BIZOMAT MAKEOS · Mechanics
Buffer Stop Design (Impact Energy, Stroke, Force and Deceleration)
What buffer stroke stops this moving carriage within my force and deceleration limits, and what peak force reaches the end stop structure?
Design of an end buffer for a moving carriage, trolley or crane: kinetic energy at impact (as the impact load tool, moving mode), extra energy from a drive force that keeps pushing through the stroke, peak buffer force and deceleration for a spring buffer (force rising linearly) or a hydraulic buffer (near-constant force at its efficiency), the stroke needed to stay within your deceleration limit, and checks of force and deceleration.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Moving mass | kg | Mass of the moving carriage and its load. |
| Impact speed | m/s | Speed at which it reaches the buffer (often a share of full speed, from the standard you follow). |
| Drive force continuing through the stroke | N | Drive or gravity force that keeps pushing during the stroke (0 if the drive is cut). |
| Buffer type | choice | Hydraulic buffers give a near-constant force; springs and elastomers build force with stroke. |
| Hydraulic buffer efficiency | % | How close the hydraulic buffer comes to a constant force (force = energy ÷ (efficiency × stroke)). |
| Buffer stroke | mm | Working stroke of the buffer. |
| Largest deceleration allowed | g | Largest deceleration the load and people allow. |
| Largest force the end stop can take | kN | Largest force the end stop and its fixings can take. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Moving mass
- What it is
- The total moving mass that strikes the buffer: carriage, trolley or crane plus any load it carries.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 10000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2000 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Impact energy rises in direct proportion to mass.
What this means: Impact speed
- What it is
- The speed of the carriage at the moment it reaches the buffer, set by the standard you follow or the speed left after slowdown.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0.000001 m/s to 20 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Impact energy rises with the square of speed.
- Get it right
- Metres per second; divide m/min by 60.
What this means: Drive force continuing through the stroke
- What it is
- Any drive or gravity force that keeps pushing the carriage while the buffer compresses, adding to the energy absorbed.
- Units and format
- Enter a number in N: newtons. The form accepts 0 N to 10000000 N. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 N as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- 0 = the drive is cut before impact and there is no slope.
What this means: Buffer type
- What it is
- How the buffer force builds through the stroke: near-constant for a hydraulic buffer, rising with stroke for a spring or elastomer buffer.
- Units and format
- Choose one of 2 options from the list: Hydraulic (near-constant force); Spring or elastomer (force rises with stroke).
- Example
- The form opens with “Hydraulic (near-constant force)” selected as a worked example. Choose the option that matches your case.
What this means: Hydraulic buffer efficiency
- What it is
- How close a hydraulic buffer comes to an ideal constant force, from the buffer maker’s data. Used only for the hydraulic type.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 50% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 90% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A lower efficiency raises the peak force for the same energy and stroke.
What this means: Buffer stroke
- What it is
- The working stroke of the buffer: how far it compresses while absorbing the impact.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A longer stroke lowers the peak force and deceleration.
What this means: Largest deceleration allowed
- What it is
- The largest deceleration the carriage, its load and any people on it may experience, expressed as a multiple of gravity.
- Units and format
- Enter a number in g: grams. The form accepts 0.05 g to 20 g. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1 g as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- In g, not m/s²: 1 g = 9.80665 m/s².
What this means: Largest force the end stop can take
- What it is
- The largest force the end stop, its structure and fixings can take, from the structural design.
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts 0.000001 kN to 100000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 20 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter it in kN, not N: divide a catalogue value given in newtons by 1000.
Method and formulas
- Kinetic energy E = ½ m v² (as the impact load tool, moving mode); total energy = E + F_d s.
- Spring: peak force = 2E_total ÷ s; hydraulic: peak force ≈ E_total ÷ (η s).
- Peak deceleration = (peak force − F_d) ÷ m; stroke for the limit found by search.
- Example: 2000 kg at 1 m/s carries 1,000 J; a 100 mm hydraulic buffer peaks at 11.111 kN and 0.56651 g.
Limitations
- Rigid carriage and end stop; structure flexibility adds stroke and lowers force.
- Spring buffers return energy: rebound must be acceptable.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size buffers for a crane or transfer car
- Check an end stop for a faster speed
- Compare spring and hydraulic buffers
Who it is for
- Machine designers
- Crane engineers
- Safety engineers
What you get
- Impact and total energy
- Peak force and deceleration for the stroke
- Stroke needed for the deceleration limit
Interpreting the result
- A hydraulic buffer of the same stroke has about half the peak force of a spring buffer.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 179–186. Topic reference; no source tables or recommended settings are reproduced.
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Open the Buffer Stop Design (Impact Energy, Stroke, Force and Deceleration) calculator