Basic Presentation On Gears
Here I will cover the basics of gears, the interaction between design variables, an introduction to basic gear design concepts, and gear failure and failure analysis.
Why hypoid ?
Nomenclature
Hypoid gear design considerations
Design for limited life; gear sizing; tooth contact development; gear optimization, Gleason dimension sheet
Q and Z factors
what do they mean ? How are they used ?
Gear manufacturing
5-cut Formate & 2-cut hobbing; 2-axis & 3-axis, a typical manufacturing scheme.
Types of gear failure
Gear testing
Why, what, how and how long to test? Accelerated testing, Weibull analysis
Questions and answer
Gear types
Parallel axis
- External spur gear
- External helical gear
- External Herringbone or double-helical gear
- Internal gear
Intersecting axis
- Straight bevel gear
- Zerol bevel gear
- Spiral bevel gear
- Face gear
- Beveloid gear
Non-intersecting Non-parallel axis
- Crossed-axis helical gear
- Worm gear
- Hypoid gear
- Planoid gear
- Spiroid gear
- Helicon gear.
Helical gears
Cross-axis helical gears
Worm gear
Double-enveloping worm gears
Straight Bevel Gear
Spiral Bevel Gear
Zerol Bevel Gear
Bevel gear set
- straight cut teeth
- pinion gear on center with ring gear
Spiral bevel gear set
- teeth cut on an angle
- pinion gear on center with ring gear
- quieter than bevel gear
- resists scoring
- allows for a large differential case
Hypoid gear set
- teeth cut on an angle
- pinion gear offset from ring gear center
- quieter than bevel gear
- sensitive to scoring
- differential case must be smaller
- requires special lubricant
Spiral Bevel VS Hypoid Gears
| Characteristics | Hypoid | Spiral Bevel |
| Quietness | Quieter | Quiet |
| Strength | As much as 30% higher | Lower |
| Pitting Resistance | 175 % higher | Lower |
| Scoring Resistance | Lower | 200% higher |
| Manufacturer | Larger pw cutters Easier to lap | Smaller pw |
| Ratio | Better for higher min-1.8 | Larger |
| Bearings | Greater thrust loads | lower |