Right Hand Side Leads - on a Garratt??

[miketaylor]

Hi there,

I am presently cut off from any of my own reference books and would like a little info re Garratt driving wheels.

Do both bogeys on a Garratt lead on the right? or is the second bogey a mirror of the lead bogey and therefore lead on the left?

I know it rather depends on how you define lead and the front of the loco but the question remains.

thanks for any help

Mike

[Deleted]

Now that's a good question...Don't the Welsh Fairlies have a similar set-up ??......"I don't know" is my first reaction BUT}----- let's imagine that you have a pair of identical 2-6-0 loco's coupled back-to-back ??...........That works OK..So, apart from the fact that the 2 Garrat "Engines" draw steam from the same boiler they are otherwise independent of each other, allbeit within the one Locomotive........Here's an LMS one >>>>>>>>>>>>>>>>>>>>

[donashton]

Doesn't matter a jot. Even the front RH hasn't a clue what the LH is doing.
Only problem was (I'm assured) the new Garratt on which the front engine was in fore gear at the same time as the rear.....
He-He, guess what!

Don.

[uuu]

OK - so I sit my loco on the track and stand behind it. Right crankpin to the front, left crank pin on top. Which side leads?

Now I walk round the front and face to the rear. The crank pin on my right is on top, and the crankpin on my left is towards me. Which side leads.

They're the same!

Wilf

[donashton]

Nice one Wilf. Do you have a coal wagon at one end?

Don.

[miketaylor]

Thank you gentlemen,

I take it that either no one knows or there is no definitive answer.

I am inclined to agree with Don - and with his exception.

However, I was clearly told by be Baggo some time ago to remember that right side leads. As I was only thinking in terms of the front bogey at the time I didn't give it a second thought.

This afternoon it struck me so to speak.

My guess would be that the they used used right side leads in respect to the cylinder end of the bogey. This could have the advantage of making everything just about identical - unless one were to optimise the whole thing for a specific direction of running.

The problem is that there is never a photograph showing both sides of both bogeys at the same time. Which I suppose means that no one will ever notice which way round you do things.

Apropos of which, some time ago I bought - from a rogue on Ebay - a set of six drivers. It was only later that I realised that this "set" was in fact 3 of one and three of a subtly different variety. Then I thought - what the hell - I can use three on one side and three on the other and no one will notice as long as I get the diameters and the throws the same.

thanks and regards

Mike

[donashton]

Taken in true spirit, Mike. I've always been given to understand that right hand crank leads 'in fore gear', but engines have been built LH leads - the engine doesn't know any difference!
A strictly technical appraisal arises whichever you choose to call the front end. If by convention the smoke box 'gets there first' a standard application of Walschaerts' gear would have a typical set of valve events. If the rear unit is an identical unit and therefore running in back gear there is the problem of matching the different set of events. They probably ignored this - wrongly in my opinion.
As you rightly say - optimisation is possible and good practice.
Cheers,
Don.

[Deleted]

Hi guys---------- wilf}--- of course they're the same as neither wheel has moved on the axle-----it's only your perception ( or viewing point ) that's altered, isn't it ??------- If it's called "R/H leading" from the one end, then it's going to be "L/H trailing" from the opposite end....Here's a loco. with both "engines" going forwards...Send the Apprentice to do a washout ?? >>>>>>>>>>>>>>>>>>>>

[Deleted]

I got a feeling Mr Stoudleys Terriers were LH lead...... Julian?
I know they were odd in that the cranks weren't opposite the coupling rod pins

Cheers
Ben

[jma1009]

hi ben,

there is a very good list in the following article

modelengineeringwebsite.com/Wheel_quartering.html

LBSCR right hand leading (except Boxhill in the NRM)

cheers,
julian

[GeorgeRay]

The article has the history of Boxhills left hand lead a bit wrong in detail though. the facts are it was Waddon that was fitted by Ashford with left hand lead crank axle. This was swapped with Boxhills post Nationalisation when Waddons wheels became onserviceable while working as the Lancing works shunter. So Waddon has Boxhills wheels and axles and Boxhill has Waddons wheels and an Ashford crank axle.

[Ben O]

Mike,

Don't forget to include the aesthetics of having the lifting links matching (if using outside gear such as Walschaerts) i.e. both 'down' for forward (chimney first) running:



Yes, there is a story that when NSWGR introduced the 60 Class (blog.project6029.com/) it was 6002 that did all the road trials as 6001's valve gear had been set to that each engine unit wanted to go it's forward (towards the cylinders)!

Ben.