{"id":54383,"date":"2016-02-11T12:31:30","date_gmt":"2016-02-11T18:31:30","guid":{"rendered":"http:\/\/www.artofmanliness.com\/?p=54383"},"modified":"2026-01-08T14:06:08","modified_gmt":"2026-01-08T20:06:08","slug":"gearhead-101-the-drivetrain","status":"publish","type":"post","link":"https:\/\/beta.artofmanliness.com\/skills\/cars\/gearhead-101-the-drivetrain\/","title":{"rendered":"Gearhead 101: The Drivetrain"},"content":{"rendered":"

\"Gearhead<\/p>\n

Welcome back to Gearhead 101<\/a> — a series on the basics of how cars work for the automotive neophytes out there.<\/p>\n

In our first article in the series, we discussed the ins and outs of how a car engine works. We learned that through a bunch of tiny explosions, your car engine creates a rotational motion in the crankshaft. This rotational movement — called torque <\/em>— is what powers the car.<\/p>\n

All well and good. But how do we transfer torque from the engine to move the car\u2019s wheels?<\/p>\n

The answer to that question is the topic of today\u2019s post: the drivetrain.<\/p>\n

What the Drivetrain Is<\/h3>\n

The drivetrain isn\u2019t a single part in your car, but rather a series of parts that work together to transfer the rotational power produced in your engine to your wheels so your car can move.<\/p>\n

You may have come across the word \u201cpowertrain\u201d before. While it\u2019s often used interchangeably with drivetrain, they\u2019re not the same thing. The powertrain encompasses everything that makes the car go, including the engine. The drivetrain encompasses the things that make the car go, not <\/em>including the engine. It\u2019s these engine-exclusive parts that we\u2019ll be focusing on below.<\/p>\n

There are several drivetrain arrangements. For this article, I\u2019ll be focusing on the two found in most vehicles: rear-wheel drivetrains and front-wheel drivetrains. In my next article we\u2019ll get into the surprisingly complicated world of four-wheel drive and all-wheel drive!<\/p>\n

Rear-Wheel Drivetrain<\/h3>\n

\"Rear<\/p>\n

In rear-wheel drivetrain arrangements, power is transferred to the rear wheels to move the car. It\u2019s the drivetrain arrangement that\u2019s been around the longest and is still used today on many cars and trucks.<\/p>\n

This arrangement provides myriad benefits over the front-wheel variety. First, it distributes weight more equally to each tire, which in turn provides better steering and handling. Second, rear-wheel drive can offer superior braking compared to front-wheel drive vehicles. Finally, and probably most importantly, rear-wheel drivetrain arrangements split the jobs of steering and driving the vehicle, which can lead to better handling and acceleration. With rear-wheel drive vehicles, the back wheels only have to move the car. In front-wheel drive cars, the wheels have to both move the car forwards or backwards and <\/em>steer it left or right. We\u2019ll talk more about this when we discuss front-wheel drivetrain arrangements below.<\/p>\n

Rear-wheel drivetrains consist of the following main parts:<\/p>\n

Transmission. <\/strong>I plan on dedicating an entire article to how transmissions work, but for now, understand that the transmission controls the amount of power that goes from your engine to your wheels. In rear-wheel drive cars, the transmission is attached to the rear of the engine by way of a flywheel. The transmission takes the spinning movement — the torque — from the engine\u2019s crankshaft and passes it along to the…<\/p>\n

Drive Shaft. <\/strong>The drive shaft is a spinning tube that connects to the rear of the transmission and transmits the spinning power that began in the engine to the back of the vehicle at the differential (more on that in a bit). Drive shaft designs come in two types: torque tube and Hotchkiss.<\/p>\n

\"Universal<\/p>\n

Torque tube drive shafts were used on older vehicles and are still used on some trucks and SUVs today. The driveshaft itself is enclosed <\/em>in a tube. Torque tubes connect the transmission and differential via a single universal joint, or U-joint for short.<\/p>\n

Hotchkiss drive shafts are the more common drive shaft design. Unlike torque tube drive shafts, Hotchkiss drive shafts have an open design, meaning you can actually see the drive shaft spin beneath your car when it\u2019s moving. Also, instead of just using one U-joint to connect the transmission and the differential, Hotchkiss drive shafts use two U-joints.<\/p>\n

Differential. <\/strong>The differential is the melon-sized part that sits between the two rear wheels. It\u2019s the last stop along the drivetrain before torque is transferred to the rear wheels. The differential transfers torque, causing them to spin, which in turn moves the car.<\/p>\n

\"A<\/p>\n

It\u2019s called a \u201cdifferential\u201d because it allows the two rear wheels on the same axle to move at different<\/em> speeds. You\u2019re probably thinking, \u201cWhen would my rear wheels move at different speeds?\u201d Well, a common instance is whenever you go around a corner. When you make a right turn, your inside wheel (the right wheel) travels less of a distance than your outside wheel (left wheel). To keep up with the inside wheel, the outside wheel must spin slightly faster. The differential makes this possible. If there was a solid connection between both wheels, one of the wheels would need to skid in order for the axle to keep moving.<\/p>\n

If you want a better idea of how a differential works, check out this awesome video from 1937:<\/p>\n