Crane Shock Absorber
POLARIS is a lightweight crane shock absorber for suitable topside impact and overload duties. It uses a small internal gas volume and CFD-designed valves in one hydraulic cylinder, with no external accumulators or needle valves. Fewer external components keep the package light, compact and economical, including at large capacities; final performance, setup and reset are case-specific.
No external accumulators. No needle valves.
Many accumulator-based shock absorbers use large external gas accumulators and needle valves. POLARIS instead uses a small internal gas volume and CFD-designed valves within one hydraulic cylinder—no external accumulators and no needle valves. Fewer external components make the package lighter, smaller and more economical for suitable topside shock duties. Energy-absorption efficiency is verified from the configured force–stroke curve; selected simulations exceed 90%.
- Small internal gas volume contained in one cylinder
- No external accumulator filling
- Setup procedure defined per configuration
- Starting position checked for the stated duty
- Reset and reuse plan checked against event recurrence
The numbers, first
SWL 75–4,000 t · stroke 1.0–8.0 m| Maximum force (SWL) | 75–4,000 tStandard steps: 75 · 150 · 250 · 400 · 600 · 800 · 1,000 · 1,250 · 1,550 · 2,000 · 2,500 · 3,000 · 3,500 · 4,000 t |
|---|---|
| Stroke length | 1.0–8.0 mStandard steps: 1.0 · 1.5 · 2.0 · 2.5 · 3.0 · 3.5 · 4.0 · 4.5 · 5.0 · 5.5 · 6.0 · 6.5 · 7.0 · 7.5 · 8.0 m |
| Application | Topside overload protection — falling-object loads such as a piling hammer |
| Architecture | Single hydraulic cylinder · internal gas spring · CFD-designed valves — no external accumulators, no needle valves |
| Efficiency | Verified from the configured force–stroke curve · selected simulations exceed 90% |
| Working principle | Gas spring ramps the force to the configured preset · valve controls force while the payload is brought to rest |
| Setup & reset | Procedure and time depend on configuration, event recurrence and deck/rigging plan · offshore reset is subject to the approved method |
| Adjustment | Small internal nitrogen volume · no external accumulator filling/draining · no external HPU for the configured preset procedure |
| Rigging | Fitted to the crane hook via slings · connected to the payload via slings |
| Monitoring | Force, stroke and pressure measurement plus data logging, as defined for the selected configuration |
| Safety | Piston-rod locking, fail-safe functions and manufacturing pull-test scope verified against the project safety basis |
| Verification basis | DNV-ST-0378 · applicable project and class scope confirmed per order |
| Budget price | Configurations from approximately USD 20,000 |
| Documentation | GA drawing · datasheet · calculation sheet · OrcaFlex model — on request via the form below |
What POLARIS does to a pile-run
A matched CONSTELLATION comparison of the same 1,500 t pile-and-hammer stack at 5.0 m/s, with the absorber flag as the only model change. The current rigid-link run supersedes the earlier analytic rigid reference shown in the application film.
One parameter set, two five-second runs: the same masses, stiffnesses, damping, gravity, initial state and integration step. With POLARIS, the 18,000 kN valve setting controls the arrest, below-absorber DAF is 1.31, and the hook stays loaded throughout.
Norwegian Dynamics / CONSTELLATION screening comparison for this stated case, not a certified analysis or a transferable load chart. Project criteria govern. The numeric screens and acceptance limits are not attributed to DNV-RP-N103.
See POLARIS in action
This earlier CONSTELLATION render documents POLARIS motion and telemetry. Its analytic rigid reference predates the matched rigid-link mode and is superseded by the current matched run.
Pile-run protection
Same nominal 1,500 t / 5 m/s scenario. Current matched result: 37.664 MN rigid-link peak versus 23.627 MN with POLARIS (hook DAF 1.43), with 4.98 of 6.0 m stroke used. Reset planning is configuration- and event-specific.
One cylinder does it all
Gas spring ramps the force
POLARIS combines a hydraulic cylinder with an internal gas spring. When a falling load, such as a running pile, engages the unit, the gas spring ramps the force up until the damping preset is reached.
The valve controls the force
A CFD-designed valve controls the force while the payload is brought to rest, shedding energy into stroke. There are no external accumulators or needle valves. Efficiency is verified from the configured force–stroke curve; selected simulations exceed 90%.
Plan reset and reuse for the duty
Starting position, reset method and reuse time are checked for the selected configuration, event recurrence and deck/rigging plan. Preset adjustment uses a small internal nitrogen volume and no external HPU under the configured procedure.
Compact and rugged package
A considered mechanical layout protects key components while making adjustment, handling, upending and maintenance straightforward.
Testing and safety basis
Applicable DNV and project testing requirements are defined for the selected configuration. Manufacturing verification can include frame pull testing and lifting-point tests within the agreed FAT scope. Piston-rod locking, pressure monitoring and fail-safe functions are verified against the project safety basis.
Integrated architecture
The package removes external accumulators and needle valves. For a comparable suitable duty, fewer external components can reduce material, deck space and servicing points; project-specific environmental claims require a defined comparison basis.
Engineered for the stated case
The integrated layout is intended to reduce common external-component and setup steps. Performance, handling and maintenance requirements are verified for the selected configuration and project basis.
POLARIS’s lane in the Knowledge Hub
Pile-run protection
Why piles run, what the punch-through does to the crane — and the modelled case.
Read → KB · SYSTEMSShock absorption
Peak-load reduction for falling-object and overload cases — the physics and the hardware.
Read → KB · FUNDAMENTALSDynamic amplification factor
What DAF means, how it is calculated — and what drives it in offshore lifts.
Read →POLARIS, answered
What applications can POLARIS shock absorber be used for?
How does POLARIS shock absorber work?
POLARIS is normally fitted between crane hook and payload with project-specific slings and interfaces. Read more in our guide to shock absorption.
What are the benefits of POLARIS versus traditional solutions?
- A small internal gas volume and CFD-designed valves are contained within one hydraulic cylinder, with no external accumulators or needle valves.
- Fewer external components make the package lighter, smaller and more economical than a comparable accumulator-based arrangement for suitable topside duties.
- Energy-absorption efficiency is verified from the configured force–stroke curve; selected simulations exceed 90%.
- Setup, preset adjustment, reset method and reuse time are defined for the selected configuration, event recurrence and deck/rigging plan.
- The configured preset procedure uses a small quantity of nitrogen and does not require an external pilot accumulator or HPU.
When should I choose another solution instead of POLARIS?
Where POLARIS sits
SWL 75–4,000 tstroke 1.0–8.0 mYou are here 01
SWL 55–1,000 tstroke 1.0–6.0 m 03
SWL 30–4,000 tstroke 2.5–8.0 m 07
Lift screeningDNV-RP-N103 Compare all systems →
Send your lift case.
Lead time and project pricing depend on capacity, stroke and classification — fill in the form and we’ll send drawings, datasheet and a project-specific quotation.
- GA drawing — sized to your duty
- Datasheet & calculation sheet
- OrcaFlex model of the unit
- CONSTELLATION screening across your sea states