Download : CALCULATIONS FOR FNR GEAR BOX AND CVT COMBINATION

**Gear Reduction Selection**

Power Requirements against:

Fr: Wheel Resistance

F_{L : }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

F_{L}:0.5ρCwAv^{2}

Ρ=Air Density

Cw=Drag Coefficient

A=Area

V=velocity

F_{L }=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 ??