What is the function of a Bull Bar?

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Bull Bars are very high on the list of desirable items on a 4wd enthusiasts shopping list. In this article, I am only referring to the full bumper replacement type bull bars and not nudge bars.

Bullbars (or Roo-Bars) became very prominent in Australia due to the increase in collisions between vehicles and wildlife (Kangaroos), especially in the Outback regions. In the early days, they were manufactured out of steel and were very heavy. They consisted of a heavy gauge channel across the front of the vehicle with tubes welded onto it to offer the required protection for the entire front of the vehicle.

The function of the bull bar was primarily to protect the occupants of a vehicle during an animal strike as well as minimise the damage sustained to the vehicle during such an incident. Without a bull bar, a vehicle could be rendered immobile should the radiator or any other critical components be damaged by the collision. This was an important consideration when travelling through rural areas hundreds of kms away from the nearest repair centre. Bullbars thus offered better protection against such misfortune.

Bullbars also serve as a mounting platform for many ancillary accessories deemed essential by the 4wd owner. Mountings for off-road driving lights, communication antennae, sand flags, winches and other recovery and jacking points have been incorporated into many of the bull bar designs available.

More recently the design of the bull bar as a whole has been changed. Typically a bumper replacement bullbar now consists of a steel pan which is similar in shape to the original plastic bumper of the vehicle with a tube hoop design welded to the top. These modern bumper replacement bullbars better suit the design of the modern 4wd than the rudimentary designs of a decade or 2 ago. Modern bull bar design engineers have also been able to design the shape of the bull bar to increase the approach angle for the front of the vehicle in many cases.

There are a few very important factors to consider before making the decision to fit a bumper replacement bull bar. The modern steel bull bar can weigh anywhere between 40 and 80 kgs depending on its design and application. A winch will add another 45kg or so. Hanging this weight off the very front of the modern 4wd chassis has some important implications.

You will lose some front suspension height due to the additional weight on the nose of your rig. When travelling through a dip in the road at speed or off-roading, the additional weight will compress the front suspension more and depending on your vehicle type, you could even start bottoming out the front suspension on full compression. You may therefore also have to upgrade the front suspension of your vehicle which pushes up the total cost.

Reputable bull bar manufacturers take this additional weight and loading forces into consideration when they design a bull bar for the modern 4wd. The design of the bar and especially the mounting system is very well researched and engineered to ensure that the additional stresses do not compromise the front portion of the vehicle's chassis. A badly designed bar that is too heavy may cause chassis fractures which could have catastrophic results.

The most important consideration however for choosing your bull bar is Airbag Compatibility. It is unfortunately not well understood and we will cover this topic in detail in our next blog.