REAR AXLE

REAR AXLE:
 The differential is not shown purposely, so as to make the general arrangement more clear. The drive form the  propeller shaft come to the pinion shaft which is supported in bearings in the axle casing casing. The crown wheel is in mesh with the pinion and is mounted on shaft on the ends of which are fixed the caps which serve to restrict the wheel in axial direction. The wheel are mounted on bearings on the ends of the axle shaft. In practice, however, there are two half shafts instead of single one shown here.
       The weight of the body and due to occupants is transmitted through spring to the axle casing, the details of which will be described in the chapter on suspension system. The casing itself  is supported by road wheels.

Rear Axle

WEIGHT OF THE BODY: 
The rear axle may be considered a beam supported at the ends and loaded at two points as shown in The rear weight W of the body is transmitted to the rear axle through two suspension springs. R1 and R2are the reaction forces form the road wheels. This weight causes shear force and bending moment in the axle shaft.

Body Weight on the rear axle

DRIVING THRUST:
Driving torque produced in the engine causes the to be produced in the road wheels, which has to be transmitted form the axle casing to the chassis frame and the body of the vehicle. the is most conveniently done by some form of member conne-cting the axle casing and the chassis frame in the longitudinal direction Such members are called thrust members or radius roads.

TORQUE REACTION:
 If the road wheels are prevented from rotation with the propeller shaft rotating, it is  roll  round   the crown wheel. The tendency is also present when the vehicle is running so climb round on  the  axle casing   (which supports the bevel pinion),  to rotate. The is called torque reaction. In the same way, the braking torque on the axle casing is opposite in direction to the torque reaction.
    The tendency on the part of the axle casing has to be opposed, because, otherwise the propeller shaft would be subjected to heavy bending loads. The can be effectively done by means of a member, one and of which is attached  to the axle casing and other end to the frame so that the member itself  remains in the direction of the vehicle axle.

Radius Rods and Panhard Rod

SIDE THRUST:
Often the rear axle experiences side thrust or pull due to any side load on the wheel, e.g., the cornering force. panhard rod may be employed to hold the axle in position against the side thrust.

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