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REVERSING PULLEY ROTATION - ANSWER | |
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1. A system of four pulley wheels are set up as shown in the diagram above. The driver pulley rotates in an anti-clockwise direction. In what direction does the output pulley wheel revolve ? Look at the animation below. The final output of pulley F is a clockwise movement. |
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2. If pulley ‘A’ (driver) rotates at 60 rpm what is the output rpm at ‘F’. |
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To answer the question spit the pulleys into pairs
and work out the velocity ration of each pair. Treat the pairs of
pulleys as separate questions. |
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Pulley wheel A has an rpm of 60. Pulley B is larger and so revolves at a lower rate than A. This means that the rpm of A is divided by the ratio of 2. |
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Pulley wheel C has the same rpm as pulley B because they form a compound pulley. Pulley D is larger and so revolves at a lower rate than C. This means that the rpm of C is divided by the ratio of 1.2 |
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Pulley wheel E has the same rpm as pulley D because they form a compound pulley. Pulley F is smaller and so revolves at a higher rate than E. This means that the rpm of E is multiplied by the ratio of 1.3 |
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