Types of CV-joints & FWD Half Shaft Operation

Construction of a Drive Axle

FWD:

• Combines the transmission and differential

• Has a transaxle, half shaft, and CV-joint

• Has half shafts that extend to the front wheels

The CV-joint:

• Transfers equal torque to the drive wheels

• Is one of the main components of the FWD driveline

• Provides a flexible coupling

CV-joints vs. U-joints:

• Preform the same function

• U-joints allow the driveshaft to move with the suspension as it transfers power to the drive wheels.

• When the shaft rotates at an angle, one U-joint starts oscillation and another U-joint cancels oscillation before it reaches the Axle.

• CV-joints can work at larger operating angles.

Types of CV-joints:

• Are categorized by location, function, and design

• Are based on:

○ Position: inboard or outboard

○ Function: fixed or plunging

○ Design: ball-type or tripod type

Inboard Joints

  • The joint near the transaxle is called the inner (inboard) joint.

  • The inboard joint connects to the transaxle’s differential.

  • The three most common types of inboard CV joints are:

    • Double-offset joint

    • Plunging tripod joint

    • Cross groove plunge joint

  • The vehicle’s make and model determine which type of CV joint is used.

Outboard Joints

  • The joint near the wheels is the outer (outboard) joint.

  • The two most common types of outboard CV joints are:

    • Rzeppa joint

    • Fixed-tripod joint

  • The vehicle’s make and model determine which type of CV joint is used.

Fixed Joint

  • A fixed joint does not move in or out to compensate for changes in the drive axle length.

  • It is typically used as the outboard CV-joint on front-wheel drive vehicles.

  • A fixed outboard joint must allow the front wheels to turn at greater angles than a plunging joint can.

Plunging Joint

  • A plunging joint can move in and out to compensate for changes in axle length as the suspension moves over varying road conditions.

  • Inboard joints are usually plunging joints, allowing the driveshaft to slide in and out of the joint housing when the front wheels move up and down.

Types of CV-joint designs are:

  • Ball-type

  • Tripod

Both are used as either inboard or outboard joints, as well as fixed and plunging designs.

Fixed Ball-type CV-joints - Components

  • The components of a ball-type CV-joint include: outer race, inner race, ball cage, balls, boot clamp, boot, retaining clip, and driveshaft.

  • The inner race attaches to the axle and has several machined grooves around its outside diameter—one for each ball bearing.

  • The bearing cage holds the ball bearings in place as they move within the grooves of the inner race.

  • As the axle rotates, the inner race and balls rotate together, with the balls acting as bearings between the inner and outer races.

  • The balls transfer engine power from the inner race to the outer race while allowing smooth rotation.

Types

  • The Rzeppa joint is a fixed ball-type CV-joint.

  • The balls operate in pairs, working together to transmit power smoothly.

  • If one ball shows heavy wear in its groove, the paired ball will also exhibit similar wear.

Description

  • The most common type of CV-joint is based on a ball-and-socket design.

  • This design eliminates vibration and binding issues caused by the joint’s operating angles.

Plunging Ball-type Joints/Double-offset - Components

  • The components of a double-offset CV-joint include: ball retainer, ball cage, balls, inner bearing race, outer race, retaining clip, and stub shaft.

  • This joint is similar to a Rzeppa joint, except it has longer grooves machined into the inner bearing race.

Description

  • A Rzeppa CV-joint can be modified into a plunging joint by lengthening the ball grooves in the inner race.

  • This design is typically used in applications requiring higher operating angles and greater depth.

  • The modified version is known as the double-offset joint.

Plunging Ball-type Joints/Cross Groove CV-joint - Components

The components of the cross groove CV-joint are the cage and balls, outer race, and inner race.

Description

  • The cross groove CV-joint is similar to the Rzeppa joint, but the grooves in the races are cut at an angle.

  • It has a flatter design than other plunging joints.

  • This design allows it to handle a large amount of plunge in a short distance.

  • The inner and outer races share the plunging motion equally, reducing the overall depth needed for a given amount of plunge.

  • This type of joint is commonly found in German-made vehicles.

Tripod Plunging CV-joints - Components

  • The components of a tripod plunging joint include the boot and outer housing (also called the tulip assembly).

  • It contains a tripod assembly with three spherical rollers that ride on needle bearings.

  • The tulip housing has three grooves, allowing the rollers to move in and out as the axle length changes.

Description

  • A plunging tripod joint has longer grooves in the outer housing than a fixed joint, allowing the tripod assembly to move in and out within the housing.

  • Some tripod joints feature a closed outer housing, while others have an open housing with machined roller tracks.

  • Both American and European vehicles commonly use plunging tripod-type joints.

Fixed Tripod CV-joints - Components

  • The components of the fixed tripod joints are the outer race, inner tripod assembly, boot clamp, and boot.

Description

  • The fixed tripod CV-joint has a central hub (tripod) with three trunnions, each fitted with spherical rollers on needle bearings.

  • The spherical rollers ride in the grooves of the outer housing, which connects to the front wheels.

  • This design provides constant velocity, regardless of hub movement.

FWD Half Shaft Operation

  • A front-wheel drive half shaft contains two CV-joints.

  • The outboard CV-joint is typically a fixed joint, while the inboard CV-joint is a plunging joint.

  • The main components of CV-joints are the inner race, outer race, and cage.

Step 1 -

  • The side gear of the differential transfers torque to the outer race of the inboard CV-joint.

Step 2 -

  • The bearing transfers torque

  • The inner race is splined to the half shaft

  • Torque is transferred to the half shaft

Step 3 -

  • The bearings transfer torque from one race to the other

Step 4 -

  • The half shaft transfers torque to the inner race 

  • The inner race transfers torque to the outer race

Step 5 -

  • The stub shaft is built into the CV housing (outer race).

  • As the outer race rotates, the stub shaft rotates with it.

  • The stub shaft drives the hub, which in turn drives the wheels.