FINAL INDEPENDENT PROJECT

Gear Train

A gear train consists of two or more gears in series. It is used to increase or decrease the speed or torque of the output shaft. The term gear ratio is used to calculate the speed and torque of output gear when torque is applied to input gear.

Aim : calculations gear ratio, torque and speed of a

(1) Two gear train.

(2) Multi gear train

(3) Compound gear train

Law of gearing

The law of gearing states that the angular velocity ratio between mating gears is always remains constant. To achieve the condition of constant angular velocity, common normal at the point of contact between mating gear teealwaysway pass throughthe pitch point. Where pitch point is the point of contact between mating gear pitch circles.

If the angular velocity of mating gear is constant we can conclude to the following relation

W1/W2 = n1/n2 = d1/d2 = T1/T2

Where ,w1 and w2 = Angular velocity in radian/sec for drive and driven gear respectively.

Then n1/n2 = Gear speed in RPM for driver and driven gear,

d1/d2 = Driver and driven gear diameter,

T1/T2 = Number of teeth on driver and driven gear.

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% number of teeth on driver gear

G1 = 40;
G2 = 30;
G3 = 20;
G4 = 10;

% speed of driver gear in rpm
n1 = 100;

% torque acting on driver gear in Nm
T = 10;

% calaculation gear ratio

GR = G1/G2;

% calculation output gear speed

GS = n1/GR;

% calculation torque generated by driver gear

DG = GR * T;

% calculation for multi gear train
% calculation gear ratio between G1 and G2 ( driver and idler ).
GR(1) = G1/G2;
% calculation gear ratio between G2 and G3 ( idler and driven ).
GR(2) = G2/G3;

% calculation gear train
GT = GR(1)*GR(2);

% calculation for compound gear
% calculation gear ratio between G3 and G4
GR(3) = G3/G4;
% calculation compound gear
CG = GR(1)*GR(3);