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GRADEABILITY

The document discusses key concepts related to vehicle performance: 1. Rear Axle Ratio is defined as the number of teeth on the ring gear of the rear axle divided by the number of teeth on the pinion gear, and is used to calculate maximum vehicle speed. 2. Tractive Force is the friction between the drive wheel and surface, and is calculated using engine torque, efficiency, transmission ratio, and rear axle ratio. 3. Gradeability is the maximum slope a vehicle can climb expressed as a percentage, and is calculated using tractive force, vehicle weight, and rolling resistance.

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Sunil Mishra
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1K views3 pages

GRADEABILITY

The document discusses key concepts related to vehicle performance: 1. Rear Axle Ratio is defined as the number of teeth on the ring gear of the rear axle divided by the number of teeth on the pinion gear, and is used to calculate maximum vehicle speed. 2. Tractive Force is the friction between the drive wheel and surface, and is calculated using engine torque, efficiency, transmission ratio, and rear axle ratio. 3. Gradeability is the maximum slope a vehicle can climb expressed as a percentage, and is calculated using tractive force, vehicle weight, and rolling resistance.

Uploaded by

Sunil Mishra
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLSX, PDF, TXT or read online on Scribd
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A Rear Axle Ratio: Number of gear teeth on the ring gear of the rear axle and the pinion

gear on the drive shaft

RAR= 2 x Pai x N x R x 60 / 1000 x V x GL

N= Maximum RPM of Engine


R= Tyre Rolling Radius in meter
V= Maximum Speed of Vehicle, KMPH
GL= Last gear ratio of Over drive Gear Box

RAR= 2 x Pai x N x R x 60 / 1000 x V x GL

B Tractive Force: The friction between a drive wheel and the surface it moves upon
TF= ET x OE x NG x RAR / R

ET = Engine Torque in Nm
OE = Overall Efficiency of Power Train =0.95 (For two axle drive)
NG = Transmission Ratio of First Gear
RAR = Rear Axle Ratio
R = Tyre Rolling Radius in meter

TF= ET x OE x NG x RAR / R

C Gradeability:

G(%)= 100 ((TF / Gravity x GVW) -RRC ))

TF= Tractive Force, N


Gravity= 9.81
GVW= In Kg
RRC = Rolling Road Co-efficient = 0.007

G(%)= 100 ((TF / Gravity x GVW) -RRC ))

D Maximum permissible Tractive Force:


TFMax = Ø x Wr

Ø = Adhesion Co-efficient between tyre and road surface = 0.7


Wr = Vehicle Weight component on the driving wheel, N

TF < TFMax = No Slip


Design is safe
ar on the drive shaft

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