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Abstract: A mechanical device or apparatus designed for lifting heavy objects or people is known as hoisting equipment. Structurally it is of diverse nature and may be classified based on the construction and application. In this work a brief introduction to these devices has been presented.
Keywords: Hoisting machines
1.Introduction
Three groups of hoisting equipment's are mainly known as [1-10]:
a. Hoisting Machines: a group of periodic action devices designed as self-lifting gear for hoisting and moving loads.
b. Cranes: a combination of separate hoisting mechanism with a frame structure for lifting and/or moving loads
c. Elevating Equipment: a group of periodic action machine intended for raising loads with guideways
A device or apparatus designed for lifting heavy objects or people. Three groups of hoisting equipment are as follows. These equipment items help to transfer loads to cover a definite area. They are non-continuous operation so risk of beak down is high.
2.Types of hoisting Machinery [11-20]
Jacks-These are directly lifting simple devices suitable for short distance use. Jacks may be categorized as follows:
- Rack and pinion type jack
- Screw jacks
- Lever type jack
- Hydraulic action jack
A)Rack and pinion type jack-They have Significant lifting height as well as ability to operate in vertical and horizontal positions, These have Compact design, excellent ergonomics, ease of operation, High maintainability, Smooth lifting ability and ability to accurately position the load at a certain height. Rotation of handle causes pinion to rotate that in turn causes reciprocating motion of rack (on which load is placed) and hence motion of load.
B)Screw Jack-This jack has a Spindle and nut mechanism. Rotation of nut causes reciprocating motion of spindle on which load is placed and hence lift of it as seen in next figure. Mechanical advantage of a jack may be written as:
(ProQuest: ... denotes formulae omitted.) (1)