OVERRUNNING: SELECTIVE ENGAGEMENT Selective driving of one or two driven units Figure 33 depicts an application for the purpose of selectively driving either one or two driven units by normal or reverse rotation of the drive input. When the motor is rotating normally (in the counter-clockwise direction), Cam Clutch A engages to drive unit A, and Cam Clutch B overruns. Conversely, when the motor is rotated in reverse (in the clockwise direction),
Cam Clutch B
Cam Clutch A
Driven Unit B
Driven Unit A
Cam Clutch B engages to drive driven unit B. In this application, the two driven units must work independently.
Figure 33: Selection based upon rotation direction
OVERRUNNING SELECTION
The following is the basic pattern for selecting a clutch for an overrunning application. At times it may be difficult to determine what Shock Factor (also referred to as Service Factor) to use for a given application. Please contact Tsubaki if there are any questions.
Calculate the torque on the Cam Clutch according to the formula below.
9550·kW
T =
× SF
SF = Motor peak torque at starting x shock factor, K. The shock factor K is obtained from the chart below by calculating inertia ratio. Use a shock factor of K = 1 when the inertia ratio is below 0.48.
N T: Loaded torque (Nm) kW: Transmitted power (kW) N: Speed of Cam Clutch shaft rotation (r/min) SF: Service factor Select clutch by: a) Design torque requirement and service factor b) Maximum overrunning speed c) Bore and installation method If the SF is not known, use the peak torque with shock factor method.
Type of Load
SF
No shock load
1 – 1.5
Moderate shock load
1.5 – 2.5
Shock load
2 – 3
Heavy shock load
4 – 6
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