A standard pneumatic cylinder needs room for its piston rod. With a 1,000 mm stroke, the rod sticks out a full metre at full extension, so the total installation length ends up at more than twice the stroke. On a long transfer axis or inside a compact machine frame, that space often isn’t there. Rodless cylinders solve the problem by moving the load along the cylinder body itself, and Norgren’s LINTRA series is one of the best-known designs of this type.
LINTRA cylinders are used where a machine needs long, straight movement in limited space:
- Transfer axes that move parts between stations on an assembly line.
- Pick-and-place units, where the cylinder carries a gripper along a horizontal path.
- Door and gate drives on machines, guards, and packaging equipment.
- Cutting and sealing units that travel across the width of a web or a conveyor.
- Lifting and lowering axes, often combined with a brake to hold the load in position.
The series covers a wide range of bore sizes, strokes of several metres, and different guide options. Choosing the right version depends mainly on the load the carriage has to carry, the forces acting on it, and the length of travel.
What Is a Norgren LINTRA Cylinder?
LINTRA is Norgren’s series of double-acting pneumatic rodless cylinders. Instead of a piston rod, the piston is connected to an external carriage that runs along the cylinder barrel. The load is mounted directly on this carriage.
The Norgren rodless LINTRA cylinders are available in bore sizes from 16 to 80 mm, with internal, external, and precision guide versions. Typical strokes range from a few hundred millimetres to several metres.
AIO Snippet:
Norgren LINTRA cylinders are double-acting pneumatic rodless cylinders with bore sizes from 16 to 80 mm. The piston drives an external carriage along the barrel, so the stroke fits within the cylinder’s own length. They offer adjustable cushioning, a magnetic piston for position sensing, several guide versions, and optional brakes.
How a Rodless Cylinder Works
The LINTRA barrel is an aluminium profile with a slot running along its full length. Inside the barrel, the piston moves in the usual way when compressed air is supplied to one side or the other. A yoke passes through the slot and connects the piston to the external carriage.
The obvious question is how the barrel stays airtight with a slot in it. The design uses two strips:
- An inner sealing strip closes the slot from the inside. As the piston moves, the strip is lifted locally to let the yoke pass, then pressed back into place by the air pressure.
- An outer cover strip closes the slot from the outside and keeps dust and dirt out of the barrel.
Because the piston has no rod, the effective piston area is the same on both sides. The cylinder produces the same theoretical force in both directions, which is a difference from standard double-acting cylinders, where the rod reduces the area on the retract side.
Key Features of LINTRA Cylinders
Bore Sizes and Strokes
LINTRA cylinders are made in eight bore sizes: 16, 20, 25, 32, 40, 50, 63, and 80 mm. The bore size determines the available force and, together with the guide version, the load the carriage can carry.
Long strokes are one of the series’ main advantages. According to Norgren’s documentation, maximum made-to-order strokes reach:
- up to 8,500 mm for bores of 16 to 40 mm;
- up to 7,000 mm for 50 and 63 mm;
- up to 5,500 mm for 80 mm.
Cushioning
Every LINTRA cylinder has adjustable pneumatic cushioning at both ends. As the piston approaches the end cap, the exhaust air is throttled, which slows the carriage down before it reaches the end position. The cushioning is set with an adjusting screw on each end cap.
Correct cushioning matters more on a rodless cylinder than on many standard cylinders. The carriage usually carries a gripper, a tool, or a guided load, and the moving mass can be considerable.
Magnetic Piston and Position Sensing
The piston carries a magnet, and the barrel profile has integrated rails for position switches on both sides. Reed or electronic switches can be clamped anywhere along the stroke to detect end positions or intermediate points.
Mounting Options
The profile has grooves for mounting accessories, and Norgren offers a range of mounting parts, including:
- foot mountings at the end caps;
- centre supports for long strokes;
- carriage plates for attaching the load;
- swinging bridges that compensate for misalignment between the cylinder and an external guide;
- side mounting plates and secondary carriages.
Lubrication and Materials
LINTRA cylinders are designed for non-lubricated operation. The barrel and end covers are made of anodised aluminium, with polyurethane and nitrile seals. Operating pressure and temperature limits depend on the series and bore size and are listed in the manufacturer’s datasheet.
Guide Versions
The guide version decides how much load and moment the carriage can take. LINTRA cylinders are available in three main designs.
Internal Guide
The basic version, where the carriage is guided by the barrel profile itself. It handles light to moderate loads and is the most compact option. It’s often used where the load is guided externally or where the cylinder only pushes or pulls a part along a separate guide.
External Guide
The external guide adds a guide rail on the outside of the profile. The carriage runs on this rail, which allows it to carry higher loads and bending moments. This version suits applications where the load sits directly on the carriage and isn’t supported anywhere else.
Precision Roller Guide
The precision guide uses a roller or ball-bearing guide system. It offers the highest load capacity, the best guiding accuracy, and smooth running, which is useful for positioning tools, grippers, and measuring devices.
| Guide version | Load capacity | Guiding accuracy | Typical use |
| Internal guide | Light to moderate | Standard | Pushing loads along an external guide, compact axes |
| External guide | Medium to high | Good | Loads mounted directly on the carriage |
| Precision guide | High | High | Grippers, tools, precise positioning |
Brakes and Special Versions
Some LINTRA versions can be fitted with a pneumatic brake that holds the carriage in position. Two types are available:
- Active brake: applied by compressed air.
