Wednesday, August 19, 2015

MOTION STUDY VARIABLES - Frank B. Gilbreth - Part 5

CHAPTER IV -VARIABLES OF THE MOTION

A DISCUSSION of variables of the motion opens up a field
so large that it is only possible here to attempt to show
the method of investigation, and to show that each vari-
able is a necessary factor in making motions standard,
leaving to the universities and to properly created and
equipped bureaus of the national government the task of
reducing motion study to an exact science.

ACCELERATION

In considering acceleration of speed as an element of
any motion, we must determine:

1. The amount of acceleration that it is possible or

economical to ebtain.

2. The means by which the acceleration can be obtained.

3. The effect of the acceleration on

a. Economy in time required to make the motion.

b. Economy in time required for rest to overcome

the fatigue of having made the motion.

Examples. i. Laying brick on a wall from a floor,
from the height of the floor level up to three feet eight
inches high above the floor, can be done with greatest speed

65



66 MOTION STUDY

when the brick to be picked up are each maintained at a
height of one foot three inches, plus two-thirds the height
that the wall is higher than the level of t he floor on which
the bricklayer stands. The brick to be picked up should
never be higher than three feet eight inches under any
circumstances.

By maintaining the height of the brick to be laid in this
relative position to the height of the wall, the brick will
always be in a position that permits the bricklayer to
accelerate the speed of transportation of the brick by using
the path of the quickest speed.

While bricklayers know nothing about this in theory,
they very soon discover it in practice by means of their
higher recorded output. Greater outputs will be notice-
able as an immediate result of maintaining the brick as
nearly as possible at the heights above stated.

2. In laying the filling tiers in any one course, it is most
economical to lay the farthest filling tier first and the next
farthest tier second, and so on. This enables the brick-
layer to accelerate the speed of transportation of the brick
up to the instant that it is deposited in the mortar.

The above practice is, of course, much more important
on shove-joint work than on brick-and-brick construction.

3. The possible benefits from acceleration should be
taken into consideration when determining the sequence
in which the tiers shall be laid. The position of the feet
of the bricklayer is an important factor in obtaining the
acceleration desired. For the best results the feet should



VARIABLES OF THE MOTION 67

be on separate springy planks, so that the transportation
of the brick can be speeded up, in addition to the speed of
the arms by simply throwing the body by the aid of the
spring of the plank. (See Fig. 13.)

AUTOMATICITY

Nearly all often-repeated motions become automatic.
This is especially true of motions that require no careful
supervision of mind or eye.

The automaticity of motions is of great assistance to
the worker whose training and methods conform to stand-
ardized motions. This fact makes it necessary to have
the apprentice taught the right motions first, last, and
always.

The automaticity of motions is a hindrance to the
worker who has been accustomed to old-fashioned sur-
roundings, equipment, and tools, and who must adapt
himself to standard surroundings.

Example. A remarkable example of making unneces-
sary motions as a matter of habit is noticeable in places
where the local bricklayers have been accustomed to laying
brick that have a decided difference in the top and bottom.
This difference makes it necessary to lay no brick upside
down on the line. When these bricklayers first worked
from packets with the brick in the right position to seize
right-side up, they would invariably flop and spin each
brick in their hands, first wrong-side up and then back
again to the original right-side-up position.



68 MOTION STUDY

The worker who has been trained wrong also finds it
difficult to change his habits when he conforms to standard
methods.

Example. Occasionally we find the bricklayer who
will spin or flop a brick that is to be laid in the middle of
the wall, although it makes no difference which face of the
brick is uppermost in these tiers.

The best way to cure motions that are not necessary but
that are made from force of habit is to count the motions
aloud, endeavoring to keep down to the standard number
of standard motions.

When work is done by both hands simultaneously, it
can be done quickest and with least mental effort if the
work is done by both hands in a similar manner; that is
to say, when one hand makes the same motions to the
right as the other does to the left.

Most work is accomplished when both hands start work
at the same time, and when the motions can be made at
the same relative position on each side of a central fore
and aft vertical plane dividing the worker's body sym-
metrically.

Even if motions cannot be planned to be similar for
each hand and performed simultaneously, the plane in
which the work is to be done should be carefully located.

