Ball Screw, Trapezoidal Screw or Hydraulic Lifting: How to Choose

Lifting systems are commonly used in AGVs, AMRs, heavy-duty mobile platforms and industrial material-handling equipment to:

• lift racks or pallets;

• adjust platform height;

• raise heavy tooling;

• align with workstations;

• transfer or position loads.

Three common technologies are:

1.ball screw lifting;

2.trapezoidal screw lifting;

3.hydraulic lifting.

All three convert input power into linear lifting motion, but they differ significantly in:

• efficiency;

• positioning capability;

• speed;

• load holding;

• installation envelope;

• maintenance;

• system complexity.

The correct solution should not be selected solely according to a simple load threshold.

The engineering review should include:

• maximum static load;

• dynamic and shock load;

• lifting stroke;

• required speed;

• positioning and synchronisation;

• duty cycle;

• power-off holding;

• available installation space;

• operating environment;

• lifecycle cost.

1. How Do the Three Lifting Technologies Work?

1.1 Ball Screw Lifting

A ball screw uses a screw shaft, recirculating balls and a ball nut to convert motor rotation into linear motion.

The balls roll between the screw and nut raceways, reducing internal friction. Ball screws are commonly selected for applications requiring efficiency, speed, positioning accuracy and repeatability. Selection normally considers axial load, linear velocity, accuracy, life, mounting arrangement, dimensions and environmental conditions.

Typical advantages include:

• high transmission efficiency;

• relatively low input torque;

• good positioning and repeatability;

• suitability for higher speeds and frequent motion;

• straightforward integration with servo motors and encoders;

• smooth controllable movement.

Because of their high efficiency, ball screws are normally backdrivable under load. They should not be relied upon to hold a vertical load without a brake, mechanical lock or other appropriate safety mechanism.

1.2 Trapezoidal Screw Lifting

A trapezoidal screw converts rotary motion into linear motion through sliding contact between the screw thread and nut.

Compared with a ball screw, a trapezoidal screw generally offers:

• a relatively simple structure;

• good robustness;

• tolerance of shock and contamination;

• lower initial cost;

• possible self-locking behaviour with certain low-lead, single-start configurations.

Sliding friction may also result in:

• lower efficiency;

• higher required input torque;

• greater heat generation;

• lower permissible speed and duty cycle;

• nut wear and increasing backlash.

Lead-screw efficiency depends on lead, thread geometry, material, lubrication and load. A lead screw can become backdrivable when its efficiency is sufficiently high. A trapezoidal screw should therefore not automatically be considered self-locking without verification of the specific product and operating condition.

Even where a screw is classified as self-locking, an independent holding system should be considered for safety-critical vertical lifting.

1.3 Hydraulic Lifting

A hydraulic lifting system uses a pump, control valves, hydraulic fluid and a cylinder to generate linear force.

The theoretical extension force can be approximated by:

F = p × A

Where:

• F = cylinder force;

• p = hydraulic pressure;

• A = effective piston area.

Hydraulic actuators provide high force density and are widely used in heavy-duty and high-force applications. Modern self-contained electro-hydraulic actuators can integrate the motor, pump, cylinder, valves and control functions into a compact assembly.

A hydraulic system may also require consideration of:

• power unit and reservoir;

• valves and hoses;

• seals;

• fluid cleanliness;

• temperature;

• load holding;

• leakage management;

• maintenance and diagnostics.

Conventional open-loop hydraulics are not normally selected for high-accuracy multi-position control without additional equipment. However, closed-loop servo-hydraulic systems with position feedback and suitable valves can achieve high positioning and repeatability performance.

2. Key Differences

The table is intended for initial screening only.

3. Load Selection Requires More Than Rated Capacity

The lifting system should be evaluated for:

• static load;

• dynamic load;

• shock load;

• eccentric load;

• side load;

• unequal multi-point loading;

• acceleration and braking forces.

Ball and Trapezoidal Screws

The required axial force may include:

• payload;

• platform and mechanism mass;

• offset centre of gravity;

• guide friction;

• lifting acceleration;

• uneven support-point loading;

• shock factors;

• mechanical efficiency;

• engineering safety margin.

