Page 287 - Gear Technology Solutions

19.9 Summary

Speed increasing bevel bear transmissions are used in many applications suc-
cessfully. In order to create a new speed increaser, the following guidelines
and rules of thumb should be considered:

· Meshing on the drive side is important

· Spiral angle not larger than 27° (single directional on drive side)
· Spiral angle not larger than 20° (bi-directional)

· Avoid profile shift as it improves the sliding condition on one member

and worsens the sliding condition on the second member

· Torque increase during start-up (acceleration because output faster than
input) can be considered with LEF factor in Table 2

· Motion error increase by speed increasing arrangement is not seen in
TCA and leads to flank separation in the case of high output inertia

· Low output inertia and ratios below 1x3, reduce profile crowning and ap-
ply factor DLF

· High output inertia and ratios above 1x3 require nearly conjugate Ease-
Off and blended Toprem plus heel relief

· Avoid worm shaped pinions with less than 5 teeth
· If high reduction gearsets with worm shaped pinions are used, apply the

recommendations mentioned with hypoids and use the largest number
of pinion teeth possible in the respective design
· Ground bevel gears should be used as speed increasers

· Surface hardness of pinion 62 HRC and gear 59 HRC (or similar)

· Superfinished flank surfaces are mostly an advantage
· Phosphate coated surfaces are always an advantage, especially for hy-

poids

· Use oil filling or forced lubrication as recommended above

· Fully synthetic high-pressure oil reduces the risk of scuffing

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