Best & Worst Locos to Drive

While on the subject of reversers I did hear that the Bulleid steam reverser was a bit temperamental and had the habit of flying into full gear for no reason. I attended a talk by Bert Hooker who said once a suitable position was found for the gear it was best left alone and then work on the regulator.

 

Which I understand is what was done with 34059 when trialled on the GE mainline. The only difference is that the driver had no choice in the matter as it got stuck in full forward, but it still timed the train. Not quite sure what happened to the fireman after stepping off the footplate...

 

The US steam reversers were a much more complex and bulkier type operating as a servo with feedback where small movements of the lever were replicated at the gear.

The British systems were much more basic relying on a locking cylinder to hold the gear in the the selected position. Certainly on the GWR system the locking wasn't totally effective allowing it to creep into full gear.

Churchward abandoned the steam reverser in favour of the simple lever, but later the screw type was reverted to for passenger classes. Apparently the Aberdares retained the steam reversers until the end.

 

To move a lever reverser on a piston valve locomotive is no problem at all, whatever the regulator opening, because the valves are balanced, steam - wise. When notching up, going fowards, you have to pull against the weight of the gear, helped by a large spring; when notching up in back gear, you have to hold back against that weight. Neither operation is very strenuous.

What Johnb describes, is the procedure when notching up on a slide valve engine, when you are fighting the steam in the chest pushing the valve on to its seat, very noticeable in such as a Pannier Tank, when you have 200psi acting on two very large "meat dishes." You have to shut off, move the lever quickly, then open up again.

When driving "Lyd," on the Ffestiniog, I was able to notch up without shutting the regulator sometimes, because "Lyd's" valves are considerably smaller than a Pannier's.

Notching up 2857 is very easy, even in full first valve. (You never need second valve; maybe with another 600 tons or so!)

 

I wonder whether this was a perception by the old GW driver. As you say, notching up with a piston valve loco should be no problem but I have known drivers habitually shut the regulator of a piston valve fitted lever reverse loco before altering the cut-off because that's what they understood was necessary with a lever reverse loco.

 

One thing not commented on about steam reversers is that, in addition to the labour saving, they also free up space in the cab. I reckon the reverser controls on the Wainwright engines probably occupy less than a square foot of space in the cab ...

For those interested, here are some photos of the reverser on the H class, which I'll try and explain the workings. Sorry for graininess, as they are all a bit mobile phone on dark days...

The first photo shows the cab controls. The wire brush gives scale - the controls are probably 8 - 10 inches high and a couple of inches wide. The large brass cylinder behind is the lubricator - not part of the reverser mechanism.

The first control is a direction setter on a quadrant. Pushing the lever forward operates a slide valve on the steam cylinder such that the next movement will be towards fore gear. Pulling it back moves the slide valve so that the movement will be towards back gear. However, the lever controls the position of the valve, but doesn't admit steam. That means the mechanism is very light - it can be moved with a finger. Just visible below the quadrant is a thin control rod that moves forward and backwards to transmit the motion to the slide valve on the actual reverser itself.

Behind, against the cab side, is an indicator to show the setting of the valve gear.

The thick control rod, disappearing out of the bottom of the picture, is the rotating control rod that opens the main steam and hydraulic valves. The lever to control this is not visible (sorry), but sticks out horizontally; pulling it up opens the hydraulic valve (releasing the reverser to move) and then the steam valve. Steam is thus admitted to the steam cylinder and, depending on the setting of the direction setter, the mechanism will move either to forward or back gear. Once the gear is set to the correct position, the control lever is pushed back down, rotating the thick control rod to close the steam valve (stopping the motion) and the hydraulic valve (locking the mechanism in position).



The next photo shows the two control rods running along the top of the tank; the thin one that slides back and forth and controls the position of the slide valve (and hence the direction of travel); and the large one that rotates to open the steam and hydraulic valves.



The next photo shows the reverser itself, bolted to the front of the tank. The steam cylinder, with its slide valve mounted on the side, is at the top and the hydraulic cylinder below. The thin control rod from the direction setter can be seen at the top; via series of cranks, it moves the slide valve on the steam cylinder. The thick control rod from the actuating lever opens the main steam valve (visible on the boiler), allowing steam to flow to the steam cylinder and thus drive the mechanism. A rod runs down from this thick control rod to simultaneously open the hydraulic valve (on the lower cylinder) that releases the mechanism to move. Just visible on the top of the steam cylinder is a small cup for lubricating the steam cylinder.



The next photo shows the hydraulic cylinder and hydraulic valve. Also just visible is a thin rod, which transmits the position of the valve gear back to the indicator in the cab. The large red pipe is the water balance pipe between the two tanks.



Finally, this is the view with the tank removed, from which it is obvious that, on the H class at least, the reverser and all its controls is attached to the tank, rather than directly to the frames. This gives a clearer view of the rotary hydraulic valve, though with the control rod disconnected. Below the hydraulic cylinder, the piston rod projects down and transmits the motion of the reverser to the valve gear itself.

