A complete technical reference covering every major cylinder category with specifications, selection criteria, and application guidance for engineers, procurement professionals, and system integrators

Types of Cylinders: The Complete Classification and Comparison

Understanding the full landscape of types of cylinders available for industrial motion applications is the essential starting point for selecting the correct actuator for any project. The word "cylinder" in engineering refers to any actuator that produces linear (straight-line) motion by pushing or pulling a rod or plunger, regardless of the energy source. The primary classification of cylinder types is by the energy source used to create force: pneumatic (compressed air), hydraulic (pressurised oil), and electric (motor-driven mechanical conversion). Within the electric category, several important sub-types exist that are increasingly displacing both pneumatic and hydraulic cylinders in precision and safety-critical applications.

Why the Shift from Fluid Power to Electric Cylinders Is Accelerating

Across virtually every sector of manufacturing and industrial automation, the past decade has seen a consistent trend toward replacing pneumatic and hydraulic cylinders with electric alternatives wherever the force and speed requirements permit. This shift is driven by five converging pressures:

• Energy efficiency: A typical compressed air system converts only 8 to 12% of the electrical input energy to useful mechanical work at the cylinder, with the remainder lost to compressor heat, pipe leakage, and pressure drops. An electric linear cylinder system converts 75 to 92% of electrical input to useful mechanical work , making it 7 to 10 times more energy efficient per unit of mechanical output.
• Precision requirements: Modern automation, battery manufacturing, pharmaceutical production, and electronics assembly require position repeatability that pneumatic cylinders cannot deliver without expensive servo pneumatic systems. Electric cylinders provide this precision as a baseline capability without additional cost.
• Cleanliness and contamination: Food processing, medical device manufacturing, and semiconductor production require zero risk of fluid contamination. Pneumatic cylinders exhaust air (which may carry oil mist from lubricated compressors), and hydraulic cylinders carry constant oil contamination risk. Electric cylinders operate completely dry with no fluid in or near the process.
• Data and diagnostics: Industry 4.0 and smart manufacturing require actuators that can report their own health and performance data. Electric cylinders equipped with encoders and force sensors are inherently data-generating devices; pneumatic and basic hydraulic cylinders require extensive additional instrumentation to provide comparable information.
• Reduced infrastructure: Pneumatic systems require a compressor, air dryer, filter-regulator-lubricator units, and a distribution network of pipes. Hydraulic systems require a power unit, oil reservoir, heat exchanger, filtration, and pipe or hose distribution. Electric cylinder systems require only electrical cables and a controller, dramatically reducing installation cost and maintenance burden.

Electric Linear Cylinder and Linear Cylinder: Core Technology and Construction

A linear cylinder is the generic term for any actuator producing linear motion. In the electric domain, the Electric Linear Cylinder is the workhorse of modern precision actuation, converting rotary motor motion into linear rod movement through a mechanical transmission. Understanding the mechanical conversion mechanism is essential because the choice of screw type determines the actuator's efficiency, speed, force, and service life.

Standard Electric Linear Cylinder Specifications and Sizing Parameters

When specifying an Electric Linear Cylinder or linear cylinder for an application, the following parameters must be determined:

• Thrust force (push and pull): The maximum force the cylinder must exert in both extension and retraction directions. For ball screw and roller screw cylinders, push and pull force capacity are typically equal. For lead screw cylinders, pull force capacity may be somewhat less than push force due to column buckling being the limiting factor for long strokes.
• Stroke length: The total distance of rod travel from fully retracted to fully extended. Standard commercial Electric Linear Cylinder products are available in stroke increments of 50 mm up to 2,000 mm or more. Longer strokes require larger screw diameters to prevent buckling and resonance, which increases cost and weight significantly beyond approximately 1,200 mm stroke.
• Speed (extension and retraction): The rate of rod movement in mm/s or m/min. Speed and force are inversely related in an electric cylinder: a given motor power can deliver either high force at low speed or lower force at high speed, following the power equals force multiplied by speed relationship. A cylinder delivering 10 kN at 100 mm/s requires 1,000 watts of mechanical power , which determines the motor size needed.
• Duty cycle: The fraction of time the cylinder is actively moving relative to the total cycle time, expressed as a percentage. A cylinder that extends in 2 seconds, dwells for 8 seconds, and retracts in 2 seconds has a duty cycle of (2 2)/(2 8 2) = 33% . High duty cycle applications generate more heat in the motor and screw mechanism and require derating of the continuous force rating compared to the peak rating. Continuous duty (100%) ratings are typically 50 to 70% of the peak force rating for the same cylinder.
• Mounting and rod end configuration: Linear cylinders are mounted using flange mounts (front or rear), trunnion mounts (pivot about the cylinder midpoint), and clevis mounts (pivot at rear). Rod ends use internal thread (FI or MS thread), external thread, rod eye (clevis), or spherical rod eye (for angular misalignment). The mounting configuration determines whether the cylinder must handle side loads, and side loads require additional anti-rotation guidance (either integrated guide rods or a separate guide system).

