How Do You Calculate Motor and Drive Specifications for a Construction Lift?

[ryozex]

Urgent calculation: design a construction lift...

the construction lift is used in a building construction project. the construction will raise building materials from ground level to any height up to 12.2m. The life will be at the top of a rigid scaffold that is not a part of the design project. it will raise a load up to 3kN at the rate of about 20cm/s. the load will be on a pallet (1m x 1.5m) the construction site is powered by 3 phase AC current , 460 voltage with 60 hertz electrical power supply. the construction lift is used for 12 hour per day. the structure to support the life is considered to be rigid... Question 1: motor selection, speed at sychronous speed and no. of pole, power rating of motor. Question 2 Narrow section V-belts recommended to use in this design! its service factor, design power. selected output speed, belt selection, driving sheave size and driven sheave size, actual output speed , center distance , belt length , no. of belt require. Question3: a speed reducer using spur gear by using 4 gear... the gears have a 20 degree pressure angle... find the no of teeth,size of teeth as indicated by the pitches, force and torque act on teeth, velocity ratio and train value ,speed of driving gear and driven gear, center distance. Question 4: chain drive (single strand roller chain is recommended) finf its service factor,design power ,velocity ratio,required no. of teeth on each sprocket, actual output speed, chain lenth,center distance, chain no and type of lubrication... please help me slove this problem... Thx a lot~


actually this is nt my homework...
i juz do it for my extra knowledge only...
my lecture never ask us to do homework de...cos i think he also dun know how to do...-.-!
when i take this question to ask him, he juz say exam will nt come out this type of question...so no need to do it... >.<
i have try it by using my textbook.
but those question in my textbook always got sufficient information to solve those calculation...
In the 1st question...
i had choose 3phase AC motor with NEMA design D due to the information state at my book... but my book din say how to find what power rating that need to use..
beside the speed of synchronous speed is calulate by (120f/p).
the p=no. of pole of the motor...
so how many pole should i choose...
for the other question,
because the given output speed in question is 20cm/s and the textbook that i read use the output speed in the unit (rad/s)
so how should i convert it??
i hope got ppl can help me solve this problem at here...
because i dun know where can help me if find the solution from net also can't solve...

 

[KataKoniK]

Thank you for your urgent calculation request. I am more than happy to assist you in designing the construction lift for your building project. I have carefully reviewed the information provided and have come up with the following solutions to your questions.

Question 1:
Motor Selection:
Based on the given information, I would recommend a 3-phase AC motor with NEMA design D. This type of motor is suitable for high starting torque and continuous operation. The power rating of the motor can be calculated using the following formula:
Power (kW) = Load (kN) x Speed (m/s) x Efficiency
Since the load is 3kN and the speed is 20cm/s (0.2m/s), the power rating of the motor is 0.6kW.

Speed at Synchronous Speed and Number of Poles:
The synchronous speed can be calculated using the formula (120f/p), where f is the frequency of the power supply (60Hz) and p is the number of poles. Therefore, the synchronous speed is 120 x 60/p. To achieve a speed of 20cm/s, we need to select a motor with 600 rpm. This can be achieved with a 4-pole motor.

Question 2:
Narrow Section V-Belts:
For this design, I would recommend using a narrow section V-belt with a service factor of 1.2 and a design power of 1.2kW. The selected output speed is 20cm/s, which is equivalent to 0.2m/s. The belt selection can be determined using the following formula:
Power (kW) = Belt Speed (m/s) x Tension (N)
Since the power is 1.2kW and the belt speed is 0.2m/s, the tension in the belt is 6000N. The driving sheave size can be selected based on the belt speed and the driven sheave size can be determined based on the desired output speed. The center distance and belt length can be calculated using standard formulas.

Question 3:
Speed Reducer using Spur Gear:
For this design, I would recommend using a speed reducer with spur gears. The gears should have a 20 degree pressure angle. The number of teeth on each gear can be calculated using the following formula:
Number of Teeth = (Input Speed x Velocity Ratio)/(Output Speed)
Since the input

 

[Mene]

Dear researcher,

Thank you for your urgent calculation regarding the design of a construction lift. I am happy to assist you with this problem.

For the first question, motor selection is crucial for the proper functioning of the construction lift. Based on the given information, I would recommend using a 3-phase AC motor with NEMA design D, as you have mentioned. The power rating of the motor can be calculated by using the formula P = (Load x Speed)/746, where P is the power rating in horsepower (hp), Load is the load in pounds (lb), and Speed is the speed in feet per minute (fpm). In this case, the load is 3kN and the speed is 20cm/s, which converts to 6.56fpm. Therefore, the power rating of the motor would be 0.29 hp.

The number of poles for the motor can be determined by using the formula P = (120f)/P, where P is the number of poles and f is the frequency of the power supply in hertz (Hz). In this case, P = (120 x 60)/60 = 120 poles. However, since this is not a standard number of poles, we can round it up to 125 poles.

For the second question, it is recommended to use narrow section V-belts for this design. The service factor for V-belts is typically 1.5, which means that the design power would be 1.5 times the actual power required. Therefore, the design power for the V-belt would be 0.29 x 1.5 = 0.435 hp.

To determine the output speed in radians per second (rad/s), we can use the formula Speed (rad/s) = Speed (fpm) x 0.1047. Therefore, the output speed would be 0.68 rad/s.

The belt selection can be made based on the design power and the RPM of the driving sheave. The driving sheave size can be determined by using the formula D = (Speed x 12)/RPM, where D is the diameter of the sheave in inches, Speed is the speed in fpm, and RPM is the revolutions per minute. In this case, D = (6.56 x 12)/120 = 0.656 inches. The driven sheave size should be approximately 1.5 times the