Design and operation of a helical gearbox
A helical gearbox is a mechanical device designed to reduce the speed of rotation and increase the torque on the output shaft. It is used in electrical, pneumatic and hydraulic drives of industrial equipment for a variety of purposes. It is considered one of the most common types of gearboxes and is characterized by high efficiency and simple transmission design.
Contents of the article:
Operating principle and scope
- Automation and control systems;
- Lifting and transport equipment;
- Drive units for construction machines and mechanisms;
- Conveyor transport and pumping units;
- Crushing equipment;
- Presses.
Thanks to their high efficiency, cylindrical gearboxes Ts2U 250 can be used to drive almost any equipment, but only if there are no strict requirements for dimensions, since installations of this class have impressive dimensions.
Advantages and Disadvantages
The design of the helical gearbox dictates many advantages of the mechanism.
- The ability to transmit high power with virtually no losses and create high torques;
- It has one of the highest efficiency rates among other gearboxes. Efficiency can reach 98%;
- Ability to work under uneven loads, with frequent starts and stops, in long-term mode;
- Lack of self-braking effect, which allows you to rotate the output shaft manually when the engine is off;
- Low heating of the housing and main structural elements during operation;
- Relatively small play of the output shaft and high accuracy of movement of spur gears;
- High reliability and sufficient service life of the mechanism, which can exceed 25, 000 hours;
- The high variability of the main working units allows you to select or assemble a spur gearbox for almost any task.
For the sake of objectivity, we note the disadvantages of this class of mechanisms.
- The gear ratios of the gearbox stages are low. The maximum value cannot exceed 1 – 6. 3. To increase the indicator, it is necessary to use multi-stage reduction schemes;
- Installations with high gear ratios increase overall dimensions;
- During operation, spur gearboxes create significant noise;
- The lack of automatic braking also somewhat limits the range or requires the use of special braking devices.
Thanks to their simple design, helical gearboxes have a very low cost.
Main types of helical gearboxes
Depending on the purpose and required technical characteristics, spur gearboxes can be equipped with several gear stages with different types of gears. In most cases, the mechanisms use straight, helical or bevel gears. By design, there are several basic mechanisms that are used in various types of drives.
Helical coaxial gearboxes
In gearboxes of this class, the input and output shafts are on the same axis. This greatly simplifies the drive layout. Please note that coaxial helical gearboxes are not single stage. A minimum of two gears are required to transmit the rotation of the output shaft back to the input shaft.
Manufacturers offer a large list of options of varying power – from a few tenths of a watt to several hundred kilowatts. Thanks to this, coaxial gearboxes are widely used both in automation and remote control systems, and in powerful industrial drives for production and lifting equipment.
Helical bevel gearboxes
Mechanisms of this type are used to ensure, if necessary, the intersection of the input and output axes. As a rule, these elements are located at an angle of 90°. Manufacturers offer modified horizontal and vertical versions.
Helical-bevel gearboxes are multi-stage systems. In this case, the bevel gear is the first stage. This ensures smoother operation when converting high angular speeds and torques transmitted from the drive motor.
We also note that they are completely interchangeable with worm-type gearboxes, which significantly expands the range of devices.
Single-stage mechanisms
This is the simplest type of helical gearboxes, characterized by a low gear ratio. As mentioned earlier, the maximum value is limited to 1/6. 3, which limits the scope of application of this equipment. It is used in drives where a significant reduction in output shaft speed is not required.
Equipment can be supplied with different shaft arrangements, but gearboxes of this class cannot be coaxial. Single stage systems are also not used with helical bevel gearboxes. The simple design of the mechanism greatly simplifies maintenance and extends the service life of the equipment.
Two-stage installations
The most widely used are two-stage helical gearboxes. This design allows you to increase the gear ratio of the mechanism without significantly increasing its dimensions. It consists of three gearbox axes. In the first high-speed stage, helical gearboxes are most often used. This increases the reliability of the mechanism due to a larger clutch area.
What to look for when choosing helical gearboxes
When choosing a helical gearbox, you should pay attention to the following characteristics:
- Gear ratio;
- Rated output shaft torque;
- Efficiency of the mechanism;
- Dimensions and weight;
- Required shaft arrangement.
When installing the drive in a work area, it is a good idea to pay attention to the noise level created during operation.
