Calculating the power and torque of the gearbox will help you to prepare and purchase a practical device that fits your work conditions and needs. Also, paying attention to the value of these parameters in choosing a gearbox helps a lot to increase the durability and lifespan of these devices. The gearbox is actually a device that changes the input power and speed and causes a change in the output torque. Accordingly, by using this device, the required torque in the system can be increased or decreased according to the work requirement. Gearboxes are widely used in many fields of work, including in the design of cars and widely used equipment in various industries, such as conveyor belts.
Two important factors in choosing an industrial gearbox, which are of great importance, are their output torque and speed, which must be taken into account when calculating the power and torque of an industrial gearbox. In choosing the torque of the gearbox, it is necessary to pay attention to the torque required in the system and according to its value, select a device suitable for the working conditions. On the other hand, the use of gearboxes that do not match the working conditions causes disruption in the execution process of the system and damage to its various parts, which requires sufficient care in this field. Considering the high importance of power and torque in working with these devices, in this article we are going to discuss how to calculate the power and torque of the gearbox, which we hope will be of interest and use to you, the audience.
The relationship between work and power in calculating the power and torque of the gearbox
Before calculating the power and torque of the gearbox, it is necessary to get acquainted with the concept of work and its relationship with the power or power of the device. According to the relationships obtained, it can be said that the amount of executive work in a process depends on the amount of force and displacement in it. In other words, the amount of executive work (W) can be calculated using the amount of force (F) and the amount of displacement (D) through the following equation:
W = F × D (1)
In the above relationship, force and displacement are in terms of newtons (N) and meters (m), respectively, and the amount of work is calculated in terms of joules (J).
After getting acquainted with the concept of work in calculating the power and torque of the gearbox, it is time to examine the relationship between work and the power of the device, which can be calculated from the following relationship:
P = W ÷ t (2)
As you can see, the amount of power (P) depends on the work done (W) per unit of time (t), which in the above relationship is power in watts (w), work in joules (J) and time in seconds. (s) will be
Now, if we insert relation (1) into relation (2), we will get the following relation:
P = (F × D) ÷ t = F × (D ÷ t) (3)
Since D ÷ t or the amount of displacement per unit of time is the same as the speed (v), by inserting the speed in equation (3), we will reach the following final equation:
P = F × v (4)
Based on equation (4), the amount of power (P) depends on the amount of input force (F) and its speed (v), in this relation, the speed is in meters per second (m/s).
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The amount of input power of the device in calculating the power and torque of the gearbox
At first, it should be mentioned that output torque and speed are two important factors in choosing a gearbox, from which the input power of the device can be calculated. Since electric motors provide the torque required for the work process through rotary motion, the following equation should be used to calculate the power in them:
P = T × ω (5)
Equation (5) is the same as equation (4) in calculating power (P), this time based on torque (T) and rotation speed (ω). In this regard, the torque is expressed in newton meters (Nm) and the rotation speed or angular speed is expressed in revolutions per minute (rpm). So, the following equation can be used to calculate the output power (P out) of the gearbox:
P out = T out × ω (6)
In the above relationship, T out is the output torque and ω is the angular velocity from which P out or output power can be calculated.
In this section, after calculating the power and torque of the gearbox, it is time to calculate the input power. Since the output power of the gearbox is the same as the output power of the electric motor, the following equation can be used to calculate the input power:
(7) Based on the above relationship, the input power of the electric motor (P in) can be obtained from the output power (P out) and the motor efficiency (η). The efficiency of the motor itself depends on various factors, including the type of electric motor, the type of gear and its gear ratio. For example, motor efficiency can be 40, 80 or 90% according to the mentioned factors, which should be used as 0.4, 0.8 or 0.9 in relation (7).
