Engg Mechanics - Numerical Examples
Belt Drive and Lifting machines
A belt 100mm wide and 8mm thick is transmitting power of a belt of speed of 1600m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.3. The maximum permissible stress in belt is 2MN/sq.m. and the mass of belt is 0.9 kg/m. find the power transmitted and the initial tension in the belt.
An open belt running over two pulleys 1.5m and 1.0m diameter connects two parallel shafts 4.80m apart. The initial tension in the belt when stationary is 3000N. If the smaller pulley is rotating at 600 rpm and coefficient of friction between the belt and pulley is 0.3. Determine the power transmitted taking centrifugal tension into account. The mass of the belt is given as 0.6703 kg/m length.
A belt 200mm wide and 8mm thick is transmitting power of a belt of speed of 1700m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.25. The maximum permissible stress in belt is 2500 KN/sq.m. and the mass of belt is 10 KN/cubic m. Find the maximum power that can be transmitted and the corresponding belt speed.
Power transmitted between two shafts 3.5m apart by a crossed belt drive round two pulleys 0.6m and 0.3m in diameters is 6KW. The speed of the larger pulley is 220 rpm. The permissible load on the belt is 25M per mm width of the belt which is thick. The coefficient of friction between the smaller pulley surface and the belt is 0.35 Determine:
· The necessary length of the belt
· The width of the belt
· The necessary initial tension in the belt.
A leather belt 200m x 10mm has a maximum permissible tension of 2 MN/sqm. If ratio of tension is 1.80. Determine at what velocity should it be run so as t transmit maximum power? Take density of belt material = 1100 Kg/cubic meter.
A leather belt weighing 1gm per cc. has a maximum permissible tension of 2.1 N. Determine the maximum HP that can be transmitted by a belt 250mm x 11mm in section. Take ratio of tensions = 2.
In an open belt drive, pulleys are 500mm and 1200mm in diameter on parallel shafts 4m apart. The maximum tension in the belt is limited to 1800N Take coefficient of friction 0.3. The driving pulley 1200mm dia. Is running at 210 rpm, calculate power transmitted by the belt drive.
A shaft running at 100 rpm drives another shaft at 200 rpm and transmit 11.25 KW. The belt is 100mm wide and 12mm thick and µ=0.25. the distance between the shafts is 2.5m and the diameter of the smaller pulley is 0.5m. Calculate the stress in the belt in case of
· Open belt drive
· A crossed belt drive
A shaft rotates at 200 rpm drives another shaft at 300 rpm and transmit 8 HP through a belt. The belt is 10cm wide and 1cm thick. The distance between the shaft is 4m. The smaller pulley is 50cm in diameter. Calculate the stress
· In open belt drive
· In crossed belt drive
· Take µ=0.3, Neglect centrifugal tension.
A rope drive transmits 80 KW through a 1.5m diameter 45 deg. Grooved pulley rotating at 200 rpm. Coefficient of friction between the ropes and the pulley grooves is 0.3 and angle of lap is 160 deg. The mass of each rope is 0.6 kg/m and can safely take a pull of 800N. Taking centrifugal tension into account. Determine
· Number of ropes required for the drive.
· Initial tension in the rope.
A flat belt is required to transmit 35 KW from a pulley of 1.5m effective diameter running at 300 rpm. The angle of contact is spread over 11/24 of the circumference and the coefficient of friction between the belt and the pulley is 0.3. The belt thickness is 9.5mm and its density is 1100 Kg/cubic meter. If the permissible stress is 2.5 N/mm square. Determine the width of belt required.
A simple screw jack has square threaded screw of 50mm diameter and 10mm pitch. The coefficient of friction at the screw thread is 0.16. Find the force required at the end of 600mm handle to raise a load of 2KN.
The number of teeth on the worm wheel of a single threaded worm and worm wheel is 60. Calculate the velocity ratio id the diameter of the effort wheel is 250mm and that of load drum is 125mm. The effort required to lift the load of 500N by this machine is 25N. Find the efficiency of the machine.
In a lifting machine, the efforts required to lift loads of 200N and 300N are 50N and 60N respectively. If velocity ratio of the machine is 20, Determine
· Efficiencies corresponding to 200N and 300N.
· Effort loss in friction in both cases
· Maximum efficiency of machine.
