Choosing the right screw jack,and hence also its proper functioning,mostly depends on the identification of the real load acting on the screw jack. Loads can be divided in two main groups:staticloads and dynamic loads; these groups are further made-up of: traction loads, compression loads, lateral loads, radial loads, eccentric loads, loads from shocks, loads from vibrations.

STATIC LOADS
A static load is the force that will be applied to the screw jack transmission devices while they are not in motion.

DYNAMIC LOADS
A dynamic load is the force that will be applied to the screw jack transmission devices while they are in motion.

TRACTION LOADS
A traction load is the force applied to the threaded spindle axis with an opposite direction to the casing.

COMPRESSION LOADS
A compression load is a force applied to the threaded spindle axis with the same direction as the casing.

LATERAL LOADS
A lateral load is a force applied perpendicular to the threaded spindle axis.

ECCENTRIC LOADS
An eccentric load is a force whose centre of application does not belong to the threaded spindle axis, even having the same direction.

LOADS FROM SHOCKS
A load from shocks is a load where the impulse forces generated by an impact are not quantifiable.

LOADS FROM VIBRATIONS
A load from vibrations is applied when a shock load increases the impulse frequency.

Depending on the type of load some solution must be applied during the design phase:

STATIC TRACTION LOAD
The maximum applicable load for all models and sizes is shown in the specification tables. Shocks and/or lateral loads limit its applications.

DYNAMIC TRACTION LOAD
The maximum dynamic traction load which can be applied to a screw jack does not only depend on its size: it could be limited by the ambient temperature, service factors and possible lateral loads and/ or shocks. It is thus necessary to check all those parameters.

STATIC COMPRESSION LOAD
The maximum load which can be applied is determined by the length of the threaded spindle as well as by the constraints it undergoes. The limit applicable load can be obtained on the basis of the Euler diagrams. Its application could be limited by possible shocks and/ or lateral loads.

DYNAMIC COMPRESSION LOAD
The maximum compression load which can be applied is determined by many factors: the length of the threaded spindle, the ambient temperature, service factors and possible lateral loads and/or shocks. In addition to all the verifications already foreseen in the case of a traction load, further verifications are necessary relative to the Euler diagrams.

STATIC LATERAL LOAD
This kind of load induces a lateral shifting of the threaded spindle causing a damaging bending which limits the ability of the screw jack. Suitable graphs show the maximum lateral load values according to the length and size of the threaded spindle. For any further and more detailed verifications our technical office is at your disposal.

DYNAMIC LATERAL LOAD
A lateral load in dynamic applications is not allowed. In case of essential use of screw jacks with lateral load is for machine requirements, it will be necessary to contact our technical office.

ECCENTRIC STATIC LOAD
An eccentric load in static applications induces the same problems as the lateral loads. For this reason the above considerations are also applicable to this kind of load.

DYNAMIC ECCENTRIC LOAD
In case of handling an eccentric load, in order to avoid problems due to lateral load, it is necessary to create a suitably guided and sized mechanical structure, in order to absorb all the lateral components of the load. The guide must be realized very carefully: too narrow backlashes could cause seizure and stick-slips, while too rough backlashes would make useless the construction of the guide itself.

STATIC LOAD FROM VIBRATIONS OR SHOCKS
A load from vibrations or from shock, if not very heavy, could be the only reasons for the reversibilityof the transmission moved by the screw jack. In that case it is advisable to contact our technical office in order to verify the screw jack applicability.

DYNAMIC LOAD FROM VIBRATIONS OR SHOCKS
A dynamic load from vibrations or from shock can be damaging for the screw jack: stick-slip phenomena and consequent local overloads can enormously increase the wear conditions. It is necessary to minimize the shocks entity and the vibrations width.