Hydraulic Buffers for Crane and Heavy-Duty Applications
A hydraulic buffer converts the kinetic energy of a moving mass into heat as oil is forced through calibrated orifices. The result is controlled deceleration — without the impact shock, noise and structural stress of a rigid end stop.
What Is a Hydraulic Buffer?
A hydraulic buffer is a deceleration device. When a moving mass strikes the piston rod, hydraulic oil inside the cylinder is forced through calibrated orifices. The viscous resistance of the oil converts kinetic energy into heat, which is dissipated through the cylinder body.
The difference from a rigid end stop is the shape of the deceleration curve . A steel bumper stops the load in a near-instantaneous spike — high peak force, high noise, and cumulative fatigue damage to the structure and the wheel bearings. A hydraulic buffer spreads the same energy over the full stroke, holding the decelerating force close to constant.
In practice that means: less stress on your structure, less noise, less maintenance, and a shorter cycle time — because the machine spends less time recovering from the impact.
Where Our Buffers Work
Four industries where Forgesail already supplies rail systems — and where a hydraulic buffer is the natural next component in the same purchase order.
Ports &Shipyards
Ship-to-shore cranes, gantry cranes, rubber-tyred gantry cranes and transfer carts. Our BHI series is the reference choice for emergency braking on port machinery, with units working at Ningbo Port and Qingdao Port.
Automated Warehouses &AS/RS
Stacker cranes, shuttles and high-bay conveyor systems. Our BHD series is validated across the full speed range of modern stacker cranes — 60, 90, 120, 150, 180 and 210 m/min — in a six-speed test programme carried out for Dematic.
Overhead &Gantry Cranes
End-of-travel deceleration and anti-overtravel protection for overhead cranes, gantry cranes and hoisting systems. Pair your buffers with our crane rail clips, sole plates and bumping posts for a complete end-of-track solution.
Heavy Industry &Rail
Steel mills, mining installations, ladle and transfer cars, railway end-of-track stops, drop-hammer testing rigs and emergency safety stops.
How to Choose the Right Hydraulic Buffer
Hydraulic buffer selection comes down to three decisions. Start at the top and work down — by the end you will know which series to look at.
How much energy do you need to absorb?
How should the piston rod return?
Do you need to adjust it on site?
Not sure? If your operating conditions are stable and you know the load, a factory-set buffer will outperform an adjustable one. If conditions change, or you are still commissioning, go adjustable.
Our Six Hydraulic Buffer Series
Six series, one standard of engineering. Every unit is built around your actual application data — not pulled off a generic catalogue page.
| Series | Energy / Cycle | Stroke | Cylinder Ø | Impact Velocity | Adjustment | Return Mechanism |
|---|---|---|---|---|---|---|
| BD Adjustable | 6 – 21,000 Nm | 7 – 250 mm | M10 – M115 | 0.02 – 5 m/s | 0–12 steps | Internal coil spring |
| BC Self-Compensating | 10 – 680 Nm | 4 – 80 mm | M6 – M36 | 0.02 – 5 m/s | Factory-set | Internal coil spring |
| BHD Air-Bag Heavy-Duty ★ | 3.2 – 900 kJ | 50 – 1500 mm | Ø90 – Ø275 | ≤ 6 m/s | Factory-set | Nitrogen air bag |
| BHDA Adjustable Heavy-Duty | 9.6 – 224 kJ | 50 – 300 mm | Ø130 – Ø275 | 0.75 – 3.25 m/s | 1–5 steps | Nitrogen air bag |
| BHS Spring-Type Heavy-Duty | 0.5 – 470 kJ | 50 – 400 mm | Ø64 – Ø360 | To specification | Factory-set | External spring |
| BHI Hydraulic-Pneumatic ★ | 4 – 720 kJ | 50 – 1000 mm | Ø65 – Ø180 | To specification | Factory-set | Nitrogen chamber |
←Swipe to see all parameters →
★ Best match for Forgesail's core markets — automated warehousing and ports. · Heavy-duty series share 60 cycles/hour max and special epoxy-painted cylinders with hard-chrome-plated piston rods.
- Very low recoil — will not push the load back
- Validated 60–210 m/min on Dematic stacker cranes
- Safety chain, bellows and position sensor options
- 2× the energy of other structures, same bore
- Landing-gear derived technology
- Strong return force for rail end stops
- Retune on site as load or speed changes
- -SP variants tolerate 30° side load
- Ships from stock in 5 business days
- Factory-set soft / middle / hard
- Maximum energy in the smallest envelope
- Lowest unit price for stable duty cycles
- Air-bag return plus on-site tuning
- One model covers several work stations
- Cuts heavy-duty spare-part inventory
- Lowest recoil force of any series
- Widest bore range, up to Ø360 mm
- Built for low-acceleration braking
How Our Buffers Work
Three damping and return technologies, each matched to a different job. The right choice depends on your energy, your space and how much recoil your process can tolerate.
