21.1.11.1 Additional Information on Gearboxes and Fluid Drives
Moderate to excessive off-line soft foot conditions have been experienced on virtually every
gearbox regardless of frame construction design. Gearboxes are frequently bolted to the
frame in more than four points and soft foot correction can be more difficult to correct the
Side view
Scale:
North
South
Side view
Scale:
West
East
30 in.
10 mils
30 in.
10 mils
Upper bearing
Thrust bearing
Lower bearing
Position A
Position B
Position C
Position D
Turbine
guide
bearing
Upper
wear ring
Lower
wear ring
Position of rotor

21.1.12 COOLING TOWER FAN DRIVES
Although cooling tower fan drives are not usually thought of as glamorous rotating machin-
ery systems, they are very critical to the operation of the plant and can experience alignment
problems as acute as any other type of rotating equipment. In fan drive systems where a right-
angled gearbox drives a six- or eight-bladed fan assembly where the drive motor is located
outside the plenum and the motor is connected to the input shaft of the gear by a long spool
piece or ‘‘jackshaft,’’ OL2R movement is usually not measured and in many cases ignored.
The saving factor in these designs is that the flexing points in the coupling are separated by a
FIGURE 21.78 Motor, gearbox, compressor drive arrangement.
FIGURE 21.79 Motor, fluid drive, pump drive arrangement.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 722 6.10.2006 12:19am
722 Shaft Alignment Handbook, Third Edition
considerable distance, thereby allowing for considerable amounts of centerline-to-centerline
offsets at the flexing points. For example, if there is a 100-in. separation between the flexing
points, you could have up to 100 mils of centerline-to-centerline deviation and still be at
1 mil=in. misalignment (100 mils=100 in. ¼ 1 mil=in.).
The shaft to coupling spool method shown in Chapter 13 or the face–face technique shown
in Chapter 14 is recommended for aligning these types of drives. Since most cooling towers
are located outside, an interesting phenomenon can occur when aligning these drive systems
during daylight hours with the sun shining. If the drive is kept stationary, the long coupling
spool can get unevenly heated from the sun and thermally bow the spool piece. As you begin
rotating the shafts to capture a set of readings, the hot or sunny side of the spool piece now
begins to rotate into the shade and the sun starts to heat a different side of the spool piece. As
the hot side cools and the shaded side warms up, the spool piece begins to change its shape
causing erroneous readings.
FIGURE 21.80 Irregular gear tooth wear pattern due to a soft foot condition distorting the gear housing.
FIGURE 21.81 Corner of gearbox in Figure 21.80 showing that the foot bolt is not supported on the
outer edge (in addition to the soft foot problem shown in Figure 21.83).
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 723 6.10.2006 12:19am
Alignment Considerations for Specific Types of Machinery 723

+
_
10
40
20
30
0
50
10
40
20
30
+
_
10
40
20
30
0
50
10
40
20
30
+
_
10
40
20
30

3–0
4–1 east
5–1 east
6–1 east
7–0
8–3 east
Final–14 east
1–4 not measured
5–0.5 up
6–3 up
7–8 up
8–9 up
1–4 not measured
5–5 up
6–8 up
7–14 up
8–16 up
1–1 south
2–1.5 south
3–3 south
4–3 south
5–3 south
6–3 south
7–3 south
8–3 south
Final–5 south
The bolts were loosened in sequence (1–8). The indicators
measured the amount of movement that was observed
as each bolt was loosened.
0

in. ID at the tip and about 18 in. at the bottom with a taper of 1 in 12 in. The bores are usually
of cast iron welded to rudders that can weigh over 35 t. The pintle pins are usually a metal-to-
metal tapered fit (some with keys, others without) and 85% fit is usually required. The rudder
stock bore has at least one keyway, which mates up with a key on the rudder stock.
Sometimes (especially older German vessels) the keys are in the bore and the keyway is on
the rudder stock. The keys are very large and are always bolted securely in place. The rudder
is usually removed from the ship (usually weighs about 35 t) for this sort of work.
The typical disassembly sequence is shown in Figure 21.86 and Figure 21.87. The rudder is
held in place with chain falls and the rudder stock is then removed along with the mechanical
connections inside the ship. The rudder stock is then lifted out through holes in the ship decks.
The rudder is then lowered and tilted until the pintle pin is free of its bearing surface in the
rudder horn. The access panels in the rudder are cut out after the ship is in dry dock. The
rudder is then removed and set up vertically in a work bay. The pintle pin nut access panel is
removed and the pintle pin nut is removed. The pintle pin is then removed.
East
Gearbox soft foot gaps and shims
Gearbox
Feeler gauge
measurements
(in mils)
0
5
8
8
5
3
25
22
22
20