The website of Sdtgear stated the formula of reducing torque as follows: Gear reducer torque = 9550 * engine power / rated engine input rotation power * ratio * gear reducer efficiency. The above calculation is the torque equation. Motor power = torque ÷ 9550 × motor input speed rated power / ratio / service factor
Equations of single conversion in calculating the power and torque of the gearbox
As we mentioned, in order to calculate the power of the gearbox, the torque and speed relationship of this device can be used, in which, based on the SI units, the torque is in newton meters (Nm), the speed is in revolutions per minute (rpm) and the power is in Watt (w) is expressed. However, other units may be used in introducing the characteristics of gearboxes and other system components such as electric motors, in which it is necessary to perform a single conversion process. Unlike the SI unit of power, which is in watts (w), in gearboxes, the unit of horsepower (horsepower) is used to introduce the power and strength of these devices, which is abbreviated as (hp). To calculate the power and torque of the gearbox, it is necessary to use the relationship of converting horsepower to watts, which is as follows:
(8) × 746 power in horsepower = hp power in watts w
If the torque value is in pound-feet and the speed is in revolutions per minute, the power is obtained in pound-feet per minute, which can be converted into horsepower using the following equation:
(9) ÷ 5252 power in pound-feet per minute = power in hp
Now, if the torque is in pound-inches, the speed is in revolutions per minute (rpm) and the calculated power is in pounds-inches per minute, the following equation can be used to convert power into horsepower:
(10) ÷ 63025 power in pound-inches per minute = power in hp
So, in order to calculate the power of the gearbox, you must first pay attention to the unit of torque and speed, and then calculate the power of the device based on them. Finally, with the help of the above relations, you can also perform the one-to-one conversion.
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Calculate the output torque of the gearbox
As we mentioned, the power of the gearbox depends on the two factors of torque and speed, which must be taken into account when calculating the power and torque of the gearbox. In the same way, the torque of the gearbox is dependent on two factors, power and speed, which can be used to calculate the torque value. The output torque of the gearbox includes the rated output torque and the actual output torque, the rated torque of these devices depends on their rated power and rated output speed. On the other hand, the actual output torque of these devices is related to their actual power (load size) and their actual output speed. If the nominal torque of the gearbox is less than the required value, the device will not work, and for this reason, care must be taken in choosing the gearbox with the appropriate nominal torque.
To calculate the torque of the gearbox, a power factor is needed, which can be the power of the electric motor connected to the gearbox. In general, the following relationship can be used to calculate the output torque of the industrial gearbox:
T out = (P in ÷ ω) (11)
In relation (11), the output torque (T out) is in (Nm), the input power (P in) is in (Kw) and the output speed (ω) is in revolutions per minute (rpm). According to relation (11), it can be said that if the power of the device remains constant, high torque cannot be achieved by reducing the speed.
Calculation of power and torque of multi-stage gearbox
Accurate calculation of the output torque of the gearbox has a great effect on the performance of this device and helps to increase its durability and longevity. Since the torque of electric gearboxes depends on its stage, it is necessary to pay enough attention to this factor before calculating the output torque.
In general, the output torque of the electric gearbox is divided into three categories: one-stage electric gearbox torque, two-stage electric gearbox torque and three-stage electric motor torque. One-stage electrogearbox with a ratio of <10:1, two-stage with a ratio of >10:1 and ≤200:1, and three-stage with a ratio of >100:1 are available. However, examples of these devices are also available that are designed as five stages and have a maximum reduction ratio of 4592:1.
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Other methods of calculating gearbox power and torque
It should be noted that calculating the power and torque of the gearbox is not limited to using the above relationships, and the torque of these devices can be calculated in other ways, which we will introduce below:
Calculate the output torque of the gearbox using the torque ratio
Another method of calculating the output torque of the gearbox is to use the torque ratio of this device and the input torque of the electric motor, which can be calculated from the following equation:
(12) Engine input torque × gearbox torque ratio = gearbox output torque
In relation (12), the input torque of the engine and the output torque of the gearbox are in newton meters (Nm).
Calculation of the output torque of the gearbox using the utilization factor
If we have the output speed of the gearbox, the engine power and the utilization factor, the output torque can be calculated from the following equation:
T out = (P in ÷ ω) × 9550 (13)
In the above relationship (13), the output torque of the gearbox is in newton meters (Nm), the input power is in kilowatts (Kw) and the output speed of the gearbox is in revolutions per minute (rpm).
Calculate the power and torque of the gearbox using an online calculator
In the third method of calculating the output torque of the gearbox, the torque of these devices can be calculated using an online calculator. Using this calculator, you can calculate the output torque with high accuracy and in the shortest time.
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Online shopping for industrial gearboxes
If you intend to buy different models of industrial gearbox, you can buy this equipment in two ways, in person and online. Nowadays, the online shopping method is more welcomed than the face-to-face method due to its advantages; Because in this method, there is no need to go to the store and spend extra time and money for this. Also, in the online shopping method, it is possible to view different models of gearboxes along with their specifications and prices through the virtual pages of stores 24 hours a day and on all days of the week, and this also facilitates the process of purchasing them.
Since many stores are active in the field of supply of these devices, we introduce to you the Rehavaran Sanat Qomes store, which provides the highest quality models of industrial gearboxes with high quality and reasonable prices. The gearboxes offered in this center, in addition to their high variety, also have high efficiency and longevity.
