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The Crossbow
casing of the cranequin, the strain would be on one side of the latter,
and its interior mechanism would then surely give way. The long hollow
in the plain edge of the ratchet bar was cut out to reduce the weight of
the instrument.
How to Use a Cranequin to Bend the Bow of a Steel Crossbow
1. The cord loop of the cranequin is first slipped over the small end
of the stock of the crossbow. It is then pushed along the stock till it
comes against, and is checked from further progress by the transverse metal
pin, fig. 93, opposite page.
This pin passes through the stock of the crossbow, some 6 or 7 in. behind
the catch for the bow-string. It projects 1 in. on each side of the stock,
and is 1/2 in. in diameter.
2. The claws of the ratchet bar are next hooked over the centre of the
bowstring, fig. 86, p. 133. By giving the handle of the cranequin a few
turns, one way or the other, the claws can be made to move to or fro till
they grip the bowstring.
3. If the handle is now turned to the right, the wheels inside the casing
of the cranequin will cause the ratchet bar to slide towards the stock-end
of the crossbow till the claws at the end of the bar finally pull the bow-string
over the catch of the lock, fig. 93.
This operation will occupy about 35 seconds if the handle is revolved
at fair speed, the force exerted by the hand in turning the handle being
so slight that a strong bow can be bent by the first finger and thumb.
The action of the cranequin is very simple and powerful, though the
instrument itself is so small, figs. 90, 92, pp. 138, 141.
By turning the handle, the small spindle attached to it revolves the
large wheel. This large wheel causes the small wheel with three cogs, which
is part of the large wheel, to work in the notches of the ratchet bar.
As a result, the ratchet bar is irresistibly forced to or fro according
to the direction in which the handle of the cranequin is moved.
The cranequin has no ' stop ' acting on its wheels or bar, so that when
the bow-string is safely hitched over the catch of the lock, a couple of
reverse turns of the handle will free the claws of the cranequin from their
grasp of the bow-string. The cranequin being then loose, can be quickly
removed from the crossbow by pushing back its cord loop over the end of
the stock. After its bolt has been laid in position the weapon is ready
for discharge.
Fig. 93 shows a crossbow having its bow bent by a cranequin. The crossbow
is held upright in the left hand with the fore-end of its stock upon the
ground, the right hand being employed to turn the handle. |