The theoretical input torque can be approximated by:

T ≈ F × L / (2π × η)

Where:

• T = input torque;

• F = axial lifting force;

• L = screw lead per revolution;

• η = screw efficiency.

For the same load and lead, lower efficiency generally requires higher input torque and generates more heat.

A compression-loaded screw must also be checked for:

• screw diameter;

• unsupported length;

• end-support condition;

• column buckling;

• maximum rotational speed;

• critical speed.

Ball-screw selection is an iterative process involving load, speed, accuracy, life, mounting and available space—not a single rated-load decision.

Hydraulic Systems

Hydraulic-cylinder selection should also consider:

• pressure losses;

• seal friction;

• back pressure;

• shock loads;

• piston-rod buckling;

• mounting position;

• load direction.

Long compression-loaded piston rods require buckling and installation-length calculations. Hydraulic-cylinder selection tools therefore include force, stroke, mounting position and buckling length as key inputs.

4. Positioning Accuracy and Repeatability

Ball Screws

Ball screws are commonly selected for:

• controlled lifting height;

• multiple stopping positions;

• repeated lifting cycles;

• servo-motor integration;

• closed-loop automation.

Actual positioning performance depends on:

• screw accuracy class;

• lead error;

• nut preload;

• bearing supports;

• installation alignment;

• structural stiffness;

• thermal expansion;

• encoder and controller performance.

Preload can reduce axial backlash, but may increase friction, torque and heat.

Trapezoidal Screws

Trapezoidal screws are suitable for:

• moderate positioning requirements;

• a limited number of stopping positions;

• low lifting speed;

• simple mechanical systems;

• cost-sensitive equipment.

Backlash may increase as the nut wears.

Performance can be improved through:

• anti-backlash nuts;

• double-nut arrangements;

• position sensors;

• closed-loop control;

• inspection and nut replacement.

Hydraulic Lifting

A conventional open-loop hydraulic system is often suitable for:

• end-position lifting;

• high-force movement;

• applications without strict intermediate-position requirements.

High-accuracy multi-position control may require:

• position feedback;

• proportional or servo valves;

• pressure feedback;

• closed-loop control;

• temperature and fluid-condition compensation.

Advanced servo-hydraulic systems can achieve high accuracy, but system cost and commissioning complexity increase.

5. Lifting Speed and Duty Cycle

Ball Screws

Rolling contact gives ball screws higher efficiency than conventional sliding lead screws and generally makes them more suitable for faster or more frequent motion. Manufacturer data typically shows higher efficiency for ball screws than for lead screws.

High-speed or high-cycle operation still requires verification of:

• critical speed;

• ball recirculation speed;

• bearing temperature;

• lubrication;

• vibration;

• motor continuous torque;

• cycles per hour;

• continuous operating time.

Trapezoidal Screws

Sliding friction generates additional heat.

Important limits may include:

• input speed;

• nut surface velocity;

• operating time per cycle;

• cycles per hour;

• temperature rise;

• lubrication interval.

Trapezoidal screws are typically better suited to low-speed, intermittent motion with relatively long holding periods.

Hydraulic Lifting

Hydraulic systems can provide a wide range of speed and force.

Duty-cycle capability depends on:

• motor and pump sizing;

• reservoir volume;

• oil temperature;

• cooling;

• valve flow;

• hose pressure loss;

• seal temperature;

• holding duration.

Cylinder force alone does not determine whether a hydraulic system can operate continuously.

6. Self-Locking, Power-Off Holding and Safety

Ball Screws

Ball screws should normally be treated as backdrivable.

Vertical lifting applications may require:

• motor brake;

• gearbox input brake;

• mechanical locking pin;

• safety nut;

• fall-prevention mechanism;

• redundant braking;

• power-off holding strategy.

A brake or equivalent holding mechanism is required where a ball screw jack may lower under load.

Trapezoidal Screws

Some low-lead, single-start trapezoidal screws can exhibit self-locking behaviour.

Self-locking depends on:

• lead;

• thread geometry;

• material;

• lubrication;

• wear;

• vibration;

• shock;

• temperature;

• external inertia.

The specific screw and operating condition must be verified.

