As opposed to the worm drive systems discussed here, a bevel gear system could be used to convert rotation to linear motion. This would offer greater efficiency to a machine screw jack because of it making a rolling contact instead of the sliding contact of worm drive elements. It could, however, come at a greater initial cost and does not cover as greater ratio range as worm drives.
Also referred to as power screws, lead screws come with a number of different types of thread profile which are ideal for different applications. Acme lead screws are defined by their trapezoidal thread profile and 29° flank position and are commonly found in American Imperial machine screw jacks. An alternative to the Acme business lead screw in a machine screw jack will be a square lead screw.
European or other international screw jacks utilise a trapezoidal lead screw with a 30° flank angle and complies to an ISO metric standard.
Ball screw jacks require the thread of the business lead screw to possess a profile which allows for the travel of the balls. To enhance load distribution and minimise put on, the ball screw monitor has a gothic arch profile.
Popularity of the trapezoidal screw thread comes from the fact that it’s easier to machine and is therefore more economical than square and ball screw thread forms. Additionally, because of the large region of contact between your lead screw threads and the worm wheel, there is certainly a sizable load carrying capability. This results in high friction which is detrimental to efficiency but does mean the system is much more likely to be self-locking. This low efficiency implies that this kind of screw jacks are more suited to non-continuous or intermittent operation.
Many applications usually do not warrant the excess expenditure of a ball screw jack given that they do not require continual drive. In configuring a screw jack a prediction is constructed of the frequency of actuation which will point to the correct screw jack to be selected.
Translating Design Jacks are most often selected. With this style, a driven insight worm functions on an internal worm gear leading to the lifting screw to extend or retract. Operation needs that rotation of the lifting screw end up being prevented. This rotation it restrained whenever several jacks are linked with the same load.
Keyed Style Jacks are used any moment rotation of the lifting screw isn’t restrained. For example, when you must lift the jack to meet up a load. This is how they work: An integral, fixed to the jack housing and inserted into a keyway milled in to the amount of the lifting screw forces the lifting screw to translate without rotating.
Keyed For Travelign Nut Style Jacks (KFTN) are another option. These jacks have a fixed size lifting screw that rotates. Loads are mounted on a flanged “journeying” nut that translates up and down the space of the rotating screw. This kind of jack is ideal for applications that cannot support a screw safety tube or that require a flush mount
The worm wheel acts on your golf ball screw (via the ball nut) which actuates the lead screw. This system offers greater efficiency between the input and the useful output weighed against a machine screw jack. Furthermore, it allows for better actuation speeds and, due to the low friction, is quite durable. Nevertheless a ball screw jack is not inherently self-locking and, as a consequence of its enhanced precision components, the original outlay is higher. The resulting improved performance however implies this is often offset against smaller drive train elements and a significant reduction in the necessary power.