2. A hoist is used on a construction site consists of a trolley running on an...

 

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2. A hoist is used on a construction site consists of a trolley running on an inclined rails as shown in Figure Q1. The trolley is designed in such a way that the wheels are always in contact with the rails. The trolley has a mass of 15K9 and its platform a mass of 7 kg. The trolley and its load are lifted by a motor driving a drum D through a double reduction gear. Raos Or DaM The moments of inertia are: 0.075 kg.m? for the motor; 2.0 kg.m2 for C; 12.0 kg.m for the drum D; Load inertia = 125 kg. Iis REDUCTIONS LOAD If the motor delivers a constant torque of 25NM (assuming negligible friction) calculate: (a) The acceleration of the loaded trolley. (12marks) (b) The time for the trolley to be raised 10m from the ground, from rest, and what speed will the trolley then have. (4 marks) (c) The total weight of the trolley and load to stall the motor. (4 marks) Fig.Q2 Hoist mechanism 2. A hoist is used on a construction site consists of a trolley running on an inclined rails as shown in Figure Q1. The trolley is designed in such a way that the wheels are always in contact with the rails. The trolley has a mass of 15K9 and its platform a mass of 7 kg. The trolley and its load are lifted by a motor driving a drum D through a double reduction gear. Raos Or DaM The moments of inertia are: 0.075 kg.m? for the motor; 2.0 kg.m2 for C; 12.0 kg.m for the drum D; Load inertia = 125 kg. Iis REDUCTIONS LOAD If the motor delivers a constant torque of 25NM (assuming negligible friction) calculate: (a) The acceleration of the loaded trolley. (12marks) (b) The time for the trolley to be raised 10m from the ground, from rest, and what speed will the trolley then have. (4 marks) (c) The total weight of the trolley and load to stall the motor. (4 marks) Fig.Q2 Hoist mechanism