Page 189 - Know and Understand Centrifugal Pumps

Know and Understand Centrifugal Pumps

was to make and repair flags, seal holes in the sails, in the sailor’s
clothes, and the hole in the bottom of the boat. The tailor would
fashion stuffing box ‘stopa’ material from saved scraps of clothing, old
sails and ropes. Out on the high seas, whenever a boat came upon an
island, the sailors would disembark to search for food, fresh water, and
stopa material. With some luck, the sailors found wild plants of cotton,
jute, ramey, linen and hemp. Without luck the sailors returned to the
boat with vines, root sprigs, and tree bark. They saved strings from
mango seeds, corn shucks, and even the feathers, hair and hides of the
animals that they hunted for food. The tailor would take these materials
and form threads for sewing. The tailor would weave the threads into
patches for the sails. Some threads would be formed into strings and
ropes for hanging sails. Other threads and strings would be formed into
stopa to seal the rudder shaft. In the port cities, the ship supply agents
began selling prepared stopa, formed with linen and cotton lubricated
with animal fat and wax, ready to stuff and press into the stuffing box
around the rudder shaft. This stopa was resistant to the abrasive rudder
shaft and the salty seawater.
Out on the high seas, the sailors would tighten the stopa around the
rudder shaft and the friction would hold the tiller steady pointing the
boat toward the horizon or a distant star. At times of war, or upon
arriving into a port and dock, the sailors would loosen the stopa gland
to easily navigate the boat. With the loosened gland, the seawater
would enter into the bilge. An apprentice sailor would get a bucket and
begin bailing the bilge, hauling the water overboard.

Reciprocating action

The ancient sailors would slowly rotate the rudder shaft to navigate the
boat. This ancient design, the rotating rudder shaft and the stuffing
box, has continued in existence down through the ages to today from
the beginning of recorded time. The moment arrived when the rotary
action was replaced with reciprocating action. In 1712, the
reciprocating steam engine became a reality. A century later, after
numerous failures, the steamboat was presented to a waiting public,
able to navigate upstream against the current in rivers. Inside the
engine, a load of steam was discharged against a piston and
reciprocating shaft. Through a camshaft mechanism, the reciprocating
shaft made propulsion paddlewheels rotate. In order to contain the
steam inside the cylinders with the reciprocating rods and pistons, the
old stuffing box design was incorporated, with its box housing, gland,
and stopa material.