Twist turns cylinder into variable-pitch screw

April 5, 2001
Amir Ziv-av, an inventor with Ziv-Av Engineering Ltd., Or-Yehuda, Israel, had developed a bidirectional (right or left-handed threads), variable-pitch screw with applications in mechanical and mechatronic devices.

The design starts with a thin-walled, flexible cylinder with "zero-pitch" threads. The threads basically form ridges around the cylinder. A longitudinal slit along the cylinder's entire length lets users apply a slight torque that realigns the ridges into right or left-handed threads, depending on the direction of the torque. Additional torque changes the thread from a single to a double.

The screw can be used with a locking nut that has teeth spanning a small arc on one side of the nut. This prevents the pitch from changing while the teeth of the nut lie across the slit in the screw cylinder. Alternatively, a nut with a slit similar to the cylinder's and with ridges or threads lining the hole can be used to lock the screw in place.

Possible applications for the variable-pitch screw include use as a bidirectional motion screw driven by a unidirectional power source such as a water or wind-driven turbine, or in a reversible screw conveyor in which the rotating screw is inserted inside a cylinder. It could also be used as a cable guide in winches to feed cable from side to side onto a spool. Such a device would cause less wear and be simpler than "moving-window" mechanisms found on conventional winches.

Sponsored Recommendations

The entire spectrum of drive technology

June 5, 2024
Read exciting stories about all aspects of maxon drive technology in our magazine.

MONITORING RELAYS — TYPES AND APPLICATIONS

May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

Solenoid Valve Mechanics: Understanding Force Balance Equations

May 13, 2024
When evaluating a solenoid valve for a particular application, it is important to ensure that the valve can both remain in state and transition between its de-energized and fully...

Solenoid Valve Basics: What They Are, What They Do, and How They Work

May 13, 2024
A solenoid valve is an electromechanical device used to control the flow of a liquid or gas. It is comprised of two features: a solenoid and a valve. The solenoid is an electric...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!