4
4
2
10
10
5
10
3
10
2
10
2
15
15
5
2
10
2
3
5
2
Motor
Extruder
FIGURE 21.83 Soft foot map of above gearbox.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 725 6.10.2006 12:19am
Alignment Considerations for Specific Types of Machinery 725
Now that the rudder has been removed from the ship, another issue needs to be addressed.
Before getting into the tapered pintle pin alignment, one should investigate whether the center-
line of rotation of the rudder stock is concentric to the bore of the pintle pin bearing in the
rudder horn. If it is possible for the ship to run aground or hit something under water, it is

Increase the shaft-to-shaft
distance to allow for expansion
in the axial direction
Slotted hole allows case to
expand in these directions only
FIGURE 21.84 Pinning a gearbox at the high-speed shaft compensating and allowing the gear case to
expand without warpage.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 726 6.10.2006 12:19am
726 Shaft Alignment Handbook, Third Edition
1. Mark off the inside or outside of the cylinder (i.e., shaft or bearing bore) into 908 arcs.
Since the rudder stock is vertically oriented, I usually try to use compass directions
(N, S, E, W) or ship coordinates (fore, aft, port, starboard) to designate the position at
each quadrant.
2. Rotate the shaft (rudder stock) all the way in one direction until it stops. Clamp the
bracket to the shaft, set the indicator at one of the quadrant marks, and zero the indicator.
3. Rotate the shaft as far as it can go in the other direction (in this case 608) taking care to
observe what the indicator is reading as you do the rotation. When the shaft stops its
rotation, record the dial indicator measurement and also scribe a mark with a pencil or
soapstone exactly where the tip of the indicator stopped on the surface of the shaft or
bearing bore. In this case, that is the bearing in the rudder horn.
4. Rotate the shaft back to its starting position, loosen the bracket on the shaft, rotate the
entire bracket or dial indicator arrangement so that the tip of the indicator is positioned
where it stopped at the pencil or soapstone mark, tighten the bracket, dial in the
measurement you observed at this point, and start rotation again. Keep in mind that
you only have 308 to go before so that you get to your first quadrant mark.
5. Repeat step 2 through step 4 until you get all the way around the shaft (see Section 6.10,
i.e., you do not have to rotate all the way around).
Once the measurements have been taken at the top and bottom of the bearing bore, you
could plot or model these measurements as described in Chapter 12. Remember, you are
Rudder stock

lowered and moved away from
the hull
1
2
3
FIGURE 21.86 Removing the rudder from the ship.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 728 6.10.2006 12:19am
728 Shaft Alignment Handbook, Third Edition
how to do this at this point, the rest of this procedure is not going to help you. If we get the
tapered bores of the rudder to be collinear, the alignment of the rudder stock bearing and the
pintle pin bearing are not in line with each other, and none of this is going to work right. As
far as I am concerned, the pintle pin is nothing more than an extension of the rudder stock
shaft. For those of you who luckily swept zeros or painstakingly positioned the rudder horn
bearing so it does sweep zeros, we can now go back to getting the rudder and pintle pin right.
Traditionally, a tight wire is strung via
jigs from the top to the bottom and the
centerline is found b
y
trial and error
Pintle pin is remachined if
necessary
Pintle pin and nut are removed
from rudder
4
5
FIGURE 21.87 Final steps of removal.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 729 6.10.2006 12:19am
Alignment Considerations for Specific Types of Machinery 729
For ships that have been in service for a while, usually the pintle pin is very loose in the
pintle pin bore which is the reason the rudder is removed. Clearances of up to 1=4 in. have

50
10
40
20
30
+
_
10
40
20
30
0
50
10
40
20
30
+
_
10
40
20
30
Upper indicator
+26
+63
+37
0
Fore
Starboard

