Crankshaft main bearings

[Scammell4199]

Has anyone ever come across an engine whereby more than one main bearing carries the longitudinal thrust?

I'm having the white metal bearings from our Scammells Gardner engine refurbished and the chap doing it says he's never seen such an arrangement.

No. 7 bearing just in front of the flywheel is the main thrust bearing, but no. 6 also has white metal thrust faces on it, while the others only have white metal on their bores. To my way of thinking you can only have one bearing locating the crank longitudinally, otherwise as the crank expands when the engine gets hot it will bind on the next closest thrust face.

 

Any experiences appreciated, Richard

[Richard Farrant]

To my way of thinking you can only have one bearing locating the crank longitudinally, otherwise as the crank expands when the engine gets hot it will bind on the next closest thrust face.

 

Hi Richard,

Not having done any work to a Garner internally, I cannot comment on whether it is normal to have thrusts on two different mains, but providing when you hold the crank in one direction, ie. push it forward, you have equal clearance on the front of each thrust position, then there should not be a problem.

[Scammell4199]

Thank you Richard, a helpful reply as ever.

The problem is, the width of bearings 1 to 5 is not adjustable only having white metal on their bores, the phosphor bronze backing is the width of the bearing.

I have told "my man" to maintain the bearing width on no.6 as it is now and will check that It and all the others don't interfere with the end float, that is only no.7 controls the end float - correct?

 

Richard

[Richard Farrant]

Thank you Richard, a helpful reply as ever.

The problem is, the width of bearings 1 to 5 is not adjustable only having white metal on their bores, the phosphor bronze backing is the width of the bearing.

I have told "my man" to maintain the bearing width on no.6 as it is now and will check that It and all the others don't interfere with the end float, that is only no.7 controls the end float - correct?

 

Richard

 

Richard

I may have misunderstood your first post, thinking there were thrust on two separate journals. Thrusts can be on any journal, I know of 6 cylinders with it one No.1, others on No.3 or no.5. Just make sure the clearance is maintained to the makers spec.

[Scammell4199]

Richard, sorry to trouble you but could I give you a call sometime to pick our brains please?

 

Many thanks, Richard

[Richard Farrant]

Richard, sorry to trouble you but could I give you a call sometime to pick our brains please?

 

Many thanks, Richard

 

Richard, PM sent to you re. this

[Scammell4199]

Many thanks, will call tomorrow either lunch time or early eve.

 

Thanks, Richard

[Richard Farrant]

Many thanks, will call tomorrow either lunch time or early eve.

 

Thanks, Richard

 

OK Richard, no problem