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I feel like I'm hearing a bunch of terminology that sounds like it may be the same thing or at the least related parts of a sub-assembly.

The part I know for sure on my car is labeled as the CV Axle from the parts store I buy from, but I've been reading the terms drive axle, drive shaft, and CV shaft pop up. A family member also used the term spindle when I was talking about possibly needing to replace my CV axle. And this guy just used the term prop shaft which he says is the same as a drive shaft. I also came across the terms shaft assembly and transaxle at Raxles. Are these things all pretty much synonymous?

  • what is a CV axle?
  • what is a drive axle?
  • what is a drive shaft?
  • what is a transaxle?
  • what is a halfshaft?
jxramos
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2 Answers2

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What is a CV Axle?

CV stands for Constant Velocity. It's a type of axle which is used on front wheeled drive vehicles which allows power to still be transmitted to the front tires even while wheel is turned. It is called "constant velocity" due to the way it's designed. No matter which way the outer section is turned, it will remain at the same speed as the inner section. This allows for smooth power to be transmitted. U-joints don't work the same, as speed actually varies as the yokes are turned over the u-joint. Here's an image of a typical CV axle:

enter image description here

What is a drive axle?

A drive axle is the part which goes from a differential out to the tire. This is usually encased within an axle housing. CV axles can actually be considered drive axles, because they transmit the power from the transaxle out to the tire. Drive axles can be found on front or rear wheel drive vehicles. Here's an image of a typical drive axle and axle housing:

Drive axle (solid axle):

enter image description here

Axle housing (with drive axles installed):

enter image description here

What is a drive shaft?

A drive shaft transmits power from the transmission (or transfer case on a 4wd or AWD vehicle) to the differential. The differential sits within the axle housing (the large part in the center from the image above). The drive shaft allows for power to be transmitted in different directions as the axle housing moves up and down while the vehicle is moving. You'll only find drive shafts on rear wheel drive vehicle (or 4/AWD), but not on front wheel drive vehicles. The reason is, everything is self contained within the transaxle, with no need to transmit power to another location. Here is an image of a typical drive shaft:

enter image description here

You'll note the slip yoke which is attached to one end (left side of the image). This (as the name implies) slips in and out of the transmission so as to allow for the difference in distance from the transmission to the differential during normal vehicle travel. As the axle goes up/down, the distance will vary between the two. The slip yoke allows this to happen without interruption.

As for the term "prop shaft", it is synonymous with drive shaft.

Pᴀᴜʟsᴛᴇʀ2
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Great answers from Paulster. I would add:

  1. Prop shaft: probably short for propeller shaft (which is the drive shaft that runs the drive or torque all the way from the transmission to the rear axle assembly in rear-wheel-drives).

  2. Drive shaft is the proper name for a shaft that runs from a final drive to a driving wheel, or a shaft between the transmission and an axle. They actually are found in front-wheel-drives too. The drive shafts ARE the axle of a FWD. Whereas the driveshaft in a RWD is the propeller shaft that runs along the car between the transmission and the axle.

FWD diagram

In this diagram you can see the drive shafts (which fall under the C.V. products). CV being constant velocity, which as Paulster said allows the wheel to drive at a constant speed while turning at any angle. (RWD don't need this because rear wheels don't turn... usually).

  1. Transaxle is actually the transmission on a Front-Wheel-Drive. It runs along the same direction as the axle and very close to it. (The engine itself, and the transaxle, run in the same direction as the axle in a FWD, whereas the drive shaft and transmission run perpendicular to the engine and axles, along the length of the car in a RWD). Hence why they call it a transaxle. It's basically a transmission that's practically right on top of the axle, as opposed to a transmission that's somewhere under the car between the engine and the axle, quite far away from the axle itself.

enter image description here

  1. Drive axle refers to the axle/drive shafts of the driving wheels (the front drive shafts in a FWD, the rear axle in a RWD).

  2. Half shafts are a kind of loose term sometimes used to refer to the drive shafts (or axles if you want to call them that) of a FWD. They're called half shafts because you have two, each one transmitting half the power from the transaxle to one of the wheels.

MattyJWolf
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