Design of Double Reduction Spur Gearbox - Desklib

REPORT
ON
DESIGN
OF
DOUBLE REDUCTION SPUR GEARBOX

Nomenclature
N1= Speed of pinion 1 in RPM
N2= Speed of Gear 1 in RPM
N3= Speed of pinion 2 in RPM
N4= Speed of Gear 2 in RPM
Z1= Number of teeth on pinion 1
Z2= Number of teeth on Gear 1
D1= Pitch circle diameter of pinion 1
D2= Pitch circle diameter of gear 1
D3= Pitch circle diameter of pinion 2
D4= Pitch circle diameter of gear 2
Y = Lewis factor
m = Module
b = Face width
CD =Centre distance between gears
σ c1= Contact stress
Fs =Pinion/gear strength
Fd =Dynamic load
FT =Transmission load
ds 1 =Input shaft diameter
ds 2 =Intermediate shaft diameter
ds 3 =Output shaft diameter
V =Velocity of gear/pinion
REDUCTION TYPE GEARBOX

Gearbox is a mechanical device generally used to transmit power from
source to output shaft. Power can be transmit by set of gears aligned in
such a manner to get desired output in required direction. Reduction type
gearbox is used where input speed can be reduced to get low speed at
high torque ,The number of gears used in this system is completely
depend on reduction ratio and input speed .
Material Selection
For selecting material of gears, the following data need be calculated:
 Speed of driving and driven gear
 Gear ratio
 Power transmitted
 Centre distance between meshed gears.
Gear drive design requirements
The main requirements to design a gear drive shown below:
 Gear teeth should have fatigue and wear characteristics to work
satisfactory in its designed life.
 It is required that gear teeth have sufficient strength that it can
withstand static and dynamic loading so that it may not fail under
during working conditions.
 Proper utilization of space.
 Deflection of shaft and gear alignment need to be considered as it
highly effect the performance.
 Material used to be economical and easily available.
 For efficient performance, the lubrication in gears is necessary.
Based on requirements, materials available for gear shown below.
Fig 1 : Material list for gears
Material for Shafts

Essential property of shaft material :-
 High strength
 High wear resistant
 Low notch sensitivity factor
 Good machinability
Fig 2 : Material list for shaft
Material for Casing
Essential property of casing material:–
 High strength
 Less weight
 High ductility
Fig 3 : Material list for casing
IMPORTANCE OF GEAR OIL (LUBRICATION)
Gear oil is one of the most important part of gearbox due to its following
benefits:-
 Gear oil provides lubrication to the different parts of gearbox.
 Reduce friction between mating parts cause less wear and tear.
 Increase life of gears.
 Act as a cooling agent and maintain temperature in casing chamber.
 Remove dirt and wear off parts from gearbox parts.