Legrest: Integration of the REGNER® 1,600 N linear actuator

Regner® Editorial Team

Aiguaviva -

03/11/2026

A 1,600 N actuator, a 100 mm stroke and a centre distance of 270 mm define only part of the challenge. The rest comes down to details that a datasheet does not cover: the fit of a pin, the geometry of a joint, the routing of a cable and how everything is assembled.

In MEYRA’s Legrest project, REGNER® combines electric linear actuator engineering, mechanical design review, industrialisation and assembly to supply the upper legrest assembly ready for installation on the wheelchair. This work links the RA35 specifications to component drawings, samples approved by the customer and production checks.

This case study explores the technical decisions behind the integration, from compatibility with the existing actuator to verification of the completed assembly.

Integrating an actuator means resolving how force is transmitted, how components articulate and how the assembly is built and verified.

1. Industrialisation while preserving compatibility

Having confirmed the reliability of REGNER’s electric linear actuators, MEYRA placed further trust in us by commissioning the adaptation of the legrest system into which the actuator is integrated.

The Legrest project did not start from scratch. The customer’s brief called for industrialisation and an assessment of alternatives to optimise manufacturing and assembly costs, with one explicit requirement: REGNER had to adapt one of its own actuators to replace the previous unit.

That requirement defines the scope of the work. Changing a process or component can reduce operations, but requires checking the effects on mountings, fits and the final configuration. Cost objectives and mechanical constraints therefore have to be addressed together.

The initial scope covers two versions, one electric and one with a gas spring, and the development plan includes assembly trials using prototypes and preproduction units.

REGNER structures the project around these requirements and coordinates actuator development with development of the assembly. The first technical question is which dimensions actually govern compatibility and movement.

2. From the 3D model to functional interfaces

A dimensional chain can meet all specified tolerances and still be sensitive to misalignment or friction. In an articulated mechanism, it is essential to identify which surfaces locate components, which guide them and which must allow freedom of movement, particularly when several areas guide the same part.

In the Legrest, the bracket and locking pin form one of these interfaces. The sample documentation includes H7 holes and specific pin tolerances. In parallel, REGNER asks the customer for the load locations, centre of mass and fatigue test specifications to complement the geometry with the actual operating conditions.

Two of the dimensions defining the bracket’s guiding surfaces are:

COMPONENT	DIMENSIONAL SPECIFICATION
Rear bracket guide	Ø8 H7, 8.000 to 8.015 mm
Intermediate bracket guide	Ø12 H7, 12.000 to 12.018 mm

Pin friction and guidance

During a review of the mechanism, REGNER analyses a pin that does not slide freely. The report identifies unlubricated aluminium contact surfaces and guidance at three locations: an oval front guide, a rear Ø8 mm guide and an intermediate Ø12 mm guide.

Sliding behaviour depends on the material pairing, lubrication and guide geometry. Adding support points does not always help. If they constrain the same movement simultaneously, the mechanism becomes more sensitive to misalignment, and changing a single edge or dimension will not resolve the problem.

The guide dimensions help explain this: the Ø12 mm guide and Ø11.9 mm pin provide a nominal radial clearance of 0.05 mm when their axes are aligned. The analysis considers this insufficient to prevent interference at that guide. A provisional trial removing the intermediate guide improves the behaviour of one assembly, although contact between aluminium surfaces remains.

REGNER proposes incorporating two polymer bushings: a custom front bushing and a cylindrical igus bushing. The prototype shows qualitatively smoother sliding, although further development requires the front bushing to be prepared for production. As an immediate measure, the Quality team matches and inspects the bracket and pin before assembly.

3. Configuring the RA35 for the operating point

When selecting an actuator, the speed at no load is only a reference. The application’s response depends on movement under load. Selection must therefore relate force, speed, stroke and duty cycle. The retracted length and mountings must also fit within the available installation envelope.

The RA35 configuration documented for the Legrest operates at 24 V DC and specifies 1,600 N at 6 mm/s, with a 100 mm stroke and a retracted centre distance of 270 mm. The manufacturing drawing defines a steel motor housing and incorporates elastomeric elements that help reduce noise.

