Garratts - Why Not Cab Forward

What's the difference to buffering up to a train needing banking ,and buffering up to a train in sidings waiting for dispatch.? Surly it was the guards job to watch out ,the same as in sidings.

 

Please click on,, Click to Expanded ,to see reply above.

 

It isn't the same thing: the guard - or shunter - would be on the ground in a siding but I don't think he would be when buffering up a banking engine. But Garratts had a few distinct problems: the two ends were a long way apart with a lot of (high volume) pipework between them. These had to be filled with steam (or possibly vacuum created; I'm not sure of the LNER Garratt's braking system), which took time. It would not therefore respond quickly when the driver realised his position, and it was easy to misjudge the braking distance required. The LMS Garratts had the same issues, and broken couplings and torn out headstocks were far from unknown. They of course were not used for banking nor worked passenger trains.

The Garratt first arrived at Bromsgrove with its chimney to the bank, but was soon turned specifically because of the problems in buffering up. It didn't solve the time lag but did make the distance easier to judge.

 

Fantastic photos! Thank you very much Dag Bonnedal!

Another nice looking french Beyer Garrat the "sister engine " CFA 231-132 AT . Must have been a lovely sight in the grey P.O. colour scheme and black outlinings when delivered. https://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/CFA_231+132_AT_1.jpg/800px-CFA_231+132_AT_1.jpg

Knut

 

I have always wondered if the Garratts were particularly difficult to handle for this very reason (lag time in response to controls)- also with the length of pipework would it have made them very liable to priming?

The other thing that struck me from a post elsewhere on the forum was the implication of having one regulator controlling both engines, meaning if one engine slips the other can be starved of steam to an extent?

Regards

Chris

 

I think Gresley's monster was periodically turned for equalising wheel wear. It did haul a passenger train once, so "new build anyone?"

 

So did an LMS version, 4999, as a test. It failed with a hot box at Leicester and had to come off, and it was never tried again.

 

More important to me would have been water level. When you are going up an incline which levels out at the top it is always a case of judging the water level so that the crown isn't uncovered when it hits the level. If you ascend the incline firebox first that problem immediately goes away because the water level over the firebox will increase. You wouldn't set off without sufficient water but when ascending the bank you know that, as long as the water is clinging to the gauge glass by capillary action, you still have sufficient to get you to the top.

 

Please click on "CLICK TO EXPANED" above my photo's to see my comments.Third time this is happened today,!!

 

Which is why most banking duties were done with the chimney at the uphill end and why the Garratt arrived at Bromsgrove that way around. There were exceptions: banking from Bolton towards Blackburn was usually done tender first. In this case it was often a Lanky A Class, which had a very low, open tender, and the rear of the train ahead afforded some protection from the weather on the climb, while the return journey had the spectacle plate in front. Which unfortunately has nothing to do with Garratts . . .

 

I think @Steve is actually suggesting the opposite. If you are working on a switchback line (steep uphill --> steep downhill; or steep uphill --> level), working backwards makes control of the water level easier, because at the point the gradient changes and you shut off, the change in levels works in your favour. If you go up chimney leading, the change in gradient works against you and you can suddenly find yourself with low water when you shut off (and made worse if you also brake at the top, as a banker might do).

Tom

 

Better explained than me, Tom.

 

I didn't know that. One thing I did read about the LMS ones is that one was used on a freight across the Peak district line towards Manchester through Dove Holes tunnel and the brake blocks melted on the steep downgrades towards Stockport

 

Probably not melted, but it did need reblocking at Manchester, and they didn't do it again!

There is a photo of 4999 on the train. It was taken by Frank Carrier, an LMS draughtsman, and is now copyright of Kidderminster Railway Museum.

 

Never really thought about it before, but I guess on an LMS Garratt, you've got less brake capacity than you would have on, say, two 4F 0-6-0s, due to not having the tenders? So you could pull what two 4Fs would manage uphill, but have less brake capacity down the other side ...

Tom

 

Presumably the same problem with diesels on unfitted freights, which gave rise to the diesel brake tenders

 

Indeed. Twelve wheels braked instead of twenty-four. Unfortunately, or possibly not, the driver's comments on reaching Manchester are not recorded.