Instead of the worm drive systems discussed here, a bevel gear system could be used to convert rotation to linear motion. This would offer greater performance to a machine screw jack due to it producing a rolling contact instead of the sliding contact of worm drive components. It could, nevertheless, come at a greater initial cost and does not cover as higher ratio range as worm drives.
Also referred to as power screws, lead screws come with several different types of thread profile which are suitable for different applications. Acme business 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 lead screw in a machine screw jack would 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 regular.
Ball screw jacks require the thread of the lead screw to possess a profile that allows for the travel of the balls. To improve load distribution and minimise put on, the ball screw monitor has a gothic arch profile.
Reputation 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 the lead screw threads and the worm wheel, there is usually a sizable load carrying capacity. This results in high friction which is certainly detrimental to efficiency but also means the system is much more likely to become self-locking. This low effectiveness means that this kind of screw jacks are more suitable for 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 stage to the appropriate screw jack to end up being selected.
Translating Design Jacks ‘re normally selected. With this style, a driven insight worm acts on an interior worm gear leading to the lifting screw to increase or retract. Operation requires that rotation of the lifting screw be prevented. This rotation it restrained whenever several jacks are tied to the same load.
Keyed Design Jacks are used any moment rotation of the lifting screw isn’t restrained. For example, when you must lift the jack to meet a load. This is one way they work: An integral, set to the jack housing and inserted right into a keyway milled in to 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 duration lifting screw that rotates. Loads are attached to a flanged “traveling” nut that translates up and down the length of the rotating screw. This kind of jack is well suited for applications that cannot support a screw safety tube or that want 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 higher actuation speeds and, due to the low friction, is very durable. However a ball screw jack is not inherently self-locking and, because of its enhanced precision components, the initial outlay is higher. The resulting improved performance however implies this can be offset against smaller sized drive train elements and a significant reduction in the necessary power.