The actuator configuration is defined by the following parameters:

PARAMETER	PROJECT CONFIGURATION
Power supply	24 VDC
Maximum axial load and corresponding speed	1,600 N at 6 mm/s
Stroke	100 mm
Centre distance (retracted)	270 mm
Nominal outside diameter	35 mm
Cable length	190 mm
Duty cycle	10%, 2 minutes in every 20
Actuator IP rating	IP54

Documented operating point of the project’s RA35. The point at 1,600 N and 6 mm/s is shown without reconstructing a complete curve from unavailable data.

Selection relates axial force and speed under load to the application’s operating point. The actuator’s axial force is not directly equivalent to the permissible load on the legrest, which depends on geometry and lever arms. Before the manufactured configuration is checked using samples, a preliminary calculation is carried out using rigid body static analysis.

4. Validation through customer measurements and testing

The customer approves the RA35 actuator following dimensional checks and durability testing. The inspected sample’s dimensions are within tolerance, and the review of the electric assemblies confirms installation on the wheelchair, subject to conditions relating to cable integration.

Dimensional inspection, assembly trials and durability testing provide different types of evidence. Validation therefore links each result to a sample, a characteristic and an acceptance criterion. A conforming sample confirms the outcome of that verification; on its own, it does not describe variation across a production batch.

Two dimensional results from the sample illustrate this verification:

CHARACTERISTIC	NOMINAL DIMENSION AND TOLERANCE	RECORDED VALUE
Centre distance	270 ± 0.5 mm	270.00 mm
Housing outside diameter	Ø 35 ± 0.3 mm	Ø 35.25 mm

5. Industrialisation with verifiable materials and specifications

When a component moves to a different process or supplier, the characteristics affecting its function must be preserved. For metal components, this means the alloy, metallurgical condition and raw material form. For injection moulded parts, it means draft geometry, texture and marking.

REGNER combines internal manufacturing with specialist suppliers. The initial proposal assesses alternative construction methods and injection moulding for plastic components originally represented as 3D printed parts. Subsequent documentation specifies, for example, black PA6, RAL 9005, 1° draft angles and VDI 3400 grade 36 texture for certain covers and plugs in the assembly.

The match between the texture grade and the required finish must be confirmed with the mould supplier before approval.

Material selection combines steel and aluminium alloys according to the component:

COMPONENT	MATERIAL AND FORM	Rm STATED IN THE CERTIFICATE
Motor mounting clamp	DD11 steel, 3 mm sheet	379 MPa
Locking pin	6026 LF T6 aluminium, Ø14 mm bar	375.55 MPa
Legrest support	6063 T66 aluminium profile	215 MPa

For the 6063 T66 profile, EN 755-2 distinguishes between wall thicknesses: for t ≤ 10 mm, the minimum Rm is 245 MPa and the minimum Rp0.2 is 200 MPa; for 10 < t ≤ 25 mm, the minimum Rm is 225 MPa and the minimum Rp0.2 is 180 MPa. These specification minima are not batch test results. The 215 MPa value in the previous version must be checked against the 3.1 inspection certificate, temper and applicable thickness before publishing the profile’s strength.

6. Manufacturing the actuator to a defined assembly configuration

Two actuators may look identical externally, but an actuator’s response also depends on its internal assembly: motor support, transmission, bearings, elastic elements and cable exit. The configuration must therefore be reproducible from specific instructions, including orientations and operations that cannot be inferred from an external view.

The manufacturing drawing for the project’s RA35 defines the 35 mm steel motor housing, elastomeric support elements, transmission assembly and arrangement of spring washers. Photographic documentation complements this definition by showing assembly of the motor and internal mechanical components.

Even the cable exit is defined: the drawing specifies a grommet and two cable ties, one inside and one outside around the grommet. Once manufactured, each actuator undergoes the first quality check before integration into the Legrest.

Individual verification is the first level of control. The actuator must then operate with the assembly’s joints, brackets and wiring.

7. Assembly with fixtures and controlled cable routing

Repeatable assembly depends on physical locating references and a sequence that allows access to the joints. Wiring also forms part of the mechanical integration, as it occupies space and flexes during movement.

At REGNER, Legrest assembly brings together the profile, brackets, joints, actuator and connections. Process photographs show the U655 fixture, marked with a spacing of 100 mm, locating the calf support on the profile. This dimension relates to the support positioning operation.

MEYRA documents three specific wiring instructions for the samples: route the cables along the side, house the connectors inside the deflection lever, and route the motor cable in a wide arc above the head towards the rear. This defines the cable routing in the configuration reviewed by the customer.