Quadrant marks
made with pencil
or soapstone
Temporary frame with
jackscrews 908 apart
Upper centering tube
support frame
Lower centering
tube support
frame
Dial indicator
Upper tapered bore
Lower tapered bore
Pintlepin jackscrews set
908 apart
FIGURE 21.89 Centering tube and radial arm arrangement.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 731 6.10.2006 12:19am
Alignment Considerations for Specific Types of Machinery 731
of tubing is used to support a ‘‘radial arm’’ holding a measuring device, in this case, a dial
indicator. Figure 21.90 shows a close-up of the radial arm assembly.
The radial arm has the capacity to slide up and down the center tube enabling one to
measure any point along the length of the tube. Due to the taper of the bores, the radial
arm must have the capacity to reach out different distances so that the radial arm is
fabricated from two tubes that can telescope in each other. The center tube is held in place
with fixtures at the top of the rudder where the rudder stock indexes into its tapered bore
and at the bottom of the lower tapered bore in the rudder, the pintle pin indexes into its
tapered bore. The upper and lower fixture has jackscrews that allow one to move top and
bottom of the center tube to establish a precise centerline. The general procedure would be
as follows:
1. Position the upper and lower center tube support frames as shown in Figure 21.89.

the indicator is not zero, adjust the jacking screws until you sweep zero from side to side.
Rotate the radial arm through a 908 arc to the other two quadrant marks and repeat the
centering procedure described in this step. At this point, the center tube should be
positioned at the centerline of the bore of the two tapered bores. You could take
additional measurements at the bottom of the upper tapered bore and at the top of
the lower tapered bore to see how much of a variation exists at these two points.
4. Slide the radial arm to a position where the pintle pin locating jackscrews will be placed.
Affix four jackscrews at 908 arcs on the top and bottom of each tapered bore (i.e., a total
of eight jackscrews).
5. Remove the radial arm, center tube, and fixturing mechanisms.
6. Proceed with the temporary installation of the pintle pin and bore repair as shown in
Figure 21.91.
7. Once the metal-based polymeric epoxy product has been poured and hardened, remove
the pintle pin and jackscrews.
The tips of the jackscrews
locating the pintle pin were
centered using the radial arm
FIGURE 21.91 Pintle pin held in position with jackscrews ready for the metal-based polymeric epoxy to
be poured.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 733 6.10.2006 12:19am
Alignment Considerations for Specific Types of Machinery 733
BIBLIOGRAPHY
Campbell, A.J., Alignment of reciprocating compressors, Orbit, February 1991, 5–8.
E-mail correspondence between Fred Lounsberry (SureTech Inc.) and author, 1998–1999.
Gibbs, C.W., Compressed Air and Gas Data, 2nd ed., Ingersoll-Rand Co., Woodcliff Lake, NJ, 1971.
Temple, D., Duncan, W., Cline, R., Alignment of Vertical Shaft Hydrounits, Facilities Instructions,
Standards, and Techniques, Vol. 2–1, United States Department of the Interior, Bureau of
Reclamation, 1967–2000.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C021 Final Proof page 734 6.10.2006 12:19am
734 Shaft Alignment Handbook, Third Edition

–2000 to –1500—Babylonia uses highly developed geometry for astronomical measure-
ments. Assyrians and Babylonians establish the units of measurement as: the cubit (now
20.5–20.6 in.), the span (10.5 in.), and the digit (%0.653 in.). Egyptians use knotted rope
to construct right angles illustrating Pythagorean theorem, which is also known in China
during this period. Water level believed to be used in Mayan culture for construction of
irrigation systems (see –600 to –500).
–1000 to –900—Chinese textbook of mathematics shows principles of plainemetry, pro-
portions, arithmetic, root multiplication, geometry, equations with unknown quantities,
theory of motion.
–900 to –800—Iron and steel production in Indo-Caucasian culture.
–600 to –500—Theodorus of Samos, a sculptor, credited with inventing ore smelting and
casting, water level, carpenters square, and lathe.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C022 Final Proof page 735 26.9.2006 8:51pm
735
–384—Aristotle was born. Credited with much of the initial discoveries in physics, biology,
and psychology contained in his book Historia Animalum. Aristotle or his student
Straton publishes Mechanika discussing the lever and gearing.
–323—Euclid writes his first book on geometry called Elements.
–300 to –200—Ctesibius of Alexandria invents the force pump (Figure 22.1) and Archime-
des of Syracuse invents the screw pump. The appearance of gears leads to the develop-
ment of the ox-driven water wheel for irrigation. Universal joint used by Greeks
(see 1550).
100—Hero of Alexandria describes the principles of an aeolipile (Figure 22.2), a simple
reaction steam turbine, in Pneumatica, describes levers, gears, motion on an inclined
plane, velocity, and the effects of friction in his book Mechanics. Hero’s book, On the
Dioptra, describes a type of theodolite, and explanations of plain and solid geometrical
figures, conic sections, formula for calculating the area of a triangle from the lengths of
its sides, and a method for determining the square root of a nonsquare number appear in
his book Metrica. Theodosius of Nithynia (also known as Theodosius of Tripoli)
authors ‘‘Sphaerica’’ dealing with spherical geometry.

