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Selection of proper HIGRIP
BELTS |
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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. |
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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.
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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
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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
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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%
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Table 1 Load
Correction Factor |
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DRIVE |
TYPE OF
MACHINES |
CORRECTION FACTOR |
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Light starting load,
uniform speed |
Centrifugal pumps, electric generators, blowers, fans,
light textile machines, automatic lathes, light duty evenly loaded
conveyors. |
1.0 |
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Medium load, uneven speed |
Metal and wood working machines, milking machines, small
lathes, rotary compressors. Group drives, belt conveyors with intermittent
loads. |
1.1 |
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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 . |
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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 |
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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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