Which axle is the drive axle

The answer is: both of them are working all the time. Both axles drive the truck, just like both the left and right tires drive a rear-axle pickup truck — as long as there is no loss of traction. When the differential or power divider lock is engaged, each axle now drives the truck whether the other axle has traction or not. A combination truck is a prime mover or rigid truck that is pulling a trailer either a semitrailer or dog trailer.

A prime mover typically has one or two steering axles and one or two drive axles. You can easily tell how many drive axles there are if you know the axle configuration which is expressed most commonly in this format: axle ends x driven axle ends. Each axle has two axle ends where the wheels are. Therefore 4 axle ends means two axles, just like a car. But it is not a bad idea to look at them any time you are under the car for an oil change or other service. Periodic inspections of the boots can keep the axles from needing to be replaced, if you catch and fix a torn boot soon enough.

Unfortunately due to the nature of the design, the axles do need to be removed if the boots are going to be replaced. Split CV joint boots exist for easy replacement, but are only a temporary solution until a proper repair can be done.

If you hear a clicking noise when turning a corner, chances are there is a bad CV joint and the axle needs to be replaced, or taken out and rebuilt with new joints.

Other symptoms of a possible bad axle or CV joint are vibrations especially through the steering wheel , and rumbling noises that vary with road speed. Raise and support the car, and with it in gear, check for faulty boots, as well as play in the axle and joints. Beginners Guide.

Additionally, vents or valves are installed on top of the housing to prevent pressure from building up, which develops from heat within the housing. Heat is produced from normal operation of the vehicle, and these vents or valves release the heat. If the pressure is not released from the housing, it may force the axle lubricant to move past the rear wheel oil seals and damage the vehicle's brake linings. Despite allowing air to pass through the housing, these vents prevent debris and dirt from entering.

It is common for the term "shaft" to be used interchangeably with "drive shaft," "CV shaft" and "axle," as it is a rotating rod within the axle's housing responsible for transferring movement or torque throughout the assembly it was designed for.

In most vehicles, a drive shaft is connected to the transmission on one end and the differential on the other. The transmission transfers power to a differential via the drive shaft.

In addition to transferring power, shafts may also receive power, or both simultaneously. This can be seen in vehicles that utilize all-wheel drive. An entire axle assembly typically contains two half shafts located on each side of the differential.

They are connected to the wheel bearing and allow the wheel to rotate. They may also be found in machines that require physical components to rotate, such as gears. A differential is a gearing found between each half shaft on the car axle that is connected to the wheel. The wheels on a vehicle traveling on any specific path must all travel at different lengths throughout the entirety of the journey.

Since wheels operate in this way, it is necessary for each wheel to have the ability to rotate at a different speed from one another. Differentials allow each wheel to turn at a different speed. A pinion gear is attached to the end of a drive shaft and rotates to turn the differential's ring gear. The ring gear is responsible for rotating side gears, which ultimately enables the two axles to turn at different speeds.

The speed of rotation for axles on vehicles traveling in a straight line remains consistent until the vehicle makes a turn. As the vehicle turns, the differential compensates for the axle's need of a different speed; thus, allowing the vehicle to operate and turn properly.

Universal joints that connect the drive axle are called constant velocity joints. These joints are typically referred to as CV joints. The outer CV joint is a ball and cage that remains in a fixed position.

The inner CV joint is called a plunging sliding ball and housing. It can also be referred to as a tripod-type joint. These types of inner CV joints act like a slip joint in a drive shaft for a rear-wheel drive vehicle. The plunging action that takes place within an inner CV joint allows for a change in distance between the transaxle and the wheel hub.

The length of the drive axle must change as the front wheels of a vehicle move up and down over bumps on the road. Overtime, this movement can cause wear and tear on the CV joints which result in the need for a replacement. A front drive axle relies on the power that is transmitted to it from the transfer case via the drive shaft to steer the wheels of a vehicle. Certain vehicles that utilize a front drive axle may have the differential housing set off center in the axle housing to allow the drive shaft to pass beside the engine oil pan and maintain adequate road clearance without excessive height at the front of the vehicle.

Universal joints, which are located on the outer ends of the axles, are used to allow the front wheels and hubs swivel while still transferring power to them respectively. UV joints are necessary as the front wheels on a front drive axle must turn on the axle spindle arm pivots by the axle shaft itself.

Vehicles that utilize a four-wheel drive axle require locking hubs for the front drive axle to function properly — locking hubs transfer power from the driving axles to the driving wheels on four-wheel-drive systems.

Manual and automatic locking hubs are the most common locking hubs found on most vehicles. They enable vehicles with four-wheel drive to temporarily switch into two-wheel drive. This is beneficial for vehicles driving on dry pavements , as the front wheels can turn without turning the front axles.

Enabling this function via the locking hubs provide the vehicle with increased fuel economy as well as reduced driveline wear. Rear drive axles are responsible for connecting the differential side gears to the drive wheels. Depending on the vehicle and the drive axle it utilizes, the rear drive axle may or may not be used to support the vehicle's weight.

Typically, they are manufactured with harder materials than other drive axle components, as this allows an increase in strength. Rear drive axles can be categorized into three types - semi-floating , full-floating , and three-quarter floating.

Semi-floating rear drive axles are found in common passenger vehicles and light trucks. The shaft and housing support the weight of the vehicle. The side gears of the differential are used to carry the inner end of the semi-floating rear drive axles to relieve the axle's shafts of the differential's weight.

Also, it relieves the shafts from the stress caused by normal operation within the axle housing. The inner ends of the axle only transfer turning effort or torque and they are not acted upon by any other force during the vehicle's operation.

The outer end is supported by a bearing located between the shaft and the housing. The load is transferred through the use of a tapered roller. The axle shafts take the stresses caused by turning , skidding or wobbling wheels.

They are flanged or tapered on each end. When using a tapered axle, it is most common for a brake drum and hub to be pressed onto the shafts. When this occurs, keys are used to prevent the assemblies from turning on the shafts. Other vehicles with a less common tapered axle have serrations or "splines" on the outer ends of the shafts rather than the more common brake drum and hub setup.

Both of these setups serve the purpose of disconnecting the wheel from the vehicle itself in the event of the axle breaking. Should the axle break during operation of the vehicle, the action of disconnecting the wheel itself assists the vehicle with not only coming to a complete stop but with the prevention of damaging the drive axle further.

Full-floating rear drive axles are used in heavy-duty trucks. A pair of tapered roller bearings carry the outer end of the axle housing. These bearings are located outside of the axle housing.