Parameter Value Unit
Mass of vehicle 250 kg
Master cylinder bore dia 19.05 mm
Speed of Vehicle 12.5 m/sec
Pedal ratio 7:1 -
Caliper bore dia 30 mm
Tire dia 533.4 mm
Coefficient between tire and 0.68 -
road
Coefficient between pad and 0.4 -
rotor
Wheel base 1.53 m
Cg height 0.592 m
No of piston in each caliper 2 -
BRAKE CALCULATION –
CG Values –
CG from front axle – 0.953 m
CG from rear axle – 0.577 m
Height of CG – 0.592 m
Wheel base – 1.53 m
Relative CG –
CG (H) – 0.592 m
Wheel base (B)- 1.53 m
X = H/B = 0.592/1.53 = 0.387
Dynamic Load on Front (Rf) -
(X’) = 0.577 = CG from Rear axle
W = 250 = 2452.5
Rf = W(X’ + μh)/b
= 2452.5(0.577+0.68*0.592)/1.53
=1570.177 N
Dynamic Load on Rear (Rr) –
(X’) = Distance from axle to CG = 0.953
W = 2452.5
Rr = W(X – μh)/b
= 2452.5(0.953 – 0.68*0.592)/1.53
= 882 N
Dynamic Weight Transfer % -
For Front = 1570.177/2452.177*100
= 64.03 %
For Rear = 882/ 2452.177*100
= 35.97 %
Deceleration of the Buggy –
Rf =1570.177 Rr = 882
Wsinθ + (W/g)a = μ(Rf + Rr)
Θ = 0 for flat road
(W/g)a = μ(Rf + Rr)
250*a = 1667.47
a = 6.66 m/s^2
= 0.67g
Required Braking Force and Torque –
Total Braking Force:
M = 250 kg a = 0.67g g = 9.81 m/s^2
Fb = M*a*g
= 250*0.67*9.81
= 1643.17 N
Braking Force on Front:
Rf = 1570.177
Fbf = U*Rf
= 1067.71 N
Braking Force on Rear:
Rr = 882
Fbr = U*Rr
= 599.76 N
Torque required on Front:
Wheel Radius = 0.2794
Fbf = 1067.71
Tf = wheel radius*Fbf
= 0.2794*1067.71
= 298.31 Nm
On each wheel = 149.15 + 90.5(By PT)
= 239.65
Torque Required on Rear:
Fbr = 599.71
Tr = wheel radius*Fbr
= 169.57 Nm
Applied Braking Force and Torque
Pedal force = 350 N
Pedal ratio = 7:1
Force on TMC = 2450 N
M.C. Diameter = 19.05 mm
Area of M.C. = 284.878
Pressure on TMC = Force on TMC / Area of TMC
= 8.6 N/mm^2
Force on Calliper(Front)-
Bore diameter of calliper = 30
No. of Piston =2
μ = 0.4
Area of Calliper = 706.5 mm^2
F = Frictional force on Disc
= 2 μ*p*a
= 2*0.4*706.5*8.6*10^
= 4860.72
Torque on Front = Reff + frictional force
= 0.06760*4860.72
328.58Nm
On singular Tyre = 328.58/2 + 90.5
= 254.5
Torque on Rear = Reff + frictional force
= 0.06760*4860.72
= 328.58 Nm
On singular Tyre = 254.5
Force on Single Front Tyre = Single Torque / Radius of wheel
= 910.88 (same for Rear)
Total Force = 3643.52
Deceleration = Total Force/ Mass
= 14.57 m/s^2
Stopping Distance = Velocity^2/2*Deceleration
= 5.36 m
Stopping Time = Velocity/Deceleration
0.85 sec
