Center pivot irrigation system having apparatus for irrigating corners

A center pivot irrigation system has first and second auxiliary nozzles, or end guns, alternately operable for irrigating substantial portions of corner regions. The system includes a main pipeline sprinkler having main fluid discharge nozzles for irrigating a central, generally circular area, and the end guns are connected to the main pipeline sprinkler and draw irrigation fluid from it. When a corner is approached, one of the end guns is actuated while maintaining actuation of the main fluid discharge nozzles. A short period of time thereafter, the second end gun is actuated, and the pivotal rate of the main pipeline sprinkler is reduced to zero. At this time the main fluid discharge nozzles and the first end gun are closed, thereby providing all of the fluid from the main pipeline sprinkler to the operating end gun. After a predetermined time period, the second end gun is inactivated, the first gun and the main nozzles are reactivated, and the system is pivoted to a new orientation. After several such sequences and the corner has been passed, only the main nozzles are actuated until another corner is approached. Timers are provided for determining the duration of the periods during which the irrigation fluid is being discharged through the various nozzles, thereby to allow effective control of the amount of irrigation fluid discharged.

BACKGROUND OF THE INVENTION 
The present invention relates generally to center pivot irrigation systems, 
and more particularly to center pivot irrigation systems which are adapted 
to selectively provided irrigation to substantial portions of corner 
regions. 
Center pivot irrigation systems for irrigating large areas, such as 
agricultural areas, are now well known. For example, the model 2200 center 
pivot irrigation system, commercially marketed by Lockwood Corporation, 
Gering, Nebr., irrigates approximately 130 acres about a center using an 
elongated main pipeline sprinkler having a plurality of main fluid 
discharge nozzles which are spaced along the main pipeline. This system 
has proven to be advantageous for irrigating the inner acres of a 
rectangular plot. However, for the rectangular plot substantial areas in 
the corners are not irrigated by the center pivot sprinkler system. 
Accordingly, it is highly desirable to provide apparatus for adapting such 
a now conventional center pivot irrigation system into a system which 
additionally will irrigate much of the corner areas lying outside the 
generally circular area. 
Various corner irrigating systems for use with center pivot irrigation 
systems have been proposed. One such proposal suggests the utilization of 
an electrically actuated water gun disposed on the end of the main 
pipeline sprinkler. Actuation of the end gun applied irrigation fluid from 
the main pipeline sprinkler to areas outside the main circular area. The 
end gun was to be actuated upon a particular orientation of the main 
pipeline sprinkler as a corner was approached, and was to be maintained in 
actuation until the main pipeline sprinkler swept past the corner. 
Although such a proposal may have been an improvement over systems without 
corner irrigation apparatus, it failed to account for the effect of the 
drain of the end gun on the rate of discharge of the main pipeline 
sprinkler. Furthermore, use of only a single end gun in the corner areas 
provided only a single level of improvement over the then existing 
systems, leaving substantial corner portions still unirrigated unless 
areas outside the corners also received irrigation. 
Other proposals for irrigating corner sections have suggested the use of an 
auxiliary sprinkler system mounted on a controllably moving boom. The boom 
was pivotally connected to the distant end of the main pipeline sprinkler 
and carried auxiliary nozzles. In such proposals, the boom would pivot 
outwardly in the corner areas and the auxiliary sprinkler system would be 
actuated for irrigating the portions of the corner areas lying outside the 
inner circular area. These systems have either required a rather 
sophisticated drive mechanism which was programmed to cause the boom to 
swing in and swing out in the corner areas, and/or such systems required a 
buried conductor which served to guide the boom outwardly and inwardly in 
corner regions. The systems according to these proposals have not received 
full commercial acceptance and success because they have been relatively 
expensive and costly to service. 
One of these proposed systems having such a boom type auxiliary sprinkler 
system suggested that, while advancing the auxiliary boom inwardly and 
outwardly, the pivotal rate of the main pipeline sprinkler should be 
reduced. This reduction in pivotal rate was to maintain sufficient water 
pressure supplied to the systems such that a special subsystem for 
regulating the rate of discharge from the various nozzles could be 
maintained operable and thus be utilized. This system did not recognize 
the advantages which could be achieved by operating the auxiliary 
sprinkler system only when the main pipeline sprinkler was neither 
pivoting nor providing irrigation fluid to the inner circular area. 