Safety-critical applications should still use an independent holding mechanism.

Hydraulic Systems

Hydraulic load holding may use:

• pilot-operated check valves;

• counterbalance valves;

• hose-burst valves;

• shut-off valves;

• mechanical locks;

• position monitoring.

The design must address:

• internal leakage and load drift;

• hose failure;

• valve failure;

• seal failure;

• power loss;

• emergency lowering.

The safety strategy should be defined through the complete machine risk assessment.

7. Installation Height, Stroke and Packaging

Screw Lifting Systems

The complete installation envelope includes:

• effective stroke;

• nut length;

• bearing supports;

• safety allowance;

• motor and gearbox;

• protective bellows;

• limit switches;

• service clearance.

For long stroke and low retracted height, consider:

• translating-screw arrangements;

• travelling-nut arrangements;

• hollow-screw designs;

• folded motor arrangements;

• belt or gear transmission;

• multi-stage structures.

The retracted length must be checked separately from the effective lifting stroke.

Hydraulic Lifting

A hydraulic cylinder can provide a compact actuator envelope, but the complete system may include:

• pump;

• motor;

• reservoir;

• valve block;

• hoses;

• filters;

• cooling components;

• maintenance access.

A self-contained electro-hydraulic actuator can reduce external piping and separate power-unit requirements, but the complete envelope must still be sized according to force, stroke, speed and thermal load.

8. Multi-Point Lifting and Synchronisation

AGVs, AMRs and mobile platforms often use two or four lifting points.

Mechanical Screw Synchronisation

Multiple screw jacks can be mechanically linked through:

• drive shafts;

• couplings;

• bevel gearboxes;

• timing belts;

• chains;

• one common motor.

Potential advantages include:

• direct mechanical synchronisation;

• relatively stable support-point relationship after power loss;

• simpler electronic control.

Important considerations include:

• shaft torsion;

• coupling backlash;

• gearbox backlash;

• alignment;

• unequal support loads;

• chassis deformation;

• shaft critical speed.

Electronic Synchronisation

Each lifting point uses an independent motor and position feedback.

Advantages include:

• flexible packaging;

• individual correction of each lifting point;

• monitoring of local load and faults.

The controller must manage:

• encoder error;

• communication delay;

• motor-response differences;

• single-axis failure;

• loss of synchronisation;

• emergency-stop posture.

Hydraulic Synchronisation

Multiple cylinders can be synchronised through:

• flow dividers;

• synchronising valves;

• mechanical linkages;

• position sensors;

• independent proportional valves and closed-loop control.

Equal cylinder dimensions alone do not guarantee long-term synchronisation because load differences, friction, leakage and hose pressure losses affect cylinder movement.

9. Environment, Noise and Cleanliness

Clean Applications

Ball and trapezoidal screw systems can use:

• protective tubes;

• bellows;

• seals;

• controlled lubrication;

• clean-compatible lubricants

to manage contamination.

Where hydraulic leakage is unacceptable, the system requires careful:

• seal design;

• hose protection;

• fluid management;

• leak monitoring;

• containment.

Self-contained hydraulic actuators can reduce external hoses and connection points, but suitability must still be verified for the specific environment.

Noise

System noise may originate from:

• motors;

• gearboxes;

• screw and nut contact;

• hydraulic pumps;

• valve flow;

• structural vibration;

• mounting resonance.

Final noise performance should be tested in the complete machine and duty cycle.

10. Maintenance and Service Life

Ball Screws

Maintenance considerations include:

• lubrication;

• contamination protection;

• bearing condition;

• preload change;

• raceway wear;

• ball recirculation system;

• installation alignment.

Ball-screw life is normally calculated from equivalent axial load, speed, cycles and dynamic load rating.

Trapezoidal Screws

Maintenance considerations include:

• thread lubrication;

• nut wear;

• axial backlash;

• screw surface;

• protective covers;

• support bearings;

• drive transmission.

The sliding nut is a wear component. Backlash, self-locking behaviour and efficiency should be monitored over time.

Hydraulic Systems

Maintenance considerations include:

• fluid cleanliness;

• viscosity and temperature;

• seals;

• filters;

• hoses and fittings;

• valve blocks;

• pump and motor;

• internal and external leakage;

• operating pressure.

