Selecting a gearmotor and its efficiency
The engine is a gearbox (“reduction” in English – reduction, reduction, “motor” – engine) – this is an electromechanical device that combines a gearbox and an electric motor in one housing.
Contents of the article:
- Classification of gearboxes
- How to choose the best option?
- Gearbox lubrication
- Gear housings
- Gearbox modernization is a stable trend
- Calculation of coefficient of efficiency (efficiency)
- Features of explosion-proof products
- Reliability table value
- Walk-behind tractor design
- Homemade creeper for a walk-behind tractor with your own hands
- Mechanism elements
The main factor when choosing an engine editor is the amount of torque transmitted.
- Regional speed;
- The relative position of the axes;
- Efficiency (utility coefficient);
- Mode of operation of the mechanism.
The gear ratio of the motor deck is equal to the product of the number of gears k for a given step
You can also find the number of gears by calculating the ratio given the number of teeth in the drive and driven gears.
Decker motor power matters – rated input and output power directly depends on the electric motor and gear ratio
The utility rate is the rate of work used. Efficiency gearbox Ts2U 250 engine is similarly equivalent to the product of its efficiency and degree.
Dynamic efficiency is the ratio of the received power at the output shaft to the power at the input shaft. Static efficiency also stands out.
Classification of gearboxes
Ground-to-top gearboxes. This type of equipment is an independent unit used in machine drives. Its technical characteristics meet the general requirements of various fields of application. Structurally, common engines may differ.
Special gearboxes are designed for automotive, aviation and other highly specialized industries. From the name it is clear that this group of devices must correspond to specific parts and application parameters.
Gearboxes can be classified according to the following criteria:
- By type of transmission and number of steps;
- The position of the axes of the input and output shafts in space and relative to each other;
- By correction.
1. 1 Number of stages and shaft arrangement
Two-stage and three-stage gearboxes in parts and branched chains (in the case of two-stage models with a coaxial circuit) have many advantages over other types of units. Helical gearboxes with crews can be equipped with low-speed stages with internal gears. Planetary and wave gearboxes with coaxial shaft axes also provide high performance and wide gear ratios.
Two- and three-stage bevel (bevel-shaped) gearboxes can be effective in machine configurations that require intersecting shaft positions.
Units with worm (worm, cylindrical world) worms are characterized by high gear ratios and low noise levels. However, the efficiency of such models is lower than that of their cylindrical counterparts.
The vertical shaft output position requires less space. In mechanisms requiring such an arrangement, worm or bevel gearboxes are more often used. Convenience lies in the horizontal position of the motor shaft.
Table 1. Classification of gearboxes depending on the position of the shaft axis:
- Shaft in a horizontal plane;
- Axis in a vertical plane (input shaft is above or below the output shaft);
- Axis in an inclined plane.
1. 2 Types of gears used
1. 2. 1 Worm gearboxes
Worm gearboxes are the most common type of gearbox. The drives are compact in size (compared to cylindrical devices). Gear ratios in worm pairs can range from 1 to 100 (sometimes higher).
The potential for increased torque when reducing shaft speed is greater with worm gearboxes than with other types of gearboxes. Working with a three-stage helical gearbox will provide a reduction coefficient of the same order. On worm gear units, one stage is sufficient to solve this problem. Another advantage is the simplicity and low cost of worm gears. The use of worm gears reduces the noise level during transmission operation and ensures high smoothness.
Self-braking is only present in worm gearboxes. The operating principle is based on braking the driven shaft when the drive shaft (worm) is stationary. Self-braking of the transmission occurs when the drive shaft elevation angle is 3. 5 degrees or less.
When selecting a worm gearbox, it is important to consider that the efficiency of the worm gear decreases with increasing gear ratio. Consequently, energy is lost due to friction between the worm and the gear teeth.
The service life of worm gearboxes averages 10, 000 hours.
1. 2. 2 Worm globoid gearbox
The threads of the Globoid worm gearbox are convex (in other worm gearboxes, they are cylindrical). This design feature improves torque transmission and driving force. Globoid gearboxes are designed for applications requiring high reliability, zero backlash, and zero dynamic loads on the output shaft. This type of gearbox is most commonly used in elevator drum drives. Globoid gearboxes can adapt to variable loads during car lifting and braking, and maintain normal reversibility during operation.
1. 2. 3 Helical Gearboxes
1. 2. 3 Helical gearboxes
Spur gearbox configurations:
Narrow expansion;
- Expanded;
- Forked;
- Coaxial.
