A variable pitch pulley includes a rotary shaft, a fixed sheave fixed to the rotary shaft, and a moving sheave forming a belt groove with the fixed sheave. The moving sheave includes an inner sheave and an outer sheave radially stacked on the inner sheave. The pitch pulley further includes a moving sheave-positing unit determining relative positions of the inner and outer sheaves. The inner and outer sheaves are simultaneously moved in an axial direction of the rotary shaft in a first moving mode, and only the outer sheave is moved in the axial direction in a second moving mode.

A gearbox includes: the first helical gear; the second helical gear to engage with the first helical gear; a casing including a first member disposed in proximity to the first helical gear and a second member disposed in proximity to the second helical gear; a screw for fastening the first member with the second member, and disposed closer to the first helical gear than an engagement position between the first helical gear and the second helical gear and penetrating at least the second member; and a clip disposed closer to the second helical gear than the engagement position, and formed of a closed curve in such a manner that the first member end and the second member end are enclosed therein.

Pulley assemblies and associated methods are disclosed. An example pulley assembly may include a first pulley and a second pulley laterally movable relative to the first pulley. The first pulley and the second pulley provide for different drive ratios. The second pulley is movable from a first position in which the second pulley is laterally offset from the first pulley and a second position in which the second pulley is laterally aligned with the first pulley. An endless drive components, such as an endless belt, maintains a constant position whether the endless drive component is engaged with the first pulley or the second pulley located in the second position.

A key pulley segment in a synchronized, segmentally interchanging pulley transmission system is either first or last in a pulley segment set to engage an endless member. The first or last key segment teeth to engage or disengage, respectively, are shortened or completely trimmed, and the adjacent pulley segment to the key segment is elongated such that the inward portion of the tooth profile extends toward the key segment. Shortened tooth or teeth and an elongated adjacent segment together allow for many pulley segments to be designed as key segments. Completely trimmed teeth may be engineered to create a supporting surface for the endless member on the key segment. The elongated adjacent segment may have an extending portion which slidably mates with the supporting surface of the key segment, thereby receiving radial support therefrom. Multiple pulley segments from different pulley segment sets may be connected or constructed to move together in a unified stack, and may be staggered such that any one segment may be in an engaging position with the endless member when the unified stack is moved along the axis of rotation. Unified stacks may have guiding rails on both inner and outer radial surfaces, and the pulley assembly may have mating features that receive such guiding rails. Any number of the pulley segments in a unified stack may be key pulley segments. Pulley segments of a stack may be vertically separated into one or more unified stacks. Unified stacks may be moved by way of a cam or roller cam system, where each unified stack has a slidably or ratably attached roller and roller-arm. Chassis-mounted cams engage the rollers outside of the contact zone, rollers and roller-arms are moved into and out of engagement with the cams, and individual segments of a unified stack are moved into or out of engagement. Rollers may be actuated into and out of engagement by electromagnets, fixable mounted in an array. Rollers may discretely engage with multiple cams, by way of several electromagnet-arrays, and thereby complete several stack axial motions. Electromagnets in an array may be selectively energized to move selected rollers to an active position in order to effect key pulley segment engagement, stack axial movement and transition.

A key pulley segment in a synchronized, segmentally interchanging pulley transmission system is either first or last in a pulley segment set to engage an endless member. The first or last key segment teeth to engage or disengage, respectively, are shortened or completely trimmed, and the adjacent pulley segment to the key segment is elongated such that the inward portion of the tooth profile extends toward the key segment. Shortened tooth or teeth and an elongated adjacent segment together allow for many pulley segments to be designed as key segments. Completely trimmed teeth may be engineered to create a supporting surface for the endless member on the key segment. The elongated adjacent segment may have an extending portion which slidably mates with the supporting surface of the key segment, thereby receiving radial support therefrom. Multiple pulley segments from different pulley segment sets may be connected or constructed to move together in a unified stack, and may be staggered such that any one segment may be in an engaging position with the endless member when the unified stack is moved along the axis of rotation. Unified stacks may have guiding rails on both inner and outer radial surfaces, and the pulley assembly may have mating features that receive such guiding rails. Any number of the pulley segments in a unified stack may be key pulley segments. Pulley segments of a stack may be vertically separated into one or more unified stacks. Unified stacks may be moved by way of a cam or roller cam system, where each unified stack has a slidably or ratably attached roller and roller-arm. Chassis-mounted cams engage the rollers outside of the contact zone, rollers and roller-arms are moved into and out of engagement with the cams, and individual segments of a unified stack are moved into or out of engagement. Rollers may be actuated into and out of engagement by electromagnets, fixable mounted in an array. Rollers may discretely engage with multiple cams, by way of several electromagnet-arrays, and thereby complete several stack axial motions. Electromagnets in an array may be selectively energized to move selected rollers to an active position in order to effect key pulley segment engagement, stack axial movement and transition.

An electromechanical front gear changer for a bicycle is provided, the bicycle having a chain, including a base member attachable to the bicycle. A linkage is movably coupled to the base member. A chain guide is movably coupled to the linkage for contacting the chain. A motor is supported by the base member. A gear transmission is driven by the motor to move the linkage. A CPU is provided for controlling the motor and a power supply is supported by the base member to power the motor and the CPU. A manually operated device is disposed on the electromechanical front gear changer.

An electromechanical front gear changer for a bicycle is provided, the bicycle having a chain, including a base member attachable to the bicycle. A linkage is movably coupled to the base member. A chain guide is movably coupled to the linkage for contacting the chain. A motor is supported by the base member. A gear transmission is driven by the motor to move the linkage. A CPU is provided for controlling the motor and a power supply is supported by the base member to power the motor and the CPU. A manually operated device is disposed on the electromechanical front gear changer.

An electromechanical front gear changer for a bicycle is provided, the bicycle having a chain, including a base member attachable to the bicycle. A linkage is movably coupled to the base member. A chain guide is movably coupled to the linkage for contacting the chain. A motor is supported by the base member. A gear transmission is driven by the motor to move the linkage. A CPU is provided for controlling the motor and a power supply is supported by the base member to power the motor and the CPU. A manually operated device is disposed on the electromechanical front gear changer.

An electromechanical front gear changer for a bicycle is provided, the bicycle having a chain, including a base member attachable to the bicycle. A linkage is movably coupled to the base member. A chain guide is movably coupled to the linkage for contacting the chain. A motor is supported by the base member. A gear transmission is driven by the motor to move the linkage. A CPU is provided for controlling the motor and a power supply is supported by the base member to power the motor and the CPU. A manually operated device is disposed on the electromechanical front gear changer.

Surgical instruments that comprise an axially movable firing member that is configured to be driven between a starting position and an ending position within a surgical end effector of the surgical instrument by an upper an upper chain-drive assembly and a lower chain-drive assembly.