To select the type of reduction gear the following instruction
concerning the applications should be known.
a) |
Torque to be transmitted (Output Torque ) |
b) |
Input speed (RPM) |
c) |
Output speed (RPM) |
d) |
Operating Condition (i.e. No of Start-ups per hour and it subject
to impacts |
e) |
Ambient Temperature (°C) |
f) |
Radial Loads on Output Shaft |
g) |
Radial Loans on Input Shaft |
h) |
Thrust Load if any |
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After knowing the above information
following steps to be followed for the selection |
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Select the reduction ratio |
| Step 1 |
|
| i = |
Input Speed
____________ |
| Output Speed |
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| Step 2 |
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Output torque to be transmitted.If the output
torque is not known then the torque can be worked as |
| Torque=
|
P
X 9546
____________ |
where P is power
in Kw |
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If
the power available is in HP,convert to Kw using relation. 1Hp=0.746
Kw
|
| This above torque either defined output
torque or calculated output torque or average output torque to
be multiplied by the service Factor shown in the service factor
table. |
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| Step 3 |
Verification Of Thermal Capacity
After selection of model it is necessary to check with thermal capacity
of the reducer Thermal Rating (Kw) Pt It is the power a reduction
gear can transmit in the continuous use at maximum operating temperature
of 900C When ambient temperature is 250C,
Oil viscosity is ISO 320 and input speed is 1400 RPM. The thermal
ratings are shown in selection chart |
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| Step 4. |
The selected Reducer is required
in Hollow input configuration then it has to be verified for available
frame size. Available frame sizes are shown in selection chart
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Check for overhang Load
When reducer is connected with sprocket, pulley, timing belt,
gear or friction wheel there is radial load generated on shaft
either high speed or low speed & this has to be checked called
as overhang load capacity. Calculate the overhang load as per
below mentioned formula.
| Overhang Load in N= |
19100000 X P
____________
|
x Fc |
Dxn |
Where P is power in Kw (1HP= 0.736Kw)
d
is diameter of Sprocket/ Pulley/Gear/Friction Wheel in mm
n
is speed of shaft in RPM
Fc
is load connection factor. Which is as under
Chain Sprocket |
Gear |
Sprocket |
V-Belt |
Friction Wheel |
1 |
1.06 |
1.5 |
2.5 |
3.5 |
Now refer the table showing the overhang load capacity for low
speed & high-speed shafts. Compare the calculated overhang
load for selected model at desired life. The value shown in table
for the life n2h=105 cycles. Now multiple the value
by life factor to get desired overhang load at desired life
Compare the calculated overhang load with actual as per the load
location the distance from shaft coller if value is within limit
then the selection is correct or else check the possibility of
increasing the PCD of wheel & reducing the distance from coller
or select next higher model. |
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