Also obvious is how the linkage from the valve gear is transmitted, via a crank and long rod running along the back of the tank, back to the indicator in the cab.



No idea if that explanation is clear!

Tom

 

Read that very story in one of RN Hardy's books this week. Quite amazing that it still hit the timings! Interestingly (well, I think it's interesting) there was a delegation of railway dignitaries in the GN Directors Saloon at the back of the train, which is also at the Bluebell with 34059...


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If memory serves, they were unaware of the problem until the train reached Liverpool Street. I think it was 1950-51, so we are approaching 70 years since they were trialled on the route. Not only that, it is nearly 70 years since 34004 showed the Highland Mainline what it was missing...

 

RHN Hardy's version:

"We climbed the 1 in 84 to Trowse Upper as if it were 1 in 300 and were accelerating brilliantly when, somewhere near Swainsthorpe, the first station out of Norwich, there was a terrifying hissing roar from the locomotive, steam was shut off and we came to an abrupt halt near the signal box. Jumping up on the footplate, I learned the worst. A steam pipe supplying he reversing gear had fractured and here we were, 107 miles from Stratford with an engine that could neither reverse not be notched up, and here we were faced with 13 coaches, a journey to London in full forward gear, a formidable General Manager, and a farm more formidable Motive Power Superintendent!' LP Parker then told him 'Hardy, I am quite sure that Theobald will be able to keep to time with that extraordinary machine even if it will neither start nor reverse.'

But if they stopped, it makes an on-time arrival even more impressive!

Not sure if Hardy was a strictly reliable storyteller or whether he embellished things, but it's a great story either way...


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Hello,

I have assembled and repaired both the ‘Q’ type Maunsel reverser and the Stirling type.
The Maunsell type is obviously a more modern design in that setting one up is pretty much an assembly job. If the bits are made correctly you just put it all together, bolt it on the running plate and connect it up.
The Stirling type is more of a fitters job.
For a start the valve on the locking or cataract cylinder requires skillful machining. Then when it is assembled on the engine you have to adjust things so the steam valve opens a little earlier than the oil valve. (Sorry Tom!). This means that the gear will only move in the direction you ask it to. There are two pin joints and one square male and female shaft joints between the two valves. You sync the valves by altering the length of the rod between them.
Steam reversers mean you need an air line to the engine while valve setting, although you can operate the reverser from the running plate.
From a driving point of view (the original topic) steam reversers are great when shunting especially doing buckeyes. You can also do a quick backwards and forwards snatch if trying to move something with a P ( sod all tractive effort) or if you have centred on starting.
It’s very easy to be in the wrong gear though, most of us leave the little direction lever in the position it would be if it was a pole reverse.
They really don’t creep at all if looked after. I believe they were used to promote economical driving, this was Ashford remember.
I like them.

Russ.

 

I don't know. Seeing as Mr Hardy was an LNER man at heart, he probably had little reason to be so charitable at that stage in his career. It was to be a few more years before he was transferred to Stewarts Lane, possibly in part due to his experience with them on the GE.

 

For a Pannier Tank 2:30 onwards is interesting in this,
Mind you, this is only first valve, main valve would be a whole different story!
Watch the valve gear carefully as it comes up 1 notch at a time, then when dropped into full forward.

 

What are small tanks like in the winter? I'd imagine something like a jinty that's got a tiny cab that the wind would properly howl straight through.

 

Yes, I think you're probably right there, Steve. Old habits frequently die hard. On a Western engine, I always turn the blower off when I open the regulator, and turn it on, immediately before I shut off, because that's how I was taught. I don't do it on other engines.

 

Not sure how to interpret what you've said. Do you mean that you don't turn the blower on on other locos or that you leave it cracked all the time? The old timers would turn the blower off when the reg was opened and turn it back on just before closing the reg on any loco, not just GW. However, if you neglect to turn the blower on with non-GWR locos you've got the ejector exhaust creating a draught to it is not too
critical. On a GW loco with air pump, the ejector would normally be shut whilst the reg was open and it then becomes imperative to open the blower before shutting the reg.

I always leave the blower cracked on any loco as, having experienced a blowback whilst having a footplate trip on a Pannier tank many years ago, I don't want to experience another.

 

I always left the blower cracked in my days as a fireman specifically as an insurance against the driver suddenly closing the regulator, whatever engine I was on. I don't remember any driver asking me to close it. That was over forty years back though; attitudes might have changed since then.

I also recall that, following a blowback on the mainline, the instruction became that the blower should be left FULLY open, which seemed more than a little OTT. Or did I imagine this?

 

Ooops, forgot that one. Just reinforces the point that we have plenty of the right size locos!

 

You mean missing in the sense of blessed relief I presume?

 

Is there not a tendency for the valve gear to try to move itself to full gear if the regulator is open? Wasn't that what happened on Blue Peter?

 

Not really. The valve gear is heavy, and although there is some form of counter-balance, the bias is generally towards forward gear. Unless the reverser is locked by its catch, the normal vibration of running will cause it to wind itself towards full forward gear, whether or not the regulator is open.