Leading the world in
energy absorption


Rotational Impact

horizontal impact
Kinetic energy to be absorbed
Energy due to drive force
Total energy to be absorbed ET = Ek + Ed
Maximum impact force
Design mass for buffer

Summary of notation

To avoid confusing conventions within calculations always use SI units in formulae then convert to more appropriate units if required.

Notation Quantity SI Unit
M Mass of body kg
Me Buffer design mass kg
S Buffer stroke m
K Radius of gyration m
Ek Kinetic energy J
Ed Energy due to drive force J
Et Total energy J
ω Angular velocity rad/s
I Moment of inertiaa kg.m2
T Torque Nm
F Impact force N
N Number of buffers in parallel
ξ Efficiency -

Worked example

Eg. Consider a swing bridge, having a moment of inertia (I) of 7500000 kgm2, buffer arm radius (r) 8m, angular velocity (ω) of 0.174 rad/sec and a driving torque (T) of 1500000 Nm. Using 2 buffers.

To find the energy to be absorbed:

Let us select a Type 4 with 114mm stroke:

Total energy to be absorbed:
Therefore ET = Ek + Ed = 113535 + 21375 = 134910 J = 134.91 kJ

To find the maximum impact force:

§To find the equivalent mass for metering pin selection:

Therefore select metering pin code 08 for masses up to 80000kg (80 tonnes).