Garratts - Why Not Cab Forward

I think that the a major part of the diesel problem was down to the size of the wheels. Because of their small size they would heat up quicker as they couldn't dissipate the heat.

 

Z

You may note that the garratts on the WHR face Porthmadog so that this applies on the climb from Beddgelert heading north. On the climb you can have no fear if you are beating the boiler as long as you can go over the summit with "just enough" as doing so will add half a glass to your water.

Facing the other way means that you lose that half glass at the end of 6 miles of 1 in 40 climb. A much more difficult scenario to manage.

 

I thought it was the fact that diesel locos are lighter in weight than steam and therefore had less brake force

 

Part of the problem but comparing (say) a Q6 at 109 tons with a class 37 at 100-105 tons available for braking doesn’t show much difference.

 

How do you handle a Double Fairlie over that summit?

 

The LMS Garrett's have always been described as having rotating bunkers but have wondered if oscillating bunkers was more accurate. Did the drum follow a complete rotation or stop before the doors reached the bottom of the circle? If not it had to be incumbent on the fireman to ensure the doors were securely closed and bolted. ( hell of a lot of weight on the doors - perhaps that is why the drums sometimes jammed )
Have read thro. the Essery book on the Garrett's but I can't remember what was recorded!

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I'm just wondering if being difficult to handle could be a re

I've just been reading this webpage.

LNER Encyclopedia: The U1 Garratt ('The Wath Banker')

The tale of the guard on the Lickey sadly being killed seems rather more than just a co-incidence with the post above.

 

I wonder if several wagon brakes should have been pinned down ,but were either not done properly or missed altogether. The Loddington to Kettering mineral line ,which was mostly worked by class 2 s, was down hill for the first couple of miles at 1 in 40 ,there was a sign saying, just outside Loddington,all train to stop and brakes to be pinned down. Quite often the driver would stop, but it was to much trouble for the guard to get off and peg brakes down.
I remember a mate of mine ,a fireman, saying he had a right barney with a guard about the mater. He said if there was a derailment at the bottom of the bank, where Cransley Furnaces were situated ,there would be no chance of them stopping, and a pile up would result.

 

Rotating,passed cleaner 16/17 year olds when told they were booked for a Garratt, one of the first things they said was I hope the bunker doesn't stick half way round. It was nothing unusual ,but cured in a short time.

 

Stop and Pin Down was common on severe gradients, but these tend to be short with the levers lifted at the bottom. In the Peaks to Manchester line, it was sixteen miles from Peak Forest to Cheadle Heath, with about 1 in 90 as the maximum gradient (a short section at 1 in 87), not one you'd normally pin down for, and I wouldn't like to run wagons with pinned brakes over that distance anyway. But they still had to have their speed controlled, which the 3F - 4F combination could do without pinning down, the Garratts couldn't.

 

One of the interesting features of a double Fairlie is that due to the symmetrical boiler there is no change in water level over the firebox when going over a summit!
Discussing things with one of the Welsh Highland drivers he commented that Garratts with a short fat boiler are at an advantage compared with many other locomotives.

 

The Australian cameraman Phil Belbin was also an accomplished artist and designer.
Talented man.

https://en.m.wikipedia.org/wiki/Phil_Belbin

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Can you further explain? Any drawings explaining how this is achieved?

 

A Fairlie is actually easier to handle in this regard. To start with the fireboxes are in the middle of the boiler rather than at one extreme and the water level is therefore less affected by the change in gradient. Also you effectively swap which firebox is higher and you have to maintain the water level there anyway. So instead of having one water gauge reading a bit lower than the other, the situation is simply reversed.

 

I wondered about it. I think my understanding is that if you have a gauge glass mounted on the centreline of a loco, then when you tip over a gradient, the loco pivots about that centreline so there is no change in level. By contrast, on a conventional loco, the gauge glass is at one end so gradient changes exacerbate the water level you perceive.

There will be a small height difference in water from the front to the back of the firebox, but assuming it is fairly short, that will be somewhat negligible.

As an example, imagine a conventional loco with a boiler that is 150 inches long and the water is mid glass on the level. We’ll assume for simplicity the boiler is a simple cylinder.

If you put the loco on a, say, 1:60 gradient, firebox end down, then the water at the front drops by 1.25” and that and the back rises by 1.25” (so there is an apparent 2.5” difference in level between ends, but you can only see the height at the firebox).

If you now head down a 1:60 gradient the situation reverses. So the apparent instantaneous change measured in the glass is that the water level drops by 2.5”, from 1.25” above half glass to 1.25” below.

Technically, on a Fairlie you get the same difference at either end of the boiler, but your glass is on the centre line so you don’t see it. Obviously the water over the “leading” crown at its front is lower than at the same position over the “trailing” crown; however, because the firebox is short, the amounts are less. For example, if the whole firebox was say 60” long (30” either side of the centreline) the same 1 in 60 gradient would mean the water level was 1/2” lower than indicated over the “front” crown and 1/2” higher over the “rear” crown; and that would switch if you went from 1:60 up to 1:60 down.

That is the static situation, ie what you would observe if you stopped the loco at various points on a gradient. As has been frequently discussed here before, movement adds an additional change, typically causing the water level to rise for a chimney first loco working uphill (due to the need to maintain a pressure head to give the necessary force to lift the water up the hill); and to fall for a chimney first loco braking to maintain speed on a descent.

Going off topic from Fairlies and Garratts, the worst situation we have is an almost instantaneous change from 1:55 up to 1:60 down. On an SECR loco, where the rise in water under motion also seems very pronounced, a general rule of thumb is that if you can see the water at the top of the glass going up, it is already probably too low for the subsequent descent. Drivers can help a lot by rolling off the speed just before the top so you go over at below line speed and therefore don’t need to brake on the descent. Doing the same thing bunker first is by contrast much easier as all three factors work to your advantage.

Tom

 

Your main concern on a double engine is having too much water rather than too little. It's very easy to prime the down hill end regulator if you don't manage the water well. Typically going up the 1 in 80 on the FR, 1/3rd of a glass is what you want. It was even more tricky in oil fired days. If you got water into the manifold it put the fire out.

The steeper gradient on the WHR means the other thing to worry about is exposing the tube ends at the uphill end.

Tim

 

I should also point out that the gauge glasses aren't in the middle of boiler. The drivers side one is a at one end of the fireboxes and the firemans side one is at the other. So you always see a a difference unless you're on the flat.

Tim

 

Presumably you can’t see both at the same time ...

On the Festiniog, who has the one at the “uphill” side (which presumably reads slightly lower) - driver or fireman?

Tom

 

Yes you have to ask the fireman how much he has. You can't see both at once unless you're very tall. On the FR the driver has the uphill one. There's usually about an inch and half difference when you're on the 1 in 80.

Tim

 

Surely part of the problem was the demand to speed up freight services and adding the diesel brake tender provided the additional brake force to provide the necessary braking power. I can recall Class 44s in the 1960s rattling through Corby at 60 mph with up to 50 unfitted wagons but a diesel brake tender in the consist; a regular sight when "Control" trains were operated to / from Toton.