- The most common expansion configuration. This allows for the production of uniform wheels, shafts, and gears suitable for gearboxes of various sizes. This factor is crucial for mass production. It helps reduce production costs.
For the same purpose, left-hand gear teeth and right-hand gear wheels are selected for all transmission stages. For certain configurations of a single gearbox, it is more practical to use the following diagram: Left-hand gear teeth are the first stage, and right-hand gear teeth are the second stage. This configuration reduces the axial load on the support.
The geometry of gearboxes designed according to the detailed diagram is elongated. The weight of such units is 15-20% higher than that of drives designed using a bifurcation diagram.
The bifurcation scheme can be applied to slow and fast stages. The second option is the most rational, since the intermediate shaft can be created on the principle of a gear shaft, and the high-speed shaft is “floating”.
The coaxial circuit ensures alignment of the axes of the high-speed and low-speed shafts. The weight and dimensions of gearboxes assembled according to a coaxial design are similar to models with an extended design. The cost of both types of units is almost the same.
One of the main technical characteristics of coaxial gearboxes is an increase in power at high speed levels, which is achieved by reducing the load. However, structurally such units are more complex.
Helical gearboxes have a service life of more than 25, 000 hours.
1. 2. 4 Bevel gearboxes
1. 2. 4 Bevel gearboxes
The gear ratios of bevel gearboxes vary from 1 to 5.
The gears are located between the gearbox supports. The transmissions are installed on the console.
1. 2. 5 Helical-bevel gearboxes
1. 2. 5 Helical-bevel gearboxes
All bevel and helical gearboxes have a high-speed bevel stage. This design feature is explained by the low load capacity and, consequently, the large size of the device. It is used to reduce disk size and reduce conical stages at high speeds.
Bevel gear can be used for low speeds and intermediate stages. This is justified by the need to reduce sensitivity to errors during production and installation and minimize the impact on the mechanism as a whole.
The direction of the teeth of a cylindrical pair of braids must be chosen taking into account the possibility of subtracting axial forces on the intermediate shaft.
1. 2. 6 Shaft-mounted gearboxes
1. 2. 6 Shaft-mounted gearboxes
In principle, the nozzle installation method can be applied to worm gearboxes and other types of gearboxes. The exception is equipment in cylindrical coaxial groups, the design features of which make such installation difficult.
Rapid load dynamics on the output shaft (in most cases an emergency situation occurs) can lead to premature failure of the drive equipment in the absence of a coupling. Therefore, for the gearbox to operate, it is necessary to create operating conditions with a uniform load. Optional – additional drive protection.
1. 2. 7 Planetary gearboxes
1. 2. 7 Planetary gearboxes
The design characteristics of planetary gearboxes can be different. Models are classified by the number of stages (1-, 2- or 3-stage), which is the kinematic scheme of the planetary gear. The type of bearing also varies. Rolling bearings are designed for low-speed operating conditions. Sleeve bearings are then designed for high speed applications. The area of application of planetary gearboxes is mechanical engineering.
Planet MPO devices fall into the category of universal drive equipment. They are widely used in agitation drives in the medical, chemical and microbiological industries, as well as in general industrial drives. MPO series editors can work 24 hours a day with a constant variable load.
High demands are placed on planetary gearboxes. The production of such equipment requires high precision to ensure that the teeth are in close contact with each other, but at the same time easy to move.
1. 3 Methods of fastening gearboxes
1. 3 Methods of fastening gearboxes
With flange mounting, the gearbox is mounted using a flange on the housing. The output shaft passes through this flange.
The nozzle is attached using a hollow output shaft, which connects the gearbox to the working mechanism. This shaft fits onto the end of the operating mechanism shaft.
How to choose the best option?
How to choose the best option?
Product type;
- Output speed (this parameter has an important impact on the subsequent choice of product model);
- Power;
- Operation function;
- Working conditions;
- Mounting type;
- Structural structure of the input and output shafts;
- Availability of additional functions;
- Overall dimensions (indicators must correspond to the location of such equipment).
- Gearbox lubrication
Gearbox lubrication
For low-power gearboxes and low hook rotation speeds, lubrication is carried out using a spray or an oil bath. The same oil poured into the housing will partially wet the worm, wheel (gear or worm) and spray ring.
To lubricate high-speed and powerful equipment, oil is supplied to the oil jacket in an oil bath. For bearings, liquid or thick grease is used.
