Classroom on demand

Welcome to Classroom on demand, your source for educational materials related to the vertical transportation industry. This site represents the knowledge and expertise of the best engineers and mechanics in the elevator industry, and will help those new to the elevator industry learn about the basic workings of elevator systems, and also will serve as a reference for people with more experience.

Conventional (Multi-Section) Jack

In some cases, conventional jacks can be as much as 75 feet in length. Therefore, it may be impractical or difficult to ship or install these lengthy jacks. The solution is to have multiple jack sections. Only a single stage jack can have multiple sections. The maximum number of sections is four. The cylinder and piston sections are coupled together using factory provided machined threads. (see file 1005-16) During the manufacturing process the steel cylinder and piston are mounted in a lathe and the threads carefully machined.
The jack sections for a single stage jack are manufactured equidistant or equal in length. So, basically, for 30 feet of travel, the most common configuration is two sections of 15 feet. The usual length for a jack section is 14-18 feet. Generally, jack sections do not exceed 20 feet unless the extra length can be accommodated in the field. Now, how would you reach 48 feet of travel if the jack needs to be shipped in sections? Answer: Use three 16 foot sections connected together in the field.

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