Frequently Asked Questions
I need a stepper gearmotor. Does Anaheim Automation offer these motors?
Yes. Anaheim Automation offers stepper motors with Planetary Gearboxes in NEMA sizes 11, 17 and 23. We also have stepper motors with Spur Gearboxes in NEMA sizes 23 and 34, and PM stepper gearmotors in sized 24 to 42 mm diameters. Visit the Stepper Gearmotor section of our web site for more details. Please Note: We also offer gearboxes and motors separately, should you not find the size or gear ratio you require.
Are planetary and spur gearboxes bi-directional?
Yes, planetary gearboxes and spur gearboxes are designed to be used for bi-directional operation. The direction the input shaft rotates and gear arrangement of the gearbox will determine the rotation of the output shaft.
Can gearboxes be backdriven?
Depending on the arrangement and types of gears used, some gearboxes can be backdriven. An example of gearbox that can be backdriven is a spur gearbox. Since spur gears incorporate straight teeth in their design, there is no issue with the gears locking. Unlike spur gearboxes, worm gearboxes make use of a helical worm gear which stays in position and rotates along its axis. The worm gearbox configuration allows the worm to turn the gear with ease; however the gear cannot turn the worm. This is prevented due to the helical teeth of the gear worm. It is this feature of a worm gearbox which makes it useful in a braking system.
How do gear reducers work?
All gear reducers work in a similar fashion. The directions the gears rotate are dependent on the input direction and orientation of the gears. For example, if the initial gear is rotating in a clockwise direction, the gear it engages will rotate counterclockwise. This continues down the line for multiple gears. The combination of different size gears and the number of teeth on each gear plays a significant role in the output torque and speed of the shaft. High gear ratios allow for more output torque and lower speeds, while lower gear ratios allow for higher output speed and less output torque. Planetary gearboxes, spur gearboxes, helical gearboxes, and etc. are all types of gear reducers. It is the way the teeth interact and cut which differentiates them from other gear reducers.
Advantages and Disadvantages
Advantages of Spur Gearboxes
• Low noise level
• High efficiency
• High reduction ratios
• Increase/Decrease output torque
• Increase/Decrease output speed
Disadvantages of Spur Gearboxes
• More costly than other drive systems
• Proper lubrication is necessary for smooth running
• Poorly cut teeth may result in excessive vibration and noise during operation
• Quality matters and adds to cost
Cost of Spur Gearboxes
The price of spur gearboxes varies and is typically affected by size, accuracy specifications, backlash, and the gear ratio, as well as the specific manufacturer. Spur Gearboxes with a backlash in the range of 30 arc-minutes may cost as low as $500. The cost for spur gearboxes with a backlash value under 5 arc-minutes will cost more than spur gearboxes with high backlash values. Below is a list of gearbox products offered by Anaheim Automation. Comprehensive specifications and pricing is available on our website at AnaheimAutomation.com, for each of the offered types:
• Economy Gearboxes
• High-Grade Gearboxes
• Right-Angle Planetary Gearboxes
• Rotating Output Flange Gearboxes
Q. Are planetary and spur gearboxes bi-directional?
A. Yes, planetary and spur spur gearboxes are designed to be used for bi-directional operation. The direction the input shaft rotates and gear arrangement of the gearbox will determine the rotation of the output shaft.
Q. Can Anaheim Automation’s motors be combined with spur gearboxes?
A. Anaheim Automation’s motors can be assembled with spur gearboxes to meet the necessary requirements of an application. Motors and spur gearboxes can be purchased separately or be purchased as an assembled unit. Customization is available. Minimum purchase requirements and a Non-Cancellable/Non-Returnable agreement will apply.
Q. What is the lifetime of Anaheim Automation’s motors and spur gearboxes?
A. The lifetime of motors and spur gearboxes varies by user application. Certain factors determine the lifetime of a product, such as environment, radial loads (torque), duty cycle, and input power. All these factors play a role in the lifetime of motors and spur gearboxes. Anaheim Automation’s experienced Application Engineers are available to provide recommendations on the best products for your specific application criteria.
Q. What types of spur gearboxes would be used for right-angle applications?
A. A bevel and worm spur gearboxes are mainly utilized in right angle applications. They offer high efficiency and low gear ratios. A straight bevel gearbox with straight cut teeth are utilized in slow speed applications, whereas spiral bevel spur gearboxes with curved teeth are utilized in high performance, high speed applications. Worm spur gearboxes are also available with right angle configurations. They are able to sustain high shock loads, low in noise, maintenance-free but are less efficient than bevel spur gearboxes.
Q. Can spur gearboxes be backdriven?
A. Some spur gearboxes, such as spur gearboxes can be backdriven, while some, such as the worm gearboxes cannot be backdriven.
Q. How many planet gears are there in spur gearboxes?
A. The amount of planetary gears in spur gearboxes differs based on specific application requirements. Most spur gearboxes consist of two or more planetary gears.
