Trailer axle load weights are calculated using a static equilibrium analysis, treating the trailer as a rigid beam supported at two key points: the kingpin and the bogie centre. The aim is to determine how much of the total payload weight is transferred to each support point.
This involves:
- Payload weight and distribution — total mass and its centre of gravity (COG) along the trailer length.
- Trailer geometry — the distance between the kingpin, COG, and bogie centre.
- Support reactions — calculated by resolving vertical forces and moments around a known point (typically the kingpin).
The basic principle follows the laws of static equilibrium — the sum of vertical forces and the sum of moments must both equal zero. This allows you to calculate the downward force (load) on the kingpin and axle group respectively.
While it’s possible to calculate manually using equations, it’s easy to make errors without precise measurements. To simplify this, Don-Bur provides a free online calculator: enter your load positions and weights, and it estimates the axle loadings accordingly.
You can access this calculator in the related links section below.