If motions are so arranged as to be balanced, as sug-
gested, it is possible not only to take advantage of automa-
ticity, but also to cut down jar to the body. It is on this
well-known principle that the shockless jarring machine is



VARIABLES OF THE MOTION 69

built. Balanced motions counteract each other. The result
is, less bracing of the body is necessary, and less fatigue
ensues.

COMBINATION WITH OTHER MOTIONS, AND SEQUENCE

A motion may be combined with motions that are
(a) similar to it, and (b) dissimilar to it.

(a) If the motions combined are similar to it, advantage
must be taken of the automaticity. Care must also be
taken that all the motions made in a series of similar
motions are necessary. Sometimes one effective motion
is preferable to several not so effective.

Examples. i . When tapping a brick down to grade
with a trowel, one brisk tap will do the work as well as
several light taps, and with much less time and effort.

2. If it is necessary to spread mortar on a face tier, one
stroke of the trowel will do the work as well as several.

(b) If the motions combined are dissimilar, two motions
may often be transformed into one.

Example. - - The motion used to spread mortar may be
combined with the motion used to butter the end of the
brick laid just before the mortar was thrown. Thus, the
two operations may be transformed into one, and a saving
of time and motions will result. In fact, so doing may
have other distinct advantages, such as leaving better
keying for plastering direct upon the wall.

This subject of combinations of motions can barely be



70 MOTION STUDY

touched here. Its full treatment involves all other vari-
ables, and it can never be considered standardized till
each separate motion is a standard.

COST

The cost of motions, absolute and relative, is a subject
too large for any person, firm, or corporation to hope to
cover. If complete data are ever to be gathered on it, the
cost keeping, recording, and deducing will have to be done
by the government.

But all work done by the individual investigator will
result in real cost reducing, with increase of output, which
is the ultimate purpose of all motion study.

The relative cost of labor and material must be considered.

Examples. i. A bricklayer should never stop to pick
up dropped mortar. The mortar dropped is not so val-
uable as the motions necessary to save it.

2. That quality of mortar that is easiest handled by
the bricklayer is usually cheapest. The cost of grinding
up the lumps in the sand, cement, and lime is less than the
cost of the motions necessary to pick the lumps out with
a trowel.

3. It is usually cheaper to fill a closer, say less than one-
half a brick in size, on the interior tiers, with even the best
of cement, than it is to cut a special piece of brick to fit or
to walk a few steps to find one the right size. The extra
cost of the mortar is negligible compared with the cost of
the motions.



VARIABLES OF THE MOTION 71

The relative cost of motions of higher and lower grades
of labor must also be considered.

It is obvious that, other things being equal, it is cheaper
to have a low-priced man instead of a high-priced man
make the same motion; but only the most careful study
can determine all of the motions that could be taken from
the high-priced man and allotted to one or more grades of
lower-priced men. This can never be wholly or properly
accomplished until our present trades, with their inher-
ited conditions and traditions, have been reclassified to
meet modern conditions.

In some trades it is very difficult to effect such division
of work, as unions are opposed to having anything relating
to skilled work done by laborers.

Examples. i. In the most highly unionized districts
carpenters only are allowed to unload the rough lumber
from the cars, and none but carpenters are allowed to
transport, lift, and erect, as well as to fabricate it.

2. In bricklaying the case is slightly different. The
work of transporting the brick to the place where they are
to be laid has always been done by tenders and laborers.
The bricklayer never wheels or carries brick. This is a
tradition long handed down. Yet he is most jealous that
no part of his own work shall be done by a tender or
a laborer.

During the time that brick construction was practically
without competitors in its field, the bricklayer could insist
on his ancient privileges and prosper.



72 MOTION STUDY

The inroads of concrete, both plain and reinforced, how-
ever, have changed conditions, and the bricklayer himself
is, more than any other one factor, the cause of many cases
of substitutions of concrete for brick.

The architecture of any country is determined by the
relative cost of building materials in place, and the history
of the world shows that the way to get the most of any one
thing used is to make it the lowest in price.

