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Selection of proper HIGRIP BELTS

Belts
To Select the proper belt for any given drive involves a simple calculation using the formula:
Belt Width (mm) =(Total H.P. Required x Service Factor / H.P./25mm rating x Arc of Contant Factor) x 25.4mm

STEP 6.

Tension: See Tensioning and Mounting.
 EXAMPLE
.60 H.P, 1440 R.P.M. Electric Motor Driving Ball Mill,  heavy load under normal conditions. Drive pulley  300mm diameter, 150mm face. Driven pulley 750mm   diameter, 150 mm face. Pulley centre distance 1850

STEP 1.
Determine Service Factor
(a) Select factor from, table 1. Insert this value in Belt Width rn formula. 31
Open Drive

STEP 1
From table 1 .service factor for Ball mill is 1 .3.

STEP 2.
Determine H.p. / 25 mm rating
(a)  First calcuate belt speed in metres per sec. (Mtrs / sec) using the formula.
Belt speed, (mtr-sec)= Drive pulley dia (mm)xR.P.M.x 3.14 / 1000 x 60
(b) Using calculated speed in mtrs/sec. refer to table II. Move across the table to the minimum pulley size (Figures shown in Red). The number shown in black is the H.P. / 25mm rating value. Insert in for  mula. The Belt type is designated at the top of the selected column. 'KHCA' types are used where only one surface of the belt comes in contact with pulleys and or pulley and jockey pulleys.

 STEP 2.

Surface Speed = 300 x 1440 x 3.14 / 1000 x 60 = 22.6mtrs / sec.

Using 22.6 mtrs I sec table II gives H.P./ 25mm rating of 21.28. HI- GRIP BELT type KHC2A 10. For simple open drive select KHC2A 10

 

STEP 3.

 Determine Arc of contact correction factor. 
(a)  If both drive and driven pulley have identical diameters no correction factor is required.
(b) If pulleys have different diameters. determine the difference  (in mm) and refer to table. Move across table to appropriate centre distance column to find Arc of contact Correction Fac tor. In sert this value in formula.

STEP 3

Table III gives Arc of contact factor of 0.94.
STEP 4.
Complete belt width formula calculations.
STEP 4
Calculate width W= 60 x 1.3 x 25.4 =99 mm

or nearest round figure-100mm

STEP 5
Calculation of of Length : Calculate length of the belt from the following formulae:
(a) Open Drive (Good approximation)
L = 2c = 1.57 (D+d) + (D-d)2 /4C
(b)  Cross Drive (Good approximation)
L = 2c + 1.57 (D+d) + (D+d) 2 /4C

"C" is Centre Distance
"D" is diameter of driven pully
"d" is diameter of driving pully

STEP 5.

Length of the belt L =2C + 1.57 (D+d) +(D+d)2 /4C = 2 x 1850 + 1.57 x 1050 +202500/4x1850 =  5375.86mm.or 537mm

STEP 6
Tension the belt to 3%
Thus Belt selected is KHC2A 10 width 100mm. length 5376mm. and tension 3%
 

Table 1 Load  Correction Factor

DRIVE TYPE OF MACHINES CORRECTION FACTOR
 Light starting load, uniform speed

Centrifugal pumps, electric generators, blowers, fans, light textile  machines, automatic lathes, light duty evenly loaded conveyors.

 1.0
  Medium load, uneven speed

Metal and wood working machines, milking machines, small lathes, rotary compressors. Group drives, belt conveyors with intermittent loads.

1.1
Medium starting load, irregular  speed, fluctuating load

Centrifuges, large fans, piston pumps, pulpers, dough mixers, ball mills. tube mills,   grinding machines, carding engines, spinning frames, prop shafts, gang saws, piston pumps. 

1.3 .
 Heavy starting, pulsating and intermittent loads

Calenders, paper mill rolls, brick machines, forging presses, power punches and shears,  vibrator, dredgers, rolling mills for nonferrous metals, piston pumps and compressors with a speed fluctuation of 1:80, pan grinders, planners.

1.5
  Very Heavy Starting, very uneven speeds

Beater mills, crushers, extrusion presses cold rolling mills. unusually severe shock loads. Heavy torque drives, oily, dusty conditions.

1.7
 

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