Dear Mr. Lamar:

I have just learned of a new type of transmission: the "Abacus drive".
It is designed "to translate the low torque, high speed rotation of a
typical electric engine into a lower speed, higher torque rotation"
Sure, they say "electric motor", but I can think of another low torque,
high speed rotating motor.  Could this Abacus drive form a lighter, more
efficient PSRU, to give the Wankel rotary engine an even greater leg up
on the piston?

Here is the link:
http://www.roadandtrack.com/new-cars/car-technology/videos/a31260/abacus-transmission/?src=nl&mag=rdt&list=nl_rdt_news&date=102416 <http://www.roadandtrack.com/new-cars/car-technology/videos/a31260/abacus-transmission/?src=nl&mag=rdt&list=nl_rdt_news&date=102416>

This Brilliantly Weird Design Is the First New Rotary Transmission Since
the 1960s


Sincerely,

Les Nordman


Rube Goldberg would love it :-) I'll pass!

Planetaries can be as good as 98% efficient.

Paul Lamar

Cyclical drives exist commercially since a long time, some 3 to 4 decades or so. See SM Cyclo Drive by Sumitomo. We have used these in our industrial plants quite often. Very reliable and durable.

This one is a variation using a 'flexible' external gear working with a circular internal gear.
The flexible external gear likely cannot be steel? If not steel and flexible what material would it be that would last and have low friction?

It seems a 'good idea' but is it practical?
Remember, power is torque times rpm, if output rpm is low torque is high that must be supported by the flexible gear teeth.

Rolph pfeiffer


Group, I have run cyclo (Sumitomo) drives and various harmonic drives. Most of these are very limited as to maximum RPM. In fact I believe that the cyclo limits to 50-100 RPM overrun maximum! That is if you run too high an RPM they overheat and fail. Not a good feature in a aircraft gearbox. If your RPM runs high in a shallow decent with your fixed pitch prop your gearbox explodes? Not a good thing. Don't know if it's true with this new reduction or not.

Bill Jepson


Planetary reduction based on auto transmission gears are inexpensive and reliable. The only caveat is not to run with no load as in descent. The gear clearance can start to chatter and bad things then happen. RPM is not much of a problem and torque or HP as long as factory design limits are not vastly exceeded is not a problem. One advantage in aircraft is you do not have the possibility of the load being released and applied quickly like a car or truck with ice or mud.

Dale Davies

The Ford planetaries have been used since 1973 in experimental rotary powered
air craft. The main dimensions have not charged that much however the number
of pinions has increased from three to six doubling  the torque capacity,
They are nearly totally trouble free.

Paul Lamar


Dear Paul
Do you have any knowledge of and rotary powered places in Greenville SC area ?

Roderick Scotto


Bruce Turrentine of Rotary Resources

I don't have a phone number.

Paul Lamar

The Rotary Engine free News Letter. Powered by Linux. If you want off
the list PLEASE let me know and I will remove  you.  ACRE NL web
site. http://www.rotaryeng.net You Tube http://tinyurl.com/beqqxas
Copyright 1998-2016 All world wide rights reserved.