Transfer case facts for kids

A transfer case is a special part found in vehicles that have four-wheel drive or all-wheel drive. Think of it as a control center that sends power from the engine to all four wheels. It's part of the vehicle's drivetrain, which is the system that makes the wheels turn.

Shown is the transfer case and driveshafts

Usually, a transfer case lets you switch between two-wheel drive and four-wheel drive. When you're driving on regular roads, most four-wheel drive vehicles use only two wheels (usually the back ones) to save fuel. When you need more grip, like on dirt roads or slippery surfaces, the transfer case helps send power to all four wheels. Vehicles that only have two-wheel drive don't need a transfer case.

The transfer case takes power from the transmission (which changes gears) and sends it to the front and back axles using drive shafts. It also makes sure that the front and rear wheels spin at the same speed. This is important for good control, especially when off-roading.

Most transfer cases have different gear settings:

• High range (often 1:1 ratio): This is for normal driving on city streets and highways. It means the power goes straight through without changing speed.
• Low range (like 2.72:1 or 4:1 ratio): This gear makes the wheels turn much slower but with a lot more power. It's perfect for tough off-road driving, like climbing steep hills or pulling heavy loads. For example, if a transfer case has a 2.72:1 low range, it means the engine's output shaft spins 2.72 times for every 1 spin of the wheels. The Jeep Wrangler Rubicon model uses a very strong 4:1 low range gearing for extreme off-roading.

How Transfer Cases Work

There are two main ways transfer cases send power to the wheels.

Gear-Driven Transfer Cases

These transfer cases use strong gears to move power to the front and rear drive shafts. They are usually very tough and heavy. You'll often find them in large trucks. Some newer light trucks and SUVs also use gear-driven cases because of their strength.

Chain-Driven Transfer Cases

These transfer cases use a special chain to send power to the axles. Chain-driven cases are usually quieter and lighter than gear-driven ones. They are also less expensive to make. Many vehicles like compact trucks, full-size trucks, Jeeps, and SUVs use them. Some people who love off-road driving might change their chain-driven transfer case to a gear-driven one to get that extra strength for really tough trails.

Images for kids

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  Inside of a 231 New Process Gear transfer case.