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VI. Developments in Harvesting Equipment
RECXNT DEVELOPMENTS I N AGRICULTURAL MACHINERY
201 per cent, and field forage harvesters by 215 per cent. Percentage
increase of machines on specialized crops is even greater, depending
upon the number needed and the degree of success in perfecting the
equipment. The harvesting of specialized crops is rapidly changing from
hand to mechanical methods. Scarcity of labor and tightening of the
economic situation is expediting this change-over.
Increase of mechanized harvesting contributed primarily to the 21
per cent reduction in man-hours used on farms in the past ten years.
There has been very little reduction in man-hours used for those crops
in which the harvesting has not been mechanized.
The general trend has been toward harvesting equipment that can
be operated by one man with the least expenditure of his energy. The
trend in design is toward more automatic operation, increased use of
hydraulic systems, V-belt drives, self-aligning prepacked bearings, and
lighter materials for construction where possible. Less vibration is experienced owing to better balancing of moving parts. The use of large
harvester-mounted bulk bins unloaded by gravity dumping or auger
conveyors is becoming standard practice.
There is a trend toward larger self-propelled machines for the bigger
farms. Smaller machines are being designed to mount on tractors or
other power units which can accommodate several types of equipment.
Harvesting machines are being designed to operate under a wider range
of crops and cropping conditions.
Forage crop production of over 100 million tons (excluding that used
for silage) constitutes approximately one-fifth of all harvested crop acreage in the United States. S t r i d e r and Phillips (1956) report that while
only 29 per cent of all hay was baled in 1944, 73 per cent was baled in
1954. This trend was due primarily to the introduction of automatic-tie
pickup balers, reduction of storage space requirements, and ease of handling as compared with loose hay. Chopped hay for curing and dehydration increased from approximately 2 to 7 per cent during the same
period. Long, loose hay has steadily declined during these same years
to a low of 20 per cent in 1954.
Although hay crops in general have a relatively low cash value per
acre, much progress has been made in equipment for mechanizing the
crop. Improvements in hay crushers have decreased the hazard of crop
loss under changing weather conditions. Automatic one-man-operated
balers with a second man loading the trailer has been a common practice
for the past ten years. Recently, one-man hay balers have been designed
to kick or throw the bale into the trailer, thereby eliminating one man
T. W. EDMINSTER AND H. F. MILLER, JR.
FIG.9. One-man baler throws bales from machine to trailer. (Courtesy Deere
and C o . )
(Fig. 9). It appears that hay pelleting or wafering by field machines may
further reduce the handling costs in the field, in storage, and in feeding.
With over 75 per cent of the mowers equipped with power drive in
lieu of ground drive, 6- and 7-foot cutter bars have become standard.
Elfes (1954) reports on the design and development of a new highspeed mower having a reduced stroke length and a dynamically counterbalanced reciprocating blade so designed that its operation is not affected
by the raising and lowering of the bar. It is equipped with special sealed
antifriction bearings throughout, and a V-belt replaces the pitman rod.
2. Hay C w h e r s
The general use of field hay crushers has increased from only a few
hundred to several thousand between 1955 and 1958.
Consisting primarily of a pair of steel rollers held together under
pressure by adjustable springs, the crusher is driven by the power-takeoff of the tractor. A pickup unit lifts the hay from the swath and feeds
it between the rolls. The crushed hay is dropped back onto the stubble
in a swath. Crushers are made as separate units or in combination with
RECENT DEVELOPMENTS IN AGRICULTURAL MACHINERY
Ramser and Kleis (1952) and Butt et al. (1956) report that crushed
hay generally dries to a safe storage moisture content in one-third to
two-thirds of the time required for uncrushed hay. Although the reduction in drying time is seldom sufficient to allow cutting and storing in
the same day, it often allows the hay to be picked up on the second day
when normally it would take 3 or 4 days for it to reach a safe moisture
content. Earlier models of the hay crushers generally had smooth crushing rolls, whereas some recent models are equipped with fluted rolls
which tend to crimp the hay.
Agricultural statistics indicate that side-delivery rakes on farms have
become the predominant type, with approximately 1.3 million in use in
1957. Bainer et al. (1955) classify side-delivery rakes as ( 1 ) cylindricalreel, ( 2 ) oblique reel-head, ( 3 ) finger wheel, and (4)drag-type. Each
of these rakes, owing to differences in design, imparts a different velocity
and movement to the hay in the raking process. Giles and Routh (1951)
in comparative tests on the three side-delivery-type rakes found that the
leaf loss with the finger-wheel rake was considerably less than with the
other two types. The increased mobility of tractor-mounted rakes facilitates their use on grassed waterways, terraced outlets, and in odd-shaped
land areas that may occur in conservation layouts.
