Shock damper

vibrationhydraulicvisco-elastic

Overview
LEBEN‑Dämpfungstechnik GmbH supplies customised shock absorbers (industrial shock absorbers, vibration absorbers, special shock absorbers and fluid‑elastomer buffers) in single units or small series according to customer specifications and special designs.

Tension/compression shock absorbers
Custom TwinStroke® designs act as hydraulic shock absorbers in both tension and compression directions. Energy dissipation occurs in both directions.
Operating principle
As a purely hydraulic variant (TwinStroke®):

• hydraulically reversible in compression via the damping medium
• hydraulically reversible in tension via the damping medium

A piston system transfers tension and compression forces gas‑hydraulically to separate gas and oil chambers. This enables immediate load absorption without idle stroke and with low wear. The TwinStroke® handles alternating loads efficiently. Only one element is required for both compression and tension, resulting in smaller size, lower weight and cost advantages over two‑element systems; a mechanical friction spring in tension can be omitted. The hydraulic buffer is replaceable if required.

Structure (variants)
Hydraulic variant (TwinStroke®)

• compression: hydraulically reversible via damping medium
• tension: hydraulically reversible via damping medium

Hydraulic with mechanical spring

• compression: hydraulically reversible via damping medium
• tension: mechanically reversible via friction spring

Return‑stroke damping can be fitted to avoid inadmissible force peaks in tension.

Hydrostatic / visco‑elastic / fluid‑elastomer shock absorbers (ED/EZ series)
Impact‑reduction elements with integrated spring‑damping principle (hydrostatic, visco‑elastic, elasto‑fluid or fluid‑elastomer buffers). Available for compression (series “ED”) and/or tension (series “EZ”).
Main components (typical)

• cylinder (container)
• filling/preload with a compressible fluid
• high‑pressure sealing system
• piston
• piston rod
• guide bearing

Design parameters include cylinder volume, piston and piston‑rod diameters, preload force and throttling geometry to adapt the visco‑elastic spring‑shock absorber to application requirements.
Advantages

• usable in both tension and compression directions
• variable characteristic curve (linear, progressive, near‑horizontal or degressive)
• compact design with high energy absorption
• very high spring preload (individual retracting force of the piston rod)
• integrated spring return without additional gas spring or mechanical coil spring
• high‑viscosity elastomer fluid can increase leakage safety
• maintenance‑free operation (depending on type)

Disadvantages

• lower energy dissipation than hydraulic principle (e.g. C‑Type, S‑Type)
• high preload force of the spring can be problematic
• high filling pressure can increase leakage risk
• low‑speed operational load cycles require relatively high counter‑forces compared to hydraulic systems

Special feature (example: hydrostatic buffer)

• total length of the shock absorber: 3.7 m
• weight: approx. 1.4 t
• application: hydrostatic buffer for damping a pre‑tensioned cable catch system (tensioned safety cable at a lock)

Operating principle of ED/EZ series
High‑viscosity, elastic fluids allow fluid‑elastomer shock absorbers to be designed for hydrostatic compression. Piston‑rod movement reduces cylinder volume; compression of the fluid increases internal pressure opposing piston movement. Damping is generated by flow paths (throttle bores or annular gaps) along the piston; reaction force depends on velocity and fluid viscosity.

Use as buffers
Typical applications include train couplings (draw gear), locks and other heavy buffering tasks.

Vibration absorber
Manufactured in various configurations and custom designs:
Single‑tube vibration absorber
For tension and compression damping in any mounting position. Diameter minimised while overall length is increased.
Twin‑tube vibration absorber
For tension and compression damping; preferred vertical mounting. Overall length reduced compared to single‑tube design; diameter increased. Damping characteristic can be progressive or degressive. (Design reference: VDI 3833 Bl.1+2.)

Swivel piston shock absorber
Displacement dampers with hydraulic flow resistance used to damp pendulum oscillations (e.g. pendulum dampers for ropeway cabins). Customer‑specific design; no standard version due to varying operating conditions.

Retrofit — replacement of various third‑party brands
LEBEN can often replace industrial shock absorbers from many other manufacturers with its own products while matching damping characteristics and dimensions. Requested shock absorbers can be manufactured in different variants in single units or small series according to customer requirements and custom designs.

Suspension strut
Gas‑hydraulic shock absorber (suspension strut) suitable for both tension and compression; compact design and variable preload. Typical uses: amphibious vehicles, underground shuttles. Special features may include in‑drive spring stiffness regulation and a nitrogen gas spring as a triple‑diaphragm accumulator.

Various shock absorbers
Increasing demands on machines, vehicles and plants (speed, mass) can create vibration problems exceeding standard mass‑produced absorbers. Space constraints or missing connection parts may require modifications. LEBEN’s design and manufacturing processes allow flexibility for special customer requests even in small quantities; required reaction/decay curves can be realised by individual throttling principles.

Technical specifications

• Manufacturer / Brand: LEBEN‑Dämpfungstechnik GmbH
• Example model / trademark referenced: TwinStroke®
• TwinStroke®: hydraulically reversible in compression and tension; gas‑hydraulic piston system; immediate load absorption without idle stroke; low wear; compact and lightweight; effective for alternating loads
• Fluid‑elastomer buffers (ED/EZ series): main components — cylinder, compressible fluid preload, high‑pressure sealing, piston, piston rod, guide bearing
• Variable design parameters: cylinder volume, piston/piston‑rod diameters, preload force, throttling geometry
• Hydrostatic buffer example: total length ~3.7 m; weight ~1.4 t; intended for damping pre‑tensioned cable catch systems
• Vibration absorbers: single‑tube (any mounting position) and twin‑tube (preferably vertical); damping curves can be progressive or degressive
• Swivel piston shock absorbers: displacement type with hydraulic flow resistance for pendulum damping; fully customer‑specific design
• Suspension strut: gas‑hydraulic, variable preload, suitable for amphibious vehicles and underground shuttles
• Typical applications: train couplings (draw gear), locks, ropeway cabins, vehicle suspension and other industrial buffering tasks