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GE fans,
Larry Elie's mail of tractor
efficiency made me think this info on mechanical drive efficiency might be
appreciated. All from memory, so if there is something I have forgotten,
ask about it and I shall look it up.
First, the efficiencies I will list
are based on a 1 to 1 ratio. As the ratio gets larger, the efficiency
drops, although until you exceed somewhere between a 3 and 5 to 1 ratio, the
loss in efficiency is not much. Also some devices, such as worm gears,
which are bad enough in speed reduction mode, are sometimes so bad they won't
even operate in speed increasing mode. They lock up.
Remember that these are general
rules and each specific application will have an efficiency associated with a
clean and proper installation of new equipment. As the equipment wears,
efficiency can change, and while in some cases (timing belts) the loss will be
minor, in others (chains) the losses can be severe.
1. Chains properly tensioned and lubed:
99% (Think of how many inroads have been made into chain replacements on
bicycles.) (Also the famous Sturmey Archer 3 speed bicycle hub can have an
efficiency as low as 80% in some speeds, although that is in part due to the use
of plain bearings.)
1A. Dry and/or dirty and/or worn chains:
Less than 75%
2. A, B, C, D series V belts:
95%
3. L series belts: A little better
than A, B, C, D series, but not much.
4. V series V belts: 96-97% (The GE
large frame motor to transmission belt uses this series because it is the
best of the V belts in terms of efficiency.)
5. Timing belts: 98%
6. Poly V belts like the serpentine belts on
newer automobiles: 98%
7. Spur gears or helical gears:
97-98%
8. Bevel, spiral bevel, hypoid, and other gear
sets that turn 90 degrees: 90-96% (It is no accident that many of
the smaller front wheel drive economy cars use transverse engines.
Eliminating the right angle gear set at the differential needed for any
longitudinal engine installation and using a helical gear set instead helps get
the fuel mileage up.
Hope you all found this
interesting.
Steve Naugler
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