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Manning Wardell Impetus Class I


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I started one about a couple of years ago and it ground to a halt when part built.

The problem I had with it was that it was designed in the very early days of compensation, before the nature and dimensions of the hornblocks and guides became standardised.  As you may have already discovered, the guides for this loco are what, for want of a better description, I'll describe as only single-sided and they are also etched from brass that's a bit on the flimsy side.  Plan A was to replace them with High Level hornguides and blocks, but that was when I discovered that the cut-outs in the chassis were slightly bigger than is normal nowadays.  In theory the High Level guides would just, and only just have fitted - there is about half a millimetre all round, which in my opinion isnt enough - but I also found that the coupling rods had slightly different centres to the chassis and would have meant that in practice High Level hornguides would have ended up with a millimetre on one side and waving in the breeze on the other.

Bigger than usual hornguides was obviously what was required and construction ground to a halt while I sought some.  I eventually decided Exactoscale hornguides and blocks would do the job, but by then the kit had been put on the back burner and has stayed there ever since so I've not yet been able to confirm that they really are the solution.

With regard to the rest of the kit, its all fairly straightforward, any problems being caused by the fact that it is such a tiny loco!  It's going to be powered by a Mashima 1016 mounted horizontally in the boiler and driving through a High Level Roadrunner+ in the firebox.  The footplate, cab and firebox are one unit, the boiler, tank and smokebox another.  I've got the same arrangement in a Peter K Manning Wardle "K" Class I built a few years ago so I know it works.  The "K" has got an 80-to-1gear ratio which I found to be a bit much, so I've got a 60-to-1 for the Old Class "I".  There is plenty of room for more than enough lead in the saddle tank and means the "K" is capable of some quite remarkable feats of haulage!  I see no reason why the Old Class "I" shouldn't do the same.

Good luck!

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Mike,

 

Many thanks for your reply - I have your 2011 log of your K Class build bookmarked and I read it often. Only that I can't see all of the pictures.

 

So far I have managed to put the chassis together and found the same problem you mentioned with the hornblocks. I'm at the stage of trying to fit the motor and gear box.

 

I came by this kit via an auction. For the next nine months I'd periodically take it out and try to work out what was what etc. After that time I realised in the box was both an I Class and a K Class, plus other bits and pieces such as wheels, open frame motor, single stage gear box with cogs.

 

The wheels are on 3mm shafts - I'll persevere with that.

 

The gearbox when made up is only 2mm wide and too narrow to take even the worm.

 

There are two drive shaft cogs, only the larger cog is in the pic, not sure what the smaller one is for but it doesn't mesh with the worm.

 

I'm not sure about the motor, I'll keep it for the K Class.

 

I've also found small motors from:

 

https://tramfabriek.co.uk/

 

which at 16mm length will fit into the fire box. They also provide a replacement for the Mashima 1016 if you are interested.

 

I'll make a gear box to the dimensions of the narrow one supplied but make it wide enough to take the motor and the gears. The critical dimension is the from the centre of the motor shaft to the rear wheel drive shaft which is 7mm, same as the centre of the cog to the centre of the worm and also centre of the rear wheel shaft to centre of the fire box.

 

I am struggling to find photos. Can you point me in that direction or could you supply me with some. I'd appreciate the pics you showed in 2011 and any you have of your I Class in the process of being built.

 

Any comments would be greatly appreciated.

 

Gympie.

 

 

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That motor looks a bit on the large size, considering where it's got to go.  I've not used one myself, but I know everyone who's used Tramfabriek motors speaks very highly of them and one would be a much better bet, assuming you can get a suitable gearbox to go with it. 

 

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Whatever motor/gearbox combination you end up with, precious millimetres can be gained to accommodate them by filing away the back of the saddle tank and the front of the firebox, as you can see I've done here with mine. (Getting it out to photograph it made me realise it hadnt progressed as far as I thought.  When I put "The footplate, cab and firebox are one unit and the boiler, tank and smokebox another" I should have put "will be one unit") 

 

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The K Class's firebox and saddle tank have also been filed out.  I also filed a little off the shoulders of its gearbox and could have taken quite a lot more off, had it been necessary.  It might be with the Old Class I because having both locos out together makes me realise its firebox is narrower than the K Class's by about a millimetre.