Q. What is the difference between straight cut gears and helical gears?
A. Straight cut gears have straight and tapered teeth, and are used for low speed applications. Helical gears are cut at angles to allow gradual contact between the gear teeth. This allows for smooth and quiet operation. Helical gears are applicable in high horsepower and efficient applications.
How are Spur Gearboxes Controlled
The output of a motor (i.e. stepper, brushless, AC and brush motors) is used as the input of spur gearboxes and controls the speed at which spur gearboxes rotate. The configuration below illustrates the driver controlling the external motor, which is connected as the input shaft of spur gearboxes. As a result, when drivers are powered, motor shafts rotate inside spur gearboxes causing the output shaft of spur gearboxes to rotate. The output speed and torque is dependent on the internal configuration of the gearbox.
How do Spur Gearboxes Work
All spur gearboxes work in a similar fashion. The directions the gears rotate are dependent on the input direction and orientation of the gears. For example, if the initial gear is rotating in a clockwise direction, the gear it engages will rotate counterclockwise. This continues down the line for multiple gears. The combination of different size gears and the number of teeth on each gear plays a significant role in the output torque and speed of the shaft. High gear ratios allow for more output torque and lower speeds, while lower gear ratios allow for higher output speed and less output torque.
Planetary gearboxes work relatively the same. A planetary gearbox system is constructed with three main components: a central sun gear, a planet carrier (carrying one or more planet gears) and an annulus (an outer ring). The central sun gear is orbited by planet gears (of the same size) mounted to the planet carrier. The planet gears are meshed with the sun gear while the outer rings teeth mesh with the planet gears. There are several configurations for a gearbox system. Typical configurations consist of three components: the input, the output and one stationary component.
For example: one possible configuration is the sun gear as the input, the annulus as the output and the planet carrier remaining stationary. In this configuration, the input shaft rotates the sun gear, the planet gears rotate on their own axes, simultaneously applying a torque to the rotating planet carrier that in turn applies torque to the output shaft (which in this case is the annulus). The rate at which the gears rotate (gear ratio) is determined by the number of teeth in each gear. The torque (power output) is determined by both the number of teeth and by which component in the planetary system is stationary.
How to Select Appropriate Spur Gearboxes
When considering spur gearboxes, many factors need to be considered to meet specific application requirements:
Gear ratios are defined as the correlation between the numbers of teeth of two different gears. Commonly, the number of teeth a gear has is proportional to its circumference. This means that the gear with a larger circumference will have more gear teeth; therefore the relationship between the circumferences of the two gears can also give an accurate gear ratio. For example, if one gear has 36 teeth while another gear has 12 teeth, the gear ratio would be 3:1.
Output torque of spur gearboxes is dependent on the gear ratio used. To obtain a high output torque, a large gear ratio would be selected. Using a large gear ratio will lower the output shaft speed of the motor. Inversely, using a lower gear ratio, a smaller output torque value would be delivered into the system, with a greater motor speed at the output shaft of the spur gearboxes. This statement illustrates the relationship that both torque and speed are inversely proportional to one another.
Speed is proportional to the gear ratio of spur gearboxes. For example, if the input gear has more teeth than the output gear, the result will be an increase in speed at the output shaft. On the other hand, having the reverse scenario with more gear teeth at the output compared to the input will result in a decrease of speed at the output shaft. In general, the output speed can be determined by dividing the input speed by the gear ratio. The higher the ratio the lower the output speed will be and vice versa.
Gear arrangement is an ingenious engineering design that offers various benefits over the traditional fixed axis gear system design. The unique combination of both power transmission efficiency and compact size allows for a lower loss in efficiency of spur gearboxes. The more efficient the gear arrangement, (i.e. spur, helical, planetary and worm) the more energy it will allow to be transmitted and converted into torque, rather than energy lost in heat.
Another application factor to be taken into account when selecting spur gearboxes is load distribution. Since the load being transmitted is shared among multiple planets, the torque capacity is increased. The higher number of planets in a gear system will increase the load ability and enhance torque density. Gear arrangements improve stability and rotational stiffness because of a balanced system, but it is a complex and more costly design.
One example is a gear arrangement that is a traditional fixed axis gear system with a pinion driving a larger gear on an axis parallel to the shaft. Or, there may be a planetary gear design system with a sun gear (pinion) surrounded by more than one gear (planet gears) and is encompassed in an outer ring gear. The two systems are similar in ratio and volume, but the planetary gear design has three times the higher torque density and three times the stiffness due to the increased number of gear contacts.
Fixed Axis Gear System:
Volume = 1, Torque = 1, Stiffness = 1
Planetary Gear System:
Volume =1, Torque = 3, Stiffness = 3
Other gear arrangements as mentioned in the Types of Spur Gearboxes segment of this guide are bevel, helical, cycloid, spur and worm.
Backlash is the angle in which the output shaft of spur gearboxes can rotate without the input shaft moving, or the gap between the teeth of two adjacent gears. It is not necessary to consider backlash for applications which do not involve load reversals. However, in precision applications with load reversals like robotics, automation, CNC machines, etc., backlash is crucial for accuracy and positioning.