Gear housings
Gear housings
The removable housing design includes a base and a removable cover. Some models of vertical helical gearboxes have connectors in two or three planes. To prevent oil leakage, the gearbox fittings are treated with sealant. It is not recommended to install a gasket between the cover and the base due to deformation when tightening the fasteners. As a result, the bearings in it may break.
Unused housings are often used for worm gearboxes and other types of light equipment. This design has a removable lid.
Score cast iron is primarily used in the production of gear housings. Steel is generally not often used in general drive equipment configurations on custom orders. In steel welded housings, the wall thickness is approximately one third less than in cast iron gearboxes. Nowadays, aluminum alloys are increasingly used in construction production.
Gearbox modernization is a stable trend
Gearbox modernization is a stable trend
The basis of modernization is as follows.
ISO standards;
- Block-modular design;
- Improved gearbox protection mechanisms;
- Gear modifications;
- Modernization of gearbox housings is focused on the production of lightweight monolithic structures characterized by high heat transfer;
- Use of injection molding technology in the production of aluminum alloy housings;
- Use of synthetic oils throughout the entire period of operation of the gearbox;
- No requirements for maintenance of the drive mechanism during operation.
- The constant process of modernization helps to improve the technical characteristics of the gearbox, expand its functions and versatility of execution. Today, the products of large Russian manufacturers are not inferior in quality to their foreign counterparts.
Calculation of coefficient of efficiency (efficiency)
Calculation of coefficient of efficiency (efficiency)
“P2” – output power indicator;
- “P1” is the input power value.
- It is worth considering the important fact that high distribution leads to low levels of efficiency. A high index has a special impact and depends on the quality of the lubricant material and the operating time of the equipment itself.
Features of explosion-proof products
Features of explosion-proof products
E – high degree of security. Models can be used in any conditions;
- D – The enclosure is explosive. This protects the engine from deformation in the event of an independent explosion. They are suitable for working with high temperatures and all types of explosives;
- I – Protection against electrical claims. Suitable for specially created production conditions.
- Reliability table value
Reliability table value
It is very easy to purchase a motor account from the manufacturer of the required size and power. Regardless of whether the selection process is problematic or not, do not hesitate to contact our specialists if you have the ability to correctly calculate the key indicators of the product.
Walk-behind tractor design
Walk-behind tractor design
The Rama is a durable structure that can accommodate other components;
- Wheels – from homemade metal to factory-made rubber. The position of the wheel or wheelset axle is fixed relative to the frame by iron posts with inconspicuous bearings;
- Engine – power from 5 to 10 hp. You can use electric motors with batteries or the most popular engines from scooters and motorcycles. This choice is suitable for ready-made speed control and availability of gear ratios;
- Gearbox is a unit for transmitting rotation from the engine to the actuator, converting speed and direction.
- Homemade creeper for a walk-behind tractor with your own hands
Homemade creeper for a walk-behind tractor with your own hands
Mechanism elements
Mechanism elements
Gear reducer
Gear reducer
Durability;
- Reliability;
- Small sizes;
- Reverse potential.
- Such drivers are not without drawbacks, the main ones being ease of service and price. In the event of a breakdown, as a rule, they require a complete replacement, which requires significant financial costs. In addition, it is necessary to monitor the availability of lubricants. The presence of lubricants can cause rapid wear.
Worm gearbox
Worm gearbox
Large transfers;
- Small sizes;
- Reverse potential.
- The main disadvantage of worm gearboxes is the lack of reverse. In addition, in case of failure, the gearbox is completely replaced.
Chain reducer
Chain reducer
The advantages of this type of movement are:
Simplicity;
- Reliability;
- Small sizes;
- Repair. .
- Combined gearbox
Combined gearbox
When planning a walking design, it is not always possible to place all devices in an ideal position. An intermediate gear is also required. This function is successfully performed by chain transmissions. The chain drive compensates for the distance from the six- or worm gearbox to the wheel or drive shaft.
What does the speed reducer consist of?
What does the speed reducer consist of?
At the same time, the driving stars and gears always have more teeth than the driven ones. Auxiliary elements can be various couplings, bearings and down. Six and worm gearboxes inevitably have their own housing, which cannot be said about chains. They may not be completely contained in the case or cover only part of the mechanism.
You might be interested in making a walking mower – behind a tractor or an adapter for a walking motor tractor.
Selecting a gearmotor and its efficiency