SUMMARY OF THE INVENTION 
The above noted and other disadvantages of the prior art are overcome by 
providing a center pivot irrigation system having an auxiliary sprinkler 
system which dispenses water when the main pipeline sprinkler is neither 
pivoting nor dispensing irrigation fluid. By mounting the auxiliary 
sprinkler directly onto the main pipeline sprinkler, the amount of extra 
hardware required is minimized, thereby lowering manufacturing and 
maintenance costs as well as obviating the otherwise required extra wheel 
tracks associated with prior art corner irrigating systems. By stopping 
the pivotal rate of the main pipeline sprinkler during operation of the 
auxiliary sprinkler, the irrigating fluid supplied to the main pipeline 
sprinkler is sufficient in amount and pressure to supply the demands of 
the auxiliary sprinkler, thereby obviating the otherwise need for booster 
pumps or modified pumps. The auxiliary sprinkler system is adapted for use 
on existing systems which are to be converted for corner watering. 
According to one embodiment of the invention, a center pivot irrigation 
system includes a main pipeline sprinkler which is rotatable about a 
center and which has a plurality of main fluid discharge nozzles spaced 
therealong for controllably providing fluid to a central, generally 
circular area. The system has a signal generator for producing control 
signals in response to and indicative of the rotational position of the 
main pipeline sprinkler about the center. 
A drive mechanism rotates or pivots the main pipeline sprinkler in response 
to the control signals. It pivots the main pipeline sprinkler at a 
substantially constant first rate for irrigating non-corner areas, and at 
an intermittent rate for irrigating the corner areas. The intermittent 
rate is defined in part by periods of predetermined duration during which 
the main pipeline sprinkler is not pivoting. The system features an 
auxiliary sprinler having at least one auxiliary nozzle at the end of the 
main pipeline sprinkler and which draws its irrigation fluid from the 
pipeline sprinkler. The auxiliary nozzle is operated by the control 
signals for irrigating the corner areas only during the periods of 
nonrotation of the main pipeline sprinkler. 
According to another aspect of the invention, the described embodiment 
includes a main nozzle control mechanism for selectively closing the main 
discharge nozzles during the periods when the main pipeline sprinkler is 
not rotating. This allows the source of water supplied to the main 
pipeline sprinkler to be sufficient in pressure and volume for operating 
the auxiliary nozzles without the need for booster pumps. This feature 
also allows corner irrigation to be achieved at a reduced brake horsepower 
and a reduced irrigation supply out-flow capacity. 
According to another feature of the invention, the described embodiment 
further utilizes a main conduit for providing water for both the main 
nozzles and to the auxiliary nozzle. Because the main nozzles may be 
selectively closed, and because the remote end of the main pipeline 
sprinkler is adapted to be directly connected to another such main 
pipeline sprinkler, increased versatility is achieved which allows one 
main pipeline sprinkler to be converted into a fluid carrying conduit 
which only transports the irrigating fluid to the second main pipeline 
sprinkler. 
According to another embodiment of the invention, the auxiliary sprinkler 
includes both first and second auxiliary nozzles. One nozzle is operated 
or opened when the main pipeline sprinkler is pivoting while the second 
nozzle is operated only when the pivotal or rotational rate of the main 
pipeline sprinkler becomes zero. The one nozzle provides a spray of a 
lesser range and volume and is operated alternately of the second 
auxiliary nozzle which provides a spray of an extended range and volume. 
By operating the lesser range nozzle first and then by operating the 
extended range nozzle, not only greater portions of the corner regions are 
irrigated without irrigating outside of the corner regions, but a highly 
uniform application of irrigating fluid is achieved. 
According to another feature of the invention, programmable timers are 
provided to adjustably determine the duration of the periods during which 
the main pipeline sprinkler is operating at the substantially constant and 
zero pivotal speeds. The timers thus determine the duration of the periods 
of operation of the auxiliary nozzles; i.e., the amount of irrigating 
fluid discharged to the corner regions. Because the pivotal rate of the 
main pipeline sprinkler is zero during operation of the extended range 
nozzle, the volume of fluid delivered to the corner areas may be 
controlled substantially independently of the volume applied to the 
central area by the main pipeline sprinkler. 
As another feature of the invention, a disable mechanism is provided for 
selectively disabling the auxiliary sprinkler for one or more corners 
during a rotational cycle of the main pipeline sprinkler. The disable 
mechanism allows the user to selectively skip the irrigation of one or 
more particular corners which need not be irrigated; for example, because 
of the presence of buildings, etc. 
