How do I choose the right screw jack? (Checklist)

A systematic process that ensures all critical parameters of your application are taken into account. Selecting the right screw jack is a multi-stage engineering process in which parameters interact with each other (for example, higher speed reduces the buckling safety margin). This guide leads you through all steps in a structured way – from load to the safety concept – and serves as a working document for design, comparison and documentation. The selection process: Step by step to the optimum gearbox Note on use: Enter your application data in the table and tick off each check/decision. For borderline cases, design conservatively (safety factors) and also evaluate system effects (shafts, couplings, guides, bearings). Step Parameter Check / decision Load & force Maximum load (kN) static/dynamic Rated load > maximum load; safety factor ≥ +30% static, ≥ +10% dynamic Direction of load compression/tension/both For compression: Buckling verification required Side loads Avoid; provide external guides Motion Speed (mm/s) Determines speed/screw pitch; n_operating ≤ 0.8·n_crit Stroke (mm) Long stroke ↑ → check buckling risk/n_crit; if necessary, larger screw/size Operation Duty cycle (ED %/h) Check thermal behaviour; > 20–30% → ball screw / larger size / cooling strategy Positioning accuracy (mm) Standard vs. low-backlash (TR) / preloaded (KGT) System & type Screw type TR/KGT TR = self-locking; KGT = dynamics/efficiency, brake for holding Version basic/travelling nut Select according to installation space/load connection Mounting Kubisches Gehäuse, Konsolen/Flansche passend zur Konstruktion ausSelect suitable cubic housing, brackets/flanges Environment Temperature/humidity/contamination/chemicals Material, seals, lubricant; bellows if necessary Safety Safety factors Document; be conservative for lifting people/loads Buckling load Euler/Tetmajer, target SF 3–6 Critical speed n_operating ≤ 80% n_crit Holding/self-locking TR may be (statically/dynamically) self-locking; KGT with motor brake Functional safety Limit switches/encoder, overload/crush protection, emergency stop ZIMM practical notes (for the concrete selection) Series selection: ZE/ZE-H/GSZ (screw jacks) depending on load/stroke/ED; ZA (actuators) for compact linear drives; KSZ-H/KST for 90° deflection and power distribution in multi-point systems. Play & stiffness: TR with low-backlash/adjustable nut = robust & self-locking; KGT with preload = backlash-free & stiff (plan brake for holding). Thermal behaviour (ED): High ED → larger size, ball screw, optimised lubrication, if necessary adapted operating cycles/cooling. System integration: Suitable connecting shafts/couplings/brackets from the ZIMM modular system for precise alignment and smooth running. Documentation: Load assumptions, calculations (buckling, n_crit), ED verification, safety considerations, assembly/test records. Short conclusion Once load, speed, stroke, ED, environment and safety have been systematically checked, the final selection of gearbox, motor, transmission (bevel gearboxes, shafts, couplings) and accessories follows. This way you avoid incorrect designs and maximise service life and operational safety.

Selecting the right screw jack: the checklist

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Author:

Florian Wenger | Team Leader Marketing & Online

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A systematic process that ensures all critical parameters of your application are taken into account.

Selecting the right screw jack is a multi-stage engineering process in which parameters interact with each other (for example, higher speed reduces the buckling safety margin). This guide leads you through all steps in a structured way – from load to the safety concept – and serves as a working document for design, comparison and documentation.

The selection process: Step by step to the optimum gearbox

Note on use: Enter your application data in the table and tick off each check/decision. For borderline cases, design conservatively (safety factors) and also evaluate system effects (shafts, couplings, guides, bearings).

Step	Parameter	Check / decision
Load & force	Maximum load (kN) static/dynamic	Rated load > maximum load; safety factor ≥ +30% static, ≥ +10% dynamic
	Direction of load compression/tension/both	For compression: Buckling verification required
	Side loads	Avoid; provide external guides
Motion	Speed (mm/s)	Determines speed/screw pitch; n_operating ≤ 0.8·n_crit
	Stroke (mm)	Long stroke ↑ → check buckling risk/n_crit; if necessary, larger screw/size
Operation	Duty cycle (ED %/h)	Check thermal behaviour; > 20–30% → ball screw / larger size / cooling strategy
	Positioning accuracy (mm)	Standard vs. low-backlash (TR) / preloaded (KGT)
System & type	Screw type TR/KGT	TR = self-locking; KGT = dynamics/efficiency, brake for holding
	Version basic/travelling nut	Select according to installation space/load connection
	Mounting	Kubisches Gehäuse, Konsolen/Flansche passend zur Konstruktion ausSelect suitable cubic housing, brackets/flanges
Environment	Temperature/humidity/contamination/chemicals	Material, seals, lubricant; bellows if necessary
Safety	Safety factors	Document; be conservative for lifting people/loads
	Buckling load	Euler/Tetmajer, target SF 3–6
	Critical speed	n_operating ≤ 80% n_crit
	Holding/self-locking	TR may be (statically/dynamically) self-locking; KGT with motor brake
	Functional safety	Limit switches/encoder, overload/crush protection, emergency stop

ZIMM practical notes (for the concrete selection)

Series selection: ZE/ZE-H/GSZ (screw jacks) depending on load/stroke/ED; ZA (actuators) for compact linear drives; KSZ-H/KST for 90° deflection and power distribution in multi-point systems.
Play & stiffness: TR with low-backlash/adjustable nut = robust & self-locking; KGT with preload = backlash-free & stiff (plan brake for holding).
Thermal behaviour (ED): High ED → larger size, ball screw, optimised lubrication, if necessary adapted operating cycles/cooling.
System integration: Suitable connecting shafts/couplings/brackets from the ZIMM modular system for precise alignment and smooth running.
Documentation: Load assumptions, calculations (buckling, n_crit), ED verification, safety considerations, assembly/test records.

Short conclusion

Once load, speed, stroke, ED, environment and safety have been systematically checked, the final selection of gearbox, motor, transmission (bevel gearboxes, shafts, couplings) and accessories follows. This way you avoid incorrect designs and maximise service life and operational safety.

Florian Wenger | Team Leader Marketing & Online

Florian Wenger leads the Marketing & Online team at ZIMM. He is responsible for the digital brand presence, the website, as well as product-related content on screw jacks, electromechanical actuators, and drive technology – including SEO/SEA, web analytics, and consistent terminology across all channels.

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