ZH90 Lift Axis in a Rail System: Calling Fixtures by Pull Cord in Vehicle Assembly
An assembly fixture for vehicle assembly can easily weigh 85 to 400 kg and has to sit exactly in the right place on every vehicle. The ZH90 lift axis in a rail system carries this load on a ceiling rail above the station. The operator calls the fixture by pull cord, works with it in balance and sends it back to the locked parking position with another pull.
Zeilhofer Handhabungstechnik from Holzkirchen, Germany, designed three of these lift axes for the assembly line of a car manufacturer. This article shows the workflow at the station, the technology behind it and what matters when designing it.
Key points at a glance
Three ZH90 lift axes in a rail system carry customer-owned assembly fixtures of around 85 to 400 kg.
The operator calls the fixture by pull cord, it lowers to a preset height and automatically switches to balance.
The fixture is bolted on via a flange, and a universal joint adjusts the connection angle by plus/minus 10 degrees.
In the parking position the fixture is mechanically locked at the top, and the station is free for the next vehicle.
Three stations share the same design, operation and spare parts, only the lifting range and dimensioning are adapted.
What is a lift axis in a rail system?
A lift axis is a lifting aid that guides loads rigidly and without swinging along the vertical Z axis. In a rail system it does not hang from a column but from a trolley on a ceiling rail. This allows it to travel along the rail while the floor below stays clear. How lift axis, lift column and manipulator differ is explained in the article Lift column, lift axis or manipulator.
The ZH90 lift axis in this application consists of these assemblies:
Trolley: Lightweight aluminium design on a double longitudinal rail, with slotted holes for adjusting the rotation angle.
Z lifting unit: Lightweight lifting unit with integrated pneumatic lifting system, low-wear guide profiles and adjustable roller heads for high lateral forces and torques.
Balancing control: 2-circuit smooth-running balancing control with automatic switchover from empty weight to load weight.
Connection: Flange plate with universal joint for the customer's fixture.
Energy supply: Energy chain with trough along the side of the rail, so hoses and cables do not hang in the working area.
The distinction is important: a cable manipulator on a ceiling rail balances the load via a cable and is fast, but the load can swing. The lift axis guides the fixture rigidly. That is decisive when a heavy fixture has to be positioned exactly on the vehicle.
Why heavy assembly fixtures on the line are a strain
Assembly fixtures are heavy, bulky and have to be moved many times per shift. Without a lifting aid, every station with such a fixture becomes critical from an ergonomic point of view.
Weight: Fixtures of 85 to 400 kg can neither be lifted nor held by hand.
Repetition: The fixture is used on every vehicle, shift after shift.
Accuracy: It has to match the stationary vehicle exactly in height and angle.
Clear station: The area must be clear between two vehicles, so the fixture needs a safe parking position.
Risk to the vehicle: A swinging or uncontrolled load damages paint and body.
The consequences of manual load handling are measurable: musculoskeletal disorders are among the most common causes of lost work days in production. What this costs is shown in the article Musculoskeletal disorders in production.
Legal framework and current situation
In Germany, the Load Handling Ordinance requires employers to assess the risks of lifting and carrying and to reduce them with technical means. Which loads are considered critical is explained in the article How many kg may you lift?
From 20 January 2027, the EU Machinery Regulation (EU) 2023/1230 applies and replaces the Machinery Directive. What this means for your production is summarised in the article EU Machinery Regulation 2027: ergonomics duties. A compact overview is provided by our free whitepaper Hebehilfen 2027 (German).
On top of this comes the labour shortage. According to the skilled labour report of the German Economic Institute, the skilled labour gap in Germany in June 2026 stood at around 383,000 positions that could not be filled, while the automotive industry is weakening. Anyone producing with scarce staff needs stations where experienced operators can work healthily for a long time and new colleagues quickly become confident.
The starting point in this application
On the assembly line of a car manufacturer, three stations were to be equipped with lifting aids. At each station, the operator works on the stationary vehicle with a separate assembly fixture designed by the customer.
The specification resulted in the following requirements:
Three fixtures with different weights and different lifting ranges, but uniform technology.
Connection of the customer fixtures via a defined flange interface.
Suspension from a ceiling rail so that the vehicle can enter and leave unhindered.
Simple operation without a control panel, working height preset and repeatable.
Safe parking position with feedback to the system control.
Same mode of operation as an application already running in the plant.
The workflow at the station in six steps
The lift axis is designed for a fixed sequence within the cycle. The operator only needs the pull cord and his hands on the fixture.
Entry: The vehicle enters the station and stops in a defined position.
Call: The operator pulls the cord. The fixture leaves the parking position and lowers to a preset Z height.
Balance: When this height is reached, the lift axis automatically switches to balance. The fixture floats.
Work: The operator takes over the fixture at an ergonomic height and carries out the work on the vehicle.
Exit: When finished, he guides the fixture out of the Z working area.
Park: Another pull on the cord lifts the fixture. In the top position it is mechanically locked and the station is free for the next vehicle.
