Mabie Todd’s Swan Leverless pens have a poor reputation in some quarters, due not to any intrinsic fault of the pens, but because they have been incompetently re-sacced. The bar in a Leverless does not flatten the sac as does the pressure bar in a lever or button filler. It entangles the sac and compresses it with a “wringing out” action. For this to work well – or indeed at all – the sac has to pretty well fill the barrel. As many Leverlesses have a comparatively small nipple, a necked sac is often needed. Re-sacced properly, a Leverless will hold a good quantity of ink. It is true that it holds less than a similar-sized lever-filler, but it will still hold a lot more than, for instance, a modern international cartridge. You’ll get quite a few pages from it.
The unskilled repairer fits a comparatively slender sac, as he would in a conventional lever or button filler, and the entangling bar compresses the sac poorly, or just rotates around it without compressing it at all. As you might imagine, fitting a sac that fills the barrel is nowhere near as straightforward, and a different method has to be used.
The Leverless has the advantage that it is one of the easiest pens to fill. Simply place the pen in the ink, rotate the turn-button anti-clockwise, then clockwise, give it a few seconds to complete filling and you’re done, and it’s all carried out at the end of the pen away from that messy ink-bottle. In addition, though there were economy Leverlesses, most were designed to be prestige pens, with two or three cap rings and the No 4 or larger nibs. They were the most successful Swan range for decades, and as long as there were skilled repairers to fit new sacs they gave no trouble as the design is strong and durable.