Electric Over Hydraulic Cylinder: Combining Hydraulic Force with Electric Control

The electric over hydraulic cylinder (also called an electrohydraulic actuator or self-contained electrohydraulic actuator, SCEHA) is a hybrid technology that integrates an electric motor, a hydraulic pump, a small oil reservoir, and a hydraulic cylinder body into a single self-contained assembly. It delivers the full force density of hydraulic actuation without requiring an external hydraulic power unit (HPU) or a complex hydraulic distribution system. The result is a unit that can be installed anywhere power cables can reach, with the hydraulic system completely sealed and self-contained within the actuator body.

Where Electric Over Hydraulic Cylinders Replace Conventional Hydraulic Systems

The electric over hydraulic cylinder is particularly well-suited to applications where the hydraulic force density is required but the installation of a conventional hydraulic system is impractical, expensive, or creates maintenance burdens that are unacceptable. Key application categories:

• Retrofit upgrades: Replacing the hydraulic power unit and distribution system of an ageing hydraulic machine with an electric over hydraulic cylinder at each cylinder position eliminates the HPU, reduces oil volume from hundreds of litres to a few litres total across all actuators, and removes the risk of systemic hydraulic circuit contamination or failure.
• Offshore and marine applications: Offshore platforms and marine vessels require actuators for hatches, ramps, ballast valves, and stabiliser systems in locations where running hydraulic pipework is expensive, corrosion-prone, and creates serious environmental risk from potential oil spills. The self-contained nature of the electric over hydraulic cylinder eliminates external hydraulic circuit exposure entirely.
• Agricultural and mobile machinery: Tractors, combine harvesters, and other agricultural equipment have limited hydraulic capacity from the vehicle's power take-off hydraulic circuit. Adding auxiliary actuators without overloading the vehicle's hydraulic circuit is solved by specifying electrically powered electric over hydraulic cylinders for the auxiliary functions, leaving the vehicle's primary hydraulic circuit free for its primary functions.
• Stadium and entertainment venue roof and seating systems: Large architectural actuators for retractable roofs, moveable seating platforms, and stage lifts in entertainment venues require very high force but are located where extensive hydraulic pipework would be both expensive and creating unacceptable maintenance access challenges. Self-contained electric over hydraulic cylinders rated to 500 to 2,000 kN are used in these applications.

Heavy Duty Electric Cylinder: High-Force Electric Actuation Replacing Hydraulics

The heavy duty electric cylinder is an electric linear actuator engineered specifically for the high-force, high-duty-cycle, and harsh-environment requirements of heavy industrial applications that have historically been dominated by hydraulic cylinders. By combining a high-power three-phase induction or permanent magnet servo motor with a large-diameter roller screw or ball screw, the heavy duty electric cylinder achieves force outputs of 50 kN to 300 kN (with some specialist designs reaching 1,000 kN or more) while maintaining the clean, efficient, precisely controlled operation that defines the electric actuation category.

