In an embodiment, a tensioning apparatus includes a housing and a fastener extending at least partially through the housing. The apparatus also includes a trolley adjustably positioned within the housing about the fastener. The apparatus also includes a pulley disposed outside the housing and coupled to the trolley, where the pulley moves in unison with the trolley along an opening in the housing.

In an embodiment, a tensioning apparatus includes a housing and a fastener extending at least partially through the housing. The apparatus also includes a trolley adjustably positioned within the housing about the fastener. The apparatus also includes a pulley disposed outside the housing and coupled to the trolley, where the pulley moves in unison with the trolley along an opening in the housing.

A saw apparatus includes a guide bar, a chain driver, and an endless cutting chain trained about the guide bar and the chain driver. A hydraulic chain tensioning apparatus has a hydraulic actuator configured to be driven by a hydraulic power source to act against the guide bar to maintain tension in the cutting chain. A tension release valve is provided between the hydraulic power source and the hydraulic actuator. The tension release valve has a check valve, and a manual override press-button configured to maintain the check valve in an open condition while depressed. The tension release valve has a spring detent configured to maintain the manual override press-button in a depressed condition until selectively released.

A saw apparatus includes a guide bar, a chain driver, and an endless cutting chain trained about the guide bar and the chain driver. A hydraulic chain tensioning apparatus has a hydraulic actuator configured to be driven by a hydraulic power source to act against the guide bar to maintain tension in the cutting chain. A tension release valve is provided between the hydraulic power source and the hydraulic actuator. The tension release valve has a check valve, and a manual override press-button configured to maintain the check valve in an open condition while depressed. The tension release valve has a spring detent configured to maintain the manual override press-button in a depressed condition until selectively released.

A pulley stopper including: a clamp portion that includes a bar-shaped upper clamp and a bar-shaped lower clamp; and a pair of fasteners that are disposed at opposite ends of the clamp portion to couple the upper clamp and the lower clamp. The pair of fasteners and the clamp portion are coupled such that the upper clamp and the lower clamp are fixed side by side through the coupling of the fastener and the movement of a belt disposed between the upper clamp and the lower clamp is stopped.

A pulley stopper including: a clamp portion that includes a bar-shaped upper clamp and a bar-shaped lower clamp; and a pair of fasteners that are disposed at opposite ends of the clamp portion to couple the upper clamp and the lower clamp. The pair of fasteners and the clamp portion are coupled such that the upper clamp and the lower clamp are fixed side by side through the coupling of the fastener and the movement of a belt disposed between the upper clamp and the lower clamp is stopped.

An actuator for transmitting an input force in a first direction from an input mechanism to a force in a second direction at an output mechanism. The actuator may be incorporated into a tensioner for tensioning a belt. The device includes a plurality of aligned spherical elements in a curved raceway. The input mechanism transmits force to a first of the series of spherical elements. The spherical elements are substantially incompressible so that the series of spherical elements transmits the force along the curved raceway from the input mechanism to the output mechanism.

An actuator for transmitting an input force in a first direction from an input mechanism to a force in a second direction at an output mechanism. The actuator may be incorporated into a tensioner for tensioning a belt. The device includes a plurality of aligned spherical elements in a curved raceway. The input mechanism transmits force to a first of the series of spherical elements. The spherical elements are substantially incompressible so that the series of spherical elements transmits the force along the curved raceway from the input mechanism to the output mechanism.

A tensioner that has a base adapted to be secured to an engine, and at least one arm hinged to a pin fixed to the base and bearing a pulley adapted to cooperate with a belt of a transmission of the engine, and elastic means for pushing the at least one arm in a direction so as to keep the pulley against the belt. The tensioner has sensor means for acquiring in real time a plurality of data relating to the tensioner to estimate the state of efficiency of the same.

A tensioner that has a base adapted to be secured to an engine, and at least one arm hinged to a pin fixed to the base and bearing a pulley adapted to cooperate with a belt of a transmission of the engine, and elastic means for pushing the at least one arm in a direction so as to keep the pulley against the belt. The tensioner has sensor means for acquiring in real time a plurality of data relating to the tensioner to estimate the state of efficiency of the same.