The characteristics and application of several common reducers

Summary: The reducer is generally used for low-speed and high-torque transmission equipment. The motor, inte...
The reducer is generally used for low-speed and high-torque transmission equipment. The motor, internal combustion engine or other high-speed power is meshed with the gear with a small number of teeth on the input shaft of the reducer to mesh with the large gear on the output shaft. The ratio of the number of gear teeth is the transmission ratio.

The reducer is a relatively precise machine, and its purpose is to reduce the speed and increase the torque. There are many types of reducers, different models, different types have different uses.

According to the transmission type, it can be divided into gear reducer, worm reducer and planetary gear reducer; according to the different transmission stages, it can be divided into single-stage and multi-stage reducers; according to the shape of the gear, it can be divided into cylindrical gear reducer and conical gear reducer And conical-cylindrical gear reducer; according to the layout of the transmission can be divided into unfolded, split and coaxial reducer.

In order to facilitate the reasonable selection of reducers, the types, characteristics and applications of several common reducers are listed for reference when selecting models.

1. Single-stage cylindrical gear reducer
Single-stage cylindrical gear reducer is suitable for reduction ratio 3 ~ 5. The gear teeth can be straight, helical or herringbone. The box body is usually cast with cast iron or welded with steel plates. Rolling bearings are commonly used for bearings, and sliding bearings are used only for heavy loads or high speeds.

2. Two-stage cylindrical gear reducer
The two-stage cylindrical gear reducer is divided into three types: expansion type, split type, and coaxial type, and the reduction ratio is 8 ~ 40.
Expansion type: high-speed long tail helical teeth, low-speed grades can be straight teeth or helical teeth. Due to the asymmetrical arrangement of the gear relative to the bearing, the shaft is required to have a high stiffness, and the torque input and output ends should be away from the gear to reduce the uneven distribution of the load along the tooth width due to the bending deformation of the shaft. The structure is simple and the most widely used.
Split type: Generally, high-speed split is used. Because the gears are arranged symmetrically with respect to the bearings, the forces on the gears and bearings are more even. In order to make the total axial force on the shaft smaller, the helical direction of the two pairs of gears should be opposite. The structure is more complicated, and it is often used in places with high power and variable load.
Coaxial: The axial size of the reducer is large, the intermediate shaft is long, and the rigidity is poor. When the oil immersion depths of the two large gears are similar, the carrying capacity of the high-speed gears cannot be fully exerted. Commonly used in the coaxial line of input and output shafts.

3. Single-stage bevel gear reducer
Single-stage bevel gear reducer is suitable for reduction ratio 2 ~ 4. The transmission ratio should not be too large in order to reduce the size of the bevel gear and facilitate processing. It is only used in the transmission where the two axes intersect perpendicularly.

4. Conical and cylindrical gear reducer
Conical and cylindrical gear reducers are suitable for reduction ratios of 8 to 15. The bevel gear should be arranged at high speed to reduce the size of the bevel gear. Bevel gears can be straight teeth or curved teeth. Cylindrical gears are mostly helical teeth, so that they can cancel part of the axial force of the bevel gear.

5. Worm reducer
There are mainly cylindrical worm reducer, arc toroidal worm reducer, cone worm reducer and worm-gear reducer, among which cylindrical worm reducer is the most commonly used.
Worm reducer is suitable for reduction ratio of 10 ~ 80. The structure is compact and the transmission ratio is large, but the transmission efficiency is low, which is suitable for occasions with small power and gap work. When the peripheral speed of the worm is V≤4 ~ 5m / s, the worm is lower-mounted, and the lubrication and cooling conditions are better; when V≥4 ~ 5m / s, the oil stirring loss is larger, and the general worm is the upper-mounted.

6. Planetary gear reducer
Due to structural reasons, the planetary reducer has a single-stage deceleration of at least 3 and a maximum of generally no more than 10. The common reduction ratio is: 3/4/5/6/8/10. The number of reducer stages generally does not exceed 3, but some are large The reduction ratio has 4 levels of reduction.
Compared with other reducers, planetary reducers have high rigidity, high precision (single stage can achieve less than 1 point), high transmission efficiency (single stage is 97% -98%), high torque, volume ratio, lifetime maintenance-free, etc. Features. Because of these characteristics, most planetary reducers are installed on stepper motors and servo motors to reduce speed, increase torque, and match inertia.

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