5.Rope Brake Dynamometer

Experiment No. Date: ROPE BRAKE DYNAMOMETER AIM: To determination of BHP for a twin cylinder Diesel engine using rope brake dynamometer and attain Power Vs Load curve.

APPARATUS REQUIRED: 1) Tachometer 2) Measuring tape 3) Spring balance THEORY: It is absorption type of dynamometer. It consist of two or three ropes wound round the fyl wheel or rim fixed rigidly around shaft of engine. The upper end of the rope is attached to spring balance while lower end is kept in position by applying dead weight. In order to prevent slipping of belt over pulley wooden blocks are placed at intervals around flywheel. In operation of brakes, engine is made to run at constant speed. The frictional torque, due to rope must be equal to torque being transmitted by engine. Net load= (W-S) N Distance moved in one revolution =  (D+d) m Work done= (W-S)* =  (D+d)

PROCEDURE: 1) Check the fuel supply to engine, lubrication oil level in the oil pump, water circulation in the cooling system, etc. 2) Start the engine and ensure no load condition on the brake drum. 3) Allow the engine to stabilize before loading. 4) Now the load is applied gradually on the rope brake dynamometer. 5) For every increase in load, the speed is measured using tachometer. 6) Repeat the procedure for various load and power is measured. 7) Calculate the torque and power using the given formulae.

SAMPLE DATA: 1) Speed, N = 1500 rpm 2) Radius of the brake drum, R = 0.2 m 3) Theoretical power applied = 1.5 kW 4) Theoretical torque = P*60/(2*pi*N) N-m 5) Actual Torque= W * 9.81 * R N-m

CALCULATION: Net load on the brake= (S1-S2) N Distance move in one revolution= DN Work done per Revolution=(S2-S1)DN Brake Power of the turbine= (S2-S1)DN / 60 watt Where , S1=Spring balance reading in Newton S2=Spring balance reading in Newton D=Diameter of the wheel in M N=Speed of the engine shaft in rpm

Tabulation: Sl.No

Load(S1)(N)

1. 2. 3.

Model Calculation:

Load(S2)(N)

Speed(N) in rpm

Brake Power in Kwatt

RESULT: Thus the torque and power measurement is done using rope brake dynamometer.