Most of all road damage can be caused by dynamic loads of vehicles that fluctuate according to the type of
vehicle that passes. This study aims to calculate the vertical dynamic load of the vehicle actually which occurs on road
construction after through the vehicle wheel suspension mechanism. The Pneumatic cylinder that was driven by
pressurized air directly weighs on the Spring and Shock Absorber that contained on the wheels of the vehicle. The load
fluctuations of the medium weight category vehicle are determined by the regulation of the amount of pressurized air
entering into the pneumatic cylinder chamber pushing the piston and connecting rods. The deviation that occurs during
compression on the spring and Shock Absorber is substituted into the vehicle dynamic load equation by taking also the
magnitude of the spring stiffness constant, and the fluid or gas coefficient of the damper. The results showed that the
magnitude of the displacement when the compression force worked has significantly influenced the amount of vertical
dynamic load of the vehicle that overlies the road construction. Experimental results using pneumatic actuators instead of
real dynamic vehicle loads illustrate the characteristics of the relationship between work pressure and dynamic load. If the
working pressure of P2 (bar) is given great, the vertical dynamic load Ft (N) which overloads the structure of the road is
also greater. From the graph shows that shock absorbers have greater ability to reduce dynamic load vertically when
compared to spring ability.
Keywords: dynamic load, pneumatic cylinder, pressurized air, suspension, road.