According to still another feature, the auxiliary system is failsafe. Upon 
a malfunctioning of the auxiliary sprinkler system, it is disabled, and 
only the main pipeline sprinkler is allowed to continue operation. 
Similarly, the auxiliary system may be completely disabled, if desired by 
the user, to allow operation of only the main pipeline sprinkler for 
irrigating only the inner, circular area. 
It is accordingly a general object of the present invention to provide a 
new and improved center pivot irrigation system which is economical to 
produce and use and which provides corner watering capabilities. 
The above noted and other features of the present invention will become 
more apparent upon considering the following detailed description of a 
preferred embodiment when read in conjunction with the drawings; wherein

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring now to FIG. 1, a center pivot irrigation system 10 includes a 
main pipeline sprinkler system 12 and an auxiliary sprinkler system 14. 
The main pipeline sprinkler system 12 is coupled to a water supply 16 at a 
central pivot point for irrigating a central, generally circular area 
about the pivot point (see area A in FIG. 2). The auxiliary sprinkler 
system 14 is disposed substantially at the end of the main pipeline 
sprinkler system 12 opposite the water supply 16. The auxiliary sprinkler 
system 14 is selectively operated as the main pipeline sprinkler system 12 
pivots for irrigating substantial portions of corner regions (see area B 
in FIG. 2) of generally rectangular plots requiring irrigation. 
The water supply 16 includes an irrigation supply pump and power equipment 
therefore. The pump is of a design of provide adequate pressure as 
required for properly operating the auxiliary system 14. 
The main pipeling sprinkler system 12 includes a pivot stand assembly 20 
coupled to the water supply, and a long boom 22 pivotally connected to the 
pivot stand 20. The boom 22 includes a plurality of sections of pipe 24 
which are connected end to end to provide a length ranging from several 
hundred feet to, for example, more than 1500 feet. The pipe 24 is directly 
connected to the water supply 16 and is of a sufficient inside diameter to 
convey water therefrom at a rate of over 1200 gallons per minute. 
The boom 22 carries a plurality of primary fluid dispensing nozzles 26 
disposed at spaced intervals along the sections of interconnected pipe 24. 
Some thirteen towers may be provided with a spacing between towers 
preferably of approximately 125 feet. The boom 22 also carries diaphragm 
type hydraulic valves (not shown) coupled in fluid passing communication 
between the pipe 24 and the primary nozzles 26. Additionally a control 
tube (not shown) for the hydraulic valves is carried by the boom 22. The 
control tube is connected to all the hydraulic valves for controlling 
operation of all the primary nozzles 26. Pressure to the control tube is 
controlled by a pair of feed/bleed valves (hereafter the FEED/BLEED 
valves). 
One of the FEED/BLEED valves is located at the pivot stand assembly 20. The 
second FEED/BLEED valve is positioned approximately 2/3 of the distance 
from the pivot stand assembly 20 to the end tower. It has been determined 
that approximately half of the total water flow is released during the 
first 2/3 of the length of the boom. Therefore, the second FEED/BLEED 
valve is connected at the 2/3 distance. 
When pressure within the control tube is bled to atmosphere, the hydraulic 
valves open, allowing discharge of the irrigating fluid (i.e. water) 
through the primary nozzles 26. Conversely, pressure, i.e., water 
pressure, within the control tube above a threshold valve, renders the 
valves into a closed condition, preventing discharge through the nozzles 
26. 
The sections of pipe 24 are supported by a plurality of motor driven towers 
28 disposed at the intersections of the sections of pipe 24 and by pipe 
supporting trusses 30 connecting adjacent towers 28. A supporting truss 
also connects the first tower to the pivot stand assembly 20. The towers 
28 and the trusses are constructed and arranged to provide a ground 
clearance of approximately nine feet with a minimum of wind resistance. 
Each of the towers 28 carries a set of wheels and a tower motor for 
driving its wheels and thereby effecting pivoting or rotation of the boom 
22 about the pivot stand assembly 20. 
A control system 32 (see FIGS. 3a-3c) controls energization of the end 
tower motor to rotate the boom 22 about the pivot stand assembly at 
operator specified pivotal or rotational rates. An alignment system is 
provided (not shown) for operating the remainder of the tower motors to 
maintain the sections of pipe 24 in alignment. The alignment system 
employs a tension wire stretched along the boom and employs mechanical 
linkage responsive to movements in the tension wire to actuate 
microswitches for respective tower motors. Actuation of the microswitches 
energizes the appropriate tower motor to bring the sections of pipe into 
alignment. 