The physical components of spur gearboxes vary from one gearbox type to another, as well as differences between manufacturers. Most spur gearboxes are constructed from steel materials such as iron, aluminum and brass. Unlike other gearbox types, spur gearboxes can also be made with plastics such as polycarbonate or nylon. Other than the raw materials used, the orientation of the gear teeth play a major role in the overall efficiency, torque and speed of the system. Straight gear teeth spur gearboxes are typically used in low-speed applications. These spur gearboxes can be noisy, and may have lower overall efficiency. Helical gearboxes are typically used in high-speed applications. These spur gearboxes are quieter in operation than straight gear teeth spur gearboxes, which may improve their overall efficiency.
Types of Gearboxes
There are many types of gearboxes manufactured throughout the world. One of the main differences between individual gearboxes is their performance characteristics. Choosing from the various gearbox types is application dependent. Gearboxes are available in many sizes, ratios, efficiencies and backlash characteristics. All of these design factors will affect the performance and cost of these gearboxes. There are several types of gearboxes which are listed below:
Bevel gearboxes are mainly used in right angle, low gear ratio applications, due to their shafts perpendicular arrangement to one another. Bevel gearboxes make it possible to change operating angles. Two different types of bevel gearboxes includes straight and spiral. Straight bevel gearboxes are used for slow speed applications, and have straight and tapered teeth. The spiral bevel gearbox has curved and oblique teeth, and are used mainly for high-performance, high speed applications. Bevel gearboxes are typically constructed of cast iron, aluminum alloy or other steel materials.
Unlike spur gears, gears on helical gearboxes are cut at angles which allow for gradual contact between the gear teeth. This design provides for a smooth and quiet operation. Helical gearboxes are compact, efficient and available in a 5:1 ratio per stage. Helical gearboxes can be used on non-parallel and perpendicular shafts. These types of gearboxes are applicable in high horsepower and efficient applications. Helical gearboxes are typically constructed with cast iron, aluminum alloy or iron material.
Spur gearboxes are compact, cost-effective, efficient and readily available. Spur gearboxes are available in a 10:1 ratio per stage, made with straight teeth mounted on a parallel shaft. The noise level of spur gearboxes is relatively high due to colliding teeth of the gears. In comparison with a worm gearbox, they are more expensive, noisier and have less shock capability. Spur gearboxes are widely used in applications requiring an increase or reduction in speed and high output torque. Spur gearboxes are typically constructed with metals such as steel or brass, and plastics such as nylon or polycarbonate.
Worm gearboxes can handle high shock loads, and are low in noise and maintenance-free, but are less efficient than other gearbox types. They are also available in right angle configuration. The worm gearbox configuration allows the worm to turn the gear with ease; however, the gear cannot turn the worm. The prevention of the gear to move the worm can be utilized as a braking system. When the gearbox is turned off, it is held in a locked position. Worm gearboxes are typically constructed of aluminum, stainless steel and cast iron.
Planetary gearboxes are named so due to their resemblance of the solar system. Planetary gearboxes consist of three main components: sun gear, ring gear and two or more planet gears. The sun gear is the located in the center, the ring gear is the outermost gear, and the planet gears are the gears surrounding the sun gear inside the ring gear. Planetary gearboxes are used in applications requiring low backlash, compact size, high efficiency, resistance to shock, and high torque to weight ratio.
What are Spur Gearboxes
Spur Gearboxes are mechanical devices utilized to increase the output torque or change the speed (RPM) of a motor. Motor shafts are attached to one end of the spur gearboxes and through the internal configuration of gears of spur gearboxes, providing a given output torque and speed determined by the gear ratio.
Where are Spur Gearboxes Used
Advancements in technology and the evolution of gears have made more efficient and powerful spur gearboxes to be developed and manufactured at lower costs. Toothed gear systems have evolved from fixed axis gear systems to new and improved gears including helical, cycloid, spur, worm and planetary gear systems. Spur Gearboxes are widely used in applications that require desired output speed (RPM), control the direction of rotation, and to translate torque or power from one input shaft to another.
Spur Gearboxes are used in a variety of industries:
• Aerospace – In the aerospace industry, spur gearboxes are used in space and air travel, i.e. airplanes, missiles, space vehicles, space shuttles and engines.
• Agriculture – In the agriculture industry, spur gearboxes are used for plowing, irrigation, pest and insect control, tractors and pumps.
• Automotive – In the automotive industry, spur gearboxes are used in cars, helicopters, buses and motorcycles.
• Construction – In the construction industry, spur gearboxes are used in heavy machinery such as cranes, forklifts, bulldozers and tractors.
• Food Processing – In the food processing industry, spur gearboxes are used in conveyor systems, the processing of meat and vegetable products, and packaging applications.
• Marine Industry – In the marine industry, spur gearboxes are used on boats and yatchs.
• Medical – In the medical industry, spur gearboxes are used in surgical tables, patient beds, medical diagnostic machines, dental equipment and MRI and CAT scan machines.
• Power Plants – In power plants, spur gearboxes are implemented in transformers, generators and turbines.