We bust the Jargon of Approach Angles, Departure Angles and Ramp Over Angles, it might all sound a bit double dutch to some and we know the word angles has got you maths haters already running for the hills but if you want to get up that hill or over an obstacle with your 4×4 in one piece you might want to read this first. For just a few moments preparation you cans save yourself a bag of trouble if you get things wrong or just go at it hoping for the best.
This is basically the lowest height at the front of the car in front of the tyres and the length of car in front of your tyres. So if approaching a ramp head on will the bumper or what ever hangs lowest at the front make contact first and prevent the tyres from gripping and climbing? If this is the case then you need to change your angle of approach, instead of driving head on to the ramp approach from a side angle so rubber can make contact and pull you up.
To get a visual guide of your approach angle, place one end of a plank or broom stick on the floor at the base of the front tyre and place the other end of the plank/broomstick level with your lowest frontal point.
RAMP-OVER/ BREAK-OVER ANGLE
Ramp-over or break-over angles are the same, just depends on what part of the world you are from, but if you get this wrong you’ll find yourself stuck teetering on a rock in a see saw action. The vehicle will be unable to get any traction from tyre contact with the ground, and you’ll be praying your undercarriage is suffering minimal damage, or grateful that you fitted underside armour.
To avoid this you’ll need to know the distance between the front and rear tyres and the lowest central point of the undercarriage. If you do have a low ramp over point, again head on is not the best approach line to take. By changing your tyres, adding a lift kit or even portal axles, all will improve your ramp over angle by some degrees. Shorter wheel base vehicles do have a higher ramp over point then the long wheelbase option, this is why competition 4×4 drivers prefer the likes of a Defender 90 to the 110 variant.
Knowing this is the ability to leave an obstacle without ripping you’re rear end off. This needs to be considered when leaving level ground to climbing an obstacle just as much as descending from the obstacle or hill. This angle measures from the lowest point at the rear of the vehicle to the base of the rear tyre with the distance from the rear tyre to the furthest point at the back end of a vehicle.
Most 4×4’s tend to have tow bars fitted, if so, this usually is the lowest point and the most rearward fixed point of the vehicle. If removable they are always to be removed before off roading, hence your departure angle has now improved somewhat.
Again by choosing a different descent line you can avoid that nasty scrapping noise. To visualise your departure angle use the same method as measuring approach angle above.
Remember there other angles to learn about your vehicle, such as climb, decent and side slope angles to consider before you push your truck to see what it can do.