As opposed to the worm drive systems discussed here, a bevel equipment system could possibly be used to convert rotation to linear movement. This would offer greater effectiveness to a machine screw jack because of it producing a rolling contact as opposed to the sliding contact of worm drive elements. It could, however, come at a larger initial cost and will not cover as greater ratio range as worm drives.
Also referred to as power screws, lead screws include several different types of thread profile which are ideal for different applications. Acme business lead screws are defined by their trapezoidal thread profile and 29° flank angle and are commonly within 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 position and complies to an ISO metric regular.
Ball screw jacks require the thread of the lead screw to get a profile that allows for the travel of the balls. To improve load distribution and minimise use, the ball screw track includes a gothic arch profile.
Popularity of the trapezoidal screw thread originates from the fact that it is easier to machine and is therefore less expensive than square and ball screw thread forms. Additionally, because of the large area of contact between the business lead screw threads and the worm wheel, there is certainly a large load carrying capability. This results in high friction which is definitely harmful to efficiency but does mean the system is more likely to become self-locking. This low efficiency means that this kind of screw jacks are more suitable for noncontinuous or intermittent operation.
Many applications usually do not warrant the excess expenditure of a ball screw jack since they usually do not require continual drive. In configuring a screw jack a prediction is constructed of the frequency of actuation which will stage to the correct screw jack to be selected.
Translating Design Jacks are most often selected. With this design, a driven input worm functions 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 several jacks are linked with the same load.
Keyed Style Jacks are used any time rotation of the lifting screw isn’t restrained. For instance, when you must lift the jack to meet a load. This is how they work: A key, set to the jack housing and inserted right 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 attached to a flanged “touring” nut that translates along the distance of the rotating screw. This type of jack is ideal for applications that cannot accommodate 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 technique offers greater performance between the input and the useful result weighed against a machine screw jack. Furthermore, it allows for greater actuation speeds and, due to 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 screw jack china resulting improved efficiency however implies this is often offset against smaller drive train components and a significant reduction in the necessary power.