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Trailer Reversing.The key to reversing a trailer is to think of it simply as reversing a car with a twist: Number the three axles involved from one to three - one for the front axle of the car, two for the rear axle of the car and three for the trailer axle. Now think of the problem as one of reversing an "imaginary car" made up of axles two and three, ie. the back axle of the car and the axle of the trailer. You have to reverse this "imaginary car" and to do so you have to control its steerable wheels (axle two) so that it goes where you want. The trouble is that you can only control axle two indirectly by swinging the front of the real car (axle one) and this becomes the main purpose of axle one. Like any reversing car, the imaginary car will travel in a straight line if its steerable wheels (on axle two) are straight ahead, and will turn in a circle if they are angled. If the aim is to reverse in a straight line and the trailer starts to deviate into a circle, axle two must be straightened up and turned the other way to correct. The way to do this is to turn the real car even more tightly into the same circle - to turn inside the trailer. If the imaginary car is reversing in a tighter circle than the real car, the circle will get tighter and tighter until the unit eventually "jack-knifes". If the real car is turning inside the imaginary car, the turn will reduce, straighten out and even recommence on the opposite lock unless correcting action is taken. For this reason novices often reverse in ever increasing zig-zags until being forced to stop. It is important to reverse very slowly and think ahead to avoid this fate. If necessary, stop, drive forward and have a second attempt. If the real car exactly follows the imaginary car in the same arc then the combined unit will follow a smooth curve. In this case the angle between the real and imaginary car will stay constant and this can be checked by lining up a point on the rear window with a point on the trailer. When reversing in a confined space do not forget the front of the (real) car. You will be making the front of the real car swing left and right as you concentrate on steering the imaginary one - don't let the real one hit something real! There is little special about reversing a trailer with a four wheel drive, but the following tips may be useful: Most four wheel drives are tall and this can make it difficult to see a low box trailer. In this case it can be useful to tie a tall stick (or a broom, or shovel etc.) to the rear of the trailer to sight on. You need to be able to drive very slowly when reversing so consider engaging low-ratio, but in order to avoid transmission "wind-up" do not lock four wheel drive unless traction is a problem. If the vehicle is full-time four wheel drive with a centre-diff', not engaging the diff'-lock will prevent transmission wind-up. If the vehicle is part-time four wheel drive, wind-up can be prevented by disengaging free-wheel hubs, if fitted, but remember that this can place excessive loads on the rear axle if lots of power is applied. Some owners who do a lot of towing fit a towing point to the front of their vehicle - this is easy to do on many four wheel drives. If the trailer (boat, caravan etc.) needs to be reversed into a tight place it can be attached to the front towing point and manoeuvred much more easily. A front towing point is also useful for four wheel drive recovery operations using snatch-strap or a solid-tow but it must be properly engineered and strong enough for the job. Finally, it is a good idea to practice reversing a trailer somewhere quiet and before you need to. Most people master the skill in a few minutes but the last thing you want is to be surrounded by critical and impatient observers!
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