Paddleducks
Paddler Information => Research => Topic started by: Roderick Smith on October 05, 2013, 08:03:19 AM
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I was asked this in a tram group with railway associations too.
When towing a steam loco, it has to be in light steam to maintain lubrication, or it has to have the driving rods removed.
What was done when towing a paddlesteamer?
Answer A, from a small-paddlesteamer engineer. Leave the engine in neutral, that stops the wheels from moving it. If worried about drag, remove some floats.
Answer B, from a large-paddlesteamer captain. I've never had to do it. I'd leave the drive train in position for a downriver tow (the drag won't matter); disconnecting the drive train isn't difficult for an upriver tow.
AFAIK there is no dog clutch in any drive train which I have seen: there must be unboltable joining flanges somewhere on the main shaft.
One of the hallmarks of the Australian river design was simplicity, for ease of construction and ease of maintenance.
With the modern paddlevessels, most drive trains come from tractors or vehicles, and drive through gearboxes which can be left in neutral.
What was the practice with the big ocean-going vessels?
What was the practice with screw steamers?
Roderick B Smith
Rail News Victoria Editor
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That's a very interesting question Roderick :thinking.........
Considering that 90>95% of steam engine lubrication on our older OZ paddlers was achieved by drip feed.......provides its own answer :goodluck
Do nothing & let the wheels "freewheel" as connected to the engine ...incorrect :shoot
The resultant RPM of the wheels [on the vessel under tow] will only be relative to the speed of the vessel in the water...which is totally different to wheels being driven under steam.......& doing work......
Lets see what others think....... :beer .....Derek
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That's a good start Derek, and great for the motion bearings, but not for the piston in the cylinder, or the admission valves (if valve, not port).
One of the railway people mentioned a lengthy shunt across a depot, and somebody was pouring oil through the blastpipe to lubricate the cylinder innards.
Roderick B Smith
Rail News Victoria Editor
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We should find out soon when the MEDWAY QUEEN is towed from the Bristol shipbuilders to her Gillingham base ;). She looks to be afloat in her building dock - see MQPS.co.uk - so watch that space!!
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If comparing to steam locos, let us talk about traditional, directly driven paddlers, not about these geared Australian things with steam tractor engines.
For direct acting steam engines, answer A would be nonsense, since there is nothing like Neutral. Putting the valve gear in the middle would not change anything, especially for an engine not being under steam. It would not keep the pistons from traveling. By the way, steam locos with piston valves have specific "free-wheeling valves" in the cylinders for the case of coasting or being towed, to avoid pressure buildup in the cylinders. Flat valves automatically act as such.
But if the engine is equipped with a forced lubrication pump (and not displacement lubrication), the is nothing bad about being towed.
If you would want to keep the engine from spinning, you would have to put the valve gear in Reverse, just like Riggenbach's counter-pressure brake for cog locomotives. But you would need certain modifications to do so.
Answer B is somehow problematic as well, since there is no easy way of uncoupling the "drivetrain". Apart from removing the pitmans, just how it is done for steam locos being towed very long distances or with damaged engines.
Finally, there are some interesting pictures of a former sidewheeler regularly being used as a barge (after blowing one engine), pushed by a tugboat:
http://quod.lib.umich.edu/t/tbnms1ic/x-80804.80852/0080804_001_F_LANSDOWNE.TIF (http://quod.lib.umich.edu/t/tbnms1ic/x-80804.80852/0080804_001_F_LANSDOWNE.TIF)
http://quod.lib.umich.edu/t/tbnms1ic/x-80804.80864/0080804_003_F_LANSDOWNE.TIF (http://quod.lib.umich.edu/t/tbnms1ic/x-80804.80864/0080804_003_F_LANSDOWNE.TIF)
From the heavily damaged paddlebox (especially in the second picture), I would guess the wheels are not spinning, but I don't know for sure . But they are visibly in place, and you can see some wake being caused by their drag. I guess they simply removed some paddlefloats.
Moritz
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Here is a the Kingswear Castle being towed from the Medway to the Dart.
http://www.kentonline.co.uk/medway_messenger/news/2012/december/12/paddle_steamer.aspx
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Mick posted...."re- the towing question, there is a flange on each end of the drive shaft with 8 (12?) bolts connecting it to the paddle wheels similar to the arrangement on this model engine (below) removal of the bolts would disconnect the drive"
These couplings basically come in two styles.....Resilient [to compensate for mis-alignment] & Mill [which are fixed & have no compensation for angularity]
1. The engine image posted does not show any support bearing outboard of the paddle wheel...if this were the case we could assume the couplings shown are of the Mill type as they help support the paddle shaft & paddle & hence would not be disconnected in use
2. PS Emmylou has similar couplings on the paddle shaft & additionally the shaft is supported on at least two plummer blocks ...so we conclude the couplings on Emmylou are Resiliant .........it may well be possible to disconnect these couplings & have the wheels fully supported by the plummer block bearings as shown [for towing]
3. PS Adelaide drawings depict a substantial single plummer block inboard of each wheel, but no detail of any additional bearing...
4. For my Adelaide build I have purchased four 5/32" shaft diameter miniature plummer blocks with 316 ZZ sealed ball bearings...so naturally one each inboard & outboard of the wheels..........
From all of this I am beginning to think that engines may have been "barred" or the shafts "locked" during a tow although some of the 3 local engineer PD members could offer some clear comment here ..........Derek
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found a photo on the MQPS website showing Medway Queen being towed, http://www.medwayqueen.co.uk/images/New_Set_Up/GALLERY/PHOTO_GALLERY/POST_WAR_YEARS/tow.jpg . looking at the wake produced by the wheels, I'd guess they are not removed, disconnected or turning at all...
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Yes in the video of the ship coming out of the dry dock, the paddle wheels are intact, but the sides of the boxes are not on.
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Medway Queen passing Hythe AT 22.00 Sunday 17/11/13
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I am building up more material in the thread on PS Adelaide, in preservation: <www.paddleducks.co.uk/smf/index.php?topic=2981.0>.
I have more photos to add, but no time today.
On the engineeringly-simply classic Australian style, towing wasn't common, but most had mechanical lubricators. If if the wheels were turning the engine, there was no problem: the lubricating oil was being pumped.
At Echuca, towing from wharf moorings to the slip is common, and for that distance, nobody bothers.
For a longer tow, it would be possible to tie or jam the paddlewheel to prevent it from moving, but nobody has had to do that in recent years.
Roderick B Smith
Rail News Victoria Editor