To provide a tensioner capable of preventing slipping between a rack portion and ratchet pawls and securing a large backlash with a simple structure. The tensioner includes a ratchet rotatably mounted on a housing and having a front pawl and a rear pawl spaced apart in a front and rear direction on a side face positioned opposite the rack portion. The ratchet includes an additional pawl formed between the front pawl and the rear pawl in the front and rear direction on the side face positioned opposite the rack portion.

To provide a tensioner unit, a rocking lever, and a tensioner, which, prevent breakage of the tensioner in use for a prolonged period of time. A protruding part is provided to a rocking lever near an abutment surface for abutment with a plunger to make contact with a tensioner body. h and H satisfy the relationship of h<H, where h denotes a protruding amount of a lead part of the plunger, where the lead part means a part protruding from the plunger bore, from a tip end surface on an opened side of the tensioner body in a state where the plunger sits on a bottom of the plunger bore, and H denotes an interval between the abutment surface of the rocking lever and the tip end surface of the tensioner body when the protruding part is brought into contact with the tensioner body.

The tensioning pulley arrangement for a belt drive in an engine, is provided. In one example, the tensioning pulley arrangement includes a first tensioning pulley and a second tensioning pulley tensioning a belt with a spring force and a spring preload force generated by a first spring device coupled to the first and second tensioning pulleys. The tensioning pulley arrangement further includes an intensifying device that decreases belt tension during low belt load conditions and increases belt tension during high belt load conditions. In this way, friction losses during low belt loads may be reduced and belt slippage caused by high belt loads and/or dynamic shifts in belt loads may also be reduced.

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.

An object of the present invention is to provide a chain tensioner which enables operations on an elastic ring member during assembly and maintenance work to be readily performed and which is capable of eliminating protrusion of an operating portion of the elastic ring member in a direction opposite to a mounting surface, with a simple configuration. A ring holding portion 112 provided on an open side of a plunger housing hole 111 includes a pressing projection 113 and a restricting portion 114 which restrict rotation of the elastic ring member 130 and which oppose both outer sides of a pair of operating portions 132 of the elastic ring member 130 in a circumferential direction, and the pressing projection 113 is arranged at a position closer to a mounting surface 115 than the restricting portion 114.

An object of the present invention is to provide a tensioner that has a reduced number of components and lighter weight and is easy to assemble. The tensioner according to the present invention is configured such that a base member is detachably and mechanically joined to a rear end opening of a cylindrical plunger with a closed front end against the resilience of biasing means that is accommodated inside the plunger such as to be freely extend and contract. The joint between the plunger and the base member is a mechanical connection that is one of a thread engagement, a press-fit, and a pin connection.

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.

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.

To provide a tensioner capable of preventing slipping between a rack portion and ratchet pawls and securing a large backlash with a simple structure. The tensioner includes a ratchet rotatably mounted on a housing and having a front pawl and a rear pawl spaced apart in a front and rear direction on a side face positioned opposite the rack portion. The ratchet includes an additional pawl formed between the front pawl and the rear pawl in the front and rear direction on the side face positioned opposite the rack portion.

An air-cooled heat exchanger has a frame assembly, a plenum supported by the frame assembly, an engine and a fan assembly. The engine includes a drive shaft and the fan assembly includes a fan connected to a fan shaft. The fan assembly is configured to move air through the plenum. The air-cooled heat exchanger also includes a drive assembly connected between the engine and the fan assembly. The drive assembly has a fan shaft sheave connected to the fan shaft, a driver sheave connected to the drive shaft, an idler pulley, and a drive belt in contact with the fan shaft sheave, driver sheave and idler pulley. The air-cooled heat exchanger has an idler bearing adjustment mechanism that is configured to adjust tension on the drive belt by adjusting the position of the idler pulley relative to the drive belt.