CAPSTAN, an appliance used on board ship and else-where for heaving up the anchor or any heavy weight. Fig. 1 represents one of Harfield <fc Co.'s patent wrought-
FIG. 1.Vertical Section of Capstan.
iron capstans as used in the Royal Navy. It has a ver-tical spindle D, passing through sockets firmly secured in the deck, a drumhead E being keyed on to the spindle, and the capstan is turned round by means of bars inserted in holes made to receive them all round the edge of the drumhead. A capstan of the kind shown would have about twenty holes for bars, and each bar would be about 15 feet in length. The capstan bars are made of tough wood, such as American ash or rock elm. Three or four men can stand to each bar, so that when the capstan is fully manned at least sixty men are employed. When a hempen cable or a hawser is brought to the capstan, three turns are taken round the barrel GG, and men are stationed to haul on the end of the rope to prevent it from slipping, and to coil it up as it comes in. When a chain cable is brought to the capstan it is passed round the " whelps " at H, and is kept upon them by the rollers a, a, a, a, as shown in the plan (fig. 2), so that the cable assumes the position shown at ABC, A being towards its outer and C towards its inner end.
Capstans in their primitive form were merely blocks of wood wrought to the required shape and made to traverse on an iron spindle,
effected in them, some important ones being introduced by Captain Phillips, R.N. In all these capstans the cable was brought in by means of a " messenger" (see article
Fid. 2.Plan of Capstan.
and improvements have been gradually
CABLE); but in 1857 Mr Thomas Brown took out a patent for dispensing with the messenger, and working the cable itself on the capstan by fitting a grooved pulley with guide rollers for securing the requisite amount of turn of the chain, as before described, at ABC. Subsequently important improvements were introduced into the details of this invention, particularly in making the stops or whelps b, b which hold the links movable, so that they may be adjusted to fit the links of the cable exactly, and also admitting of their renewal when worn.
The capstan shown in figs. 1, 2, and 3 is constructed of wrought iron, no cast-iron or wood being used. It is fitted with treble purchase gear, which is a simplification of Captain Phillips's original power capstan, and has the advantage of the toothed gearingremaining at rest with respect to the capstan, when the single purchase only is required. The treble power is obtained by withdrawing the connecting bolts c, c from the capstan barrel, and locking the plate d, which carries the intermediate pinions e, e to a fixed point in the deck, by sliding the horizontal paul / into one of the recesses g, g provided for the pur-pose. The action then is as follows :The drumhead E, which is keyed to the spindle D, drives the centre pinion It; this drives the intermediate pinions e, e, which rotate around their centres, as the pinion plate d is fixed to the deck by the paul /; these pinions in their turn drive the annular wheel I, which forms part of the capstan proper.
In large ships the spindle D is frequently continued down to the deck below, and another capstan is worked on it. In such cases the two capstans are so arranged that they may be worked either separately or together; thus, if required, the power applied by the men on both capstans may be brought to bear on a chain or hawser attached to either. In large ships of the navy and in many merchant vessels steam power is employed to drive the forward capstan, which is the one most used. Small engines specially constructed for this purpose, and secured to the under side of the deck beams at K are generally used. All capstans are provided with pauls to prevent them from running back.
Figs.l and 4 show a new form of "cable-holder," which has been
tlon, and is in use in a few ships of British and foreign navies. The cable-holder is placed on the fore side of the deck pipe, and is fitted with a grooved pulley M for the cable to pass
Fig. 4. Cable-holder.
over, similar to the whelps of the capstan shown in fig. 1. It revolves on a horizontal spindle fixed to the deck by brackets. The interior is made hollow, and contains a double series of disks, which can be screwed together by means of a hand-lever L, thereby causing sufficient friction to let the cable run out slowly, or to stop it entirely, and also to hold the ship when riding at anchor. Means have been devised, and are now being fitted in one of the ships of the British navy for connecting these "cable-holders" with the capstan, so that the cable may be hove up by them without taking it to the capstan. (T. M.)