Shear points

[Vfrpilotpb]

On several big military aero engines that I have in my little collection, many ancillary items such as Gen and Hyd PTO's are all covered by the inclusions of engineered shear break points near to points of known stress, so that in the event of a major catastrophe in the actual remote equipment the shaft would have a cleanish break and not detract from engine performance.

Do any of the helicopters flying now either civvie or military have such things engineered into any of the many PTOs that run such things as T/R's and or main rotor, or even turbines when in twin config?

PeterR-B
Vfr

[Lu Zuckerman]

To: Vfrpilotpb

When I last worked on the EH-101 the main rotor shaft had a shear point in the event of a transmission lock-up. Upon shearing the rotor drive shaft would be restrained by the upper shaft bearing and the “Jesus nut”. The shaft was configured to drive one of the hydraulic pumps providing control power during autorotation.

Of course there was an excellent possibility that the main rotor and the dampers would self-destruct during the shearing action.

Most transmission or engine driven accessories have shear points.


:E :E

[GLSNightPilot]

self-distrust ????
Why would they begin to distrust themselves? Why would they trust themselves in the first place? I'm confused, Lu. :p :8 :p

[sprocket]

All of the starter/gens that I have looked at, have a shear point on its shaft in case of 'self-distrust'.

[Lu Zuckerman]

To: GLSNightPilot


My spell check was on automatic and I didn't catch the errer.

:E :E

[RDRickster]

Don't you mean, "error?"

[Lu Zuckerman]

To: RDRickster

I turned off that automatic spell check and did not ketch my spelling error.

:E :E

[GLSNightPilot]

See what happens when you trust a spell checker? The wrong word spelled correctly won't be caught. I never use one; if I'm in doubt about a word, the dictionary keeps me straight. :ok:

[Vfrpilotpb]

Hey GLS,

You'll have to expand on that one, I normally use the compass!;)
PeterR-B
Vfr

[GLSNightPilot]

Compasses vary too much, especially around big chunks of iron like offshore platforms :rolleyes:

[IHL]

Vfrpilotpb:

What types of engines do you have in your collection? Do they Run ?

[Vfrpilotpb]

Ihl

Several would run, and I have been contemplating whether to make a frame that would hold them to ground run, but I need to load them with something to take the power surge on start up, a lot of my like wise crazy friends who share my interest are very fearful of me doing such a thing, examples

Griffon 58, Bristol Hercules14 Cyl, Issotta Fraschini W18, Defunct 9 cyl Germany torpedo engine, Merlin, and a few recoverd from deep holes that wont work, plus a share of an old T34 with the gun disabled, suppose I am really an old boring fart, eh!

[MightyGem]

Peter, I saw a static Merlin last year. Bolted to the front was a very short bladed "propeller" with a very wide chord and a coarse pitch to soak up the power.

[Vfrpilotpb]

Mighty ,

Yes I think they are refered to a a " Slave or Dumb" propellers, I was trying to use one of my old Shackleton Props but kept running into problems of mass balance, or lack of it, I then looked at making a hybrid using a huge water pump attached by a propshaft, but again ran into problems of connection, the frame for the engine is no problem, really its soaking up the power that is the serious thing, for it has to be foolproof and not able to let the engine run wild, it only needs to run wild for about 3 seconds at there would be shrapnel everywhere for hundreds of feet.

A friend of mine used to be the tractor pulling Champeen of the UK and Europe, he used two Griffon 58s siamesed into one humongoose gearbox reduced down to drive a tank transporter stepped drive diff, the gearbox was designed and specially built for him by David Brown Gears and had to cope with HP in the range up to 7000 horse power and torque beyond belief, the cost of that box was never released but he broke three and exploded 5 Griffons, along with many stripped diffs, but in the end they cracked it but never told anyone at what cost,

so I gave up!

PeterR-B