Screw-jacks and a worm-driven rack for lifting

Spring-screw jack with simple and toothed levers

The device N f at the right is judged good but is to be proved first without fire and then with fire, and first with the simple lever and then with the toothed one. One does as much as the simple lever allows, then adds the fire-box and, if need be, resorts to the toothed lever.

Rack driven by a worm screw: reckoning the purchase

With a first lever of one and a third braccia and a second of two braccia, the note claims 60 pounds will lift 40,000. Making 6 teeth in a third of a braccio of the toothed crutch-lever, a whole turn of the final effect comes only after lever a b has been worked 1944 times; M lengthens the screw-lever, and F lets the crutch be removed for a longer lever.

Five elements threaded on a bar

A bar carries five pieces threaded onto it, the thickest to be one finger across. The arrangement is noted approvingly as 'good'.

Two forks to be screwed on

At the bottom two forked pieces are shown for screwing on. The point marked a is described as a way to take off and put back on.

A destra. Apparecchio munito di due leve semplici, con:

Cremagliera mossa da vite senza fine azionata da una leva, con:

Tre cunei vuoti e congiunti.

Gruppo di cinque elementi infilati in una sbarra:

Presente in una terza figura. Ferri a T, con:

A sinistra figura analoga.

In basso, due forcelle da avvitare:

At right. Device fitted with two simple levers, with:

Rack moved by an endless (worm) screw worked by a lever, with:

Three hollow wedges joined together.

Group of five elements threaded on a bar:

Present in a third figure. T-irons, with:

At left, a similar figure.

Below, two forks to be screwed on:

Screw-jacks and a worm-driven rack for lifting

On this page

Spring-screw jack with simple and toothed levers

Rack driven by a worm screw: reckoning the purchase

Five elements threaded on a bar

Two forks to be screwed on