Another difference between the two is the brake gear.  The K Class had early pattern brake gear, with the pull rods tucked up under the footplate, well out of the way, while the Old Class I has later, more conventional brake gear with the pull rods lowdown and behind the wheels.  Manning Wardles are extremely low slung and it wasnt easy arranging the pickups in the minimal space twixt chassis and railheads on the K Class.  Having to thread them through the brake gear as well will make doing the pickups on the Old Class I even more difficult.

As you are finding out, being a fan of Manning Wardles isnt easy!

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Thanks mike for the pics and your reply.

 

I measured and drew up what I think the gearbox should be. I'll order a motor from Tramfabriek and attempt to make a single stage gearbox this weekend.

 

If my 5mm measurement from centre of rear axle drive to the centre of motor is correct, I should be OK.

 

I'll keep you posted on progress,

 

Gympie.

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Hi! Mike,

 

Gear box built, it sits a bit high but I didn't take into account the thickness of the Nickel Silver, the bit that is a bit high is inside the firebox, so all being well, that little bit hopefully wont foul the motor inside the fire box.

 

If this works well, I might build this part of the K Class, I don't have gears as yet but was thinking of using an Ultrascale worm gear set for single stage gear box.

 

The motor wont be delivered will next week, so I need to wait patiently for that before proceeding.

 

I don't have any photos for an I Class or a K Class, if anyone can point me in the right direction to get some photos, I would appreciate it.

 

Gympie.

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You wouldnt be the first to forget to allow for the thickness of the metal (Including numerous kit designers!) but the height shouldn't be a problem - you could lose a few millimetres off the top of the gearbox and several more off the firebox throatplate.  Don't forget to drill a hole for a locating peg in the back of the saddle tank and another hole for it to locate into in the firebox throatplate.

 

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Looks like a promising build - Impetus were greats kits in their time.

 

You mention 3mm axles - are you sure they aren't 3/32" ? It may have Sharman wheels and some of those did use 3/32".

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Motor and gearbox now in the model. I needed to make another gearbox to lower it a bit and now the motor is sitting neatly in the firebox.

 

I acquired some 15thou nickel sliver to make the gearbox, so that made it easier all round, the original was 22thou.

 

The motor is such a tight fit I may not secure the gearbox motor in the chassis. Leaving the firebox to hold it in place allows that sub-assembly to sit where it is comfortable.

 

I also need to review the size of the axles. I started this kit some time ago, packed it up and moved house. In the box is included an I Class and K Class plus assembly notes. The K Class refers to 2mm axles and these are bigger than that, I have assumed they are 3mm, I have a feeling they are 1/8. The I Class refers to 1/8 axles.

 

These pictures are for an I Class. When I get the chassis sorted I might build the the K Class to the the same point. I am sure problems occur because of trying to fit a High Level gearbox with motor in the boiler. Fitting a small motor in the firebox as intended hopefully will make the build easier.

 

Ultrascale provide suitable Worm Wheel gear sets- just need to be careful making the gearbox.

 

I'll make up the connecting rods and see if I can get it motorised. I am not fast, so it might take me a little time.

 

Gympie.

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  • 4 weeks later...

It is a while since I have replied and had a chance to get back to this project. Sadly this modelling is well down on the priority list. We bought a house although relatively new, has been mothballed for four years and getting it up and running is considerable work.

 

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This is the Before and After of the back garden - the front is yet to be completed.

 

Work has progressed slowly

 

 

 

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I'm using Gibson Crankpins, can someone please tell me which way the screw goes on the crankpin- bottom left or top right.

 

I have needed to cut a bit out of the lower spacer to accommodate the the shaft and worm seeing I have lowered the height of the gear box. I haven't yet had a chance to test run this, next part of the project is to connect power to the motor and see if it moves.

 

The next photo is one of the gear box

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The pic on the left is before it has been folded up. The gap to the left of the worm hole is to help removing the motor if needed. The diameter of the worm is greater than the hole I can drill at that point. I hope I don't need to remove the motor as that will need dismantling the whole model.

 

I have made a bit of a mess of the rods, I may need to make some more, however they are of an usual dimension.

 

Gympie.

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