Improvements in equipment for baling have increased the popularity
of this method of harvesting and handling hay. Outstanding changes
have been the development of the automatic baler and the use of twine
for tying. There has been a threefold increase in the number of automatic pickup balers since 1950. Of the approximately 600,OOO in 1958,
approximately 80 per cent used twine. In addition to the shift toward
more twine-tied balers, there has been a trend toward smaller bales.
These bales are easier to handle and are particularly adapted to the
one-man balers equipped to eject the bale into the trailer. At least one
company is proposing a control which permits the tractor driver to
change the direction in which the bale is thrown.
The two main types of balers are the plunger type (rectangular bale)
and the round-bale type. Hay buyers have generally demanded denser
Burrough and Graham (1954) developed a method employing strain
gages and a sensing unit for measuring the power input to various drives
of plunger-type forage balers which show the effects of varying moisture
content, bale density, baling rate, and plunger speed. The maximum
T. W. EDMINSTER A N D H. F. MILLER, JR.
force required for an increase in bale density of 8 to 10 pounds per cubic
foot increased from 4500 to 10,OOO pounds, and the baling energy increased from 1.2 to 2.2 horsepower-hour per ton. For only a 14-pomd
increase in a 7-cubic foot bale, almost twice as much energy is required.
Automatic twine-tying devices have been refined and improved. Baler
twine is heavier than binder twine, having a tensile strength of approximately 275 pounds. The normal rectangular twine-type bales use slightly
over 3 pounds of baler twine per ton, while round bales require slightly
over 2%pounds of binder twine per ton.
Bainer et al. (1955) describe the need and present-day use of safety
devices or shear pins in such places as (1)between the flywheel and the
plunger, ( 2) in the drive ahead of the baler flywheel on power-take-off
driven balers, (3) in needle drive should it strike an obstruction, (4)
in the drive to the tying mechanism, ( 5 ) in the pickup and conveying
drive, and (6) in the feed-mechanism drive to prevent overloading.
With different attachments, field forage harvesters can be used to
harvest row crops for silage, grass from a standing crop or windrow for
silage, straw and other kinds of forage, and green chopped hay for direct
feeding or dehydration. Field forage harvesters, developed first about
1936, have increased rapidly in recent years from approximately 80,000
in 1950 to 240,000 in 1957. These machines took the place of the row-crop
Field forage harvesters are of two major types, cIassified as to placement of cutting knives into a flywheel or cylinder arrangement. The
flail-type forage harvester developed from the swinging-blade stalk
shredders since World War I1 has recently increased in importance Fig.
Bockhop and Barnes (1955) ran tests on power distribution and requirements of a flail-type forage harvester, reporting the power requirements as relatively high when compared with conventional-type forage
harvesters but having comparable capacity. The flail-type machine is of
simple design with relatively few working parts and can be utilized as
an ensilage harvester, hay and straw chopper, stalk shredder, weed
cutter, beet topper, and for other purposes. The authors further state
that it can probably be used economically by a farmer who uses an
ensilage harvester an average number of hours per year and who already
has a three- or four-plow tractor. The economy-model flail harvester
results in a product with somewhat longer length of cut, and when this
is not objectable, farmers should find it acceptable, especially where
green-feeding practices are used.
RECENT DEVELOPMENTS I N AGRICULTURAL MACHINERY
King and Elliott (1955) report on the development of a semi-selfpropelled baler and forage harvester, both pickup and direct cut. The
tractor is used as a prime mover, with mounting hitches so designed
and arranged that the tractor may be hitched to the harvester in a matter
of 2 or 3 minutes. A separate power unit when needed may be mounted
on the three-point hitch behind the tractor and beside the harvester.
Cykler (1950) tells of harvesting Napier grass in Hawaii with a harvester developed and used for harvesting green feed the year around.
FIG. 10. Flail-type harvester cuts, chops, and loads forage by direct-cut or
from windrow. (Courtesy Lundell Manufacturing Co., Inc. )
It was mounted on a track-type tractor for use on small, rough, rocky,
and irregularly shaped fields.