Construction Features That Distinguish Heavy Duty Electric Cylinders

A heavy duty electric cylinder differs from a standard electric linear actuator in its engineering margins and construction details:

• Roller screw as standard: At force outputs above approximately 50 kN, ball screws reach the practical limit of their load capacity in reasonable screw diameters (typically 40 to 63 mm for ball screws, requiring very large diameter and heavy construction). Planetary roller screws carry the same load with a smaller screw diameter because the load is distributed across many roller contact lines rather than a limited number of balls. Heavy duty electric cylinders above 50 kN almost universally use roller screw drives rated for millions of kilometres of travel life under rated load.
• Integrated anti-rotation guide: At high thrust forces, any torque component applied to the cylinder rod (from off-centre loading or angular mounting) would rotate the screw nut if unrestrained, causing irregular motion and accelerated wear. Heavy duty cylinders integrate a robust anti-rotation system (typically a guide rod running parallel to the main screw, or a non-circular section on the rod that engages a matching bore in the front flange) to prevent this rotation under the highest practical side loads.
• IP65 to IP67 environmental sealing: Heavy industrial environments expose actuators to metal chips, coolant, hydraulic oil mist, and water wash-down. Heavy duty electric cylinders use labyrinth seals, wiper seals, and sealed motor enclosures to maintain protection class IP65 (dust-tight and water-jet resistant) or IP67 (immersion to 1 metre depth for 30 minutes). This sealing eliminates the ingress of contaminants that would rapidly destroy precision screw mechanisms if unsealed.
• Integrated electromagnetic brake: Because roller and ball screws are back-drivable, a heavy duty electric cylinder holding a large load (such as a press platen weighing several tonnes) will retract if power is lost without a brake. An integrated electromagnetic (spring-applied, power-released) brake engages automatically when power is removed, holding the rod position with no electrical power required. The brake holding force must exceed the maximum back-drive force from the rated load.

Heavy Duty Electric Cylinder Applications in Steel, Mining, and Press Industries

The leading application areas for heavy duty electric cylinders in the transition away from hydraulics include:

Electric Servo Cylinder: Maximum Precision Through Closed-Loop Control

An electric servo cylinder is an Electric Linear Cylinder in which the driving motor is a servo motor connected to a servo drive (amplifier) that implements closed-loop feedback control of position, velocity, and force simultaneously. The addition of the servo control system transforms the actuator from a simple electromechanical device into a fully programmable motion axis capable of executing complex motion profiles with extraordinary precision and repeatability.

What Makes an Electric Servo Cylinder Different from a Standard Electric Cylinder

A standard Electric Linear Cylinder with a stepper motor or a variable speed AC motor provides open-loop or simple closed-loop position control, typically using a limit switch or a linear potentiometer for feedback. An electric servo cylinder adds:

1. High-resolution encoder feedback: A servo motor encoder (typically 17 to 24-bit resolution, providing 131,072 to 16,777,216 counts per revolution ) allows the servo drive to know the motor's angular position to a fraction of an arc-second, which translates to nanometre-level resolution at the cylinder rod when combined with a fine-pitch screw.
2. High-bandwidth control loop: The servo drive's position, velocity, and current (torque) control loops update at rates of 1 to 16 kHz , detecting and correcting position errors faster than any mechanical disturbance can accumulate. This high bandwidth produces the stiffness needed to hold a precise position against varying external forces without position drift.
3. Programmable motion profiles: The servo controller can execute S-curve, trapezoidal, or custom velocity profiles that accelerate and decelerate the load smoothly, minimising mechanical shock and vibration. This is critical for precision assembly processes, scientific instruments, and measurement systems where abrupt acceleration would disturb sensitive components or measurements.
4. Force control mode: By monitoring motor current (which is proportional to motor torque, which multiplied by the screw lead equals thrust force), the servo drive can regulate the force applied by the cylinder rod to a set value, regardless of position. This torque-to-force mode is used for pressing, clamping, and joining operations where a controlled force (not a controlled position) is the required output.
5. Integrated process monitoring: The servo drive continuously logs position error, current, velocity, and temperature data. This data can be analysed by process monitoring software to detect tool wear, joint quality in press-fit assembly, material property variations in forming operations, and imminent mechanical faults before they cause a failure.