Maintainability depends on system integration, hose quantity, diagnostic functions and service access.

11. Energy Consumption and Lifecycle Cost

The lowest purchase price does not always produce the lowest lifecycle cost.

Compare:

• motor or pump power;

• energy per lifting cycle;

• holding energy;

• brakes and safety devices;

• controllers;

• sensors;

• lubrication and hydraulic fluid;

• wear components;

• service labour;

• downtime;

• expected life;

• spare-part availability.

Ball Screws

High efficiency can reduce motor torque and energy consumption, but brakes or locks are usually required for vertical holding.

Trapezoidal Screws

The mechanical and control systems can be simple, but lower efficiency may increase motor size, heat and energy use.

Hydraulic Lifting

High force density is valuable for heavy loads, but complete cost includes the pump, valves, hoses, fluid and service requirements.

Variable-speed pumps and self-contained electro-hydraulic actuators can improve energy efficiency and simplify installation compared with conventional hydraulic layouts.

Which Applications Are Better Suited to Ball Screw Lifting?

Ball screws are generally a strong fit where the application requires:

1. Controlled Lifting Height

Examples include:

• multi-height workstation docking;

• inspection equipment;

• assembly platforms;

• height compensation;

• automated production lines.

2. Frequent Lifting Motion

Low friction can reduce input torque and heat, provided that the screw, bearings, motor and duty cycle are correctly sized.

3. Servo Control

Ball screws integrate effectively with:

• servo motors;

• encoders;

• PLCs;

• motion controllers;

• CANopen or EtherCAT systems.

4. Clean Electrified Systems

Electric screw systems can simplify contamination control where hydraulic fluid is undesirable.

5. High Efficiency in Battery-Powered Vehicles

In an AGV or AMR, lifting efficiency can affect motor size, heat generation and battery runtime.

Which Applications Are Better Suited to Trapezoidal Screw Lifting?

Trapezoidal screws are generally suitable for:

1. Low-Speed Intermittent Lifting

For example:

• a limited number of cycles per hour;

• long holding periods;

• moderate speed;

• fixed or simple lifting positions.

2. Cost-Sensitive Mechanical Systems

The structure is relatively simple and suitable where accuracy and speed requirements are moderate.

3. Robust Equipment

Sliding-thread systems can tolerate shock and contamination, provided that the threads remain protected and lubricated.

4. Applications Seeking Self-Locking Behaviour

Some low-lead trapezoidal screws can be self-locking, but the specific design and operating conditions must be verified.

Which Applications Are Better Suited to Hydraulic Lifting?

Hydraulic lifting is generally a strong fit for:

1. High Force and Heavy Loads

Examples include:

• heavy-duty mobile platforms;

• large tooling;

• dies and fixtures;

• automotive manufacturing equipment;

• steel and heavy machinery;

• shock-intensive handling.

2. High Force Density

A hydraulic cylinder can generate large force from a relatively compact actuator cross-section.

3. Variable or Shock Loads

Hydraulics can tolerate demanding force conditions when the cushioning, valves and safety circuit are properly designed.

4. Machines with an Existing Hydraulic Power Source

Where the vehicle or machine already includes a hydraulic system, additional hydraulic lifting may be easier to integrate.

5. Wide Force and Speed Control

Pumps, valves and feedback can be used to control force, velocity and position.

AGV/AMR Lifting Selection Matrix

Seven Common Lifting-System Selection Mistakes

1. Selecting Only According to Rated Load

Speed, stroke, duty cycle, installation arrangement and safety requirements can lead to different solutions at the same rated load.

2. Assuming a Ball Screw Is Self-Locking

Ball screws are normally backdrivable and require an appropriate load-holding strategy.

3. Assuming Every Trapezoidal Screw Is Self-Locking

Self-locking depends on lead, friction, lubrication, wear and operating load.

4. Comparing Maximum Force Without Duty Cycle

Producing sufficient force for a short period does not mean that the system can operate continuously at the required frequency.

5. Ignoring Screw Buckling

Long compression-loaded screws may be limited by column stability.