A commercial machine for field hay pelleting was announced during
1958. While not yet in wide commercial use, it should have great potential if present experimental harvesting and feeding trials continue to be
successful. It will greatly reduce the cost of handling forage both from
the field to storage and from storage to feeding. Dobie (1959) reports
that by far the greatest activity is being exerted in the field of producing
large wafer-type pellets. He states that numerous manufacturers are
T. W. EDMINSTER AND H. F.
making pellets 3 to 4?iinches in diameter and % to 1%inches thick. Most
of these machines are plunger-type machines with the application of the
high pressure necessary to make the wafer of suitable density resulting
in terrific impact pressure at the forward end of the stroke. A heavy
frame plus the heavy flywheel needed to move the pulsating load, results in a fairly heavy machine per ton per hour output. The principal
advantage of the plunger machine for wafering is that it will handle
either long or chopped hay; this reduces the cost of processing prior to
pelleting and places field pelleting in a more favorable position because
less auxiliary equipment is needed. Wafers made from chopped hay are
usually more uniform in shape and thickness than long hay wafers. The
present field machines for making wafers have the capacity of about
one-half that of a conventional baler and make wafers best from hay
containing from 12 to 20 per cent moisture.
6. Mbcelluneous Equipment
Windrowers, hay tedders, and various types of buck rakes and hay
loaders are passing through a period of redesign and modernization.
Hydraulic-operated, tractor-mounted units of many types are available
for putting up loose hay.
Corn is the largest acreage field crop in the United States and the
most important source of feed, with 90 per cent of the total corn acreage
harvested for grain. Ninety per cent of the total annual production of
corn, 3%billion bushels, is from the twelve North Central States. There
are approximately 745,000 corn pickers in the United States, an increase
of about 42 per cent since 1950. According to Scoville (1956) over onehalf of these are in the Corn Belt, but the most rapid rates of increase
in the past few years have been in the South, Northeast, and Far West.
A new type of picker-sheller unit, introduced since 1953, is a modified
grain combine for picking and field shelling of corn. According to the
best estimates, there were slightly over 5000 picker-sheller units in use
in 1957 and approximately 9OOO grain combine attachments for picking
and field shelling.
Corn harvesters may be classified as snappers, picker-huskers, or
picker-shellers. Bainer et al. (1955) report a fourth type, introduced
commercially in 1954 as a combination picker-chopper. This machine
picks the ears and delivers them into a wagon while the stalks are cut
and fed into a conventional forage-chopper and either discharged on
the ground or delivered into a truck or moving wagon beside the harvester.
RECENT DEVELOPMENTS IN AGRICULTURAL MACHINERY
Safety is one of the greatest problems to consider in the use of a
mechanical corn picker. Scranton (1952) reports that in a survey it was
found that nearly all accidents with corn pickers were caused by carelessness. There is a major educational task in teaching users of such
machines to be careful. There are some twenty-one rules listed for normal and safe operation of corn pickers by the Farm Division of the
National Safety Council.
1. Snappers and Picker-Huskers
A snapper-type corn harvester is essentially the same as a pickerhusker except that there is no provision for removing the husks. The
snapped ears are conveyed directly into a wagon. The snapping rolls
are generally operated at about 500 to 600 f.p.m. (peripheral speeds).
The rolls are ordinarily made of cast iron or cast steel, with spiral ribs
or lugs on their surfaces. On a picker-husker, the husking rolls may be
on a separate bed, incorporated in the snapping-roll elevator, or may
be a direct extension of the snapping rolls. Most husking units have one
roll of each set made of rubber; the other roll may be of steel, wood,
rubber, or cast iron. Field losses generally run in the range of 5 to 10
per cent. Field losses may be kept to a minimum by proper adjustment
of the machine, careful driving, and avoiding high speeds. Under most
conditions, speed should not exceed 3 to 3%m.p.h.
Richey et al. (1956) report a new design for corn-snapping rolls. The
new principle varies from the conventional in that the stalk is bent sideways and passes through the snapping rolls at about a 45-degree angle.
This action clears the ears from the rolls and reduces the shelling losses.
The side-snapping action tends to spread the rolls in a 45-degree plane
and is referred to as the side-snapping principle.
2. Picker-Shellers and Combine Attachments
Picker-sheller corn harvesters may be of the same general design as
the picker-huskers, except for the addition of the shelling unit and a
grain bin or elevator to elevate the shelled corn into a trailing wagon
or one pulled beside the harvester. Corn may be harvested with pickershellers with a moisture content ranging from 14 per cent (dry enough
to store) up to 30 per cent or higher. When the early-harvest method
is practiced, the corn will be too high in moisture content to store and
must be artificially dried down to approximately 14 per cent moisture.
Ear corn will keep in storage up to moisture contents of around 20 per
cent. Hurlbut (1955) and Pickard (1955) tell of experimental work
between 1950 and 1954 on an experimental ear-corn harvesting attachment which mounts on the front of a combine, and also compare differ-
T. W. EDMINSTER AND H. F. MILLER, JR.
ent types of cylinders and concaves for efficiency in shelling of corn.
