Inferior trochlea

Latin Construction

inferior trochlea. fem.

1. ‘The lower pulley block’ in a system of multiple pulleys.

Loci

• αʹ Vitruvius, De Architectura 10.2.3:

Cum vero in ima troclea duo orbiculi, in superiore tres versantur, id pentaspaston dicitur.

But it is called a pentaspaston when there are two sheaves turning in the bottom block and three in the upper one.

• βʹ⁻² Vitruvius, De Architectura 10.2.6:

Ita funis ductarius traicitur in inferioris trocleae foramen, uti aequalia duo capita sint funis, cum erit extensus, ibique secundum inferiorem trocleam resticula circumdata et contenta utraeque partes funis continentur, ut neque in dextram neque in sinistram partem possint prodire.

So the tow rope is fed through an opening in the lower block, so that both ends of the rope are even when it is stretched out, and then both parts are held along the lower block by a cord wrapped around and tied so that they can't come out, either on the right side or the left.

• γʹ Vitruvius, De Architectura 10.2.1:

Per orbiculum 〈 summum 〉 traicitur ductarius funis, deinde demittitur et traducitur circa orbiculum trochleae inferioris. Refertur autem ad orbiculum imum trochleae superioris et ita descendit ad inferiorem et in foramine eius religatur.

The tow rope is passed over the top wheel, then it is dropped down and passed around the lower block's wheel. It is then brought back to the bottom wheel of the upper block, and so comes down to the lower one and is fastened through the hole in it.