ypical Globoid gear.
Globoid (or Double Enveloping Worm or Hour Glass) gear has advantage versus a traditional worm gear because of increased driving efficiency ( 6-10% higher in 25:1 ratio) and increased loading capacity (on the subject of 30%).
The disadvantage of a globoid gear is higher manufacturing cost and sensitivity of the enveloping pinion to the axial location.
Because of the geometrical character of the tooth geometry Globoid pinion can mesh not merely with the mating enveloping gear but also with a properly designed cylindrical helical gear. Using a helical equipment with a Globoid pinion is common in reduced cost in applications such as automotive electric powered equipment actuators. The significant cost advantage comes because of the probability to injection mold the helical plastic material gear. The load capability of the simplified helical/Globoid transmitting is decreased to the level below the load capacity of the standard worm gear. Nevertheless the driving efficiency continues to be better compare to the regular worm gear.
There are simply a few suppliers of the Globoid gear. division of Textron, positioned in Traverse City, MI. The detailed details about procedures used at Cone Drive for making of its gear could not be found. However, based on publicly released info it can be understood that the gear is manufactured by CNC milling with use a small ball shaped cutter.
Ever-power has capacity to design, prototype and supply Globoid gear products. The experience of Ever-power is 3-dimentional simulation and modeling of the Globoid and double enveloping tooth geometry. Ever-power 3-dimentional Globoid and double enveloping gear CAD models can be used in various CNC machining shops for generating globoid gear at considerably reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It needs to be noted that production of the Globoid gear is more technical compare to production of the Globoid pinion. The Globoid pinion can be produced in high amounts by turning, whirling or grinding. Through the machining process of the Globoid pinion the trimming tool has to be capable to tilt to be able to produce the enveloping form.
The newer production methods are under development. The most promising creation method of the Globoid pinion can be continues grinding process, which incorporates a grinding steering wheel (diamond or CBN plated) with specific Ever-power simulated geometry. The complication of the novel process is the problems with simulation of the geometry of the grinding device. The grinding tooth would have to generate 
a correct kind of the Globoid pinion without tilting therefore the production rate and the production price would be significantly reduced. Ever-power is rolling out a computer based device for making of 3-dimensional CAD types of grinding tools for high volume creation of the Globoid products.
The most common usage of the Globoid gear set was noticed in 1961-1989 on automotive steering systems in Italy and in Soviet Union.
VAZ-2101 with Globoid steering technology.
The Globoid pinions have already been made by grinding with a tilting grinding wheel. The Globoid gears have been cut by a special hub, which replicated the shape of the Globoid Pinion. Special machines for making the slicing hubs have already been developed. As the modern motor vehicle steering systems started to use classic Bishop or advanced Ever-power variable ratio rack and pinion technology, the demand for the Globoid gears has been reduced.
Variable ratio technology comparison
Bishop
Ever-power
Vr-rack technology was introduced:
Before 2000
2000
Underlying mathematical model is founded on:
Classic
gear
theory
Direct
Digital
Simulation
Rack geometry calculation accuracy is:
Tied to the boundaries of the traditional gear theory
Unlimited
Capacity to produce the vr-rack with not involute type for reduced noise
NO
YES
Capability to generate vr-rack with an increase of ratio gain is:
Limited
YES
Cost of vr-rack design is:
High
Low
Ever-power advanced Adjustable Ratio rack and pinion high ratio gain technology for electric motor sport racing applications.
Ever-power low sound Variable Ratio rack and pinion not involute technology.
Ever-power pioneered in developing of the next era of Globoid gears. In 1999 Ever-power released a skew axis Globoid gear as a higher load capacity and increased driving performance option to the classic Globoid equipment.
Ever-power skew axis (wormoid) gear.
It has to be noted that the name WORMOID will not relate to any scientific term and it is something of Dr. Stepan V. Lunin, who was the initial in proposing this design and, moreover, he was the first who produces a precise functioning model of the apparatus in 3-dimantional CAD system. The accurate 3-d CAD of the WORMOID equipment has proved the ability of the concept such as for example conjugated transmission action and significant increase of number of teeth in the get in touch with compare to the traditional Globoid gear.
CAD 3-d style of Ever-power wormoid gear.
Ever-power is currently offering assistance for design and development of products predicated on Ever-power wormoid technology.
It needs to be noted that wormoid gear design from Ever-power is actually promising unique advantages compare to the basic Globoid (double enveloping) gear. One of the obvious advantages is elevated load capacity due to increased number of the teeth in the mesh. The gear torque is carried by even more teeth therefore the load on every individual tooth is reduced. The other apparent advantage is boost driving efficiency. As you can see, the portion of the pinion with larger diameter is generating the corresponding portion of the gear, that includes a larger diameter aswell. Such of unique feature of Ever-power wormoid is normally globoid worm missing in the traditional Globoid gear and results in higher sliding velocities and higher friction medication on the traditional globoid gear. An experienced in the art engineer would instantly derive possible design advantages of the wormoid equipment. For instance, using of the wormoid gear can significantly reduce price of electric powered help mechanisms that are commonly applied to modern automobiles. Because of the bigger driving efficiency, wormoid equipment set can be designed with increase ration and offer the same driving efficiency as the initial worm or double enveloping worm gear. For instance NSK worm gear steering actuator with a ration around 20:1 delivers about 80% of traveling efficiency. The plastic equipment would hold about 80 Hm of torque. An alternative solution wormoid gear design from Ever-power will be capable to boost the ratio up to 30:1 and the torque on the apparatus up to 150 Hm without enhance of the guts distance between the gear and the pinion.