Multi-Orifice Damping
Most European and American brands use a single orifice. We use multiple orifices. Under identical conditions the multi-orifice design produces a lower peak damping force and completes the deceleration in less time — which is why our buffers protect your equipment better and run quieter than a single-orifice unit of the same size.
Nitrogen Air-Bag Return
Instead of a mechanical return spring, a sealed nitrogen bladder does the work. Oil displaced during compression squeezes the bladder; on the return stroke the bladder expands and pushes the oil back, resetting the piston rod. The result is a shorter overall body, a lower peak damping force and — critically — a very small recoil force, so the buffer does not shove your load back after stopping it.
Hydraulic-Pneumatic Synergy
This technology originated in aircraft landing gear. Hydraulic oil and nitrogen gas absorb the impact energy together: the oil handles the damping, while a small nitrogen chamber stores part of the energy as potential energy and drives the return stroke. In the same cylinder diameter and stroke, BHI absorbs more than twice the energy of other structures — which is why it is the reference solution where space is tight and the energy is not.
Two Results Worth Knowing
Six-speed stacker crane programme
We ran a six-speed buffer test programme for Dematic covering the full operating envelope of a modern AS/RS stacker crane.
"Our BHD buffers are validated across the full speed range of modern ASRS stacker cranes — from 60 to 210 m/min."
Curve-matched buffers for crash testing
For a child-seat safety testing laboratory we engineered a buffer with a tailored deceleration curve that reproduces a vehicle impact energy profile.
"We engineer buffers to match a target deceleration curve — not just a peak force."
Get the Installation Right
Most buffer failures are installation failures. These are the mistakes we see most often — and what to do instead.
- Using the buffer as an end stop. Fit a stop collar 1 mm before end of travel, and never remove the steel strike head.
- Ignoring side load angle. Standard limit is below 2°; heavy-duty is 2.5° up to 300 mm stroke and 1° above that.
- Fitting a standard buffer on a rotating station without checking the geometry.
- Jumping straight from notch 0 to notch 4 on a BD, or starting a BHDA at notch 5.
- Leaving the locking screw loose after adjusting the notch.
- Mixing models or notch positions on buffers working in parallel.
- Painting the piston rod, or painting over the buffer body.
- Treat the buffer as a decelerator, not a limit device — install a stop collar.
- Keep side load under 2° (standard) or within the heavy-duty stroke-based limits. Use -SP variants for angles up to 30°.
- On rotating stations keep the centre of rotation at least 15 × stroke away, or fit a side-load adapter.
- Always step the adjustment up one notch at a time: 0 → 1 → 2 → 3 → 4.
- Tighten the locking screw with a hex key after every adjustment.
- Use identical models, with the knob on the same notch, for every buffer in a parallel group.
- Add a piston-rod bellows in dusty service, and a safety chain above 2 m installation height.
| Limit | Value | Note |
|---|---|---|
| Impact velocity — BD / BC | 0.02 – 5 m/s | Up to 20 m/s with custom orifice design |
| Impact velocity — heavy-duty | ≤ 6 m/s | At 60 cycles per hour |
| Max cycle rate — heavy-duty | 60 cycles / hour | Governs heat build-up |
| Side load angle — BD / BC | <2° | -SP variants up to 30° |
| Side load angle — heavy-duty ≤ 300 mm stroke | <2.5° | Exceeding it bends the rod and causes leaks |
| Side load angle — heavy-duty >300 mm stroke | <1° | |
| Temperature — BD / BC | -10 to 80 °C | Extended range -30 to 100 °C |
| Temperature — heavy-duty | -10 to 60 °C | Extended range -35 to 100 °C |
| Maintenance — safety/emergency duty | Every 6 months | Check rod, oil seal, fasteners and full return |
| Maintenance — frequent duty | Monthly |
Selection Terminology
The terms that appear on every sizing report and datasheet.
- Max. Energy per Cycle (ET)
- The maximum energy the buffer can absorb in a single impact (Nm or kJ).
- Max. Energy per Hour (ETC)
- Cumulative energy absorbed per hour. Governs heat build-up and service life.
- Max. Damping Force (Fp)
- The peak reaction force during deceleration. Determines the load your structure must carry.
- Effective Weight (We)
- The load range the buffer is tuned for, used together with impact velocity.
- Impact Velocity (V)
- Speed of the moving body at contact.
- Recoil Force
- The force with which the piston rod returns. Low recoil means the buffer does not push the load back.
- Side Load Angle
- Permitted angular misalignment at installation. Exceeding it bends the rod and causes leaks.
- Stroke
- Usable piston travel (mm).
- Adjustable vs. Self-Compensating
- Adjustable units are tuned on site with a knob; self-compensating units have fixed orifices set at the factory.
- Air Bag
- A sealed nitrogen bladder used to return the piston rod.
- Orifice
- A calibrated metering hole. Oil forced through it creates the damping force.
- DU Bushing
- A metal-polymer composite bearing that carries side loads.
Talk to an Engineer
Tell us your application and we will come back with a recommendation, a sizing calculation and a quotation. If you are still at the design stage, we are happy to work from drawings.
