Parts of a CV Axle – Labeled Diagram with Names

All 10 parts on the diagram

Show the list

The whole axle 5

Axle shaft Carries the turning from the inner joint out to the outer joint.
Rzeppa joint (outer CV joint) Can bend through the large angles needed when the front wheels steer. It still turns the wheel smoothly.
CV boots A boot keeps the grease in the joint. It keeps dirt and water out. A band at each end holds it on.
Splines They lock the axle to the part it drives. The two must then turn together. This end goes through the wheel hub, and a nut on its tip holds it there.
Circlip It snaps into a groove to hold a splined end in place.

The two joints, end on 5

Tripod joint (inner CV joint) A three-armed piece on the shaft carries a roller on each arm. The rollers slide in three tracks in the housing, so the axle can get a little longer or shorter as the wheel rises and falls.
Outer race The balls run in grooves on its inside. It is the bell you see in the first view, and the splined end is part of it.
Balls They pass the drive from the inner race to the outer race. Nothing else does.
Cage It keeps all six balls in one plane as the joint bends.
Inner race It is splined onto the end of the axle shaft. It has a groove for each ball.

How this list was compiled: Part names checked on 2026-09-30; a name is kept only when two independent sources use it. (1) Missouri Auto Mechanics Curriculum Guide, Module 7, Manual Drive Train and Axles, University of Missouri, 1990, https://archive.org/details/micro_IA41155136_1006 (half shaft, axle shaft and its splines, the Rzeppa and the tripod as the two common half shaft joints, Rzeppa joint with inner and outer races and steel balls, cage, tripod joint with a spider in a housing, boot and CV boot, boot clamp, circlip, hub nut). (2) US Army TM 9-8000, Principles of Automotive Vehicles, 1985, chapter 28, paragraph 28-7 and figure 28-6, https://archive.org/details/tm-9-8000-principles-of-automotive-vehicles-1985 (Rzeppa constant-velocity joint: inner race splined to the axle shaft, outer race, ball cage, six balls as the only points of driving contact). (3) Wikipedia, Constant-velocity joint, text only (CV joint, Rzeppa joint with a cage and six balls and a splined shaft held by the axle nut, tripod joints at the inboard end with rollers in a grooved cup and plunge movement, CV boot, circlip). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's axle, nothing traced. Licence: own work

How it works

The parts of a CV axle are a shaft, a constant velocity joint at each end, and a rubber boot over each joint. It is the half shaft that turns one front wheel of a front-wheel-drive car.

Read the full guide

The whole axle

The wheel end is on the left. Its splines go through the wheel hub, and a nut on the tip holds them there. Next is the outer CV joint, a Rzeppa joint, which lets the wheel steer. The axle shaft joins it to the inner CV joint, and a CV boot covers each joint. The far end fits into the transaxle.

The joints, end on

The Rzeppa joint has six balls between an inner race and an outer race, with a cage to hold the balls. The inner joint here is a tripod joint: three rollers slide in three tracks, so the axle can change length a little.

CV stands for constant velocity: the joint passes on a steady turning speed at whatever angle it is bent.
The textbook name for a CV axle is a half shaft.

Questions and answers

What are the parts of a CV axle?

An axle shaft, an outer CV joint at the wheel end, an inner CV joint at the transaxle end, a rubber boot over each joint, and a splined end beyond each joint.

What is the difference between the inner and outer CV joint?

The outer joint, often a Rzeppa joint, bends through the large angles needed when the front wheels steer. The inner joint, often a tripod joint, bends less but lets the shaft slide in and out a little.

What does a CV boot do?

It is a flexible rubber cover over a CV joint. It keeps the joint's grease in and keeps dirt and water out.

What is inside a CV joint?

In a Rzeppa joint, six steel balls held in a cage, between an inner race on the shaft and an outer race. In a tripod joint, a three-armed piece with a roller on each arm, inside a housing with three tracks.