A tensioner includes a movable section, a fixed section, a flat spiral spring, and a back-up spring. The movable section receives load from an entrained transmission body through a tension member. The fixed section supports the movable section so as to be capable of displacing. The flat spiral spring biases the movable section so as to resist the tension member. The flat spiral spring unwinds in a state in which there is a small inter-plate friction force in cases in which there is a large biasing force applied to the tension member to counter load acting from the tension member. The flat spiral spring winds-up in a state in which there is a large inter-plate friction force in cases in which there is a small biasing force applied to the tension member to counter load acting from the tension member. The back-up spring limits wind-up of the flat spiral spring.

The invention relates to a tensioner (100) comprising: a hollow body (10) provided with a bottom (12), said bottom comprising a central zone (120), a peripheral zone (121) raised relative to the central zone and an intermediate zone (122) an axis (30) two guide means (40, 50) for said axis two cups (60, 124), the cup (124) comprising a first portion (124A) in front of the peripheral zone and a second portion (124B) in front of the intermediate zone a spring (70) held between the cups and arranged around the second guide means so that there is a gap between the spring and the second guide means a valve (80) with a channel (90), the channel opening in front of the second portion of the cup (124) away from said second portion.

An orifice member is disposed in a plunger including a plunger hole that forms a hydraulic chamber in conjunction with a plunger housing hole in a housing. The orifice member includes a deformed fitting section deformed to fit on the inner circumferential surface of the plunger hole, a communication section that causes a surface in contact with the top surface on the front side of the plunger hole and a surface on the hydraulic chamber side to communicate, and an orifice groove that communicates with the communication section and an external relief hole provided in the plunger on the surface in contact with the top surface on the front side of the plunger hole to constitute an orifice.

A resister clip (35) includes engage portions (35a) engaging with an engage groove, a spring portion (35b) and operating portions (35c). The spring portion (35b) can be designed with a high degree of freedom in terms of a coil number of turns, a winding diameter and others and the engage portions (35a) are widened centering on the spring portion (35b), so that diameter-widening resistance can be optimized.

To provide a tensioner that is simply structured and easy to assemble, and that is capable of preventing plunger deformation during press-fitting of a relief valve unit, obviating the need for outside diameter grinding after the assembling, and reducing the thickness of the side walls of the plunger. A relief mechanism, which releases oil inside an oil pressure chamber to the outside of the plunger when the oil pressure in the oil pressure chamber becomes high, has a fixing member that is made of resin, that is located between the outer circumference of the relief valve unit and the inner circumference of the plunger hole, and that fixes the relief valve unit in the plunger hole on the front side thereof.

An endless band drive system having a variable center distance between the drive pulley and the driven pulley also has a rotatable control shaft and an endless band guide, where the guide is positioned by the rotatable control shaft for maintaining a slackless endless band with change of pulley center distance. Rotation of the control shaft pivots the endless band guide thereby maintaining a slackless endless band with change of the pulley center distance. Preferably, the rotatable control shaft also provides means for adjusting the center distance between the drive pulley and the driven pulley. The present invention provides a slackless endless band system for a variable compression ratio engine having a variable center distance between the drive pulley mounted on the crankshaft and the driven pulley mounted on the camshaft. The system provides slackless operation of the endless band at two or more compression ratio values.

To provide a chain tensioner that can suppress oil leakage from a gap between a plunger bore and a plunger to achieve stable damping characteristics and that can avoid an increase in production cost, with a simple structure. The chain tensioner includes a packing member that is provided on an inner circumferential side of the plunger bore and that suppresses oil leakage from a cylindrical outer surface of the plunger. The plunger is provided with an oil leak passage that extends from an oil pressure chamber inside the plunger to the outside.

A vibrating apparatus includes two axles, two composite wheels, a timing belt, a multi-ridged belt and four rods. The axles are parallel to each other. Each of the axles includes two eccentric sections. The composite wheels are respectively connected to the axles. Each of the composite wheels includes a timing pulley and a multi-ridged pulley coaxially in one piece with the timing pulley. The timing belt is wound around the timing pulleys. The multi-ridged belt is wound around the multi-ridged pulley. The rods are pivotally connected to the eccentric sections of the axles.

A belt tensioner having a tensioner base and a tensioning arm axially aligned about a pivot shaft defining a pivot axis, the tensioning arm pivotal in relation to the tensioner base about the pivot axis. The tensioner has a bearing positioned around and sealed against the pivot shaft, with the tensioning arm positioned around the bearing. The bearing forms a radial seal between the bearing and the tensioning arm and between the bearing and the pivot shaft. A torsion spring is positioned externally around a portion of the tensioning arm.

Transmission belt tensioner includes (a) a housing, (b) a set of disc springs, (c) a tensioning arm which is connected to the disc springs for compressing the disc springs upon a movement of the tensioning arm out of a neutral position in a deflection direction (A) relative to the housing. In an embodiment, a second set of disc springs is provided, wherein the tensioning arm is connected to the disc springs of the second set for compressing them upon a movement of the tensioning arm out of a neutral position in an opposite direction (G) to the deflection direction (A).