Morrison (1955) reports on the commercial adaptation in 1953 of a
com-harvesting attachment on a self-propelled combine. He lists fourteen different advantages of combining corn, including more economical
and efficient harvest, an earlier harvest, crop residues left in the field,
and less storage space required.
Goss et al. (1955) reported on tests, conducted in California during
the 1954 harvest season with corn-harvesting attachments, which indicated that the ordinary grain combine equipped with a rasp-bar cylinder
is well suited for shelling corn under California conditions. The major
problem in harvesting corn with adapted combines was the delivery of
the unshelled corn to the cylinder without loss of corn, primarily ear
corn on down or lodged stalks.
The combine attachments for corn are relatively simple, and fast
change-overs from grain to corn are possible on most machines because
both front ends attach to the same bearing points and use common
drives and the same lifting system. There is no wagon to pull and the
machines operate better in soggy fields.
C. GRAIN,LEGUME,AND GRASSSEED HARVESTING
Although grain combines are used primarily to harvest small grains
and soybeans, they are used for many other crops, such as rice and
various legume and grass seeds. In the United States, combines have
almost completely taken over the job of threshing grain, either by direct
cutting or combining from a windrow. Brodell et al. (1952) reported
that 85 to 95 per cent of the barley, wheat, and soybean crops in the
United States were harvested with combines in 1950.
There were approximately 1,040,OOO combines in the United States
in 1957, compared to approximately 700,000 in 1950. Approximately 20
per cent of the combines on farms today are the self-propelled type, and
this trend is rapidly increasing, since approximately one-half of the combines manufactured during 1956 and 1957 were of the self-propelled
type. The main advantages of self-propelled combines over the trailingtype machines are that they have greater flexibility and maneuverability,
save more grain in opening up fields, and permit the driver to have
better control of his machine and a better view. Gray (1955) gives the
function, operation, and care of the combine, as well as details with
respect to adjustments for twenty different crops,
Witzel and Vogelaar (1955) report that the first self-propelled combines on rolling ground did not gain widespread popularity, probably
because during the period from 1910 to 1930 the track-type tractor came
into being as the primary answer to pulling the large hillside combines.
RECENT DEVEMPMENTS IN AGRICULTURAL MACHINERY
During the period from 1910 to 1949, hillside combine development was
marked by general design improvements, such as universal adoption of
steel frame and body, antifriction bearings, V-belt drives, rubber tires,
and weight reduction. Another advance during this period which helped
to reduce manpower requirements was the adoption of bulk handling
of threshed grain, thereby eliminating the sack sewer and sack “jigger.”
In addition, several ingenious automatic leveling-control devices had
been developed, making possible a two-man crew in place of the original
They further report that the relatively recent development and widespread adoption of level-land, self-propelled, pusher-type combines was
watched with a great deal of interest by the hillside area farmers. At
least two hillside self-propelled pusher combines went into the field in
1949. A limited number of hillside self-propelled combines were put in
the field by one manufacturer in 19%. Inventors converted several hillside combines to the self-propelled type.
Several makes of hillside combines were available by 1954. This year
also marked the introduction of the first hillside combines with factoryinstalled automatic leveling controls. The main difference between a
hillside combine and a conventional combine is that the separator body
is kept level in the lateral direction regardless of the ground slope. Some
combines have a part of, or the entire, separator kept level to some
degree in the longitudinal direction. The need for and advantage of
longitudinal leveling depends somewhat on the separator design.
The two main types of sensing devices for automatic controls are
those in which the force of gravity acts on a solid mass and those in
which it acts on a liquid. The first of these is primarily the pendulum
type which controls hydraulic valves directly and is also used to control
electric switches which energize hydraulic-valve solenoids. The second
type depends on the force of gravity acting on a liquid, such as a mercury switch.
Safety is important in the use of hillside combines. They are designed
with a wide wheel base so that the center of gravity falls well within the
wheel base at extreme hillside conditions. Each individual wheel also
has a brake. Power steering used on models produced during the last
few years is itself a good safety device. Automatic controls also assist
in safety since they guard against the operator leveling the wrong way.
Heitshu (1956a) describes the chain of events leading to the development of one manufacturer’s self-propelled hillside combine. The
complete drive-axle assembly and a schematic drawing of the automatic
leveling circuit is given. Many of the operating characteristics and safety
features of the hillside combine are described in detail.
T. W. EDMINSTER AND H. F. MILLER, JR.
Pool (1958) describes controls for full-leveling of hillside combines.
