> The reason for suggesting Enstrom has more to do with its unique sytem.
> I think it uses a single belt whereas the Robinson use two sets of
> something.  I have known an Enstrom mechanic for some time and he claims
> the Enstrom belt system is very reliable and durable.  This does not
> mean he does not think well of the Robinson system.  Another is the
> Hughes/Schweiser belt system.
>
> Paul, do you know What the Robinson system consists of?   Many years ago
> the protoype use multiple V belts but I have not seen the production
> unit details.
>
> Bob Y
>
>
> Just from a distance. Multi V belts and a pilot
> controlled idler that serves as a clutch.
>
> Paul Lamar



Paul,

The Robinson uses 2 double vee belts tensioned by an electric jacking

screw

controlled by a compression spring working a limit switch. During flight

the

re-tension light comes on very occasionally, particularly when using high
power. There is no extra idler. The bottom sheave is on the engine. The

top

sheave is on the tail-rotor drive shaft which is also the input shaft to

the

gearbox. The Shaft centre distance is changed  to tension the belt. Very
simple system.

Colin Smith

That is interesting. Changes the center to center distance.
Does the gear box move up and down or the engine?

If none of the above sounds like a minimum of four ujoints
are required.  You have a picture of this thing?

Paul Lamar ...No rotor no motor.

Both engine and gearbox are rubber mounted, but essentially fixed in
position. There are 2 flexible couplings, using ss flex plates between yokes
at 90 deg. one joint being mounted on the gearbox input shaft and the other
at the front end of the long tail-rotor shaft. Between the joints is a short
layshaft. The driven pulley is mounted on the layshaft towards the rear
end.. The jacking is between a bearing on the engine shaft at the rear of
the drive pulley and a bearing on the layshaft to the rear of the driven
pulley. During jacking the rear end of the layshaft is moved up and tends to
align with the long tail-rotor shaft. There is a further flex plate joint at
the tail-rotor gearbox. When the movement and angle change of the layshaft
exceed a specified figure, the belts are considered stretched, and must be
changed. Not an easy job. The whole drive system is rotated (over-run clutch
allows this) and the flex plates fingernail checked for cracks during
pre-flight.

Will see if I can find a photo.

Colin Smith


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