Freewheeling unit

[nightsta1ker]

 

 

It's been a while since I logged all of my 10 hours in an R22, but don't they work by tightening that belt between the engine and transmission? That's a lot different than the H-60 freewheeling unit.

Do not mistake sprag clutch/freewheeling unit with the rotor engagement clutch. Two completely different components.

[helo.mech]

The only difference between a sprag clutch and a freewheeling unit is nomenclature and is essentially a one way roller bearing. Wikipedia has a pretty good explanation here. This is a good manufacturers video on the operation of a

. In this

at about 2:18 the guy demonstrates a sprag clutch on an air turbine starter.

[Rob1237051]

To say that a generator always supplies DC isn't quite on the mark. A generator creates electrical energy. It can be rectified into DC or inverted from DC back to AC. You'll find multiple instances on a variety of airframes where generators are providing an AC or DC output.

 

It all goes back to the composition of the generator. For instance, a brush and commutator setup with windings will provide an AC output. However, some tricky engineer may have added a rectifier to the end of it to confuse you.

 

-A&P Mechanic with experience on multiple rotary wing aircraft.

 

(Sorry, I know this is neither the topic nor am I replying to the most current post)

[Rob1237051]

Sorry, that was supposed to be "brush and stator with windings" not "brush and commutator with windings." The latter is in regards to DC where the former generates AC. Again...composition of the generator governs the output. Unfortunately, I'm not vetted for this forum so I can't edit yet.

[aeroscout]

I like where my thread has gone, and I don't mind at all that it is flirting with derailment with the generator/alternator discussion. All good discussion on both topics and replies. My little thread I gave birth to is really going somewhere ! Awww...

[Counterrotate]

Right up until 7 minutes ago...

[aeroscout]

Update. I am watching a series "Birth of a Chopper" I believe is the title, and on discovery channel. The project for the series is to assemble a Scorpion 162 executive. They detailed their free wheeling unit design, and it was a set of roller bearings inside of a somewhat octagonally shaped housing. Spring loading keeps the unit free wheeling, but the weak spring loading , when overcome by the least bit of friction on the rollers in one direction causes the roller bearing assembly to ratchet into a locked position inside the octagonal shaped housing. A very interesting design.

As I recall the design of the Huey sprag clutch, it consisted of cetrifugally positioned dogbone shaped sprags to extend out into the surrounding housing and locking it into drive mode. One caution I remember was that you had to leave the collective down until the N2 needles were married or you would damage the sprag clutch assembly.