Q: What's a low-ratio transfer gearbox? Charles Finch
A: A low ratio transfer ‘box effectively reduces the gearing of the main gearbox to provide more pulling power for off-road driving. It is usually operated by a separate control mounted near the main gear stick. This reduction in gearing also cuts the final speed of the car, and gives more control when negotiating difficult terrain. Low-ratio ‘boxes are especially useful when going up or down steep slopes, or ploughing through water.
Some off-roaders also feature locking differentials, which stop power being wasted if one wheel losses traction. With a differential locked both wheels constantly turn at the same speed and the vehicle can pull itself out of a slippery situation.
Both of these features can only really be used when driving off-road, or in very difficult conditions, such as deep snow. Some manufacturers don’t include them because their vehicles if it is not really designed to perform in such extreme conditions. Many of today’s 4x4s are really designed to drive on the road, with only mild adventures in the rough.
True off-roaders, such as the Land Rover Defender, are able to negotiate very difficult conditions, but sacrifice on-road manners and sophistication as a result. Some of the newer 4x4s manage to combine comfort and Tarmac focused driving with genuine off-road ability by using a combination of electronic and mechanical components. However, these are still compromised do not usually perform as well as a true off-roader.