How are screw jacks installed and aligned?

Precision during installation is the key to the service life and reliability of the entire system.

The reliable operation of a screw jack system depends not only on the quality of the individual components, but to a large extent on their correct installation and precise alignment. Errors during installation are among the most frequent causes of increased wear, noise and premature failures. Basic rule: a screw jack is designed to absorb purely axial forces – bending moments and transverse forces caused by misalignment must be avoided at all costs.

The reliability of the system is therefore largely determined by the quality of the integration. A professional installation guideline is a key contribution to long-term, safe operation.

1. Preparation of the mounting surfaces

The basis for precise installation is an appropriately designed machine structure.

• Flatness and parallelism: The mounting surfaces on which the gearbox housings and any pedestal bearings are fastened must be flat, parallel and perpendicular to each other.
• Cleanliness: Surfaces must be cleaned before installation; chips, dirt, paint runs or burrs must not impair the contact and reference surfaces.

2. Installing the gearboxes and connecting elements

For systems with several gearboxes, a systematic approach is essential.

• Positioning the gearboxes: First fasten the screw jacks only loosely to the mounting surfaces in order to retain adjustment options.
• Inserting the connecting shafts: Guide the connecting shafts through the bevel gearboxes and pedestal bearings. The shafts must slide easily, without binding, into the gearbox inputs and bearings.
• Alignment (coaxiality): This is the most critical step: all shafts must lie exactly on one line. Use dial gauges, straightedge measurements or laser alignment to check the positions of gearboxes and bearings and readjust until no significant deviations are detectable.
• Tightening: Only after successful alignment should all fastening screws be tightened evenly and with the specified torque.
• Check for smooth running: The complete shaft train must then be able to be turned uniformly and smoothly by hand (without motor). Noticeable stiffness or “notchy” spots indicate stresses in the system that must be eliminated before commissioning.

3. Attaching the load

• Axial load introduction: The load must be attached to the screw or travelling nut in such a way that the force is introduced purely axially and centrally. Eccentric load introduction generates bending moments and increases wear on screw and nut.
• Anti-rotation device: For translating screw versions, the load itself or an external guide must prevent the screw from rotating. Without an anti-rotation device, no lifting motion will take place.
• External guides: If transverse forces act on the load, they must be absorbed by a separate linear guiding system (e.g. rail guides). The screw jack may only provide the lifting force and must not be used as a guiding element.

Careful, stress-free installation is an investment that pays off through quiet, reliable and long-lasting operation of the screw jack system – and sustainably safeguards the performance of the entire drive.