MACHINE DESIGN EXCEL SPREAD SHEETS

Spread Sheet Method:1. Type in values for the input data.2. Enter.

Angle B Input Small sheave pitch circle radius, R1 = 4 inLarge sheave pitch circle radius, R2 = 6 in

Center distance, C = 14 inCalculation

Sin (B) = (R2-R1) / CSin (B) = 0.1429

B = 0.1433 radn.B = 8.21 degrees

Copy write, © Machine Design Spreadsheet Calculations by John R Andrew, 6 July 2006

3. Answer: X = will be calculated.4. Automatic calculations are bold type.

V-BELT DRIVESV-belts are used to transmit power from motors to machinery.

Sheaves have a V-groove. Pulleys have a flat circumference.

A V-belt may be used in combination with a drive sheave on a motor shaft and a pulley on the driven shaft.

V-Belt Drive Input Drive power, HP = 30 hpMotor speed, N = 1800 rpm

Drive sheave pitch diameter, D1 = 10 in Driven sheave pitch diameter, D2 = 36 in

Center distance, C = 40 inSheave groove angle, A = 40 deg

Sheave to V-belt coefficient of friction, f1 = 0.2 -Pulley to V-belt coefficient of friction, f2 = 0.2 -

B1 = 0.75 inB2 = 1.5 inD = 1 in

V-belt weight per cubic inch, w = 0.04 lbm/in^3Tight side V-belt allowable tension, T1 = 200 lbf

CalculationV-belt C.G. distance, x = D*(B1+ 2*B2)/ 3(B1+B2)

= 0.556 inDriven sheave pitch diameter, D2 = D2 + 2*x

= 37.11 in

Angle of Wrap AnSmall sheave pitch radius, R1 = 5.00 inLarge pulley pitch radius, R2 = 18.56 in

Sin (B) = (R2-R1) / CSin (B) = 0.3389

B = 0.3457 radn.B = 19.81 degrees

Small sheave angle of wrap, A1 = 180 - 2*BA1 = 140.38 degrees

Large pulley angle of wrap, A2 = 180 + 2*BA2 = 219.62 degrees

e = 2.7183

Sheave capacity Cs = e^(f1*A1/ Sin(A/2)) = 4.77

Pulley capacity, Cp = e^(f2*A2/ Sin(90/2)) = 2.15

The smaller of Cs and Cp governs design.Belt section area, Ab = (B1 + B2)/ (2*D)

= 1.125 in^2V-belt weight per ft, W = Ab*w*12

= 0.54 lbm/ftV-belt velocity, V = π*(D1/12)*(N/60)

V = 78.55 ft/sec g = 32.2 ft^2/sec

Slack side belt tension, T2 = (T1-W*V^2/g)/(Csp)+ (W*V^2/g) = 148 lbf

Horsepower per belt, HPb = (T2-T1)*V / 550 = 7.4 hp

Number of belts, Nb = HP / HPb = 4.1 belts

Input Use 4 belts

This is the end of this work sheet.