REAR AXLE DRIVE AND REAR AXLE SHAFTS

1. PRESENTATION ON
REAR AXLE DRIVE
AND
REAR AXLE SHAFTS

2. TO : UDAY RAJ SIR
 BY
NAWAL KISHORE BABUL 100109034
NEELESH MAHESHWARI 100109035
PRAYAS NAVAL 100109040

4. Forces on rear axle
 Wt. of the body
 Driving trust
 Torque reaction
 Side thrust

11. Automakers have developed a number of common methods of
locating a live axle
 First approach
uses four trailing arms, two above the
axle, two below it, angled inward so that they resist
lateral motion of the axle.

12.  Another approach,
 used by Buick in the 1960 .
 uses two lower control arms and a single upper arm,
mounted next to the differential, with a lateral track bar
(a Panhard rod) or parallelogram linkage (Watts linkage) to
limit lateral motion. Both the three-link and four-link
layouts are reasonably effective, but the control arms and
track bars make the rear suspension more complex, and
thus more expensive to build .

13. THIRD
OPTION IS

14.  The Hotchkiss drive is a system of power
transmission .
 It was the dominant form of power transmission
for front-engine, rear-wheel drive layout cars in the
20th century

17.  Simplest and most widely used type of rear axle drive .
 The spring besides taking weight of the body also take the
torque reaction , driving thrust and side thrust .
 propellar shaft is provied with two universal joints also a
sliding joint .
 The front end of the spring is fixed rigidly on the frame
while the rear end and is supported in the shackle .

19.  In a Hotchkiss layout,
 the axle is suspended by a pair of longitudinally
mounted semi-elliptical leaf springs, which serve to
locate the axle, as well as supporting the weight of the
body.
 The front portion of each spring functions like a
trailing arm, transmitting drive torque to the body and
resisting squat and axle tramp .

22.  The rear portion of the spring acts as a leading arm,
resisting wheel hop under braking.
 The stiffness of the springs also serves to resist lateral
motions. By making the springs perform multiple
duties, Hotchkiss drive is very simple, and thus very
cheap.
 Since it has few parts, it's also very sturdy, which is
useful for heavy-duty vehicles like trucks.

24. The HOTCHKISS drive requires that the springs be rigid
enough to withstand the twisting action (torque) of the
rear axle and the driving and braking forces that the
springs transmit to the frame. This type of drive is
common to the equipment you will encounter in the
Navy .

25.  The differentiating characteristic of the Hotchkiss
drive is the fact that it uses universal
joints at both ends of the driveshaft, which is not
enclosed .
 The use of two universal joints, properly phased and
with parallel alignment of the drive and driven shafts,
allows the use of simple cross-type universals .

26.  Used in pick-up trucks and sport utility vehicles .

28.  The design problem that the torque tube solves is how
to get the traction forces generated by the wheels to
the car frame .
 The "torque tube" transmits this force by directly
coupling the axle differential to the transmission and
therefore propels the car forward by pushing on the
engine and then through the engine mounts to the car
frame .

29.  In contrast, the Hotchkiss drive has the traction forces
transmitted to the car frame by using other suspension
components such as leaf springs or trailing arms .
 A ball and socket type of joint called a "torque ball" is
used at one end of the torque tube to allow relative
motion between the axle and transmission due to
suspension travel

30.  Since the torque tube does not constrain the axle in
the lateral (side-to-side) direction a panhard rod is
often used for this purpose.
 The combination of the panhard rod and the torque
tube allows the easy implementation of soft coil
springs in the rear to give good ride quality .

31. Torque tubes differ from the Hotchkiss design in
that a solid
drive shaft is enclosed in a hollow torque tub
e and rotates within a support bearing to prevent
whipping

33.  In both types of drive shafts the side thrust is taken the
leaf springs .
 A separate member is employed to overcome this
situation : Panhard Rod
 it si fixed parallel to wheel axis with one end pivoted to
the axle and other to chassis frame

36. EXAMPLES OF THE TORQUE
TUBE
 American cars of the Ford brand up through 1948,
which used the less expensive transverse springs that
could not take the thrust.
 The C5 and C6 Chevrolet Corvette , Mercedes-Benz
SLS AMG

38. Loads on rear axle shafts
 Shearing force due to wt. of vehicle .
 Bending moment on account of load applied through
spring seats .
 End thrust caused by side forces on account of
cornering , side wind
 Bending moment by end thrust and its reation offered
by tyres on ground
 Driving torque

39. Types of rear axle shaft
 Semi floating axle .
 Full floating axle .
 Three quarter floating type.

40. SEMI FLOATING AXLE
 With a semi-float axle, the axle shaft both carries the
weight and transmits torque.
 The wheel is often bolted directly to the flange on the
axle.
 Semi-float axles are seen on cars and light duty trucks.
 Semi floats are more limited in capacity, but lighter
and cheaper to manufacture.

42. FULL FLOATING AXLE
 the weight of the vehicle is supported by the axle
housing- more specifically, a bearing spindle attached
to the axle housing , and a set of bearings in a separate
wheel hub.
 Torque is transmitted by a separate axle shaft that
carries no weight.
 As commonly built, full-floaters are considerably
heavier, but also much stronger

44. SEMI FLOATING AXLE FULL FLOATING AXLE

45. THREE QUARTER FLOATING
TYPE

46. THREE QUARTER FLOATING
TYPE
 A three-quarter floating axle is the same as semi-floating, with
one difference. The outer bearing is moved to the outside of the
outer end of the axle tube, supporting a hub assembly via the
bearing's outer circumference edge.
 The splined or keyed shaft drives this hub, to which the wheel is
attached.
The shaft now supports minimal vehicle weight (so has much
reduced radial load), but still locates the wheel axially, and
transfers axial cornering loads (side thrust) to the axle inner
bearing.