Balance: the fixture becomes almost weightless
Step 3 is decisive. The 2-circuit smooth-running balancing control automatically switches from the preset empty weight to the load weight. The operator hardly feels the weight of the fixture any more and guides it with little hand force, rigidly and without swinging. A compensating cylinder with infinitely variable manual adjustment allows fine tuning of the lifting movement, and end position damping brakes gently.
The interface: flange and universal joint
The customer fixture is bolted on via a flange plate whose dimensions are agreed with the customer. A universal joint adjusts the connection angle by plus/minus 10 degrees in X and Y, and the main axis can be rotated by plus/minus 10 degrees. A pneumatic brake prevents the carrier unit from twisting. If the customer does not bring its own fixture, Zeilhofer designs it, see Custom grippers and fixtures.
Operation, energy and signals
Calling and parking is done by pull cord, and a position indicator shows the working position. If you prefer push buttons or handles instead of a pull cord, you will find the options under Controls. An electrical sensor for the top lifting position provides a signal that the operator can integrate into the system control.
The lift axis works pneumatically at 6 bar operating pressure and needs oil-free and particle-free compressed air according to DIN ISO 8573-1. A pre-filter unit with micro particle filter and oil separator is integrated. Air consumption is 20.5 standard litres per double stroke, and noise is below 70 dB. When pneumatic or electric is the better choice is shown in the guide Pneumatic or electric drive.
Three stations, one basis
All three lift axes share the same design, the same operation and the same spare parts. Only the lifting range and dimensioning for the respective fixture weight are adapted.
Station | Fixture weight | Lifting range (underside of rail to underside of flange) |
|---|---|---|
Station 1 | approx. 400 kg | 970 to 2,580 mm |
Station 2 | approx. 235 kg | 770 to 2,290 mm |
Station 3 | approx. 85 kg | 1,070 to 1,855 mm |
The rail gauge is 915 mm on all three systems. The profiles are made of silver anodised aluminium, attachments are galvanised. Permanent air and switched lines are colour coded, which makes maintenance easier.
Solutions compared: lift axis, crane, cable manipulator and robot
For heavy fixtures at an assembly station, several solutions are generally possible. They differ mainly in who carries the weight and how precisely the load is guided.
Chain hoist or crane
A chain hoist or crane takes the weight but is slow, and the load swings on the hook. Rigid guidance for precisely positioning a fixture on the vehicle is missing.
Cable manipulator
A cable manipulator is fast and covers large areas, but guides the load on a cable. That is ideal for light parts, less so for heavy fixtures that need an exact position on the vehicle. More on this in the article What is a rope balancer?
Articulated jib manipulator
An articulated jib manipulator guides rigidly and can also swivel and rotate loads. On a fixed column, however, it needs floor space at the station. Which solution fits better is shown in the comparison lift axis or manipulator.
Industrial robot and cobot
A robot needs safety equipment, programming and complex integration. Cobots are limited in payload and not designed for fixtures weighing several hundred kilograms. More on this in the guide Manipulator or cobot?
Lift axis in a rail system
The lift axis carries the entire weight, the human guides with eye and hand. It keeps the floor clear, works without programming and stays flexible when the fixture or workflow changes. This principle is described in the guide Semi-automated handling.
Safety, inspection and operation
Lifting aids in series production have to be designed safely, inspected regularly and serviced reliably. The ZH90 lift axis in this application offers the following functions:
Power failure: A compressed air reservoir with non-return valve holds enough air to safely finish the current work cycle.
Release lock: The fixture can only be released after it has been set down safely and is fully unloaded.
Load loss and hose rupture: A safety device prevents the axis from shooting up, additional non-return valves secure against hose rupture.
Fall and overload: A mechanical fall protection is integrated, the overload protection is factory set and sealed.
Shut-off: A manual shut-off valve disconnects the axis from the compressed air network of the hall.
CE conformity: Designed in accordance with the Machinery Directive 2006/42/EC, EN ISO 12100 and DIN EN 14238, with risk assessment, declaration of conformity and operating instructions.
Documentation: Documents can be accessed directly at the system via a password-protected QR code.
Statutory inspection: Lifting aids are inspected regularly. The procedure and intervals are explained in the guide UVV inspection for lifting aids.
Service: Maintenance, original spare parts and technical support are provided by our service team.
Checklist: designing a lift axis in a rail system
With these ten points, a lift axis for an assembly station can be requested and designed properly:
Fixture weight: Weight of the complete fixture including all attachments and variants.
Centre of gravity: Position of the centre of gravity relative to the flange plate, decisive for design and guidance.
Lifting range: Lowest and highest point, measured from the underside of the rail to the underside of the flange.
Ceiling height and steel structure: Load capacity for the rail and freedom from interfering contours for the stroke.
Rail system: Existing or new rail, rail gauge and required travel.
Compressed air: Pressure and quality at the station, oil-free and particle-free.