The one thing that will reduce the price of brickwork
more than any other is to reduce the cost of the motions,

After the laws underlying motion study have all been
applied, the cost of motions can still be reduced from one-
third to one-half by separating the motions of the brick-
layer into at least two classes, such as, for example:

1. Those that require skill.

2. Those that require nothing but strength, endurance,
and speed.

Those that require skill should be divided into several
classes, according to the amount of skill required; those
that chiefly require skill should be handled by mechanics,
and those that chiefly require strength, endurance, and
speed should be handled by specially trained laborers.
This is the only way to enable brickwork to compete with
concrete, when all of the architects, engineers, owners,
and contractors shall have learned the full possibilities of
concrete.

It will be urged that such division of the work of
bricklaying will lower the general skill of the bricklayers



VARIABLES OF THE MOTION 73

as a class. Far from it! All operations requiring skill
will remain in the hands of the bricklayer, who, escaping
all work that unskilled hands could do, will have the more
time and energy to devote to the "art" element of his work.

But we are not at this time discussing " brickwork as a
lost art" -we cite bricklaying here as an example of the
cost of motions, the result of the effects of cost of motions,
and of the possibilities and importance of motion study as
a method of attack in cost reducing and in standardizing
the trades for the greatest possible economy.

What greater service can the bricklayer do both his trade
and the people who own or occupy houses than to reduce
the cost of the motions in brickwork without reducing his
own wages or increasing his hours?

The elimination of wastes is the problem that has been
forced to the attention of the entire world to-day, and of
America particularly. The elimination of wastes in the
trades offers the largest field for savings.

Every trade must be reclassified, and must have the
brawn motions separated from the skill motions. Scien-
tific division of the work to be done is as sure to result in
higher wages and lower production costs as did F. W.
Taylor's separating the planning from the performing.

The reason that our country is not astounded and con-
fused at the appalling unnecessary loss to its inhabitants
on account of unnecessary, wasteful, and improper mo-
tions of its workers is due to ignorance of the existence of
this loss, and to ignorance of any method of eliminating it.



74 MOTION STUDY

The loss due to the present classification of the trades
alone is probably more than sufficient to pension, under
full pay, one-half of the workers of the country; is cer-
tainly enough to enable all of the women and children in
the trades to remain out of the trades and be paid at
their regular wages.

While such action is not even recommended, the illus-
tration is used to emphasize the enormous waste going
on daily and yearly.

That we go on year after year submitting to this waste
because our present trades are handled in accordance
with ancient conditions entirely out of place in our pres-
ent civilization, is no longer necessary and without
excuse.

Let the government call its scientific managerial experts
together and make a test of one trade, reclassify it, and
publish the data. The object lesson thus presented will
cause to be taken the necessary further steps to remedy
the present system of handling the trades. The workers will
each be able to earn higher wages when the unions see that
they are benefited, and the labor interests will cooperate.
The cost of living will be reduced as by no other means,
and all this by scientifically reclassifying the trades!

DIRECTION

In most cases, the direction of a motion that is most
economical is the one that utilizes gravitation the most.
Oftentimes delivering material to a high-priced work-



VARIABLES OF THE MOTION



75



man by leaving the material in a high position also makes
easy unloading for the low-priced workman.

Example. Stacking up packs 2 feet high saves motions,
and saves stooping when the laborer unloads his trucket.
(See Fig. 21.)

" Direction" admirably serves as an illustration of the




Fig. 21. Trucket for storing reserve packs stacked up 2 ft. high,
to save stooping when it is being unloaded.



close interrelation of the variables. It is closely con-
nscted with "path." It involves discussions of anatomy,
acceleration, and speed. It demands consideration of all
variables of surroundings, equipment, and tools.

The best ''direction of motion" is not only important
in itself for increase of output; it must also be kept con-
stantly in mind in standardizing the placing of both
materials and men.



76 MOTION STUDY

EFFECTIVENESS

Effectiveness has been touched upon in discussing
" combination with other motions."

An effective motion is one that produces the desired
result. Oftentimes whole processes, methods, and oper-
ations can be so changed as to make the succeeding
motions much more effective.

Example. The introduction of the fountain trowel,




Fig. 22. The Fountain Trowel.

used in connection with an ordinary trowel, made each
motion in handling mortar much more effective. (See
Figs. 19, 22.)