Belt Drive and Lifting machines
A belt 100mm wide and 8mm thick is transmitting power of a belt of speed of 1600m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.3. The maximum permissible stress in belt is 2MN/sq.m. and the mass of belt is 0.9 kg/m. find the power transmitted and the initial tension in the belt.
An open belt running over two pulleys 1.5m and 1.0m diameter connects two parallel shafts 4.80m apart. The initial tension in the belt when stationary is 3000N. If the smaller pulley is rotating at 600 rpm and coefficient of friction between the belt and pulley is 0.3. Determine the power transmitted taking centrifugal tension into account. The mass of the belt is given as 0.6703 kg/m length.
A belt 200mm wide and 8mm thick is transmitting power of a belt of speed of 1700m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.25. The maximum permissible stress in belt is 2500 KN/sq.m. and the mass of belt is 10 KN/cubic m. Find the maximum power that can be transmitted and the corresponding belt speed.
Power transmitted between two shafts 3.5m apart by a crossed belt drive round two pulleys 0.6m and 0.3m in diameters is 6KW. The speed of the larger pulley is 220 rpm. The permissible load on the belt is 25M per mm width of the belt which is thick. The coefficient of friction between the smaller pulley surface and the belt is 0.35 Determine:
· The necessary length of the belt
· The width of the belt
· The necessary initial tension in the belt.
A leather belt 200m x 10mm has a maximum permissible tension of 2 MN/sqm. If ratio of tension is 1.80. Determine at what velocity should it be run so as t transmit maximum power? Take density of belt material = 1100 Kg/cubic meter.
A leather belt weighing 1gm per cc. has a maximum permissible tension of 2.1 N. Determine the maximum HP that can be transmitted by a belt 250mm x 11mm in section. Take ratio of tensions = 2.
In an open belt drive, pulleys are 500mm and 1200mm in diameter on parallel shafts 4m apart. The maximum tension in the belt is limited to 1800N Take coefficient of friction 0.3. The driving pulley 1200mm dia. Is running at 210 rpm, calculate power transmitted by the belt drive.
A shaft running at 100 rpm drives another shaft at 200 rpm and transmit 11.25 KW. The belt is 100mm wide and 12mm thick and µ=0.25. the distance between the shafts is 2.5m and the diameter of the smaller pulley is 0.5m. Calculate the stress in the belt in case of
· Open belt drive
· A crossed belt drive
A shaft rotates at 200 rpm drives another shaft at 300 rpm and transmit 8 HP through a belt. The belt is 10cm wide and 1cm thick. The distance between the shaft is 4m. The smaller pulley is 50cm in diameter. Calculate the stress
· In open belt drive
· In crossed belt drive
· Take µ=0.3, Neglect centrifugal tension.
A rope drive transmits 80 KW through a 1.5m diameter 45 deg. Grooved pulley rotating at 200 rpm. Coefficient of friction between the ropes and the pulley grooves is 0.3 and angle of lap is 160 deg. The mass of each rope is 0.6 kg/m and can safely take a pull of 800N. Taking centrifugal tension into account. Determine
· Number of ropes required for the drive.
· Initial tension in the rope.
A flat belt is required to transmit 35 KW from a pulley of 1.5m effective diameter running at 300 rpm. The angle of contact is spread over 11/24 of the circumference and the coefficient of friction between the belt and the pulley is 0.3. The belt thickness is 9.5mm and its density is 1100 Kg/cubic meter. If the permissible stress is 2.5 N/mm square. Determine the width of belt required.
A simple screw jack has square threaded screw of 50mm diameter and 10mm pitch. The coefficient of friction at the screw thread is 0.16. Find the force required at the end of 600mm handle to raise a load of 2KN.
The number of teeth on the worm wheel of a single threaded worm and worm wheel is 60. Calculate the velocity ratio id the diameter of the effort wheel is 250mm and that of load drum is 125mm. The effort required to lift the load of 500N by this machine is 25N. Find the efficiency of the machine.
In a lifting machine, the efforts required to lift loads of 200N and 300N are 50N and 60N respectively. If velocity ratio of the machine is 20, Determine
· Efficiencies corresponding to 200N and 300N.
· Effort loss in friction in both cases
· Maximum efficiency of machine.
3 comments:
thank you sir..
i hope that ill solve them .. but thanks for posting it online
Aditya
prove relationship T1/T2 = eμθ
where can i get the solutions of this problems?
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