In an aspect, a tensioner includes a pulley, a main piston chamber, a reservoir, and first and second fluid passageways connecting the main piston chamber and reservoir, a main piston that is movable in the main piston chamber, a check valve, a control valve, and a movable reservoir member. The check valve prevents flow in one direction through the second passageway and permits flow in an opposing direction through the second passageway. The control valve is movable between to provide a first flow resistance, or a second flow resistance. The movable reservoir member is movable based on the amount of fluid in the reservoir in such a way as to change the volume of the reservoir, such that the reservoir, the main piston chamber and the first and second passageways together are included in a fluid circuit that is substantially free of any compressible fluids.

A method for controlling a belt connecting an engine and a hybrid integrated starter and generator (HSG) of a hybrid vehicle includes steps of: driving an engine of the hybrid vehicle; detecting a rotational speed of the engine and a rotational speed of the HSG; and controlling a tension of the belt connecting the engine and the HSG by using the rotational speed of the engine and the rotational speed of the HSG.

In an aspect, an endless drive arrangement for an engine is provided and includes a crankshaft pulley that is drivable by a crankshaft of the engine, a secondary motive device that is operable to drive a secondary motive device pulley; an endless drive member that is engaged with the crankshaft pulley and the secondary motive device pulley, wherein the endless drive arrangement is operable in a first mode in which tension in a first span of the endless drive member is lower tension than a second span of the endless drive member and in a second mode in which tension in the second span of the endless drive member is lower than tension in the first span of the endless drive member; first and second tensioners may move as needed to maintain tension in first and second spans of the belt.

A tensioner device for a belt or chain defines a housing defining a bore with a plunger disposed in the bore. A spring is engaged with the plunger for biasing the plunger in an outward direction. The housing further includes an oil chamber connected to an oil passage in communication with the oil chamber for delivering pressurized oil to the oil chamber, wherein when the oil chamber is pressurized the pressurized oil applies a counter force opposing a force of the spring.

A tensioner for a start-stop accessory drive comprises a movable support, a pulley carried by the support to contact a belt of the drive, a spring to load the support so as to tension the belt, and an actuator controlled and movable to push said pulley against the belt in one direction by means of a load in parallel and additional with respect to that of the spring and an irreversible device which enables the action of the actuator and prevents a displacement of said support in response to the loads of the belt.

A tensioner comprising a piston slidably received within a piston bore of the housing having a plurality of grooves formed on an outer circumference, the piston forming a first pressure chamber with the piston bore. The tensioner uses a mechanism to remove a sliding pawl or expandable clip from engaging the grooves on the piston, such that the piston can move towards the housing and reduce chain load when fluid pressure is reduced in the first pressure chamber during engine shutdown, but not so much as to leave the chain uncontrolled during engine restart. The mechanism may for example be a fluid biased spool piston which engages the expandable clip or a pawl piston that engages a sliding pawl.

A camshaft-drive tensioner system is disclosed for an internal combustion engine having a camshaft-drive element. The camshaft-drive tensioner system includes a tensioner configured to be energized by a pressurized fluid in order to apply a force to the camshaft-drive element. The camshaft-drive tensioner system also includes a fluid pump configured to supply the pressurized fluid. The camshaft-drive tensioner system additionally includes a controller configured to regulate either volume or pressure of the fluid supplied to the tensioner by the fluid pump to thereby selectively vary the force applied to the camshaft-drive element. An internal combustion engine having such a camshaft-drive tensioner system and a method of selectively varying a force applied to the camshaft-drive element are also disclosed.

A drive system for an agricultural work machine having a primary drive system configured to drive a performance system for performing a crop preparation or handling operation including a fluid motor, a fluid pump and a tensioner system. The fluid motor is configured to produce a drive force and to be driven by a flow of fluid moving through the motor. The fluid pump is operatively connected to the fluid motor and is configured to drive the fluid motor. The tensioner system is operatively connected to the fluid motor and to the fluid pump, wherein the direction of fluid flow through the fluid motor adjusts the application of at least one force applied to a belt in the drive system. The fluid motor is configured to adjust the force applied to the belt by regulating a belt tension in proportion to a torque provided by the fluid motor.