FOOT-POUNDS OF WORK ACCOMPLISHED
After all, a human being or a work animal is a power
plant, and is subject to nearly all the laws that govern
and limit the power plant. It is a law of motion study



VARIABLES OF THE MOTION 77

that, other things being equal, the less number of foot-
pounds of work done by the workman, the smaller percent-
age of working hours he must devote to rest to overcome
fatigue.

It is therefore of great importance in obtaining the
largest possible output that the work shall be so arranged
and the workman so placed that he can do his work with
the least possible amount of foot-pounds of work done per
unit of output accomplished. This is where the philan-
thropic employer has often been rewarded without know-
ing it. In his desire to make conditions such that the
workman was most confortable while working, he re-
duced the number of foot-pounds of work to that which
was absolutely necessary to do the work. He surrounded
the workman with conditions that enabled him to have no
fatigue, except that which was acquired from the motions
of the work itself. He made conditions such that the
workman was enabled to overcome the fatigue from his
motions in the quickest possible time. (See Fig. 23.)

INERTIA AND MOMENTUM OVERCOME

There are two ways by which the amount of inertia
and momentum may be reduced.

i. By standardizing surroundings and equipment so
that the inertia and the momentum are limited to practi-
cally that of the materials, and not the materials plus
arms and body.



78 MOTION STUDY

Example. Picking up ninety pounds of brick at one
lifting.

2. By so standardizing motions that as few starts and
stops as possible occur from the time the material leaves
the stock pile till the time it is in its final resting place in
the work.

Example. In laying brick by the " pick-and-dip "
method on face tiers, a brick is lifted in one hand and a
trowel full of mortar in the other. The brick must come
to a full stop in the bricklayer's hand while the mortar is
being laid and the bed prepared, and then move to its
final resting place, unless brick and mortar are dropped in
two different places.

In laying brick by the " stringing-mortar " method, the
mortar is laid and the bed prepared before the bricks are
lifted. The brick are conveyed from the pack to the wall
without interruption or delay.

Standard methods of performing work may enable the
worker to utilize the momentum.

Example. If the bricks are conveyed from the stock
platform or pack to the wall with no stops, the momentum
can be made to do valuable work by assisting to shove
the joints full of mortar. If, instead of being utilized,
the momentum must be overcome by the muscles of the
bricklayer fatigue, not full joints, will result.

The ideal case is to move the brick in a straight
path and make the contact with the wall overcome the
momentum.



VARIABLES OF THE MOTION 79

LENGTH

A general rule of motion economy is to make the short-
est motions possible.
Eliminating unnecessary distances that workers' hands




Fig. 23. Common type of Trestle Horse Staging. Bricklayers cannot be
expected to lay as many brick per day when working in this position as
when standing up between a wall and a stock platform, each 2 ft. high.

and arms must travel, will eliminate miles of motions per
man in a working day as compared with usual practice.

Example. Put the wheelbarrow body as close as pos-
sible to the pile that is to be put into it, so that the dis-
tance the packets are carried from the pile to the barrow,



80 MOTION STUDY

or the sand from the pile to the barrow, will be the shortest
distance possible.

Of the necessary distance to be walked or reached,
have as much of it as possible done by the low-priced
man, and have as little of it as possible done by the high-
priced man.

Example. - With brick, have the tender put the pack
of brick as near the final resting place of the brick as con-
ditions will permit, so that when the high-priced man picks
up a pack of, say, eighteen bricks, he requires a short mo-
tion only.

Have the high-priced worker always use first the stock
that is nearest, this rule requiring the shortest motions
in conveying the stock to its final resting place.

Example. In picking up brick from a packet or a
scaffold the nearest brick should be picked up first. The
brick that are farthest away serve as a reserve stock pile,
to be picked up only in the emergency of not having any
others nearer to pick up. It .may be that the brick farthest
away may not need to be used on that piece of work at
all, or at least their place will not be occupied so many
times by bricks to be transported with longer motions.

Standard tools, equipment, and surroundings are essen-
tial if length of motions is to be made standard.

As already said when discussing clothes, the workman
of the present should have even his overalls, belt, and
clothes so designed that they will hold the different kinds
of tools that are oftenest used, so that they may be picked
i p in the shortest time that is, with pockets for nails,
clips, clamps, etc. The tools should be so placed that
the least and shortest motions can be used after they are
picked up, as cartridges are placed in a cartridge belt.

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