Selecting a heavy vehicle

Your choice of vehicle impacts your business. The right choice can improve your fuel efficiency, safety and profitability. This guide contains advice on the features you need to consider when purchasing your next vehicle.

The five-step selection process

1. Operating environment and vehicle layout

Ask...

• What will you use the vehicle for? What load space do you need?

• What conditions will it operate under?

• What other legal or operational constraints apply? See:

  • Land Transport Rule: Vehicle Dimensions and Mass 2016
  • Information on vehicle dimensions and mass
  • Land Transport Rule: Heavy Vehicles 2004
  • Guide to importing a vehicle
  • Vehicle classes and standards
  • Information for commercial drivers and operators

• Other requirements will affect the vehicle's configuration, including number of axles, deck length and suspension. Consider:

  • road user charges that will apply

  • static rollover threshold limits – use the SRT calculator(external link) to work out the nominal SRT

  •  

    the Land Transport Rule: Vehicle Dimensions and Mass 2016.

2. Vehicle performance

Next, consider factors that affect performance, such as engineering and vehicle components. Some of these are subject to legal requirements. See the vehicle standards you have to meet.

As a foundation, your vehicle needs sufficient power to handle the workload, using the least amount of fuel and at the lowest life cycle costs. Consider:

• engine power

• torque requirements

• transmission gearing

• differential ratios

• wheels and tyres.

Also consider investment in new braking technology(external link). 

Fuel efficiency

You can reduce your fuel costs by:

• carefully matching the engine size to the workload demand. Every additional 5hp can increase fuel consumption by 2%

• fitting aerodynamic cab deflectors to help reduce aerodynamic drag and inter-vehicle spacing. These can improve fuel efficiency from at least 6% to more than 20%, depending on the body and the load

• using road speed limiters or cruise control features, which can save up to 6% if set correctly

• using semi-automatic and fully-automatic transmissions which now use the same or less fuel than manual transmissions.

Performance checkpoints

• An engine geared to run at 1450rpm at 100km/h uses approximately 4% less fuel than one geared to run at 1600rpm at the same speed.

• Idling can add 20 to 30% to engine hours.

• A fixed drive fan can use 10% of the engine power if it operates all the time, but may only be required for 2–5% of the time. Consider fitting electrically-driven thermostatically-controlled fans. Determine whether it is necessary for the fans to turn on automatically when the air conditioning system turns on.

• At highway speeds, over half the energy required goes into overcoming aerodynamic drag. Reducing aerodynamic drag by 25% will reduce highway fuel consumption by 10–15%. Reductions in aerodynamic drag of up to 50% are achievable. However, the power-train still needs to receive sufficient cooling.

• Dead insects behind the front windshield indicate an airflow problem.

3. Health and safety

Ensure your chosen vehicle meets all legal requirements under the applicable transport regulations, the Land Transport Rules and the Health and Safety in Employment Act(external link) (HSE).

Other things you need to consider:

• Features that affect the normal driving of the vehicle or its driveability – the vehicle's handling, the effectiveness of the lights and cab layout.

• In-service reliability, to reduce risk of a failure that could cause a crash.

• Active safety features that help avoid a crash occurring – ABS, traction control and road speed limiters.

• Passive safety features that protect the driver and other road users when a severe crash is unavoidable – safety belts, under-run protection and crashworthy cabs.

• Driver occupational safety and health issues such as safe access into the cab, the quality of the driver's seat, cab noise, the fitting of tail lifts and other devices.

• Features that increase the vehicle's visibility – for example daytime running lamps, conspicuity tape.

• Features that reduce noise and emissions.

• Anti-lock braking system (ABS), electronic brake stabilisation (EBS) and other brake technologies can significantly improve brake performance.

• Many trucks now comply with the European ECE 29 cab strength requirements, providing added protection in head-on crashes and rolls.

• Under-run protection saves lives. Some trucks are now factory-fitted with front, side and rear under-run protection.

• The Health and Safety in Employment Act(external link) (HSE) recognises the cab as the driver's place of work, placing greater consideration on health and safety.

Safety checkpoints

4. Maintenance

Maintenance typically makes up 5–10% of operating costs and increases as the vehicle ages or when operated in hard conditions. Choosing the right vehicle and regular maintenance will save your business more expensive downstream repairs and the cost of delayed delivery to your clients.

Ask other operators if the vehicle you're considering is reliable. Consider features that improve reliability – the use of synthetic lubricants in axles and transmissions and sealed-for-life bearings.

Maintenance checkpoints

• The amount of fuel consumed is a better indicator of engine wear and when to service your vehicle than distance travelled.

• Synthetic lubricants outperform mineral lubricants at all temperatures. They can reduce fuel consumption by up to 0.5% in summer and 2% in winter.

• A 15psi under-inflation of tyres will increase rolling resistance by 6%.

• Keeping tyres inflated to the manufacturer's recommendations decreases the likelihood of tyre blowouts and flats.

5. Appearance

Vehicle appearance can contribute to attracting business and retaining drivers.

Consider:

• cab layouts that enhance driver comfort

• vehicle styles that appeal to your clients (aggressive looking vehicles may detract)

• livery that enhances your company image and inspires pride in your drivers.

Checklist for vehicle specification

Use this checklist to work out the specifications for your next vehicle.

Operating environment and vehicle layout

Vehicle performance

Health and safety

Maintenance

Appearance

Calculating axle weights

Use the axle weights calculator to the calculate axle weights of your vehicle under various loading conditions.