GCM – Gross Combination Mass – is the vehicle manufacturer’s plated rating in kilograms to operate with a trailer in a combination or as an articulated rig. It is the combined mass of the towing vehicle gross vehicle mass (GVM) plus the trailer GVM.

GCM is dependent braking systems and is often the unused capacity of a truck to produce extra ton/kilometres work output. For example, a 16-ton GVM freight carrier with an 8-ton payload could be spec’d with a 32-ton GCM. This means that the truck could haul a 16-ton GVM trailer should the
situation demand it which is a productive answer to seasonal peaks and demands.

A truck with high GCM rating also allows for business expansion – it pays to invest at the outset in the unit with adequate GCM capacity so that the truck can keep pace with business growth over its 10-year life.

There are technical and driver issues in the background that must be taken into account:

  • Trucks up to and around 8,5-ton GVM are usually equipped with vacuum/hydraulic brakes that limits trailer size to a small luggage trailer of 750kg to 2000kg GVM
  • To comply with the Regulations, any trailer over 3,5-ton GVM must be equipped with ABS air-assisted brakes
  • When forecasting the first economic life of a truck, the question to ask is what work will this unit be doing in a few years’ time, and what routes will it be running? Installing a truck with a high GCM offers flexibility to match market demands.
  • Towing a trailer, caravan, or any unit over 750kg GVM requires an E-coded driver licence. A C1 Coded driver licence allows a driver to operate a 750kg GVM trailer behind a 16-ton GVM truck – an EC1 driver licence allows a truck to tow a trailer over 750kg GVM.
  • It’s not just simply hooking up a tow-eye to a locking pin – brake and light connections, combination brake-valve systems, towing cross-member strength, and rated tow-hitch capacity to match the trailer GVM, all come into the final package.

If you wish to discuss this or for more information, please contact Hennie Botha at 031 713 3146 or at 074 331 1354