6. Evaluating Each Actuator Separately in a Multi-Point System

Synchronisation, chassis stiffness, unequal loading and fault states must be reviewed at system level.

7. Failing to Validate Power-Off and Fault Conditions

Testing should include:

• power loss;

• brake failure;

• sensor failure;

• communication loss;

• single-axis failure;

• emergency stop;

• load-holding performance.

Recommended Lifting-System Selection Process

Step 1: Confirm the Load and Centre of Gravity

Provide:

• platform mass;

• maximum payload;

• centre of gravity;

• eccentric loading;

• shock conditions;

• number of lifting points.

Step 2: Define the Motion Requirements

Provide:

• effective stroke;

• lifting speed;

• acceleration;

• positioning accuracy;

• repeatability;

• cycles per hour;

• daily operating time.

Step 3: Confirm the Installation Envelope

Review:

• retracted height;

• maximum extended height;

• available length, width and height;

• motor and gearbox space;

• hydraulic power-unit and hose space;

• maintenance access.

Step 4: Define the Safety and Holding Strategy

Confirm:

• power-off holding;

• personnel access;

• permissible load drift;

• mechanical locking;

• emergency lowering;

• redundant braking.

Step 5: Compare Candidate Systems

Evaluate:

• force;

• speed;

• accuracy;

• duty cycle;

• energy use;

• noise;

• maintenance;

• initial cost;

• lifecycle cost.

Step 6: Validate the Prototype

Test:

• unloaded and fully loaded lifting;

• eccentric load;

• maximum stroke;

• lifting speed;

• positioning repeatability;

• temperature rise;

• noise;

• synchronisation;

• power-off holding;

• endurance;

• fault conditions.

Lifting-System Selection Checklist

Conclusion

Ball screw, trapezoidal screw and hydraulic lifting systems each have distinct advantages.

Ball screw lifting is generally suitable for:

• high efficiency;

• accurate positioning;

• frequent lifting;

• servo control;

• electrified AGVs and AMRs;

• applications sensitive to hydraulic fluid.

Trapezoidal screw lifting is generally suitable for:

• low-speed intermittent operation;

• simple structures;

• cost-sensitive equipment;

• moderate positioning requirements;

• applications seeking verified self-locking behaviour.

Hydraulic lifting is generally suitable for:

• high force;

• heavy loads;

• shock conditions;

• high force density;

• machines with an existing hydraulic power source.

The final selection should evaluate:

• load and centre of gravity;

• stroke and retracted height;

• speed and duty cycle;

• positioning and synchronisation;

• power-off holding;

• environment;

• maintenance capability;

• lifecycle cost.

Need Support Selecting a Lifting Solution?

Please provide:

• load;

• stroke;

• lifting speed;

• installation envelope;

• duty cycle;

• positioning requirements;

• load-holding requirements;

• estimated quantity.

The JY ROBOT engineering team can help compare ball screw, trapezoidal screw and hydraulic lifting solutions and identify an appropriate product series and configuration.

Request a Lifting Application Review >>‍‍

Frequently Asked Questions

Can a ball screw lifting system hold the load after power loss?

A ball screw should not normally be relied upon for self-locking. A motor brake, gearbox brake, mechanical lock or fall-prevention mechanism should be selected according to the risk assessment.

Is every trapezoidal screw self-locking?

No. Self-locking depends on lead, thread geometry, friction, materials, lubrication, wear and actual load.

Is hydraulic lifting always less accurate?

No. Conventional open-loop hydraulics have limited intermediate-position control, but closed-loop systems using position sensors and proportional or servo valves can achieve high positioning and repeatability.

Must every heavy-duty lifting system use hydraulics?

No. Large ball screws, trapezoidal screws and other electromechanical actuators can also carry high loads. Stroke, speed, duty cycle, installation space and safety requirements must be considered.

How can multiple screw jacks be synchronised?

They can be mechanically connected through shafts, gearboxes, belts or chains, or electronically synchronised using individual motors, encoders and a motion controller.

Which lasts longer: a ball screw or a trapezoidal screw?

Service life cannot be determined from screw type alone. It depends on load, speed, lubrication, contamination, alignment, duty cycle and maintenance.