Once component assembly is aligned with the actuator integration requirements, the remaining step is to verify the completed assembly.

The fixture defines the assembly position. The wiring review defines how the connection must accommodate movement.

8. Verifying the assembly against failure modes

What can go wrong when the components, actuator and assembly operations come together in a single unit? An individually verified actuator can still end up in an assembly with an unsuitable fit or an incorrect assembly operation. Verification of the finished subassembly therefore complements verification of the component.

REGNER establishes two inspection stages: each actuator before integration, and the complete unit after assembly. The project definition document already identifies risks associated with locking mechanism fits, component assembly and actuator operation. Matching the bracket and pin adds a specific action to address the sliding issue discussed in section 2, concerning pin friction and guidance.

Each risk has a corresponding action: component inspection for fits, procedures and training for assembly, and individual testing for actuator operation. The final inspection completes the sequence on the assembled unit.

The second check is performed on the unit the customer will receive. Once it has passed, REGNER prepares the assembly for delivery, allowing the manufacturer to install a subassembly that has been assembled and verified according to the agreed process.

9. The industrial outcome for the customer

For the customer, the value of an integrated supply lies in receiving an assembled subassembly. The supplier takes responsibility for the operations and interfaces, while a single technical contact coordinates components, actuator integration and checks before delivery.

For the Legrest, REGNER links the RA35 configuration with the mechanical components, supplied materials, fixtures and assembly instructions. Collaboration with MEYRA includes sample approval, integration feedback and the revisions arising as the product evolves.

The result combines the 1,600 N actuator with mechanical integration and assembly work. The customer receives a verified subassembly ready for installation on the wheelchair, with these operations completed as part of REGNER’s scope of supply.

REGNER provides the capability to progress from the component to mechanical integration and subassembly production. For a similar application, the starting point is to share the loads, kinematics, interfaces and production requirements. These are the inputs needed to turn a motion requirement into a configuration that can be manufactured and verified.

Standard RA35 datasheet and custom configuration

The standard RA35 datasheet describes catalogue options. The Legrest RA35 uses a custom configuration defined by the project drawing, with a 190 mm cable and a retracted centre distance of 270 mm. The standard values below do not replace the project parameters in section 3.

CHARACTERISTIC	STANDARD RA35 DATASHEET
Minimum mounting dimension	156 mm + stroke
Cable length	150 or 500 mm
Mounting hole diameters	8.1 or 10.1 mm
Front mounting bracket	Standard or clevis
Connector	Molex 39-01-2066
Finish	Black anodised

10. Frequently asked questions

What does REGNER®’s integrated Legrest supply include?

REGNER® delivers the upper legrest assembly fully assembled and verified, ready for installation on the wheelchair. It brings together the RA35 electric linear actuator, profile, brackets, joints, wiring and connections. The customer has a single technical contact coordinating components, actuator integration and checks before delivery.

What are the specifications of the RA35 actuator configured for the Legrest?

It operates at 24 V DC and delivers 1,600 N at 6 mm/s, with a 100 mm stroke and a retracted centre distance of 270 mm. It has a nominal outside diameter of 35 mm, a 190 mm cable and an IP54 rating. Its duty cycle is 10% (2 minutes in every 20). This is a custom configuration defined by the project drawing and is not equivalent to the standard RA35 datasheet.

Does the actuator’s 1,600 N rating correspond to the load the legrest can support?

No. The actuator’s axial force is not directly equivalent to the permissible legrest load, because this depends on geometry and lever arms. Before the configuration is checked using samples, a preliminary calculation is therefore carried out using rigid body static analysis. The speed at no load is also insufficient on its own: the application’s response depends on movement under load.

How is correct operation of the assembly verified?

REGNER® establishes two inspection stages: each actuator before integration, and the complete unit after assembly. Each identified risk has a corresponding action: component inspection for fits, procedures and training for assembly, and individual testing for actuator operation. As an immediate measure to address pin sliding difficulties, the Quality team matches and inspects the bracket and pin before assembly.

What information does REGNER® need to address a similar application?

The starting point is to share the loads, kinematics, interfaces and production requirements. These inputs turn a motion requirement into a configuration that can be manufactured and verified. For the Legrest, REGNER® also asked the customer for the load locations, centre of mass and fatigue test specifications.