The calculation of speed ratio and torque of bevel gearbox

release time:

2019-10-25 15:46

  Transmission ratio

  It is a transmission ratio of reducer, which means the ratio of the instantaneous input speed and output speed in deceleration. For example,input speed 1500r/min and the input 2.4 hp, with  the  torque 11.6 Nm, the transmission speed ratio is 1:1.

1.Calculation of ratio

Define the calculation method:

I = input speed/ output speed 

2.Common calculation:

I= torque ÷ 9550 ÷ power × input RPM ÷ operating coefficient. 

3. Gear system calculation method:


  Reduction ratio = number of gears ÷ automatic gear teeth.


  Reduction ratios calculation method for belt, chain and friction wheel: reduction ratio = driven wheel diameter ÷ automatic wheel diameter.




  The output torque of the motor, is one of the basic parameters of the motor with the unit of N.M.

1. Formula:T=9550P/n


  This formula is commonly used torque, power and speed to  calculate in engineering.

  T--torque; 9550--constant (do not have to investigate its source); P--motor power (KW); n--output speed (r/min). 

Attention:If the torque is calculated by the reducer, the efficiency loss of gear transmission should be considered.

  1. Calculation formula of servo motor’ torque : T=F*R* I.

  For example: drive an object of 100kg, R = 50mm, the reduction ratio is 1:50, the torque of the servo motor?


  Answer: 100x9.8(acceleration of gravity)x0.05x0.02=1.98N.M.


  Reducer torque calculation formula


1. Speed ratio=motors output RPM ÷ gears output RPM ("speed ratio" is also called "gear ratio")

2. If motor power, speed ratio and the operating coefficient is clarified: reducer torque = 9550 × motor power ÷ motor power input RPM × speed ratio × operation coefficient

3. If the torque, reducer output RPM and the coefficient is clarified,the reducer that the motor power required follows:


 motor power = torque ÷ 9550 × motor power input speed idling ratio ÷ operating coefficient


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