Engine Bearings.
Thread Starter
Joined: Jan 2001
Posts: 609
Likes: 1
From: Around the world.
Engine Bearings.
Hi,
I understand how for example an oil pressure bearing works on the turbo on my car, or how the shell bearings work on the crank; but both of these have no real thrust transmitted onto the bearings laterally…i.e. in my car engine or turbo, the shaft isn’t being ‘pulled.’ On both piston and turbine aircraft engines, how is the thrust produced by the prop or fans transmitted to the rest of the engine? I assume you effectively have to have 2 bearing surfaces…1 retaining the circumference of the shaft, and a second stopping the shaft moving by being effectively ‘pulled’ by the produced thrust. Sorry if this doesn’t make too much sense….
Cheers,
Tom.
I understand how for example an oil pressure bearing works on the turbo on my car, or how the shell bearings work on the crank; but both of these have no real thrust transmitted onto the bearings laterally…i.e. in my car engine or turbo, the shaft isn’t being ‘pulled.’ On both piston and turbine aircraft engines, how is the thrust produced by the prop or fans transmitted to the rest of the engine? I assume you effectively have to have 2 bearing surfaces…1 retaining the circumference of the shaft, and a second stopping the shaft moving by being effectively ‘pulled’ by the produced thrust. Sorry if this doesn’t make too much sense….
Cheers,
Tom.
Joined: Apr 2002
Posts: 75
Likes: 0
From: North Carolina, USA, Planet Earth
There are one or more 'thrust bearings' which can be ball/roller type or plain ('oil') bearings. They might be separate bearings or one bearing may have both functions. Many automotive engines have a thrust face on one of the crank bearings since there is some thrust load due to clutch actuation forces (if a manual transmission). Obviously the loads are much higher on an aircraft engine, however.
Do an internet search on 'thrust bearing' and you'll probably find a lot of info
Do an internet search on 'thrust bearing' and you'll probably find a lot of info
Joined: May 2002
Posts: 501
Likes: 0
From: Cheshire, UK
411A,
Not sure where you are coming from here. As an ex-engineer with a major airline I believe that RR engines are the best one can purchase for any a/c. Apologies for being a tad light, but their bird ingestion testing is the best for example. OK there may have been pylon issues wrt 767's but who else throws frozen chickens into engines as part of their testing ?
Just my two-pennyth worth
Not sure where you are coming from here. As an ex-engineer with a major airline I believe that RR engines are the best one can purchase for any a/c. Apologies for being a tad light, but their bird ingestion testing is the best for example. OK there may have been pylon issues wrt 767's but who else throws frozen chickens into engines as part of their testing ?
Just my two-pennyth worth
Joined: Feb 2002
Posts: 554
Likes: 0
From: The Sandpit
Surely, using the incorrect/superceeded/non approved bearings in an engine would mean that the engine no longer conformed to the manufacturers specs which would mean that the only way it could be legally flown would be with an NTO (no technical objection) from the manufacturer. Without this the said engine would be illegal, the certifying engineer shouldn't sign for it and even if he did, as it did not meet specs without authority, its' C of A would be invalid.
I have a feeling this is another aviation myth.
I have a feeling this is another aviation myth.
Joined: Mar 2000
Posts: 8,571
Likes: 3
From: Arizona USA
Unfortunately mono, not a myth, and a LOT of guys are out of work as a result.
When these RB.211 machines arrived on the property, I asked the DirMaintenance if he was going to send guys to RR for training. His only reply was..."we have no problem with DC-8s, why should we send guys to Derby?"
Big mistake, IMHO.
When these RB.211 machines arrived on the property, I asked the DirMaintenance if he was going to send guys to RR for training. His only reply was..."we have no problem with DC-8s, why should we send guys to Derby?"
Big mistake, IMHO.
Joined: Jun 2001
Posts: 452
Likes: 0
From: In da north country
As I was part of that little bearing debacle, I am, with alot of other folks, kinda pissed about losing our jobs because of this cheap judgement.
We had a good thing going, and life on the ole tristar was rather good!!!
Oh well! life goes on, Time to get over it
We had a good thing going, and life on the ole tristar was rather good!!!
Oh well! life goes on, Time to get over it
Avoid imitations
Joined: Nov 2000
Aviation Qualifications: ATPL
Posts: 15,114
Likes: 1,088
From: Wandering the FIR and cyberspace often at highly unsociable times
Taper Roller bearings can take axial as well as radial loads, they have the bearing surfaces at approximately 45 degrees to each other with rollers in between.
Ball or plain bearings can also be designed to work in the axial plane. Instead of the two bearing surfaces being inside one another like two sections of tube, they oppose one another like a record player turntable (or bicycle wheel) bearing.
If you can't remember record players (Gosh, I'm so old) try imagining two CDs placed on on top of another. The type of bearing to allow them to rotate against each other would be the same type as that required in an engine as a thrust bearing.
Over the years they have all been tried!
Ball or plain bearings can also be designed to work in the axial plane. Instead of the two bearing surfaces being inside one another like two sections of tube, they oppose one another like a record player turntable (or bicycle wheel) bearing.
If you can't remember record players (Gosh, I'm so old) try imagining two CDs placed on on top of another. The type of bearing to allow them to rotate against each other would be the same type as that required in an engine as a thrust bearing.
Over the years they have all been tried!