mineral veins, surveying, tools, machines, pumps, hoists, water power, ore prepara-
tion, smelting, and manufacture of salt, soda, alum, vitriol, sulfur, bitumen, and glass.
These works were later translated to the English language by American President
Herbert Hoover.
1576—Franc¸ois Viete
´
introduces use of decimal fractions.
FIGURE 22.3 Da Vinci’s smokejack.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C022 Final Proof page 738 26.9.2006 8:51pm
738 Shaft Alignment Handbook, Third Edition
1600—Dutch optician Johann Lippershey invents telescope, which is adapted for astro-
nomical observations a year later by Galileo Galilei who manufactured hundreds of
telescopes that were in great demand by ‘‘amateur’’ astronomers of his time. Galileo is
also credited with the invention of the thermometer, was the first person to coin the term
‘‘moment’’ meaning the effect of force, founded the science of strength of materials, and
his fascination with the periodic swing of pendulums began his inquisition into falling
objects laying the ground work for gravity and acceleration.
1601—Giovanni Battista della Porta develops principles of condensing steam turbine.
1611—Marco de Dominus publishes scientific explanation of a rainbow (electromagnetic
spectrum).
1614—Scottish mathematician, John Napier publishes Canonis Descripto, describing his
discovery of logarithms. Napier was the first to use the decimal point to express
fractions.
1621—William Oughtred devises the first slide rule using Napiers logarithms.
1629—Giovanni Branca describes using a jet of steam impinging on blades projecting from
a wheel to produce a rotating shaft.
1631—Pierre Vernier invents slide caliper.
1639—Prior to his death at the age of 24 in the Civil War of 1642, astronomer William
Gascoigne invents micrometer from his work of attempting to determine the diameter of
celestial objects. By devising a caliper whereby two fingers were moved toward or away

thermometer 2 years later followed by Anders Celsius centigrade thermometer 28
years later.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C022 Final Proof page 739 26.9.2006 8:51pm
The History of Machinery Alignment 739
1720—Theodolite made by Sisson Benjamin Cole in London was the first to employ two
spirit levels (see Figure 22.6).
1729—English scientist Stephen Gray discovers that some bodies are conductors and
nonconductors of electricity.
1745—Ewald Jurgen von Kleist invents capacitor (Leyden jar).
1750—Swiss mathematician Leonard Euler and his son Albert experiment with impulse
driven water turbines. Leonard also developed equations describing buckling of struts,
the catenary curve, and formulated the laws governing the flow of fluids and the
relationship of pressure to flow (see 1770).
1754—P. Van Musschenbroek at the University of Leyden in Holland first demonstrated
that when two insulated metal plates are brought in close proximity to each other
without making contact, considerably more electrical charge could be stored than in a
single plate (the Leyden jar) commonly known today as a capacitor. When a wire is
connected to one plate of an electrically charged Leyden jar and then made to touch the
other plate, an electrical discharge occurs.
1762—Cast iron first converted to malleable iron at Carron ironworks in Scotland.
1764—James Watt invents steam condenser for improvement to steam engines patenting
his improvements in 1769. Files a second patent in 1781 describing sun and plant wheels
Supplementary
boiler
Gauge cocks
Vessel
A
Valve
B
Valve

1774—John Wilkinson constructs boring mill to manufacture cylinders for steam engines.
1786—Galvani discovered electric current occurs when two dissimilar metals come into
contact with each other. By suspending zinc and copper plates in an acid solution
Galvani showed that a steady flow of current would flow (chemical battery).
1787—Ernst Chlandi experiments with sound patterns on vibrating plates.
1790—The French National Assembly committee members decided that the meter would
be one ten-millionths of a quadrant of the Earth’s meridian. In 1799, a platinum–iridium
end bar was produced and became known as the ‘‘Metre des Archives,’’ the master
standard of length in the world. The bar’s length was based on a slightly inaccurate
geodetic survey made to establish the distance of the Earth’s meridian. As of 1983, the
meter is currently defined as the distance light travels in a vacuum after 1=299,792,458 of
a second.
1791—John Barber patents first gas turbine. After working with Joseph Bramah, 22-year-
old British engineer Henry Maudslay starts his own business and develops a metal lathe
(most former lathes were mostly made from wood) capable of accurately cutting threads.
Using his new machine, Henry cuts 50 threads per inch in a long rod that is eventually
used as a micrometer to check his work. Henry is also credited with the leather ‘‘U’’ seal
when working with Bramah in the development of the hydraulic press.
1800—William Herschel discovers existence of infrared solar rays, Richard Trevithick
constructs low-pressure steam engine, and Alessandro Volta was the first to produce
electricity from zinc–copper battery.
1802—John Dalton introduces atomic theory in chemistry.
1806—Oersted discovers that a magnetic field is produced around a wire where electric
current is flowing proving for the first time that electricity and magnetism are indeed
related.
1815—Augustin Fresnel begins research on diffraction of light.
1816—Ernst Werner von Siemens born in Hanover. Credited with the invention of the
armature initially used in telegraphy and later used in the larger generators (dynamo)
demonstrating the dynamo-electric principle. Along with his brothers Karl Wilhelm
(developed a type of governor for steam engines), Friedrich, and nephew Alexander

