Load Lifting Devices, Self-Locking, Mating Worm, Worm Pair System
In most of the load lifting devices it is necessary to use a pair of two identical or different parts for the motion transmission. In most of the devices the pairs used are worm-gear, belt-pulley, rope-pulley, chain-pulley etc. The selection of appropriate pair depends on parameters such as space requirement, type of load to be handled, desired efficiency of the system. In Most of the cases the worm-gear pair is used due to its advantages over other systems such as higher efficiency, compactness and simple construction. It also exhibits the self-locking ability which allows the input member (gear) to rotate the output member (worm) in either directions but it does not allow the output member to rotate the input member when the driving force on input member is suddenly reduced. This self-locking ability is also useful for the safety of operators working in the vicinity of this system. It prevents the probable accidents due to falling of lifted load when the driving force on the input member is removed or suddenly released. This paper is focused on the study of probable alternative methods for the conventional worm and gear system to achieve better efficiency and simplicity. The self-locking ability can also be obtained with help of worm pair system. So our paper comprises of the various uses of self-locking ability of mating worm pair system. In our paper various systems are studied in which the self-locking ability of worm pair system is used.