DRIVE DESIGN EXAMPLE FOR RAW EDGE COGGED SECTION BELTS

Condition 1: Prime mover A.C. motor; 75 kw, 1450 r.p.m. (Driver Pulley)

Condition 2: Reciprocating pump, 310 r.p.m., 18 hrs. per day,

Condition 3: Approximate centre Distance 1050 mm

STEP 1    Calculate Speed Ratio (SR)                         

           Speed Ratio (S R ) =

R/r

Refer to conditions 1 & 2

S R = R/r = 1450/310

 = 4,67

STEP 2    Select Service Factor (K)

Service factor is obtained from table Service Factor K=1,4

STEP 3    Calculate Design Power (Pd)

Design Power (P d ) = P x K                                Pd= 75 x 1,4 = 105 Kw

STEP 4    Select Belt Cross Section                Belt Section indicated is "C"

Belt cross section is obtained from the Belt Cross Section Selection Chart.

STEP 5    Select Pulley Pitch Diameters            d = 212 mm,  D = 990 mm

Refer to  Recommended Pulley Diameters for selecting pulley pitch diameters.

STEP 6    Calculate Belt Pitch Length (Lp) and Center Distance (C)

           Belt Pitch Length (Lp) =              2C + 1.57  (D + d) + (D-d)^2 Lp =  2(1050)+1.57(990+212)+ (990 - 212)^2
4C 4 x 1050
          Where, D & d are pitch diameters of           larger & smaller pulleys respectively. Lp =  4131.25

         Choose the nearest Pitch Length ( Lp)           from  V-Belts Production Range

Standard Lp = 4120

C=A+ v A 2 -B                                                                  C=A+ v A 2 -B  

STEP 7    Determine Power Rating (P)

Refer to Power Rating Tables from for different belt sections.

Power rating per belt (P) = rated power + Additional power for speed ratio                                               P = 10.94 kw + 1.27 kw            P = 12.42 kw

STEP 8    Find Arc of Contact Correction Factor (Fc) &                Fc = 0.88

                Belt Pitch Length Correction  Factor (Fd)                       Fd = 1.03

Refer  for Arc of Contact Correction factor & Belt Pitch Length Correction .

STEP 9    Find Number of Belts (N)

       Number of Belts (N) = Pd N = 105 = 9.32 (10 belts)
P x Fc x Fd 12.42 x 0.88 x 1.03

STEP 10    SUMMARY

           i. Smaller Pulley Fitted to Prime mover Smaller Pulley of 212 mm pitch dia. With 10 grooves of "C" Section
          ii. Larger Pulley Fitted to reciprocating pump Larger Pulley of 212 mm pitch dia. With 10 grooves of "C" Section
          iii. Classical belts required 10 belts of "C" section each of 4120 mm pitch length.