Driving pawls

A pawl can engage with a ratchet, either to prevent it moving, or to impart movement to it, and two distinct types of pawls were used with the windlass: retaining pawls, sometimes referred to as detents, or if spring-loaded as clicks, were much commoner in mechanisms than the second type, driving pawls, or dogs。 Figure 6 shows a simple mechanism featuring both types。 The ratchet-wheel (A)is caused to rotate in a clockwise direction bythe

8Falconer, Dictionary of the Marine, 633。

Figure 7 Windlass with long lever and ratchet wheel with 16 teeth

crank (BC) secured to the driving pawl (D)。 Backslip is prevented by the retaining pawl (E)。

Windlasses using ratchet and driving-pawls

In considering improvements to the windlass proposed during the period 1790 to 1860, we will first consider modifications using a ratchet wheel and pawls, then those using gears and finally a miscellaneous set。 As to the first group, we start with a windlass described by William Hutchinson in 1794, and shown in figure 7。9 He envisaged a long lever, fitted with two driving pawls (A) and (B), engaging a ratchet, or as he calls it a ragged-wheel, with 16 teeth。 Because the fulcrum is on the circumference of the windlass-barrel, rather than at its centre, the levers could be longer than the common handspike, giving the men greater purchase than with the traditional arrangement。 The major advantage, however, was that the handspikes no longer needed to be inserted and withdrawn。 With such a fitting at each end of the barrel, one going up while the other went down, four men could heave in cable without interruption。 Michael Lourenço Berford applied for a patent in 1776,10 and Robert Gibson in 1801,11 which mention actuating the barrel with ‘long levers, furnished with a spring catch’, but we lack any further details。

Unfortunately, we cannot date these exactly, but two models in the Navy Collection of the Rijksmuseum exhibit ratchets。 The earlier of the two, number 207, shown in figure 8, features clumsy wooden pawls that engage in a notch in each face of the barrel。 Number 209, shown in figure 9, uses a retaining ratchet with 16 teeth。 It can be seen that the driving pawls are arranged slightly differently in the two devices, but work similarly。12

An important step forward came in 1832 with the granting of a patent to Benjamin Cowle Tyzack, Thomas Storer Dobinson and John Robinson, all of North Shields, for the windlass shown in Figure 10。13 This employed a creeper or pawl case (A), and a ratchet wheel (B) and three push pawls (C), moved up and down by fore- and-aft levers (D)。 The levers were connected to lever-sockets (E) and the levers (F), terminated in crossbars (G)。 One of these mechanisms is seen at each end of the barrel, as is the ratchet for the retaining pawls (I), just forward of the bitt post。 It

9Hutchinson, Naval Architecture, 138–40, plate V。 10Patent no。 1,117 (1776)。

11Patent no。 2,484 (1801); Patents for Inventions, 98。

12Obreen, Catalogus, 40。

13Patent no。 3,284 (1832); Newton, London Journal, II,68–71。

Figure 8 (above) Model 207 in the Rijksmuseum, Amsterdam, with notches on the barrel

Figure 9 (right) Model 209 in Rijksmuseum, which has a retaining ratchet with 16 teeth Figure 10 (below) Tyzack & Co。’s windlass with the lever system, probably invented by the company

is possible that Master Mariner James Moffat’s patent, obtained in 1828, may have presaged Tyzack’s version。14 It ‘employed a ratchet wheel at each end of the barrel of the windlass, and certain hand levers furnished with palls and arranged that by working the hand levers to and fro, the palls propel the barrel’, but in the absence of a detailed description or drawings, credit for the idea goes by default to the North Shields group。 十九世纪锚机的发展英文文献和中文翻译(3):http://www.youerw.com/fanyi/lunwen_96310.html