A miniature handheld electric traction device including a shell, a power supply part, a power motor, a reduction gear set, a braking part and a winding drum, wherein the power motor, the reduction gear set and the winding drum are arranged in the shell; the power motor is linked with the winding drum through the reduction gear set; a surface of the winding drum is wound with a traction rope; the reduction gear set includes a planetary gear; the sun gear of the planetary gear is coaxial with the winding drum; the power motor or the motor shaft of the power motor is inserted into the inner ring of the winding drum; the motor shaft is linked with the planetary gear.

A miniature handheld electric traction device including a shell, a power supply part, a power motor, a reduction gear set, a braking part and a winding drum, wherein the power motor, the reduction gear set and the winding drum are arranged in the shell; the power motor is linked with the winding drum through the reduction gear set; a surface of the winding drum is wound with a traction rope; the reduction gear set includes a planetary gear; the sun gear of the planetary gear is coaxial with the winding drum; the power motor or the motor shaft of the power motor is inserted into the inner ring of the winding drum; the motor shaft is linked with the planetary gear.

Units for distributing three-phase power to a plurality of chain motors are provided, as are used to raise and suspend production elements such as lighting, sound, video, and scenery. Remote switching and phase reversal of such power are also provided. In the prior art, such switching has been performed by large, heavy contactors inserted between the single power input and its distribution to plural outputs for motors, making the unit difficult to handle and ship. Provided herein are power switching and phase reversal performed by a plurality of parallel such means, reducing the current requirements for each, and thereby the size, weight, and cost of the whole. In some embodiments, the single power input is replaced by a by a cable delivering a plurality of two-phase circuits to the unit which derives the three-phase circuits necessary for chain motors therefrom.

Units for distributing three-phase power to a plurality of chain motors are provided, as are used to raise and suspend production elements such as lighting, sound, video, and scenery. Remote switching and phase reversal of such power are also provided. In the prior art, such switching has been performed by large, heavy contactors inserted between the single power input and its distribution to plural outputs for motors, making the unit difficult to handle and ship. Provided herein are power switching and phase reversal performed by a plurality of parallel such means, reducing the current requirements for each, and thereby the size, weight, and cost of the whole. In some embodiments, the single power input is replaced by a by a cable delivering a plurality of two-phase circuits to the unit which derives the three-phase circuits necessary for chain motors therefrom.

A winch drum is disclosed. In a first aspect, a first set of teeth are positioned around an outer perimeter of a drum. The first set of teeth taper from a first crown to a first base. A second set of teeth are positioned around the outer perimeter of the drum. The second set of teeth taper from a second crown to a second base. The second set of teeth are offset from the first set of teeth such that a gap between the first bases and the second bases forms a sinusoidal channel for a line to follow the first set of teeth and the second set of teeth becomes a guide for the line so that the line can engage the sinusoidal channel. The line follows the sinusoidal channel and each change of direction along the sinusoidal path causes the line to engage by friction with the first bases and the second bases. In a second aspect, the drum includes a trough that follows a sinusoidal path and wherein the trough is narrower at its bottom than at its top.

A winch drum is disclosed. In a first aspect, a first set of teeth are positioned around an outer perimeter of a drum. The first set of teeth taper from a first crown to a first base. A second set of teeth are positioned around the outer perimeter of the drum. The second set of teeth taper from a second crown to a second base. The second set of teeth are offset from the first set of teeth such that a gap between the first bases and the second bases forms a sinusoidal channel for a line to follow the first set of teeth and the second set of teeth becomes a guide for the line so that the line can engage the sinusoidal channel. The line follows the sinusoidal channel and each change of direction along the sinusoidal path causes the line to engage by friction with the first bases and the second bases. In a second aspect, the drum includes a trough that follows a sinusoidal path and wherein the trough is narrower at its bottom than at its top.

Embodiments of the present disclosure describe methods and apparatuses for a load lifting system.

Embodiments of the present disclosure describe methods and apparatuses for a load lifting system.

Various embodiments of the present disclosure provide a parasail-assisted system for launching a fixed-wing aircraft into free flight and for retrieving a fixed-wing aircraft from free flight.

Various embodiments of the present disclosure provide a parasail-assisted system for launching a fixed-wing aircraft into free flight and for retrieving a fixed-wing aircraft from free flight.