Our Elliptical Gears
We manufacture elliptical gears for machines and systems in which the speed of the output shaft is to be specifically varied within a single revolution. While the drive runs at a constant speed, the output gear accelerates and decelerates according to a defined motion profile.
This mechanical solution is suitable for, among other things, packaging machines, textile machines, printing presses, automation systems, and specialized conveyor and metering systems. We manufacture elliptical gears according to drawings, technical specifications, or based on existing components—as single units or in small batches.
Elliptical gears for demanding motion profiles
With a conventional pair of round gears, the gear ratio remains constant. A variable motion must therefore often be generated by servo drives, electronic controls, cam discs, or additional mechanical components.
This can cause several difficulties:
Especially with existing machines, it is therefore not enough to simply manufacture a gear with similar external dimensions. The elliptical gear must be compatible with the specified center distance, the tooth profile, the mating gear, and the required motion profile.
Elliptical gears manufactured to drawings and technical specifications
As a result, the instantaneous gear ratio between the drive and output shafts also changes. If the drive gear rotates at a constant speed, the output gear alternates between moving faster and slower during each revolution. Depending on the design, the transmitted torque may also change.
We tailor our manufacturing process to the specific requirements of the machine. These include, in particular:
Geometry of the Elliptical Gear
Module and Gear Tooth Data
Number of teeth
Center distance of the gear pair
Advantages of Elliptical Gears with Variable Ratio
A motor running at a constant speed can generate a periodically varying output motion. No continuous adjustment of the motor speed is required for the specified cycle.
Mechanically defined motion sequence
The acceleration and deceleration phases repeat with each revolution. This is particularly advantageous when a machine performs the same operating cycle continuously.
High repeatability
Since the motion is determined by the gear geometry, the sequence remains reproducible from cycle to cycle when the system is properly assembled.
Reduced control system complexity
In suitable applications, elliptical gears can replace additional electronic control components or complex cam mechanisms.
Suitable for existing machine designs
A mechanical solution can also be a good choice for older systems if electronic drives are not planned or if an existing motion principle is to be retained.
Robust design for cyclic processes
A fixed gear pair is suitable for machines that repeat the same motion profile over long periods of time.
Elliptical gears and their variable gear ratio
In a circular gear, the distance between the axis of rotation and the effective point of engagement remains constant throughout one full revolution. The resulting gear ratio is constant.
In an elliptical gear, this effective pitch diameter changes during rotation. In one part of the revolution, a larger effective pitch diameter is engaged. In another part, the effective pitch diameter is smaller. As a result, the instantaneous ratio between the rotational motion of the driving gear and the driven gear changes.
The driven wheel therefore goes through recurring phases:
- It speeds things up
- It reaches a specified range of higher speeds
- It's slowing down again
- The process starts over with the next rotation
The two elliptical gears must be considered as a functional unit. Their geometries, the tooth profile, the center distance, and their orientation during assembly collectively determine how motion is transmitted.
The installation orientation also plays a more significant role than with many round gears. If the gears are mounted with a twist relative to each other, the timing of acceleration and deceleration shifts. Therefore, clear reference positions, proper installation, and careful adjustment are required.
Elliptical gears for precisely defined operating cycles
Elliptical gears offer clear advantages, but they also have design limitations. We address these points openly because they are crucial for selecting the right solution.
Their design and manufacture are more complex than those of ordinary round gears. The tooth profile does not follow a simple circular contour. In addition, both gears must be designed as an integrated system.
The motion sequence is fixed. Once the machine is manufactured, the speed profile cannot be arbitrarily changed via software. If a machine needs to switch frequently between different motion programs, an electronically controlled drive may be more suitable.
Assembly and adjustment require clear reference points. The relative position of the two gears determines at which point in the cycle acceleration or deceleration occurs.
When it comes to replacement parts, existing geometries must be taken into account precisely. A gear that is only roughly a good fit can result in irregular operation, incorrect motion times, or problems with tooth engagement.
Elliptical gears therefore work particularly well when the following conditions are met:
Under these conditions, a compact and straightforward solution for repetitive movements is created.
Elliptical gears from the manufacturer Dittler GmbH
We have been active in the fields of drive and machining technology since 1999. At our facility in Straubenhardt, we manufacture gears, gear teeth, and mechanical components for companies in the mechanical engineering sector and other industrial sectors.
A key focus of our work is on special-tooth gears, non-circular gears, and oval gears. Elliptical gears are therefore not just a casual addition to our product line, but rather one of the types of gears for which we have specifically developed manufacturing capabilities.
For machining elliptical gears, we use, among other machines, the PSA 300 Gleason Pfauter machine tool. In addition, we have the capability to perform gear cutting, CNC turning, CNC milling, and grinding. This allows us to carry out multiple machining steps within a coordinated production process, depending on the component.
We manufacture custom gears as single units and in small batches. This is particularly beneficial for machinery manufacturers, maintenance technicians, and operators of older equipment who do not require large production runs.
Our quality management system is certified according to DIN EN ISO 9001. Our in-house quality assurance program also includes standardized testing procedures and a climate-controlled measurement room equipped with 3D measurement technology.
