(1) Cylindrical gear transmission
For transmission between parallel shafts, the general transmission ratio can be up to 8 in a single stage, the maximum is 20; the two stages can be up to 45, the maximum is 60; the third level can be up to 200, and the maximum is 300.
The transmission power can reach 100,000 kilowatts, the speed can reach 100,000 r/min, and the peripheral speed can reach 300 m/s.
The single stage efficiency is 0.96 to 0.99.
The spur gear drive is suitable for medium and low speed drives.
The helical gear drive runs smoothly and is suitable for medium and high speed transmission.
The herringbone gear drive is suitable for transmissions that transmit high power and high torque.
There are three types of meshing gears:
- The external meshing gear is driven by two external gears, and the steering of the two wheels is reversed;
- The internal gear transmission is engaged by an internal gear and a small external gear, and the steering of the two wheels is the same;
- The rack and pinion drive can change the rotation of the gear into a linear movement of the rack, or vice versa.
(2) Bevel gear transmission
Used for transmission between intersecting shafts.
The single-stage transmission ratio can reach 6 and the maximum is 8; the transmission efficiency is generally 0.94 to 0.98.
Straight bevel gear transmissions deliver up to 370 kW and a peripheral speed of 5 m/s.
The helical bevel gear transmission runs smoothly and the gear carrying capacity is high, but the manufacturing is difficult and the application is less.
The curved bevel gear drive runs smoothly with a transmission power of 3700 kw and a peripheral speed of over 40 m/s.
(3) Hyperboloid gear transmission
Used to drive the drive between the axes.
The single-stage transmission ratio can reach 10, up to 100; the transmission power can reach 750 kw, the transmission efficiency is generally 0.9 to 0.98, and the peripheral speed can reach 30 m/s.
The pinion cantilever mounting can be avoided due to the axial offset.
Widely used in the transmission of cars and tractors.
(4) Helical gear transmission
For the inter-interlacing transmission, the transmission ratio can be up to 5; the bearing capacity is low, the wear is severe, and the application is rare.
(5) Worm drive
The main form of the staggered shaft drive, the axis stagger angle is generally 90 °.
The worm drive can obtain a large transmission ratio, usually 8 to 80 for single stage and up to 1 500 for transmitting motion;
Transfer power up to 4500 kw;
The speed of the worm can reach 30,000 r/min;
The peripheral speed can reach 70 m/s.
The worm drive works smoothly, the transmission ratio is accurate, and it can be self-locking, but the transmission efficiency is less than 0.5 when self-locking.
The worm gear has a large sliding between the tooth surfaces, generates more heat, and has low transmission efficiency, usually 0.45 to 0.97.
(6) Arc gear transmission
A gear transmission with a convex and concave arc as a tooth profile.
When the no-load is carried out, the two tooth profiles are point contacts.
During the meshing process, the contact points move along the axis direction, and the longitudinal coincidence degree is greater than one to obtain a continuous transmission.
It is characterized by high contact strength and load-bearing capacity, easy formation of oil film, no root cutting phenomenon, uniform tooth surface wear and good running performance;
However, the sensitivity to the center distance, the cutting depth and the helix angle are very sensitive, so the manufacturing and installation accuracy is high.
(7) Cycloidal gear transmission
A gear train with a cycloid as a tooth profile.
The contact between the tooth surfaces of the transmission is small, the wear resistance is good, and there is no root cutting phenomenon, but the manufacturing precision is high, and the center distance error is very sensitive.
Used only in watches and meters.
(8) Planetary gear transmission
Gear drive with the moving axis.
There are many types of planetary gears, and the performance of different types varies greatly.
It is very important to choose the type reasonably according to the working conditions.
Commonly used are ordinary planetary transmissions consisting of sun gears, planetary gears, internal gears and planet carriers, planetary gears with small tooth differences, cycloidal pin drives and harmonic drives.
Planetary gear transmission is generally composed of parallel shaft gears, featuring small size and light weight.
The input and output axes can be on the same line.
Its application is becoming more and more extensive.
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