The control system 32 includes an angle sensor 34 for providing signals in 
response to and indicative of the rotational position of the boom 22 about 
the stand assembly 20. One embodiment of the angle sensor 34 utilizes cam 
operated switches. The cam rotates according to the pivotal movement of 
the boom 22 and has lobes which actuate the switches to generate signals 
representative of the orientation of the boom 22 about the pivot stand 
assembly 20. 
According to an outstanding feature of the invention, the control system 32 
drives the boom 22 about the pivot stand assembly at intermittent rates 
while controlling fluid discharge from the sprinkler system 12 and 14. 
Fluid is discharged in accordance with the pivotal rate to maintain 
uniformity of irrigation within the central, generally circular area as 
well as in substantial portions of corner regions. The control system 32 
is also advantageously designed to allow operation of the system 10 with 
or without operation of the auxiliary sprinkler system 14 according to the 
desires and needs of the operator. Furthermore, the control system 32 
allows one or more corner regions not requiring irrigation to be skipped, 
such as corners having farm buildings, roads, etc. 
The described center pivot irrigation system may offer operational features 
such as: (1) low pressure and temperature shutdown whereby the operation 
of the system 10 is automatically discontinued in the event of a drop in 
the irrigation fluid pressure below a threshold value or a drop in the 
ambient air temperature below a preselected value; (2) automatic reversing 
whereby the irrigation of any section of a field may be accomplished by 
cycling the boom 22 back and forth over a given section; (3) a preselected 
stop feature whereby operation of the system may be automatically stopped 
at any predetermined orientation of the boom 22 about the stand assembly 
20; (4) overwatering detection whereby the system is automatically shut 
down if, while continuing to discharge irrigation fluid, a malfunction 
causes stopping of the rotation of the boom 22 for a predetermined period 
of time; and (5) an adjustable high level pressure switch to protect the 
system from high pressure surges caused by malfunctions of the sprinkler 
systems 12, 14. All such options are suitably contemplated as part of the 
invention and are only briefly described in conjunction with the control 
system 32. 
The main pipeline sprinkler system 12 as described is generally well known 
in the art, and its operation is well understood. For example, the model 
2200 Center Pivot Irrigation System marketed by Lockwood Corporation, 
Gering, Nebr., is generally of this construction and is readily modified, 
for example, to include the control tube and hydraulic valves as above 
described. Accordingly, the main pipeline sprinkler system 12, its 
alignment system, and its control system 32 are not described in great 
detail; they are only described in as much detail as necessary for an 
understanding of operation of the auxiliary sprinkler system 14. 
Referring now to the auxiliary sprinkler system 14, first and second 
auxiliary nozzles 40, 42 respectively are disposed substantially at the 
end of the boom 22 on the last section of pipe 24 (i.e., at the last tower 
28). The nozzles 40, 42 are coupled respectively to valves 43, 44 which 
are carried on the last pipe section of the boom in fluid passing 
relationship with the pipe. Operation of the valves 43, 44 is controlled 
by respective valve actuators 45, 46 which open and close the valves 43, 
44 according to control signals from a control system 48 (FIGS. 4a-4b). 
The first nozzle 40 is of a relatively lesser size and the second nozzle 
42 is of a relatively greater size to respectively discharge lesser and 
greater volumes of irrigating fluid. The nozzles 40, 42 are disposed to 
rotatingly provide (referring to FIG. 2) the irrigation respectively to 
inner (P1) and outer (P2) peripheral corner regions. 
The nozzles 40, 42 in the preferred and illustrated embodiment are 
commercially available from Nelson Irrigation Corporation as models P100 
and P200 sprinklers respectively. The model P200 sprinkler is modified to 
provide a 21 degree trajectory, rather than the 27 degree trajectory 
specified by the manufacturer. The P200 and P100 sprinklers are each 
equipped with a secondary nozzle which is not utilized in the preferred 
embodiment. Use of such secondary nozzle could be designed into the system 
10 according to the teachings of the present invention. 
