4x4 PROFESSOR
What is the difference between a powertrain and a drivetrain? How does 4x4 differ from diff locks, and should a diff lock be fitted on the front or rear axle? Here are the answers…
Apowertrain consists of your vehicle’s engine, gearbox, drive shafts, transfer case, differential gears, side shafts and wheels. In effect the entire mechanism that makes your 4x4 vehicle go.
A drivetrain, on the other hand, excludes the engine and wheels and focuses only on the gearbox, front and rear drive shaft, transfer case, differential gears and all four side shafts.
The final drive of your off-road vehicle only includes the differential and the side shafts. By the way, in a boat, the final drive is its prop, and in a motorcycle, it’s typically the chain and rear sprocket.
A four-wheel drive system involves delivering power to all four wheels as opposed to only the front or rear wheels. All cars, whether front-wheel, rearwheel or all-wheel-drive, use differential gears.
Why differential gears? None of your vehicle’s four wheels rotate at the same speeds when you go around a bend, and yet all four wheels are connected to just one mechanical component via the powertrain: the engine’s crankshaft. For example, if you turn left, the left front wheel rotates at 1 rpm and the right front wheel at 0,8 rpm. In turn, the left rear wheel rotates at 0,7 rpm and the right rear wheel at 0,9 rpm. (These figures are only an example to explain geometry and aren’t necessarily mathematically correct.)
To send engine power to all four wheels, each rotating at their own speed without breaking anything or slipping the wheels, we have to use differential gears.