Elevator Jacks

A jack is the component of an elevator that moves the hydraulic up and down. In order for this to happen, the jack needs to be pressurized with oil. When the elevator moves down the hydraulic de-pressurizes the jack. 

 There are two types of common jacks used in the elevator business. There are single bottom jacks and double bottom jacks. As you can probably tell, single bottom jacks have only one bottom while the double bottom jacks have an extra bottom. Double bottom jacks began being manufactured after 1971 until about 1989.