What Calculation Formulas Do I Need To Know When Buying Gear Reducers?

We may not know how to calculate some relevant parameters when we buy the reducer. Let me share with you how to calculate some specific parameters, including known data and unknown parameters.

1. Type selection calculation of reducer (hand calculation); (known parameters)

1.1 The original motive

Motor power: P1 KW
Motor speed: n1 / min
Maximum starting torque: TA Nm

1.2 Working machine

Working machine shaft power: P2 KW
Speed: n2 /min
Daily running time: h/day
Number of starts per hour
Hourly duty cycle: ED =XXX%

1.3 Motor

Motor power: P1 =75KW
Motor speed: n1=1500/min
Maximum starting torque: TA=720 Nm

1.4 Belt conveyor

Belt conveyor shaft power: P2=66KW
Speed: n2=26/min
Daily running time: 12h/day
Number of starts per hour: 7 times
Hourly duty cycle: ED=100%

2.Selection and calculation of reducer; (known parameters)

Environment temperature: °C
Installation location: indoor small space; indoor large space; outdoor;
Altitude: m
Environment temperature: 30℃
Installation location: large indoor space
Altitude: <1000m

3. the structure selection design of the reducer

According to the belt conveyor installation position and the size of the space, it is decided to choose the right-angle shaft gearbox.
Installation method: horizontal installation
Output shaft position and shape: located on the right side of the gearbox, part type C, solid shaft
Rotation direction of the output shaft: When facing the end of the output shaft, it is counterclockwise (CCW)

4. Type selection of reducer (determination of type and specification)

Select the reducer specification and type to determine
Transmission ratio: n1/n2=1500/26=57.7 in=56
Determine the rated power of the reducer: P2N≥P2×f1×f2=66×1.3×1=85.8kw
Select type B3SH from the power meter, reducer specification No. 9, and the corresponding rated power P2N=100KW
f1: working machine factor; f2: prime mover service factor
Check whether the reducer selection is appropriate: (The calculation meets 3.33 × P2 ≥ P2N) 3.33 × P2 = 3.33 × 66 = 219.8KW> P2N (100KW) meets the requirements.

5. Type selection of reducer (determination of type and specification)

Starting torque check: P2N≥(TA×N1/9550) ×f3
P2N≥ (720×1500 /9550) ×0.65= 73.5kwf3

6. determine the lubrication method of the reducer

Determine the lubricating oil supply method of the reducer
It is determined according to the installation method and rotation speed of the reducer; this reducer can be oil-immersed splash lubrication, and you can check the table to determine whether to use forced lubrication or splash lubrication.

7. the heat capacity calculation of the reducer

Determine the required heat capacity PG
Calculation of heat capacity without auxiliary cooling device (natural cooling);
Calculation formula: PG=PGA×f4×f8
Where: PG—–the actual thermal power of this type of reducer
PGA—Theoretical heat capacity without auxiliary cooling device: 64.8kw
f4——-Environmental temperature coefficient; 0.88
f8——- reducer oil supply coefficient; 1.0
The calculated result PG value must be greater than the shaft power P2 of the working machine

8. Calculation of the heat capacity of the reducer

Heat capacity of reducer when using fan cooling
Calculation of heat capacity with fan cooling device;
Calculation formula: PG=PGB×f4×f8
Where: PG—–the actual thermal power of this type of reducer
PGB—Theoretical heat capacity without auxiliary cooling device: 140kw
f4——-Environmental temperature coefficient; 0.88 (cooling coefficient without auxiliary cooling device or only with fan cooling)
f8——- reducer oil supply coefficient; 1.0
The calculated result PG value must be greater than the shaft power P2 value of the working machine

9.Reducer heat capacity calculation

The heat capacity of the reducer when the cooling coil is used for cooling
Calculation of heat capacity when cooling with cooling coil:
Calculation formula: PG=PGC×f5×f8
Where: PG—–the actual thermal power of this type of reducer
PGC—Theoretical heat capacity of cooling coil device; 174kw
f5——-Environmental temperature coefficient; 0.93 (Environmental temperature coefficient with cooling coil, refer to Table 5)
f8——- reducer lubrication oil supply coefficient; 1.0 (horizontal installation value)
The calculated result PG value must be greater than the shaft power P2 value of the working machine

10. Calculation of the heat capacity of the reducer

The heat capacity of the reducer when the fan and the cooling coil are used for cooling at the same time
Calculation of heat capacity when cooling with fan and cooling coil;
Calculation formula: PG=PGD×f5×f8
Where: PG—–the actual thermal power of this type of reducer
PGC—Theoretical heat capacity of cooling coil device; 241kw
f5——-Environmental temperature coefficient: 0.93 (Environmental temperature coefficient with cooling coil device or with cooling coil and fan at the same time)
f8——-Oil supply coefficient of reducer: 1.0
The calculated result PG value must be greater than the shaft power P2 value of the working machine
The above calculation is based on without cooling device→with fan→with cooling coil→with fan at the same time
Sequential calculation with the cooling coil, and calculate which step is satisfied.
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