The ABC of HGV

Every business and every industry has its terminology, acronyms and codes that seem to make it impenetrable to anyone outside of the business. In truth, in the HGV world it is a common shorthand that does make sense once you have the code.

A is for ‘axles’ which are fundamental to the whole proposition.

  • Axles can do a number of things but in general they can steer, power or just spread the load. Most trucks have a description that is at least partly familiar 4x2, 6x4 etc. We all know that a 4x4 is an all-wheel drive vehicle. The code is simple, 4x2 means the truck has four wheels of which two are powered. Similar to many cars the front two steer and the rear two provide drive.

  • 6x2 offers a higher load capacity with more wheels to spread the load, while 6x4 offers more powered wheels which is vital if the road surfaces can be less than ideal. Larger and more challenging configurations go up to 8x4 which is a common specification for HGVs that operate heavy loads in muddy conditions i.e. quarrying, earth moving and similar applications.

  • Axles other than the front can also steer. Sounds scary but in reality, it offers assistance to the front steering wheels only. An upshot of this is that rear- or mid- steer vehicles can operate in more confined spaces that many people suspect. This can sometimes be a surprise to drivers around them. So, look out for stickers or signs on vehicles that say ‘rear steer’ or similar, they are for your benefit.

  • Some axels can lift off the road. It may sound counter-intuitive but when HGVs are running at low loads, non-steering, non-driving wheels do nothing except add rolling resistance. A clever pneumatic system raises the wheels off the road reducing both the running cost for the operator and the emissions for all of us. Note that the lifting axle can be the rear or middle axle.

  • B is for ‘bodies’ which is everything to the rear of the cab. First-off is the fact that bodies can be contiguous with the cab chassis (rigid body HGV) or a separate trailer with a tractor unit (articulated) providing the motive force and steering. Articulated versus rigid bodies:

  • HGVs can have a rigid body up to 12m long, that’s nearly 40’ in old money. Anything longer than that needs to be articulated but a rigid HGV can tow a trailer behind it, often referred to as a draw bar configuration.
  • Articulated trucks are typically a tractor unit (cab, engine, steering) with a trailer attached behind, sometimes called a ‘combination’. An interesting piece of trivia is that what we call a trailer is referred to in the US as a ‘semi’ or ‘semi-trailer’ as it doesn’t have a set of wheels at the front.
  • Chassis bodies are basically a structure behind the cab that is the foundation for whatever construction is needed to provide the required function of the vehicle.
  • The descriptions of chassis bodies following also applies to trailers:
  • o Box – Probably one of the most common configurations with solid roof and walls making a secure, weatherproof payload area. Boxes can have additional structures built inside but are generally hard-floored for pallets, trolleys and similar cargo handling containers.

    o Curtain side – The other candidate for most common format. The curtain side does as its name suggests and replaces the solid side walls with flexible, waterproof weather protection. The simple reason is that they make easy access to the sides typically by forklifts, which has made the ‘double deck’ curtain side possible. Note; some HGVs carry their own forklift trucks at the rear. Pioneered by Moffett, there are several alternatives now that provide a more flexible option to an onboard crane arm.

    o Dropside – Often on smaller vehicles ideal for building and construction trades, dropsides provide open air storage for heavier, lower value commodities such as aggregates and cements in addition to being stock in trade for tool hire company deliveries. The dropside makes for easy manual access to the cargo. Tippers are a step up from the dropside with a powerful hydraulic ram at the front of the cargo area and a pivot to the rear. They make easy unloading of bulk loose cargo and vary in size from van sized to large (8x4!) earth movers.

    o Platforms – Platform bodies are workhorses that can be adapted to include loading ramps. You’ll still find platforms being used by coal merchants on their deliveries. Generally speaking, platforms will include several lashing points as they are often used for outsize loads such as roof trusses, generator parts, mobile homes etc

    o Refers – The stock-in-trade of the food industry, refrigerated boxes or refers, are often seen as large and small box HGVs in addition to box trailers. A refrigerated HGV or trailer is a box with thermal insulation to the floor, ceiling and solid sides in addition to a standalone refrigeration unit. The ‘refer unit’ that cools the cargo is often self-powered and you will see the grill, for air cooling the heat exchanger, prominently in the airflow either at the top of a rigid HGV or the front of the trailer in an articulated unit. It is worth noting that a refrigerated unit can have more than one temperature zone with baffles and bulkheads allowing or blocking flow of air to the refrigeration unit. Interestingly, a refrigeration unit does not blow cold into a space, rather they suck the heat out of a space.

    o Skeletons – Skeleton trailers are another common format and are designed to work with standard shipping containers from ports and intermodal terminals. Containers come in two sizes 40’ and 20’. Unusually, a driver of a container that has been sealed at the point of loading will often have absolutely no idea of what they are carrying to their point of delivery. At the destination a serial numbered security closure will be removed, with bolt-cutters, compared to dispatch documentation, to confirm that the delivery has not been opened or tampered with since loading.

    o Skip loader – Skip loaders and their close kin, the hook loader, are designed to handle large open containers. Often seen at building renovation sites and refuse or recycling points, the lifting bar with chains or container hook, both lifts and loads the container.

    o Tankers – A very specialised unit that delivers everything from milk to industrial chemicals to water and petrochemicals. Tankers always display, on the back and sides, a code for what they are carrying to aid emergency services in the event of an accident. Tankers are often pressurised and whether they carry dangerous chemicals or not, driving them is one of the most responsible jobs on Britain’s roads.

    o Vehicle transporters – Varying from small single to double vehicle units (variants used by AA, RAC and other vehicle recovery organisations) to double-deckers delivering cars to dealerships nationwide, are easily identified by the open metal supporting framework. However, there are dedicated variants such as low-loaders that deliver larger specialist vehicles that are not allowed or sensible, to drive on the UK’s roads.

  • C is for ‘cabs’ which are the heart and brain of whole enterprise. Modern cabs are a mixture of workspace and accommodation for the driver, generally positioned above the engine. Few trucks have the cab behind the engine except for the Mack, an American brand not often seen in the UK, immortalised in the film Convoy, which was in turn based on the song by C.W. McCall.
  • o Day cabs – Essentially a workspace for the driver and a co-driver or passenger. A modern truck’s cab is ergonomically designed so that the, many, controls are at the driver’s finger tips helping focus their attention on the road.

    o Sleeper cabs – For longer journeys, behind or sometimes above the driver operating area, is a bed space. While not luxurious compared to a hotel there is the space for one, sometime two people, to get their rest. Additional storage is available both in the cab and in external lockers, for possessions, food and supplies.

    There are a great many variants of cab offering additional height, space, sunroofs and similar driver comforts such as fridges and microwave ovens.

    This guide is simply an introduction to the world of HGVs and an attempt to demystify the nomenclature so that, if someone mentions a ‘6x4 curtain side’, you will not be completely in the dark.

    They next article will cover some of the other definitions based around the powertrain and emissions. So, look forward to hearing about EURO 6, AdBlue and DPFs in the next few weeks.