Automobile Engineering | State the different types of rear axle. Explain construction details of any one of them.

 Types of Rear Axle:

1) Semi floating Rear Axle

2) Quarter Floating rear axle

3) Fully floating rear axle

1. Semi floating Rear Axle

Construction details:

• The figure shows a schematic diagram of the semi floating rear axle. 
• A single ball bearing is inside the axle casing. 
• The axle of the wheel is at the centre of the axle casing and the wheels are fitted at the end of the axle. 
• This is done by means of key, bolt and nut. 
• The whole weight of the vehicle is first transmitted to the suspension spring. From there it is transmitted to the axle casing from there to the axle and wheel. 
• Finally it is transmitted to the ground. 
• The axle can be removed by first placing a support below the axle casing.

2. Quarter floating rear axle:

Construction details:

• This axle is generally used on large vehicles and high performance cars. 
• In this axle, a bearing is provided inside the axle housing to carry the final drive unit. To support the weight of the vehicle, an outer bearing is also placed between the wheel hub and the axle housing. 
• The weight of the vehicle is transferred to the axle casing while the side trust and the driving torques are supported on the axle shaft.One bearing of the brake drum is fitted on the axle while the other on the axle tube. 
• The hub bearing housing flange carries the wheel studs. It is either integral with the half shaft or carried on a keyed taper pass through the half shaft flange. 
• During cornering, the half shafts are only subjected to a bending load. As shown in the figure , this axle is quite complicated but more reliable as compared to semi-floating axle. 
• The wheel will still be attached to car on case of half shaft failure. But the side loads may cause it to rock on the bearing.

3. Full Floating Rear Axle:

Construction details:

• In this type of axle two taper roller bearings are used. Bearings are placed between the axle housing and the wheel hub. Since the load of the vehicle is supported completely by the axle housing. 
• The axle only transmits driving torque. 
• The inner end is supported inside gear of differential and outer end have a flange to which wheel hub is bolted. 
• The axle may be removed or replace from the housing without disturbing the wheel by removing the nut. 
• This type of axle is more expensive and heavier than other axle. 
• This type is used in trucks or commercial vehicles.