Download : CALCULATIONS FOR FNR GEAR BOX AND CVT COMBINATION
Gear Reduction Selection
Power Requirements against:
Fr: Wheel Resistance
FL : Air resistance
Fs: Gradient resistance
Fa: Acceleration resistance
Wheel Resistance= Rolling resistance + Slip Resistance + Road Resistance
Tr: Brake Torque
Assumption taken
Unmade road coefficient of friction fr= .16
mass of vehicle being=Mf
CALCULATIONS
Fr=fr*Mf*g*Cosαst where αst=30˚
Fr=0.16*200*9.81*Cos 30
Fr=280N
Total Load R=113kg(driver)+200kg (vehicle)
R=313*9.81=3070.50N
Static Resistance=µR
=0.65*3070.5=1995.84N
Vmax=60kmph
Wheel Radius r=221.875mm
= .221m
Air Resistance
FL:0.5ρCwAv2
Ρ=Air Density
Cw=Drag Coefficient
A=Area
V=velocity
FL =0.5*1.99*0.0315*(16.66)2
=0.52N
Gradient Resistance:
Fst=Mf*g *Sinαst
Putting the corresponding value
Fst=131.725N
Acceleration resistance:
Fa=m*a
=956N
Ftotal=2662.247
Power Required: Ftotal*v/(Nrpm*η)
can you share a sample calculation of max torque which can be applied on wheels so that it doesn’t slip . Actually I know how to do it just want to verify as i am getting very low value. Pls reply soon I have to finalize my baja report
1.) Calculate normal force: F = M* 9.81 = X N
2) Multiply normal force by a friction coefficient – (Rolling resistance not static one, lets say its 0.6) and wheel radius: T = X * 0.6 * 0.4394 = Y Nm
3) Divide by number of wheels: T/4 = Z Nm.
Note : A BAJA buggy will have a different load on the front and rear wheels, so they have different required torques.
where we can buy FNR gear box ?
can you give a sample calculation for calculating efficiency of transmission including all the resistances
hey,
you have calculated the aero drag at 60kmph and also considered the acceleration resistance, so when ur car is already at top speed, e.i. 60kmph than how can it accelerate?
Hello mate…
In calculating Air resistance…..what do u infer by “area”… On what basis you’ve taken it as 0.0315..?
…… eagerly waiting for reply
wht is ast ???
What is rolling radius
Rolling radius is same as rolling circumference.
rc= rolling circumference
rc= 2*3.14*RADIUS OF THE WHEEL
how can i calculate gear ratio of spool ??