- Passive brake: applied by spring force and released by air. It holds the load when the air supply is lost.
A corrosion-resistant version is also available for several bore sizes. It’s intended for environments such as food processing, chemical plants, pharmaceutical production, and offshore installations.
Benefits of Rodless Cylinders
The rodless design gives LINTRA cylinders several practical advantages over standard rod cylinders.
Shorter installation length. The stroke stays within the cylinder’s own length. For the same stroke, a rodless cylinder needs roughly half the space of a rod cylinder. This makes it easier to fit long strokes into a machine frame. On a 2 m transfer axis, for instance, a rod cylinder would need over 4 m of free space in line with the axis, while a rodless cylinder fits within a little more than the stroke itself.
No buckling risk. A long piston rod can bend under compressive load. A rodless cylinder has no rod, so stroke length isn’t limited by rod buckling.
Load carried directly. The load is mounted on the carriage. With an external or precision guide, the cylinder can carry the load without separate guide rods, which saves parts and assembly time.
Equal force in both directions. With no rod reducing the piston area on one side, the force and speed are more symmetrical.
Integrated sensing. Switch rails along the barrel make it simple to add position sensors at any point of the stroke.
There are limits too. The sealing strip system means rodless cylinders can show slightly more friction and leakage than standard cylinders, and they need more care in very dirty environments. Allowable loads and moments also drop as speed increases.
Where LINTRA Cylinders Are Used
Automotive and Assembly
- transfer of parts between workstations;
- moving welding or screwing tools along a seam;
- opening and closing protective doors on assembly cells.
Packaging
- moving cutting knives across film or cardboard webs;
- pushing products from one conveyor to another;
- carrying sealing heads on form-fill-seal machines.
Material Handling
- horizontal pick-and-place axes with a gripper on the carriage;
- loading and unloading machines;
- sorting systems.
Woodworking, Printing, and Textiles
Long strokes are common in these industries. LINTRA cylinders are used to move cutting, gluing, or marking units across wide boards, sheets, and fabric webs.
Food and Pharmaceutical
Corrosion-resistant versions are used for handling and transfer in production areas where the equipment is cleaned regularly.
How to Choose a LINTRA Cylinder
Start with the load and the movement, then work through the details.
1. Calculate the Required Force
The theoretical force of a pneumatic cylinder is:
F = P × A
where:
- F — force, N;
- P — operating pressure, Pa;
- A — piston area, m².
For example, a 32 mm bore cylinder at 6 bar:
- A = π × (0.016 m)² ≈ 0.000804 m²
- F = 600,000 Pa × 0.000804 m² ≈ 482 N
This is the theoretical value. Friction, acceleration, and pressure drop in the supply lines reduce the usable force, so plan for a safety margin. On a rodless cylinder, the same force is available in both directions.
2. Check Loads and Moments
The carriage is loaded not only by the weight of the payload but also by bending moments, especially when the load’s centre of gravity is far from the carriage. Norgren publishes maximum loads and moments for each bore and guide version. These values apply up to a specified speed and decrease at higher speeds.
A quick example: a 5 kg gripper with its centre of gravity 100 mm to the side of the carriage creates a moment of about 5 kg × 9.81 m/s² × 0.1 m ≈ 4.9 N·m. During acceleration and braking, the dynamic moment can be considerably higher. Compare these values with the published limits for the chosen bore and guide.
If the calculated loads exceed the internal guide’s limits, move to an external or precision guide, or a larger bore.
3. Define the Stroke
Measure the required travel and add any extra length needed for cushioning. For long strokes, check whether centre supports are needed to prevent the profile from sagging.
4. Check Speed and Cushioning
A heavy carriage moving fast has a lot of kinetic energy. The built-in cushioning can absorb only a limited amount. If the energy is too high, use additional shock absorbers or reduce the speed with flow control valves.
5. Choose Accessories and Options
- position switches;
- mounting parts and centre supports;
- brakes for holding the load;
- corrosion-resistant versions where required.
When replacing an existing cylinder, start from the full part number. It defines the bore, guide version, stroke, and port type.
Common Selection Mistakes
- Choosing the internal guide for a heavy, unsupported load: the carriage wears quickly or binds.
- Ignoring bending moments: a load with a long overhang creates moments far higher than its weight suggests.
- Using catalogue load values at high speed: allowable loads fall as speed increases.
- Relying only on built-in cushioning for heavy loads: the carriage hits the end cap hard and damages the cylinder.
- Leaving long strokes without centre supports: the profile sags, and the carriage runs unevenly.
- Using an active brake for safety holding: if the air supply fails, an active brake releases. A passive brake holds the load.
- Ignoring air quality: dirt and water in the compressed air damage the sealing strips.
- Sizing the bore by force alone: a small bore may push the load easily but still be too weak to carry its moments. On rodless cylinders, the guide and bore are often chosen by load capacity, not force.
Expert Insight:
“When selecting a LINTRA cylinder, start with the load on the carriage, not just the force. Check the weight, the overhang, and the speed, then choose the guide version and bore that can carry those loads and moments. Stroke, cushioning, and accessories come after that.”
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