An electric motor drives a coaxial rotor through a single-plate clutch which has two pairs of driving
Question:
An electric motor drives a coaxial rotor through a single-plate clutch which has two pairs of driving surfaces each 300 mm external and 120 mm internal diameter; the total spring load pressing the plates together is 500 N. The normal pressure p varies with radius, r (in mm) according to the relationship p(r+40)=k. The mass of the motor armature and shaft is 800 kg and its radius of gyration is 210 mm; the rotor has a mass of 750 kg and its radius of gyration is 170 mm.
The motor is brought up to a speed of 700 rpm; the current is then switched off and the clutch suddenly engaged with the rotor which was originally rotating at 200 rpm. The coefficient of friction in the system is 0.40.
- Determine the final speed of the motor and rotor.
- How much energy is lost during slipping?
- Find the time taken to reach that speed.
The engineer at the plant wants to use this clutch to transmit power to a system that has a load torque of 54 Nm. Describe what would happen if this system was put into service (time of slip, final angular velocity). Would you recommend this clutch for use? Justify your response.
Fundamentals of Physics
ISBN: 978-0471758013
8th Extended edition
Authors: Jearl Walker, Halliday Resnick