A hydraulic lifting device is a technical system for lifting, lowering and positioning loads using pressurised fluid. It converts hydraulic pressure into a linear lifting motion and thus enables precise, powerful and safe operation. In the electrical industry, tool manufacturing and automotive production, such systems are standard. They are used for assembly, maintenance, testing and for mould changes. Simply put: a pump generates pressure in the oil. The pressure acts on the piston area of a cylinder. This creates force that lifts the load.
Functional principle in brief
The basis is Pascal's law. Pressure acts equally in all directions within an enclosed fluid. The pressure p multiplied by the piston area A gives the lifting force F. Thus F=p*A. The higher the pressure or the larger the piston area, the greater the force. Typical industrial systems operate at 150 to 700 bar. Hand pumps, electro-hydraulic power units or compressed-air motors generate the required pressure.
Structure and components
A hydraulic lifting device generally consists of the following assemblies:
- Hydraulic cylinder with piston, seals and guide
- Hydraulic pump, operated manually or electrically
- Oil reservoir for the pressure medium, usually hydraulic oil HLP 32 or HLP 46
- Valves for control and safety, e.g. check valve, pressure relief valve, lowering brake valve
- Hose lines and quick couplings
- Pressure gauge and optional sensor technology
- Control block or proportional valve technology for precise movements
- Mechanical locks such as load wedges, support jacks or interlocks
Technical parameters and design
The following parameters are decisive for selection:
- Load capacity in kilonewtons or tonnes
- Lifting height and available installation space
- Operating pressure and required oil quantity per stroke
- Stroke speed and controllability
- Duty cycle and thermal load on the power unit
- Temperature range and oil viscosity
- Safety factors and emergency release
- Protection class of electrical drives, if fitted
Example calculation for order of magnitude:
A load of 8 tonnes corresponds approximately to 8000 kg. The weight force is about 78.5 kN. With a safety factor of 1.5, about 118 kN is required. At 700 bar, i.e. 70 MPa, a required piston area of approximately 0.00168 m² results. The corresponding cylinder diameter is around 46 mm. In practice, a cylinder with a 50 mm bore would be chosen to provide margin.
Safety and standards
Safety takes priority. Important measures are pressure limitation, load-pressure-dependent valves, lowering brake valves, hose burst protection and mechanical support for static holding. Risk assessment is mandatory. Depending on the design, standards and rules such as the following apply:
- ISO 4413 for hydraulic systems, general rules and safety
- EN 1493 for vehicle lifts in workshops
- EN 1494 for mobile trolley jacks and transportable lifting devices
- Machinery Directive 2006/42/EC and CE conformity
- BetrSichV and DGUV regulations for operation and inspection
Which specific requirements apply depends on device type, application and market. The operating instructions and inspection intervals must be observed.
Typical designs
Hydraulic lifting devices are available in many designs:
- Bottle jacks and trolley jacks for maintenance and service
- Hollow piston cylinders for pulling and pressing in confined installation spaces
- Synchronised multi-cylinder systems for synchronous motion of heavy assemblies
- Scissor lifts and portal lifts for assembly and logistics
- Special devices with proportional valves for millimetre-precise positioning
Applications in electrical and automotive industries
In the electrical industry, hydraulic systems lift transformers, stators, coil packages or switchgear bays. They position tools and fixtures in winding machines and test benches. Insulation parts made of GFRP, FR4 or aramid paper provide safe creepage distances and thermal barriers in fixtures carrying electric drives, sensor technology or high-voltage test loads.
In the automotive industry, lifting devices support the setup of injection moulds, changing of press tools, joining of body nodes and the assembly of heavy components such as e-drives or battery packs. Sliding and wear plates made of PTFE or POM reduce friction in guides. Elastomer seals made of NBR or FKM ensure leak-free operation across the temperature range.
Materials, insulation parts and peripherals
For fixture construction and safety, suitable materials are decisive:
- Insulation parts: aramid paper, hard paper, FR4, GFRP profiles
- Sliding and wear partners: PTFE, POM, UHMW-PE
- Seals and wipers: NBR, PU, FKM
- Spacers and shims: HPL laminate, stainless steel, aluminium
- Sensor carriers and cable management with insulating holders
Precise selection increases operational safety, reduces downtime and protects electrical components in hybrid or fully electric assembly cells.
Operation, maintenance and quality
Clean oil is the life insurance of every hydraulic system. Filtration, regular oil changes and leak tests are mandatory. Hoses are replaced according to age and load. Valves and cylinders must be checked for leaks and stick-slip. For electrically driven power units, protection class, cable routing, EMC and insulation distances must be considered. Predictive maintenance with pressure and position sensors helps to detect early indicators such as internal leakage or increased duty cycles.
Selection criteria at a glance
- Load, stroke, geometry and safety factor
- Type of control: simple, proportional, synchronised
- Media choice and viscosity matched to the environment
- Safety functions and mechanical locks
- Compatibility with insulation parts and materials in the working environment
- Service accessibility, spare parts availability, test options
GOBA Takeaway
Hydraulic lifting devices combine high power density with precise motion control. For industrial use, in addition to load capacity and stroke, safety, controllability and maintenance-friendliness are essential. Those who consider the interfaces to materials and insulation parts early on design robust fixtures that protect electrical components and stabilise assembly processes. Clean design with suitable valve technology, matched oil viscosity and well-thought-out mechanics reduces downtime and increases process reliability. In this way, the lifting device evolves from a pure power pack into a reliable building block in manufacturing and service.
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