- Basic Knowledge FAQ
-
- What is a ratio?
- How is the size of a gear expressed?
- What types of gears does Nissei produce, and in what volume?
- How is the precision of gears evaluated?
- What methods are available for improving gear precision?
- What facilities and equipment does Nissei operate?
- What is MD (mounting distance)?
- What is the shaft angle?
- What is HRH?
- What is a Zerol bevel gear?
- Can straight bevel gears be ground?
- Can I purchase and replace just the gear side of a bevel gear?
- FAQ for designers
-
- Is a self-locking mechanism available on HRH gears?
- What order of assembly is recommended for spiral bevel gears and hypoid gears?
- What is a service factor of 1?
- Is the allowable transfer torque for bevel gears calculated on a bending or contact pressure basis?
- What formula is used to calculate bevel gear strength?
- Is it acceptable to use a backlash of 0?
- Is there a difference in efficiency between forward and reverse rotation?
- What formula is used to calculate gear strength?
- What lifetime is used for transfer capacity charts?
- Can bevel gear backlash be measured at the pinion?
Basic Knowledge FAQ
What is a ratio?
For gears, the ratio refers to the gear ratio (the ratio of the number of teeth on the pinion to the number of teeth on the ring gear ).
How is the size of a gear expressed?
The units used to express gear size are the module (metric) and DP (English).
What types of gears does Nissei produce, and in what volume?
Nissei produces at least 1.5 million cylindrical (spur and helical) and bevel gears each month.
How is the precision of gears evaluated?
For spur gears, precision is generally expressed by runout, profile tolerance, and lead tolerance. For bevel gears, precision is generally expressed by tooth contact pattern, and runout.
What methods are available for improving gear precision?
For cylindrical gears , gear grinding , shaving and direct cutting are applied. For bevel gears , gear grinding and CBN gear grinding are applied.
What facilities and equipment does Nissei operate?
Please see the "Introduction to Nissei's Facilities" page.
What is MD (mounting distance)?
Distance from pitch apex to axial stop when a gear set is mounted. (H dimension in the catalog)
What is the shaft angle?
For bevel gears, the shaft angle refers to the angle at which the center lines of the pinion and gear intersect.
What is HRH?
HRH stands for high ratio hypoid gears, that is, gears with a gear ratio greater than 1/10
What is a Zerol bevel gear?
A Zerol bevel gear is a bevel gear with a spiral angle of 0°.
Can straight bevel gears be ground?
No.
Zerol bevel gears, which offer equivalent performance to straight bevel gears, can be ground.
Can I purchase and replace just the gear side of a bevel gear?
It is possible to purchase and replace just the gear side of a bevel gear for some products but not for others.
Please contact Nissei for more information.
I'm looking for a bevel gear with the reverse of the spiral angle shown in your catalog/website.
Nissei can provide this gear as a custom-ordered product.
FAQ for designers
Is a self-locking mechanism available on HRH gears?
Yes (at 1/45 and higher). However, because the effectiveness of the mechanism is affected by factors such as machining precision and the lubricating oil used, the self-locking mechanism should be supplemented by an additional control device for applications that require full reversal prevention.
What order of assembly is recommended for spiral bevel gears and hypoid gears?
These gears should be assembled using the following procedure:, contact pattern adjustment, backlash adjustment, break-in operation, and normal operation.
What is a service factor of 1?
The service factor is used when calculating torque capacity.
Is the allowable transfer torque for bevel gears calculated on a bending or contact pressure basis?
Allowable torque values are calculated on both a bending and contact pressure basis, and the lower of the two values is used.
What formula is used to calculate bevel gear strength?
Strength is calculated using the Gleason formula. However, HRH gear strength is calculated using a proprietary formula based on the results of in-house strength testing.
Is it acceptable to use a backlash of 0?
As a rule, this value is not acceptable for metal gears running together due to factors such as individual gear precision, assembly precision, and thermal change.
Is there a difference in efficiency between forward and reverse rotation?
Although there are slight differences depending on the particular product in question, in general pinion efficiency drops approximately 2% to 3% during counterclockwise rotation.
What formula is used to calculate gear strength?
With the exception of HRH gears, bevel gear strength is calculated using Gleason”Ēs strength formula. HRH gear strength is calculated using a proprietary formula based on the results of in-house strength testing. Cylindrical gear strength is calculated using the JGMA strength formula. It should be noted the coefficients used in these calculations have been determined by Nissei.
What lifetime is used for transfer capacity charts?
| Spur gears | At least 107 repetitions |
|---|---|
| Bevel gears (straight, spiral) | At least 107 repetitions |
| Hypoid and HRH gears | At least 109 repetitions |
Can bevel gear backlash be measured at the pinion?
Although backlash can be measured at the pinion, note that the value obtained at the pinion will differ from the value measured at the gear.
