Technical Data Reducers Worm Gear Reducers Selection
Notes
Efficiency
Calculating efficiency
Use the formula shown below to calculate the efficiency at the listed input speed.
Efficiency (%)= Output torque (N・m) × Input speed (r/min) × 100 9550 × input kW × Reduction ratio
※The efficiency refers to the efficiency of the reducer running under these conditions: load ratio at 100%, using manufacturer-specified lubrication oil, running continuous and at steady oil temperature, with all parts fully run in. Theoretical efficiencies of the gears, frictional resistance of the bearings and oil seals, and loss of oil during operation due to splash up are not reflected.
Start-up efficiency
When using the reducer for lifts, elevators, and variable frequency control applications, it is necessary to consider the starting efficiency when determining the required input torque.
Please refer to the starting efficiency ratios for single reduction reducers, and for double reduction reducers. Contact us for the Troi Drive TD Series.
Necessary input torque (%)= Load torque (Start-up efficiency × Reduction ratio )
Motor sizing
An undersized motor may result current overload due to the reducer’s no-load loss.
Always select a motor with enough capacity.
Transfer capacity before oil temperature settles
The transfer capacities listed in the product page assume the reducer is driving a load rate of 100% using the recommended oil in continuous operation, and at constant oil temperature.
Efficiencies will lower during cold starts, and when the oil temperature has yet to stabilize due to frequent starts and stops. This is due to the low fluidity of the lubrication oil which increases the mixing resistance of the oil, thus resulting in less transfer capacity than published in the product page.
To make a general estimate, discount the capacity using the ratios given below.
Efficiency ratio (reference) to use before oil temperature settles.
| Reduction ratio | Efficiency ratio |
|---|---|
| 10 ～ 15 | -4% ～ -8% |
| 20 ～ 30 | -7% ～ -11% |
| 40 ～ 60 | -12% ～ -15% |
※Contact us for information about the double reduction type.
About Self-Lock
A reducer is said self-locking if the input shaft does not begin to turn when force is applied to the output shaft, or it is said to have self-locking properties if the input shaft turns but requires a large force on the output shaft.
This is the characteristics of the worm gear reducer.
Our standard Worm Power Drives with a reduction ratio of 1/60 and our Troi Drive TD Series with a reduction ratio of 1/60 can be expected to be self-locking from a standstill condition. However, because the drives are designed for efficiency, self-locking performance is slightly less than conventional models.
Notes about self-locking
Self-locking reinforced specifications (made to order) are available when a self-locking mechanism is expected for lifts or reversing machines. Contact us for more information.
- (1) Shocks or vibration may reduce the self-locking effect. Since self-locking cannot be guaranteed, be sure to install a separate holding device when a secure stop or retention is required.
- (2) If the braking effect occurs in applications where an extremely heavy load inertia is being moved (such as equipment that travels or swings), the self-locking effect or properties can be dangerous. For such applications, select a reduction ratio from 1/10 to 1/20.
Using a servo motor for the input
Servo motor may be used within the input capacity (kW) rating given for each input speed of the reducer.
Always slowly accelerate and decelerate.
Contact us if you wish to drive the input faster than 1750 r/min. We also offer “TERVO ” (TERVO reducer for servo motor) , which can be driven at speeds of up to 3000 r/min.