1867—Parisian gardener Joseph Monier obtains patent for reinforced concrete. J.R. Brown
and Lucian Sharpe while visiting the Paris Exposition saw a Palmer micrometer (see
1848). Taking the best features of the Palmer micrometer and another micrometer
designed by S.R. Wilmot (superintendent of Bridgeport Brass) Brown and Sharpe
released the first U.S. made micrometer in 1867.
1868—R.R. Musket introduces tungsten into steel manufacturing a self-hardening metal
used for cutting tools. The U.S. Navy’s Bureau of Steam Engineering adopts William
Sellers Unified Screw Thread design using 608 as the thread angle. Not until after the end
of World War II did American, British, and Canadian representatives finally agree on
this standard thread design.
1869—W.J. Rankine publishes paper ‘‘On the Centrifugal Force of Rotating Shafts’’ in
Engineer (Vol. 27, p. 249).
1872—F. Stolze of Germany develops gas turbine consisting of a separately fired combus-
tion chamber, a heat exchanger, and a multistage axial flow compressor coupled to a
multistage reaction turbine.
1877—Sir Charles Parsons begins work at Armstrong Works in Elswick England. In 1884,
serving for a year on the experimental staff of Messrs. Kitson of Leeds where he patents
the modern day steam turbine. Leroy S. Starrett invents combination square.
1878—Centralized generating station first proposed by St. George Lane Fox (England) and
Thomas Edison (United States). Carl De Laval builds a small 42,000 rpm reaction steam
C
f
n
g
e
B
B
A
c
c

1882—First electric direct current generating stations installed in London, England, on
January 12th and in New York city on September 4th. British electrical engineer,
William Ayrton invents ammeter, electrical power meter, improved voltmeters, and
meters to measure self and mutual inductions.
1883—John Logan of Waltham, Massachusetts files a U.S. patent for the dial indicator as
shown in Figure 22.9.
1884—Nikola Tesla begins work with Thomas Edison’s company patenting the induction,
synchronous, and split phase electric motors and new forms of generators and trans-
formers. In 1892, Edison General Electric and Thomson-Houston Electric companies
merged to form General Electric. American Society of Electrical Engineers formed.
1886—George Westinghouse and William Stanley (credited with perfected the transformer)
first demonstrated the practicality of generating and transmitting alternating current
over long distances in Great Barrington, MA. F. Hooks theorizes idea behind flexible
disk coupling. British electrical engineer, Sebastian Ferranti, working at Grosvenor
Gallery Co. in London also proposes using high-voltage alternating current for power
transmission that would be utilized at discrete sites through step-down transformers.
1887—Heinrich Hertz of Leipzig experimentally confirms Maxwell’s prediction by observ-
ing radiation emanating from an oscillating electric circuit. While a professor at Case
School of Applied Science in Cleveland, OH, Albert Abraham Michelson devises the
interferometer capable of measurements to one-millionths of an inch.
1889—De Laval builds a large number of steam turbines ranging in size from five to several
hundred horsepower and in 1892 builds a 15 hp turbine for marine applications. British
engineer, Charles Parsons forms his own company after developing the multistage steam
turbine while working at Clarke, Chapman and Co. in Gateshead, England.
1893—Rudolph Diesel invents engine named after him. Sulzer of Switzerland acquires
patent rights to the diesel 4 years later.
FIGURE 22.8 De Laval turbine.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C022 Final Proof page 744 26.9.2006 8:51pm
744 Shaft Alignment Handbook, Third Edition