunger releasing mechanism for turning a ratchet pawl against the force of a plunger spring to disengage a locking prong of the ratchet pawl from a rack tooth of a plunger. The plunger releasing mechanism has a pin insertion hole formed in a plunger housing transversely across a recessed groove formed in the housing for mounting the ratchet pawl, and a sloped surface formed on the ratchet pawl and normally extending obliquely across the axis of the pin insertion hole. The sloped surface, upon abutment with the tip end of a pin which is inserted in the pin insertion hole, is capable of causing the ratchet pawl to turn against the force of the ratchet spring to thereby disengage the locking prong of the ratchet pawl from the rack tooth of the plunger for releasing the plunger.

Abstract: The invention comprises a self-contained mechanical belt tensioner that produces damping which is a function of the applied hubload through the effect of frictional forces derived from the sliding action of mutually opposing wedges. A first wedge or conical piston is contained within a housing. The conical piston cooperates with a second or conical wedge. A surface of the conical wedge slides on the inner surface of the housing. The conical wedge is expandable in a direction normal to the inner surface of the housing. A spring urges the conical wedge into engagement with the conical piston. As the pulley is loaded, as with an impulse load, the piston will move into the conical wedge. This, in turn, will cause the conical wedge to expand against the inner surface of the housing. The expansion of the conical wedge in the housing will increase the frictional force between the conical wedge and the housing. This will have the effect of damping movements of the conical piston and, in turn, of the pulley.

Abstract: A blade-type tensioner for chain drives which is suitable for use as a tensioner on the timing chain of a motor vehicle engine. The present invention is a chain tensioner particularly suited for use in confined spaces having a blade spring element mechanically interlocked with a plastic shoe. The shoe may be of rigid filled nylon and engages the chain to be tensioned. The spring element is interlocked to the plastic shoe by having ends inserted into grooves formed in the opposite ends of the shoe. The shoe has a metal bushing fixed in one end. The shoe is rotatably attached to a metal pin inserted through the bushing, the pin being fixed to a base.

Abstract: A tensioner, for a timing chain, belt or the like in an internal combustion engine, has a projection-preventing hook that secures a spring-urged plunger in a withdrawn condition prior to installation of the tensioner, but releases the plunger during operation so that the plunger can exert a force on a pivoted chain- or belt-engaging tensioner lever. A resisting member is provided on a fulcrum pin on which the hook is pivoted, in order to exert a frictional force on the hook, thereby preventing the hook from unexpectedly returning to its plunger latching condition and preventing vibration noise to movements of the hook. The tensioner can be mounted without regard to its direction, and therefore a threaded mounting can be used, simplifying mounting and demounting of the tensioner.

Abstract: A cartridge type hydraulic tensioner for a chain or belt is described comprising a cylinder (11) with an inner bore (13) and a hollow piston (12) sliding in the cylinder and biased outward by an elastic means and by pressurized fluid fed into said bore (13), at least one rack (20) being formed on the skirt of said piston (12) and engaged by a toothed pad (21) passing through a corresponding aperture (22) formed in the wall of the cylinder and biased against said rack by an annular spring (25) housed in an annular seat (24) formed in the skirt of the cylinder (11) without protruding from the bulk of said cylinder.

Abstract: A tensioning and damping element for chain drives, which comprises an elastically deformable ring part and a toothed rim arranged at the periphery thereof, the ring part being circular in the stress-free, uninstalled state and assuming, in the stressed, installed state, an ellipse-like shape between a non-loaded strand and a loaded strand of the chain drive, the toothed rim engaging with the non-loaded strand and the loaded strand and in so doing transmitting to the two strands a tensioning force which is caused by the ellipse-like deformation of the ring part. The ring part is constructed in such a manner that its cross-sectional profile steadily changes with increasing deformation of the ring part, in such a manner that the ratio of the height of the cross-sectional profile to the width of the cross-sectional profile in the maximally biased state of the ring part is at least 4% smaller than in the stress-free state of the ring part.

