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) + 
(Dd)^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 VBelts 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. 
