A tensioner is disclosed. The tensioner includes an arm, a tong, and a clutch. The arm is rotatable about a first axis in an opposite direction. The arm includes at least one stopping element. The tong is selectively engaged with the at least one stopping element of the arm. The arm is substantially prevented from rotating in the opposite direction if the tong is engaged with the at least one stopping element. The clutch is operatively coupled to the arm. The clutch includes an engaged and a disengaged position. If the clutch is in the engaged position, then the tong is engaged with the at least one stopping element of the arm.

An assembly comprising: a fixed support such as an engine block, a plurality of pulleys mounted rotatably on the support a belt mounted on said pulleys a tensioner comprising: a plate a rotary element mounted on the plate via a rotating shaft fixed relative to said plate, the tensioner being capable of turning relative to the support, in a predefined direction of rotation, between an idle position in which the rotary element is separated from the belt and an operating position in which the rotary element is in contact with the belt, it being specified that, in the operating position, the belt exerts a force on the rotary element, the direction of said force tending to rotate the tensioner in said same predefined direction of rotation; at least one stop for preventing the tensioner from rotating in the predefined direction of rotation beyond the operating position of same, the latter thus being defined by the stop; wherein in order to rotate the tensioner relative to the support between the idle position and the operating position of the tensioner, the assembly comprises: at least one closed port arranged on the plate of the tensioner or on the support at least one means for engaging with the or each closed port, said engaging means being fixed relative to the support when the closed port is located on the plate or fixed relative to the plate when the closed port is located on the support.

A tension control mechanism includes a drive wheel and a jack wheel rotatably mounted with respect to a chassis of a self-propelled power tool. An idler arm is pivotally mounted to the chassis and carries an idler wheel. A flexible drive member entrains the drive wheel and the jack wheel and drives the idler wheel. First and second bias members bias the idler arm in opposing rotational directions, which move the idler wheel toward or away from the flexible drive member to respectively increase or decrease tension. A ratchet arm is attached to the idler arm has a hook. A ratchet head is fixed to the chassis and has ratchet teeth for engaging the hook to permit relative motion between the hook and the ratchet teeth to increase tension, and to limit relative motion between the hook and the ratchet teeth to prevent an excessive decrease in tension.

A tension roller assembly includes a tension roller, a pivotable support arm, a tension arm, a compression spring, a rod, first and second spring stops, a mounting plate, and an overcenter assembly connected to an end of the tension arm. The overcenter assembly connects the tension arm to the mounting plate. The overcenter assembly is configured to make a pivoting movement over a pivot trajectory between engaged and disengaged positions. The overcenter assembly further has a center position located between the engaged and disengaged positions. The pivot trajectory between the center position and the disengaged position is divided into a tensioned section in which the end stop does not engage the stop surface and the spring exerts a force on the overcenter assembly, and a free-moving section in which the end stop engages the stop surface and the spring does not exert any force on the overcenter assembly.

In an aspect, a tensioner for an endless drive member, comprising a shaft and base that are mountable to be stationary relative to an engine, a tensioner arm that is pivotable relative to the shaft about a tensioner arm axis, a pulley on the tensioner arm rotatable about a pulley axis that is offset from the tensioner arm axis, and that is engageable with an endless drive member, a tensioner spring that is positioned to urge the tensioner arm towards a free arm position, a damping element that engages the tensioner arm and that is engaged by a plurality of axially spaced segments of the tensioner spring.

A tensioner comprising a first pivot arm having a first pulley journalled thereto and engagable with a mounting surface through a first pivot axis, a second pivot arm having a second pulley journalled thereto, the second pivot arm pivotally engaged to the first pivot arm through a second pivot axis, the second pivot axis disposed from the first pivot axis, a biasing member engaged between the first pivot arm and the second pivot arm urging the first pulley toward the second pulley, and the second pivot axis is between the first pulley and the first pivot axis.

A tension roller assembly includes a tension roller, a pivotable support arm, a tension arm, a compression spring, a rod, first and second spring stops, a mounting plate, and an overcenter assembly connected to an end of the tension arm. The overcenter assembly connects the tension arm to the mounting plate. The overcenter assembly is configured to make a pivoting movement over a pivot trajectory between engaged and disengaged positions. The overcenter assembly further has a center position located between the engaged and disengaged positions. The pivot trajectory between the center position and the disengaged position is divided into a tensioned section in which the end stop does not engage the stop surface and the spring exerts a force on the overcenter assembly, and a free-moving section in which the end stop engages the stop surface and the spring does not exert any force on the overcenter assembly.

A tensioner is disclosed. The tensioner includes an arm, a tong, and a clutch. The arm is rotatable about a first axis in an opposite direction. The arm includes at least one stopping element. The tong is selectively engaged with the at least one stopping element of the arm. The arm is substantially prevented from rotating in the opposite direction if the tong is engaged with the at least one stopping element. The clutch is operatively coupled to the arm. The clutch includes an engaged and a disengaged position. If the clutch is in the engaged position, then the tong is engaged with the at least one stopping element of the arm.