Alignment: Required angles and tolerances between fixture and vehicle.
Operating concept: Pull cord, push buttons or controls on the handle, plus the working height.
Signals: Which feedback the system control needs, such as top end position.
Inspection and maintenance concept: Statutory inspection, maintenance intervals, spare parts supply.
The costs involved are explained in the guide What does a manipulator cost? How quickly a lifting aid pays for itself is shown in Calculating the payback of a lifting aid. As an alternative to buying, you can finance via leasing or hire purchase.
How a project with Zeilhofer works
From the enquiry to the running system, Zeilhofer supports the project from a single source. Since 1999, the company has delivered over 2,500 systems in 18 industries to customers in over 50 countries.
Specification and on-site meeting: Survey of fixture, station, steel structure and layout directly in the hall.
Concept: Design of lift axis, rail system and interface to the fixture.
Design and manufacturing: Engineering and manufacturing in Holzkirchen, Germany, according to ISO 9001.
Pre-acceptance: Test at the plant in Holzkirchen or digitally via video.
Installation and commissioning: By Zeilhofer or by the customer, including documentation.
Service: Statutory inspection, maintenance and spare parts over the entire service life.
Confidentiality matters, especially in the automotive industry. Zeilhofer is certified to ISO 9001 and TISAX Level 2 with prototype protection. What this means is explained in the article What is TISAX?
Glossary
Lift axis: Lifting aid that guides loads rigidly and without swinging along the vertical axis. More terms in the handling technology glossary.
Rail system: Ceiling rail with trolley from which the lift axis hangs and travels.
Rail gauge: Distance between the two rails of a double longitudinal rail.
Flange plate: Mechanical interface to which the fixture is bolted.
Universal joint: Joint for adjusting the connection angle in two axes.
Balance: State in which the control compensates for the weight of the load and the operator guides it with little force.
Z axis: Vertical axis of movement of the lift axis.
End position damping: Braking of the lifting movement shortly before the end position.
Compressed air reservoir: Reservoir that allows the work cycle to be completed safely in the event of a power failure.
Load handling attachment: Component-specific fixture or gripper on the handling device, for example on a manipulator, lift axis or lifting device.
Frequently asked questions
What is a lift axis in a rail system?
A lift axis in a rail system is a vertical lifting aid that hangs from a ceiling rail via a trolley. It guides the load rigidly and without swinging along the Z axis and can travel along the rail. The floor at the station stays clear, for example for vehicles on an assembly line.
How much can the ZH90 lift axis carry?
The ZH90 lift axis from Zeilhofer carries up to 1,200 kg. Each system is designed for the actual weight of the fixture and the required lifting range.
Can I mount my own fixture on the lift axis?
Yes. The lift axis ends in a flange plate whose dimensions are agreed with you. A universal joint adjusts the connection angle by plus/minus 10 degrees in X and Y, and the main axis can additionally be rotated by plus/minus 10 degrees. On request, Zeilhofer also designs the fixture.
How is the lift axis operated at the station?
Via a pull cord. One pull calls the fixture from the parking position to the preset working height, where the axis switches to balance. After the work, another pull brings the fixture up, where it is mechanically locked.
What does it mean that the lift axis switches to balance?
In balance, the control compensates pneumatically for the weight of the fixture. A 2-circuit smooth-running balancing control automatically switches from empty weight to load weight. The operator then guides the fixture with little hand force, as if it were almost weightless.
What happens if the compressed air fails?
A compressed air reservoir with non-return valve holds enough air to safely finish the current work cycle. Additional non-return valves secure against hose rupture, and a mechanical fall protection is integrated.
Can the lift axis be integrated into the system control?
Yes. An electrical sensor reports when the axis is locked in the top position. The operator can integrate this signal into the line or station control, for example as a condition for the vehicle to move on.
Can a lift axis in a rail system be retrofitted to an existing line?
In many cases, yes. The prerequisites are a load-bearing structure for the rail, sufficient height without interfering contours in the steel structure and oil-free, particle-free compressed air. Zeilhofer clarifies these points during an on-site meeting.
Is a lifting aid mandatory from 2027?
There is no general obligation to use a specific lifting aid. However, employers must assess and reduce risks when lifting. In addition, from 20 January 2027 the EU Machinery Regulation (EU) 2023/1230 applies to machinery placed on the market.
Your application: bringing heavy fixtures to the line ergonomically
Are you planning a new assembly station or want to make an existing one more ergonomic? We design the lift axis for your fixture, your lifting range and your workflow. Call us on +49 (0)8024 / 46330-60 or send us your enquiry.
More practical examples from vehicle production can be found in the guide Lifting aids for automotive final assembly and under Handling technology for the automotive industry. Further applications of the ZH90 lift axis: car seat assembly, cockpit modules, vehicle axles and trailer hitches in series production. An overview of all 18 industries is provided on the page Applications.
More about the product: the Hebelift ZH is Zeilhofer's mobile, battery-powered lifting aid, designed for your component.