Many of our customers do not need off-the-shelf products. They are looking for a component that fits a specific machine, an existing assembly, or a precisely defined motion sequence. Our manufacturing process is tailored precisely to these kinds of tasks.
Elliptical gears for recurring speed changes
This makes elliptical gears a suitable solution for precisely defined operating cycles in packaging machines, textile machines, printing presses, automation systems, and conveying and dosing systems.
Their strength lies in their mechanically defined, repeatable motion. At the same time, design, manufacturing, and assembly must be coordinated more precisely than with standard round gears. Since the motion profile is determined by the geometry, this solution is particularly well-suited for continuously recurring processes.
We manufacture elliptical gears according to drawings and technical specifications, and—depending on the specific situation—also for existing machines. We can produce single units, small batches, and customized replacement solutions, as well as gear sets for new systems.
Request and Have Elliptical Gears Manufactured
Send us your drawing, technical specifications, or a description of the installation situation using the contact form. It is helpful to include information on the module, number of teeth, center distance, material, bore, quantity, and the desired motion profile.
For replacement parts, please also provide information about the existing mating gear and the installation position, if possible. The more complete the initial data is, the more accurately we can assess feasibility and determine the appropriate manufacturing method.
Frequently Asked Questions About Elliptical Gears
What distinguishes elliptical gears from circular gears?
With circular gears, the gear ratio remains constant during rotation. Elliptical gears, on the other hand, have an effective pitch diameter that changes during a single revolution. As a result, the driven gear runs alternately faster and slower despite a constant drive speed. The resulting motion profile repeats with each revolution.
Are elliptical gears and out-of-round gears the same thing?
Elliptical gears belong to the group of non-circular gears. The term “non-circular gear” generally refers to gears whose effective contour is not circular. An elliptical gear has an elliptical basic shape. Therefore, not every non-circular gear is automatically an elliptical gear, since other non-circular geometries are also possible.
Can elliptical gears replace an electronic control system?
In suitable applications, they can produce variable motion without continuous electronic speed control. This applies especially to machines that perform the same cycle continuously. If the motion profile needs to be changed frequently, reprogrammed, or adapted to different products during operation, an electronic solution is generally more flexible.
Why are elliptical gears usually designed in pairs?
The desired gear ratio results from the interaction of both gear geometries. The gears must mesh correctly with each other throughout their entire rotation and maintain the specified center distance. For this reason, the geometry and tooth profile of a single gear cannot be considered independently of its mating gear. When replacing a part, it is necessary to determine whether a single gear can be manufactured to fit the existing mating gear or whether a new set would be more practical.
What specifications are required for the manufacture of elliptical gears?
Ideally, a complete technical drawing should be available. Important details include the gear profile, module, number of teeth, center distance, gear tooth data, bore, hub, material, quantity, and installation position. In addition, the desired speed or motion profile should be known. For replacement parts, an existing sample, specifications for the mating gear, and information about the machine are helpful.
How does the assembly affect the operation of an elliptical gear pair?
The angular position of the two gears relative to each other determines when the driven gear accelerates or decelerates during the cycle. Incorrect alignment can cause a time shift in the motion profile. Therefore, reference marks, installation positions, and adjustment values should be clearly documented. The specified center distance must also be maintained to ensure that the gear teeth mesh correctly.
For which machines are elliptical gears particularly suitable?
Typical applications include packaging machines, textile machines, printing presses, automation systems, conveyor systems, and dosing systems. The key factor is not so much the industry as the motion requirements: Within a repetitive work cycle, a component must be moved slowly at times, then faster, and then slowly again.
What are the disadvantages of elliptical gears?
Design and manufacturing are more challenging than with round gears. Assembly also requires precise alignment. Furthermore, the motion profile is mechanically fixed after manufacturing. It cannot be freely adjusted without changing the gear geometry. For applications with frequently changing processes, an electronically controlled drive may therefore be more suitable.
Can damaged elliptical gears be replaced individually?
That depends on the condition and documentation of the existing gear pair. If reliable drawings and geometric data are available, it may be possible to manufacture a single gear that matches the mating gear. If this data is missing or if the mating gear also shows signs of wear, it should be determined whether manufacturing a new, matched pair makes more technical sense.
What materials can be used to manufacture elliptical gears?
The appropriate material depends on the load, rotational speed, wear requirements, environment, and existing design. Depending on these requirements, various steels, stainless steels, non-ferrous metals, or engineering plastics may be suitable. The choice of material should not be made in isolation, but should be evaluated in conjunction with the gear geometry and the intended application.
Are elliptical gears also available for small-volume production?
Yes. Elliptical gears are often not required for large-scale standard production runs, but rather for custom machines, spare parts projects, or specialized assemblies. We therefore manufacture these gears as single units and in small batches. If there is a recurring need for spare parts, it may be advisable to plan for additional sets of gears that are designed to work together.
How is the speed profile of an elliptical gear determined?
The motion profile results from the geometry of both gears and the effective pitch diameter, which changes during rotation. For the design, it is necessary to know in which parts of the cycle the driven shaft is to accelerate, run at a higher speed, and decelerate again. The required change in gear ratio is derived from these motion requirements.