Page 72 - Parker - Gearheads and Gearmotors

Gearhead Sizing/Selection

Stealth Gearhead 9 Step Sizing/Selection Procedure
®

To properly select an appropriate gearhead for a 3) Calculate the Root Mean Cube Output Torque
specific application requires consideration of several 3 (T 3 )(N )(t ) + (T 3 )(N )(t ) + (T 3 )(t ) ]
interrelated parameters including: [ acc cont acc cont cont cont dec dec
2
2
• Speed T mean =
)(t
)(t
)(t
• Continuous torque [ (N cont acc ) + (N cont cont ) + (N cont dec ) ]
• Repetitive peak torque or acceleration 2 2
torque
• Emergency stop torque + T acc
• Duty cycle T cont
• Ambient temperature Torque 0
• Radial and axial shaft load T dec Time
The following 9 step procedure provides a quick, – t acc t cont t dec t dwel
straightforward method for selecting a gearhead
that will provide an L-10 life of 10,000 hours.
4) Select Gearhead Type and Size
1) Load Parameters
Choose the gearhead type (PS, PX, etc) and frame
Evaluate the following requirements of the load: size to match the motor frame size.
Load inertia
Acceleration time (t acc ) 5) Check Selected Gearhead Size Ratings
Continuous run time (t cont ) Check the specifications of the gearhead selected
Deceleration time (t dec ) and confirm that it meets the following criteria:
Dwell time (t dwel )
Maximum continuous speed (N cont ) Rated nominal torque (T nom r ) > T mean
) > T
From these, calculate: Rated accel torque (T acc r acc or T dec
Acceleration torque (T acc )
Continuous torque (T cont ) 6) Determine Maximum Allowable Gearhead
Deceleration torque (T dec ) Ratio
Dwell torque (T dwel )*
*Although not used in the following torque calculations, torque Using the selected gearhead’s listed specification
requirements during dwell (zero speed) must be considered when for maximum rated speed (N maxr) , determine the
selecting gearhead size. maximum allowable ratio:
2) Duty Cycle Maximum ratio = N maxr /N cont
Determine if the application duty cycle is intermittent
or continuous by calculating the duty cycle as follows: 7) Calculate the Mean and Maximum Input
Speed
/t
+t
+t
Duty cycle = (t acc cont dec total ) x 100%
Choose a ratio for the selected gearhead (must be
Speed N cont less than the maximum determined in Step 6). With
)
this ratio, calculate the mean input speed (N
mean i
and the maximum input speed (N max i ):
)
(
)(t
) + (N
(N
)(t
) + N
)(t
)
cont dec
cont cont
cont acc
N mean i = (ratio)
2
2
Time
t acc t cont t dec t dwel t acc + t cont + t dec
t total
N = (N ) (ratio)
+t
+t
If the duty cycle is <60% and (t acc cont dec ) is less max i cont
than 20 minutes, the motion is considered intermittent. Note: Reflected inertia requirement may determine
+t
If the duty cycle is >60% and (t acc cont dec ) is greater the actual ratio, as long as it does not exceed the
+t
than 20 minutes, the motion is considered continuous. maximum ratio value calculated in Step 6.
72 Parker Hannifin Corporation • Electromechanical Automation Division • 800-358-9070 • www.parkermotion.com