Electric Servo Cylinder Applications in Precision Manufacturing

Electric servo cylinders are the dominant actuator choice in precision manufacturing applications where position accuracy below 0.1 mm and force repeatability within 1 to 5% are required:

• Battery cell assembly: Electrode stacking, cell welding, and electrolyte injection in lithium-ion battery manufacturing require position accuracy of 0.05 to 0.1 mm and force control within 2% to prevent electrode deformation that causes cell capacity loss or internal short circuits.
• Semiconductor packaging: Wire bonding, flip-chip attachment, and package compression testing require servo cylinder motion resolution of 1 to 10 micrometres and force control in the range of 0.1 to 10 N, where conventional electric cylinders lack the precision and pneumatic cylinders lack controllability.
• Automotive assembly: Press-fit bearing and bushing installation, seat track adjustment systems, sunroof actuators, and door hinge torque testing all use electric servo cylinders for their combination of high force, precise stroke control, and process data logging that enables 100% quality verification of every assembled joint.
• Medical device assembly and testing: Implantable device crimping, stent deployment testing, and syringe pump actuation use servo cylinders with force accuracy of 0.5 to 1% and stroke accuracy of 0.01 to 0.05 mm in clean-room environments where hydraulic actuators are absolutely excluded.

Electric Pneumatic Cylinder: Electrifying Pneumatic Systems and Drop-in Replacements

The term electric pneumatic cylinder is used in two distinct contexts in industrial practice, and understanding both is important for selecting the correct product. The first context is an electro-pneumatic cylinder: a conventional pneumatic cylinder fitted with an integrated proportional solenoid valve and position feedback sensor, creating a pneumatic actuator with electric position control. The second context is an electric actuator specifically designed as a dimensional and functional drop-in replacement for a standard ISO pneumatic cylinder, fitting the same mounting, having the same rod diameter and thread, and being controllable from the same signal that previously drove the solenoid valve.

Electro-Pneumatic Cylinders: Adding Precision to Compressed Air Systems

An electro-pneumatic version of the electric pneumatic cylinder retains compressed air as its energy source but replaces the simple on-off solenoid valve with a proportional valve that can meter airflow to any fraction of maximum flow based on an electrical control signal (typically 4 to 20 mA or 0 to 10V DC). Combined with a linear position sensor (magnetic strip or optical scale) on the cylinder body, the proportional valve receives feedback-corrected commands from a position controller, creating a closed-loop pneumatic servo system.

Electro-pneumatic servo systems can achieve position accuracy of ±0.1 to ±0.5 mm depending on the cylinder friction, load characteristics, and controller tuning. This is significantly better than the end-stop-only positioning of a conventional pneumatic cylinder but falls short of the ±0.01 mm achievable with an electric servo cylinder . The advantage is that the existing compressed air infrastructure is retained, which may be economically decisive when a large facility has a compressed air system already paid for and maintained.

Electric Drop-In Replacement Cylinders: Eliminating Pneumatics Without Redesigning the Machine

Electric actuators designed as drop-in replacements for ISO pneumatic cylinders represent one of the most commercially active segments in the electric actuation market. These products are dimensioned to match ISO 15552 or ISO 6432 pneumatic cylinder mounting standards, with the same tie-rod mounting pattern, the same piston rod diameter and thread, and the same clevis and foot bracket interfaces as the pneumatic cylinders they replace. The replacement process involves:

1. Remove the pneumatic cylinder from its mounting brackets and disconnect its air supply hoses and solenoid valve wiring.
2. Mount the electric replacement cylinder using the same mounting brackets and the same bolt pattern.
3. Connect the electric cable from the replacement cylinder to a 24V DC power supply or directly to the machine's control panel where the solenoid valve was previously connected (for versions designed to accept direct 24V solenoid-equivalent signals).
4. Adjust the controller parameters (speed, acceleration, end-of-stroke detection) through the cylinder's integrated controller interface.
5. Cap the air supply ports no longer needed, and isolate the relevant section of the compressed air circuit if this cylinder was the only user in its branch.

The energy saving from this retrofit is immediately measurable. A single electric pneumatic cylinder replacement eliminates the compressed air consumption of that cylinder, which for a cylinder cycling 60 times per minute with 100 mm stroke and 63 mm bore could be 80 to 120 litres per minute of compressed air at 6 bar , equivalent to approximately 0.5 to 0.8 kW of compressor power running continuously. Across a machine with 20 such cylinders, the annual energy saving at 6,000 operating hours per year can exceed 50,000 kWh .

Frequently Asked Questions About Types of Cylinders and Electric Actuation