Relations between size and gear ratio in spur and planetary gear trains

• In this report equations for the minimum gear sizes necessary to drive a given load are derived. The equations are based on the Swedish standards for spur gear dimensioning:SS 1863 and SS1871. Minimum size equations for both spur gear pairs and three-wheel planetary gears are presented. Furthermore, expressions for the gear weight and inertiaas function of gear ratio, load torque and gear shape are derived.For a given load torque and gear material, it is possible to retrieve the necessary gearsize, weight and inertia as function of gear ratio. This is useful for gear optimization,but also for optimization of a complete drive system, where the gear size, inertia and weight may affect the requirements on the other parts of the drive system.The results indicate that the Hertzian flank pressure limits the gear size in most cases.The teeth root bending stress is only limiting for very hard steels. Furthermore, then ecessary sizes, weights and inertias are shown to be smaller for planetary gears than for the equivalent pinion and gear configuration. Both these results are consistent with state of practice; planetary gears are commonly known to be compact and to have low inertia.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Tillförlitlighets- och kvalitetsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Reliability and Maintenance (hsv//eng)

Nyckelord

Construction engineering

Konstruktionsteknik

Publikations- och innehållstyp

vet (ämneskategori)

rap (ämneskategori)