Abstract: A tensioning device for a chain (1) comprising a housing (3), said housing (3) carries a first sliding shoe (6) for contact with a first side (7) of the chain (1) with the tensioning device further comprising a tensioning piston (5,23) that is guided on the housing (3) and comprises a second sliding shoe (8,24) for contact with a second side (9) of the chain (1) whereby in an economic and simple-to-manufacture tensioning device, the housing (3) and the first sliding shoe (6) are made in one piece with each other.

Abstract: The present invention relates to a hydraulic type tensioner with a relief valve. In this tensioner, a relief valve, which is opened and closed in accordance with the oil pressure of oil supplied under pressure from an oil pressure generating source such as an oil pump or the like through an oil supply port, is provided in a bypass oil path, which detours a check valve mechanism formed in a tensioner body and communicates between the oil supply port and a high pressure oil chamber.

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 tensioning device for a chain (1) comprising a housing (3), said housing (3) carries a first sliding shoe (6) for contact with a first side (7) of the chain (1) with the tensioning device further comprising a tensioning piston (5,23) that is guided on the housing (3) and comprises a second sliding shoe (8,24) for contact with a second side (9) of the chain (1) whereby in an economic and simple-to-manufacture tensioning device, the housing (3) and the first sliding shoe (6) are made in one piece with each other.

Abstract: An engine tensioning system including tensioner arms and a rotary actuating tensioner capable of driving multiple tensioner arms making multiple chain or belt contacts. The rotary actuating tensioner has connector pins fixed to a rotating surface to which tensioner arms are attached. Rotation of this surface is accomplished through a combination of springs and hydraulic pressure. When the surface rotates, the attached tensioner arms are driven laterally against the engine chain or belt, keeping it taut.

Abstract: A closed hydraulic tensioner has a high-pressure chamber, a low-pressure chamber and a reservoir that are previously filled with an oil sealed in the hydraulic tensioner. The hydraulic tensioner further has a pressure chamber disposed next to said reservoir with a movable member disposed therebetween so as to displace the movable member toward the reservoir to thereby pressurize the oil inside the reservoir. The pressure chamber is supplied with an oil from the exterior of the tensioner.

Abstract: In an auto-tensioner, a damping device is used to control a fluid communication between a first fluid chamber and a second chamber for adjusting an engagement of an idler pulley with a belt-shaped power transmission member in such a manner that when a tension thereof is decreased, a quick propulsive movement of the idler pulley to the belt-shaped power transmission member is allowed by the first urging member, while when the tension is increased, the idler pulley is retracted gradually from the belt-shaped power transmission member by a registration of the belt-shaped power transmission member.

Abstract: The present invention relates to a hydraulic type plastic tensioner comprising a body of the tensioner, which is made of plastics, a hollow metallic cylinder fit into a circular hole formed in the body, a plunger and a check valve mechanism. A ball seat in the check valve mechanism is provided on a bottom portion of the circular hole, and a retainer in a retainer-integrated type cylinder is press-fit onto the check ball to hold the cylinder in the circular hole.

Abstract: A tensioner includes a plunger stopper mechanism for holding a plunger in an inoperative position in which the plunger is retracted into a cylinder chamber formed in a tensioner body. The plunger stopper mechanism has a radial pin hole formed in the tensioner body and communicating with the cylinder chamber, an annular pin stopper groove formed in a circumference of the plunger, and a stopper pin removably inserted through the radial pin hole into the annular pin hole. The radial pin hole has a center line extending parallel to a tangent to the bottom of the annular pin stopper groove and offset from the tangent toward an open side of the annular pin stopper groove, and the annular pin stopper groove has a depth slightly greater than a diameter of the stopper pin, so that a side face of the stopper pin is held in contact with the bottom of the annular pin stopper groove.

Abstract: This tensioner comprises a casing, a first shaft member rotatably stored in the casing so as to be restrained from moving in its axial direction, a second shaft member in screwed engagement with the first shaft member, and a spring for applying a turning force to the first shaft member. The second shaft member is restrained from rotating relatively to the casing and allowed to move in the axial direction. An axial load from a force transmitting member, such as a chain or belt, acts on the first shaft member. An end face of the first shaft member touches a receiving surface of the casing across a washer. The end face receives the axial load that acts on the second shaft member. The flatness of at least the end face of the first shaft member is adjusted to 15 &mgr;m or less.