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 on 25:1 ratio) and increased loading capacity (on the subject of 30%).
The disadvantage of a globoid gear is higher production cost and sensitivity of the enveloping pinion to the axial location.
Due to the geometrical character of the tooth geometry Globoid pinion may mesh not only with the mating enveloping equipment but also with a correctly designed cylindrical helical equipment. Using a helical gear with a Globoid pinion is definitely common in reduced cost in applications such as automotive electric powered equipment actuators. The significant cost advantage comes due to the likelihood to injection mold the helical plastic gear. The load capability of the simplified helical/Globoid transmitting is decreased to the particular level below the load capacity of the regular worm gear. Nevertheless the driving efficiency continues to be better evaluate to the regular worm gear.
There are simply a few suppliers of the Globoid gear. division of Textron, situated in Traverse Town, MI. The detailed details about procedures utilized at Cone Drive for manufacturing of its gear cannot 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.
globoid worm Ever-power has capability to design, prototype and offer Globoid gear products. The knowledge 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 numerous CNC machining shops for creating globoid gear at significantly reduced cost.
Ever-power Globoid 3-dimentional CAD model.
It needs to be noted that production of the Globoid gear is more complex compare to production of the Globoid pinion. The Globoid pinion can be produced in high quantities by turning, whirling or grinding. Through the machining procedure for the Globoid pinion the trimming tool has to be capable to tilt to be able to produce the enveloping shape.
The newer production methods are under advancement. The most promising production method of the Globoid pinion is continues grinding process, which incorporates a grinding wheel (gemstone or CBN plated) with specific Ever-power simulated geometry. The complication of the novel process is the difficulties with simulation of the geometry of the grinding device. The grinding tooth would need to generate a correct form of the Globoid pinion without tilting so the production price and the production cost would be considerably reduced. Ever-power has developed a computer based tool for creating of 3-dimensional CAD types of grinding equipment for high volume production of the Globoid products.
The most common use of the Globoid gear set was seen in 1961-1989 on automotive steering systems in Italy and in Soviet Union.
VAZ-2101 with Globoid steering technology.
The Globoid pinions have been produced by grinding with a tilting grinding wheel. The Globoid gears have already 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 began to use classic Bishop or advanced Ever-power variable ratio rack and pinion technology, the demand for the Globoid gears offers been reduced.
Variable ratio technology comparison
Bishop
Ever-power
Vr-rack technology was introduced:
Before 2000
2000
Underlying mathematical model is based on:
Classic
gear
theory
Direct
Digital
Simulation
Rack geometry calculation accuracy is:
Limited by the boundaries of the traditional gear theory
Unlimited
Capacity to produce the vr-rack with not involute type for reduced noise
NO
YES
Capacity to generate vr-rack with increased ratio gain is:
Limited
YES
Cost of vr-rack design is:
High
Low
Ever-power advanced Variable 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 another era of Globoid gears. In 1999 Ever-power released a skew axis Globoid gear as a higher load capability and increased driving efficiency alternative to the classic Globoid equipment.
Ever-power skew axis (wormoid) gear.
It needs to be noted that the name WORMOID does not relate with any scientific term and it is a product of Dr. Stepan V. Lunin, who was simply the 1st in proposing this style and, more importantly, he was the 1st who produces a precise operating model of the apparatus in 3-dimantional CAD system. The accurate 3-d CAD of the WORMOID equipment has proved the ability of the idea such as conjugated transmission actions and significant increase of number of teeth in the contact compare to the classic Globoid gear.
CAD 3-d style of Ever-power wormoid gear.
Ever-power happens to be offering assistance for design and development of products based on Ever-power wormoid technology.
It needs to be noted that wormoid equipment design from Ever-power is obviously promising unique advantages review to the classic Globoid (double enveloping) gear. One of the obvious advantages is increased load capacity because of increased number of the teeth in the mesh. The gear torque is normally carried by more teeth therefore the load on every individual tooth is decreased. The other obvious advantage is boost driving efficiency. As you can see, the part of the pinion with bigger diameter is driving the corresponding part of the gear, which has a larger diameter aswell. Such of exclusive feature of Ever-power wormoid is usually missing in the traditional Globoid gear and outcomes in higher sliding velocities and 
higher friction drug on the traditional globoid gear. A skilled in the art engineer would immediately derive possible design benefits of the wormoid gear. For instance, using of the wormoid equipment can significantly reduce cost of electric powered assist mechanisms that are commonly used on modern automobiles. Because of the higher driving efficiency, wormoid gear set can be made with increase ration and provide the same driving performance as the original worm or dual enveloping worm gear. For instance NSK worm gear steering actuator with a ration of about 20:1 delivers about 80% of traveling efficiency. The plastic gear would hold about 80 Hm of torque. An alternative solution wormoid gear style from Ever-power would be capable to increase the ratio up to 30:1 and the torque on the gear up to 150 Hm without boost of the guts distance between the equipment and the pinion.