As opposed to the worm drive systems discussed here, a bevel equipment system could possibly be used to convert rotation to linear motion. This would offer greater performance to a machine screw jack because of it producing a rolling contact instead of the sliding contact of worm drive parts. It could, nevertheless, come at a larger initial cost and will not cover as higher ratio range as worm drives.
Also known as power screws, lead screws include a number of different types of thread profile which are suitable for different applications. Acme business lead screws are described by their trapezoidal thread profile and 29° flank angle and are commonly within American Imperial machine screw jacks. An alternative solution to the Acme business lead screw in a machine screw jack will be a square lead screw.
European or other worldwide screw jacks utilise a trapezoidal lead screw with a 30° flank position and complies to an ISO metric standard.
Ball screw jacks require the thread of the lead screw to possess a profile that allows for the travel of the balls. To enhance load distribution and minimise put on, the ball screw monitor includes a gothic arch profile.
Reputation of the trapezoidal screw thread originates from the fact that it is easier to machine and is therefore more economical than sq . and ball screw thread forms. Additionally, because of the large region of contact between the business lead screw threads and the worm wheel, there can be a sizable load carrying capability. This outcomes in high friction which can be detrimental to efficiency but also means the system is much more likely to end up being self-locking. This low efficiency means that such screw jacks are more suitable for non-continuous or intermittent operation.
Many applications usually do not warrant the extra expenditure of a ball screw jack given that they usually do not require continual drive. In configuring a screw jack a prediction is made of the frequency of actuation and this will stage to the appropriate screw jack to become selected.
Translating Design Jacks are most often selected. With this design, a driven input worm works on an interior worm gear leading to the lifting screw to increase or retract. Operation needs that rotation of the lifting screw end up being prevented. This rotation it restrained whenever two or more jacks are tied to the same load.
Keyed Design Jacks are utilized any moment rotation of the lifting screw isn’t restrained. For instance, when you must lift the jack to meet a load. This is one way they work: A key, fixed to the jack housing and inserted into a keyway milled into the length of the lifting screw forces the lifting screw to translate without rotating.
Keyed For Travelign Nut Style Jacks (KFTN) are another choice. These jacks have a fixed size lifting screw that rotates. Loads are mounted on a flanged “traveling” nut that translates along the length of the rotating screw. This kind of jack is ideal for applications that cannot support a screw protection tube or that require a flush mount
The worm wheel acts on the ball screw (via the ball nut) which actuates the lead screw. This system offers greater efficiency between the insight and the useful output compared with a machine screw jack. Furthermore, it allows for higher actuation speeds and, because of the low friction, is very durable. However a ball screw jack isn’t inherently self-locking and, because of its improved precision components, the initial outlay is greater. The resulting improved effectiveness however implies this could be offset against smaller drive train parts and a significant decrease in the necessary power.