This article is the partial history and gives details of engineering developments leading to the manufacture of a hillside combine by another
major company. The pendulum system with direct-acting valves was
used to activate the mechanism for leveling this particular combine.
Bigsby (1958) describes power requirements of a combine cylinder
when threshing solid and hollow-stemmed varieties of wheat. By the
use of strain gage equipment, he determined that 20 to 25 per cent more
power is required on the cylinder when threshing solid-stemmed wheat
than is required to thresh hollow-stemmed wheat at the same rate. This
problem became one of major interest when severe losses in wheat yield
in western Canada caused by the wheat stem sawfly resulted in the
development of solid-stem varieties of hard spring wheat.
Self-propelled combines are now being offered with 18-foot-wide
cutter bars, both for the level and the hillside types. Many features are
now being built in the combines, such as lifetime lubricated bearings,
improved V-belt and pulley drives with mechanisms for easy adjustment
or changes in speed, as the case may be. Many combines are also offered
with windrow pickup attachments for combining grain and other crops
from the windrow if desired. Many companies are offering attachments
for corn harvesting, as previously discussed.
Air-conditioned cabs are now available for self-propelled combines
which give year-round heating or cooling. The compressor for cooling is
belt-driven from the combine engine. Full-view windows with tinted
safety glass are featured for greater comfort for the operators,
Although soybeans are harvested primarily by conventional-type combines, problems of germination in connection with cracking of seed during harvest are common, as discussed by Moore ( 1957). Heitshu ( 1956b)
discusses the problems of ridging and low pods as being serious to contend with in combining and the necessity of keeping the ridges low so
that the height of beans on the ridge and those in the middles will not
be too different. He also points out the important contribution which
could be made by plant breeders and agronomists with respect to soybeans, as has been the case with many other crops. He feels that, through
the cooperation of plant breeders and engineers, soybeans which have
higher fruiting characteristics and a more desirable row profile can be
grown, and that machines can be made which will do a more efficient
job of harvesting and reduce cracking.
Bunnelle et al. (1954) say that successful harvesting of small-seeded
legumes depends as much on the cultural practices used to produce the
crop as on the operation of the harvester. Combines, when properly
adjusted, are capable of doing a good job of harvesting these crops,
RECENT DEVELOPMENTS IN AGRICULTURAL MACHINERY
although most machines require some modification for the best performance. They further conclude that at normal load rates, the factors
affecting combine performance in small-seed legume harvesting are
cylinder speed, loss of free seed over the straw walkers, and the cleaning shoe adjustment. Park and Webb (1958), reporting on southeastern
seed harvest studies, give several conclusions for different crops. They
conclude that angle-bar cylinders threshed more crimson clover seed
with less seed damage than rasp-bar cylinders. Supplemental angle bars
are available for most combines with rasp-bar cylinders for use on
hard-to-thresh crops. Rubber on angle bars significantly reduced seed
damage. Low ground speed was necessary to minimize seed losses in
crimson clover. In small grains tests, when comparing the angle-bar and
rasp-bar cylinders and comparing open and closed grates, Park and Webb
found no appreciable differences in threshing performance. The most
serious losses in rescue, fescue, and lespedeza seed were due to weather
and cutter-bar shattering, often amounting to over 50 per cent. Cutter-bar
loss was reduced and cutting performance was improved by use of a
tined pickup reel.
Klein and Harmond (1959) give the development of a suction-type
field reclaimer for shattered seed which was mounted on a combine and
used as a once-over operation. The attachment for picking up shattered
seed used revolving swinging chains to loosen the seed at the ground
surface within the suction head mounted behind the combine. The seed,
straw, and soil are conveyed back into the combine separating mechanism where the seed is saved. Tests show an increase in recovery of pure
live seed from 46 per cent to 68 per cent in crimson clover and from
24 per cent to 62 per cent in sub clover when compared with combining
without the benefit of the suction seed reclaimer.
Mechanical cotton harvesters available today are of two basic types,
commonly referred to as pickers and strippers. Picking machines remove
seed cotton from the open bolls, the unopen bolls being left on the plant.
Stripper-type harvesters strip the entire plant of the cotton, including
the open or closed bolls and many leaves and stems. It was 1946 before
mechanical cotton harvesters were manufactured in any appreciable
number; by 1957 about 20,400 pickers harvested 19 per cent of the crop
and 26,500 stripper-type machines were used on farms to harvest 13 per
cent of the crop, making a total of one-third or less of the cotton crop
in the United States machine-harvested.
Colwick and Regional Technical Committee members (1953) describe the Beltwide harvesting results from several phases of regional