It always amazes that this handful of gears that I can

hold

at arms length are strong enough to transmit 200 HP
continuously. They only weigh about six pounds.

Old Lou Ross was a genius for coming up
with this PSRU concept.

Thank you Ford and Lou Ross.  May Lou rest in peace.

Paul Lamar

-George Lendich wrote:

Paul,
You know their is some criticism of the Ross PSRU but when

it

all

boils

down

he did a marvelous job on getting it al together i.e.

thinness

of

housing

and shaft for weight savings and although the bearings are

somewhat

minimalist in design, but they seem to work OK except for

the

rear

sun

gear

thrust bearing which was non existent - over all a bloody

good

job.

Interestingly I was speaking to a Diesel mechanic who has

his

own

large

business and he was telling me the M-Benz trucks have a

similar

planetary in

the axels and guess what - they had serious thrust problems,

it

would

seems

they omitted a thrust bearing.
Having very limited room guess what they used, flat brass

bearing -it

seems

it does the job !
George (down under)-

I agree George. Except for a few minor details like the

missing

sun

gear

thrust bearings the original Ross was brilliant. Too bad they

are

not

still

in business. It was a simple matter for Ross to add the trust

bearings

on

the latter versions as in this picture. This consisted of

several

low

cost

needle bearings back to back reducing the RPM of each, greatly

and

disproportionally increasing their life. This alone was a

brilliant

idea.

A simple needle thrust bearing will take a tremendous amount

of

load

as long as the RPM is kept low.

Paul Lamar

-William Stevenson wrote:

Hi Paul   Do you know where I could get the thrust bearing

installed

for

a

Ross 2.17:1 redrive. Thanks Bill-

Anybody want to tackle this job for Bill? It will probably require

some

grinding

on the stock Ford sun gear to gain clearance necessary for the
thrust bearing.

I am tempted do it but I am over committed right at the moment.

Paul Lamar

Not to disparage Ross's work, it was a nice piece, but I consider

the

lubrication scheme to the weakest link in the design.  Fixing the

missing

thrust bearing was easy by comparison.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

Well perhaps but there are plenty of them out there on 13B gyro
coptors running flat out at 7500 RPM with no mods to the lube system.

Ian, did you mod the lube system on your Ross 2.85?
Paul Lamar

Yes, It appeared to me that the planet gears had inadequate lubrication

and

my thrust bearing even less. I added a feed to the  gears via an

existing

hole in the top of the stationary ring gear. 160hrs and still going

strong.

Ian.

Paul, most of my true rotor head friends have changed over to 2.85 drives,
and except for one guy, (Steve McGowan in Georgia) all of them (that I know)
have an added oil tap to the sun gear area... the same is true for the subie
guys as well... we all saw one trash the teeth and lock up once... it was a
Chrysler gear set, but didn't have the oil galleys.......... the post mortem
indicated a blueing from the heat!!

Gary Buster
Bridgeport, Texas
N263GB

Is that mod a recent development Gary? I did not notice that last year 
at Bensen Days. I had heard about the Chrysler gear set failure but I thought
it was the one way clutch.

Paul Lamar

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