Pontoon Crane

2:1 scale pontoon crane built from web photos, sent to me by French constructor Jacques Vuye.

The basis of the model is SML 28 of around 1928, which I have shown before at SELMEC.

The model is driven by a French MO motor mark 2 from a battery box containing three cells. This motor is geared to drive the motions of the crane by a series of worm and pinion reductions to the two winding drums, the slewing drive and the luffing screw.

The model is very tricky to build and get to work smoothly due to the worm gears on the central drive shaft; this is a particular failing of the design and still needs work to cure jamming problems.

At present there are no detailed instructions available.


Very nice model Brian. Congratulations, looks much better than my own original! Good idea to “beef up” the hull and adding the (non standard) circular girder, even though that seem to change the “proportions likeness” with the full scale SML The problem you seem to have with the worm drive probably originates in a light wobble of the main axle. It needs to be absolutely perfectly straight. Also adding a thin shim washer under the 1“x 1” angle bracket that carries it may help. I am not using spring clips on the winding drums, rather anchor springs with the anchoring eyelet right next to the gear weel. This way it never jams. As for the bearing of the luffing threaded rod, I agree it needs a bearing. I have one on my crane , but maybe the pics I sent you did not show that part. I apologize! Finally the trick with the chain drive is to have the toothed part of the 168 perfectly centered. Yes, it is a tricky model, requiring a little more adjustment and measuring than usual. Now, I also have a mini model of SML19a… ready for the challenge?

Hi Brian. I spoke with you at Kew regarding the cord you use in your models. We were discussing your excellent tower crane at the time. I believe it is PVC covered Rayon? Grateful if you could confirm. Regards Graham.

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