Ergonomically mounting sliding steps for rail vehicles – with two synchronously moving lifting axes ZH90
- abella074
- Apr 30
- 5 min read
How a custom-made assembly device from Zeilhofer HHT makes the production of sliding steps and boarding aids for rail vehicles faster, safer and more reproducible.
Sliding steps – the underestimated key component in passenger flow
A sliding step extends and retracts well over a million times during its lifespan – in all kinds of weather, in ice and snow, at every single stop. It is the transition between the platform and the vehicle, closes the gap to the platform edge, and is therefore one of the most safety-relevant components on the rail vehicle.
Behind this seemingly simple feature lies a technically sophisticated product with an electric toothed belt drive, safety interlock, switching strips, light barriers, and sensors for motor current and distance-time measurement. Manufacturers such as Bode (with the BISS, BMBS, and BCBS product families) and Knorr-Bremse/IFE (e.g., with the X4 sliding step) supply these systems for light rail, metros, regional trains, intercity, and high-speed trains worldwide. The designs are becoming ever wider, more complex, and more varied. Before they can be put into service, however, they undergo a complex assembly process. This is precisely where our new assembly device comes in.
The challenge in assembly
Complete sliding steps are large, heavy, and geometrically unwieldy. The drive mechanism, locking system, sensors, safety edges, light barriers, tread plate, control unit, and wiring are all integrated into a single module, sometimes weighing several hundred kilograms and with component widths of up to 1,500 mm. For the operator, this means the following in a classic setup:
gripping, holding and aligning – component by component, screw by screw
Working overhead or on the ground because the footrest doesn't rotate.
Lift with two people or position using improvised crane solutions.
The top and bottom surfaces must be constantly rearranged, depending on the installation type (insert, built-in or under-counter step).
This costs strength, time, and concentration. It leads to inconsistent tightening torques, a higher reject rate, and—above all—physical wear and tear on employees. Often, the assembly of a single sliding step is the bottleneck for an entire production line.
The solution: A mounting device with two synchronously moving lifting axes ZH90
Instead of pushing the process to its limits, we reimagined it. Our solution combines two linear aluminum lifting axes (ZH90) that support the sliding step on the left and right, with a continuously swiveling mounting frame in between. The entire system rests on a floor-guided rail system – movable and precisely reproducible.
Specifically, this means for the worker:
The entire sliding step is clamped in place once – and stays there.
The two ZH90s lift the component weightlessly and in parallel to any desired height.
The operator can rotate the step step continuously into any working position using the swivel mechanism.
All activities – above, below, on the drive, sensors and switching strips – are carried out at an ergonomic height.
Operation is via a central terminal that triggers both axes synchronously.
The system does not work against the worker – it works with him.
The unique selling point: synchronized parallel stroke
What makes this device unique on the market is the precisely synchronized movement of both ZH90 lifting axes. Both columns move parallel – at identical speed and in identical position – throughout the entire stroke. There is no overshoot, no tilting, and no need for subsequent alignment.
This is precisely the technical requirement for being able to guide a rigid, wide sliding step smoothly. With classic single-lift columns or conventional crane solutions, this plane-parallel load guidance cannot be reliably achieved – even the slightest deviations cause stress on the component and damage attachments such as switching strips, light barriers, or locking elements.
The ZH90 already offers the necessary prerequisites as standard: rigid load guidance, high torsional stiffness (3,000 Nm), a load capacity of up to 1,000 kg per axis, and a repeatable linear stroke of up to 1,600 mm. We have mounted two of them on a common rail system, synchronized them mechanically and in terms of control – thus creating a lifting unit that can move an entire sliding step as a single component.
Continuous swiveling – the component follows the worker
The second key component of the device is the continuously rotatable mount. The sliding step is not rigidly held between the two ZH90s, but rather mounted on a continuous pivot axis. This allows it to be positioned at any desired angle – horizontally, vertically, and in any intermediate position.
In practice, this means that the worker adapts the component to their body position, not the other way around. Screw points that previously had to be reached while lying down or overhead are now more easily accessible.
The result:
ergonomic working height in every assembly phase
Reproducible movement sequences and more consistent tightening torques
significantly less strain on shoulders, back and knees
Shorter cycle time because no changeover of the workpiece carrier is necessary.
Higher quality due to a constant field of view of the respective mounting point
Which sliding steps can be mounted with this device
The device is designed for the entire range of modern sliding step platforms. Stroke, pivot axis and mounting geometry are measured for each individual component – the underlying double ZH90 platform remains identical.
Technical specifications of the device
Performance feature | Value |
Used lifting axles | 2 × ZH90, parallel synchronized |
Total load capacity | up to 2,000 kg (2 × 1,000 kg) |
Suitable component width (clear entry) | approx. 800 – 1,500 mm (suitable for BISS, BMBS, comparable systems) |
Working area | max. 1,600 mm per axis |
Swivel range component | stepless, > 180° |
Travel path on rails | customized |
drive | electric, synchronized |
steering | Operating terminal with central release |
Security category | compliant with Machinery Directive 2006/42/EC, CE compliant |
Certifications | ISO 9001, TISAX, TÜV-certified |
The stroke, swivel range, mounting geometry and travel length of the floor rail are individually designed for each customer's specific sliding step.
Who might find this device interesting?
Manufacturers of sliding steps and entry aids
The solution is specifically designed for the final assembly of sliding steps for rail vehicles. It is suitable for OEMs and their Tier 1 suppliers in the rail sector, as well as other European and international providers of sliding steps and boarding aids for high-speed trains, regional trains, metros, and trams.
Manufacturers of other large-area, heavy panel assemblies
The combination of parallel synchronized lifting and stepless swiveling is valuable wherever a large, bulky component needs to be mounted in different positions across several stations.
Typical applications outside of sliding step installation include:
Ramps, platform lifts and extendable boarding aids for vehicles and buildings
Large-area high-voltage storage systems and battery housings in electromobility
Body modules, floor and side wall assemblies in commercial vehicle and special vehicle construction
Control cabinet and enclosure construction in energy technology
Large equipment and machine modules in plant engineering
Plate-shaped heavy-duty components in cleanroom and semiconductor manufacturing
Engineering from Bavaria – Complete solutions from a single source
We develop, design, manufacture, and maintain every system ourselves – from the initial requirements specification through design and steel construction to commissioning at the customer's site. Using the standard ZH90 modular system, we create a device that is precisely tailored to your component, cycle time, and warehouse logistics.
What you as a customer receive from us:
complete mechanics including floor rail system and mounting frame
Synchronized control of both lifting axes with a customer-specific operating concept
CE conformity assessment and full documentation
On-site commissioning, training and service – worldwide
Certified quality according to ISO 9001 and TISAX
Talk to us
Do you manufacture sliding steps for rail vehicles or a similar heavy, wide-area component and are looking for a solution that allows your employees to work more ergonomically, faster, and more reproducibly? Then please get in touch with us.