The control systems 32, 48 operate the primary nozzle hydraulic valves and 
the valve actuators 45, 46 in a relationship with one another and to the 
pivotal speed of the boom 22 in a manner to provide a highly uniform 
application of irrigating fluid. Referring to FIG. 2, as the boom 22 
pivots towards point A, the auxiliary sprinkler system 14 is completely 
disabled, effecting irrigation of only the central, generally circular 
area A by the main pipeline sprinkler system 12. This mode of operation 
with only the main pipeline sprinkler 12 operating will hereafter be 
referred to as the NORMAL mode of operation. During the NORMAL mode of 
operation, the sprinkler 12 is said to rotate at a substantially constant 
rate. This term, substantially constant, is understood to describe the 
operation wherein the sprinkler 12 is either continuously rotating or its 
intermittently rotating due to operation of a PERCENTAGE TIMER, as will 
hereafter be described in detail. 
When the boom 22 reaches point A, the angle sensor 34 generates a control 
signal which excites the valve actuator 45 for the valve 43 to discharge 
fluid through the first auxiliary nozzle 40. The boom 22 continues to 
pivot, and the first auxiliary nozzle 40 sprays the P1 inner peripheral 
corner area. The auxiliary nozzle 40 rotates about the end of the boom 22 
at a rate considerably faster than the pivotal rate of the system, 
effecting irrigation on both sides of point A outside the inner circular 
area A. As the boom 22 travels from point A towards point B, the primary 
nozzles 26 and the auxiliary nozzles 40, continue to discharge the 
irrigating fluid. This mode of operation, with the boom 22 pivoting and 
with the primary nozzles 26 and the auxiliary nozzle 40 open, will be 
referred to as the P1 mode of operation. During this mode of operation the 
volume of fluid supplied to the boom 22 and the pressure of the supplied 
fluid is sufficient to allow continued uniform application of fluid to the 
inner circular area, notwithstanding the drain due to operation of the 
auxiliary nozzle 40. 
When point B is reached, the angle sensor 34 generates a signal to the 
control systems, 32, 48 which: (1) de-energizes the tower motors, stopping 
the pivoting of the boom 22; (2) closes the valve 43 for the first 
auxiliary nozzle 40; (3) opens the valve 44 for the second auxiliary 
nozzle 42; and (4) renders the FEED/BLEED valves into the feed position 
for allowing pressure into the control tube. Pressure within the control 
tube increases closing the hydraulic valves for the primary nozzles 26. 
Pressure begins to rise in main sprinkler line as the primary nozzles 
begin to shut off. When the threshold pressure is reached at the pressure 
switch the contact conducts to send an opening signal to the auxiliary 
nozzle 42. This assures sufficient pressure at the nozzle 42 before the 
valve will open, minimizing crop damage and soil erosion. Thus, the 
pressure switch effects operation of the valve actuator 46 corresponding 
to the second auxiliary nozzle 42. The control system 48 thereupon 
energizes a timer, referred to as the STOP timer, for a predetermined 
period of time to allow irrigation by only the second auxiliary nozzle 42. 
This mode of operation will be referred to as the P2 mode of operation. 
This stopping of the pivoting of the boom 22 while only the nozzle 42 is 
discharging fluid is an outstanding feature of the invention as it allows 
all of the fluid supplied to the boom 22 to be provided to the nozzle 42 
for irrigating the second peripheral corner region P2. Because the fluid 
is no longer being discharged through the primary nozzles 26 or through 
the first auxiliary nozzle 40, sufficient volume and pressure is provided 
to the second auxiliary nozzle 42 to obviate the otherwise need for a 
booster pump for operating this high volume auxiliary nozzle. 
After a predetermined period of time, the STOP timer times out and causes 
the control system 48 to generate a control signal which de-energizes the 
valve actuator 46 for stopping discharge through the second auxiliary 
nozzle 42. Timing out of the STOP timer also effects energization of the 
valve actuator 45 for opening the first auxiliary nozzle 41, as well as 
opening the FEED/BLEED valves to atmosphere for bleeding the control tube 
and thereby opening the hydraulic valves for the primary nozzles 26. At 
this time the tower motors are also energized for restarting pivoting of 
the boom 22 about the pivot stand assembly 20. The P1 mode of operation is 
thereby re-effected for a period of time determined by another timer, 
referred to as the RUN timer. 
As the boom 22 pivots from the point B toward the point C, the nozzles 26 
and 40 discharge fluid into the circular area and into the first 
peripheral corner region according to the P1 mode of operation. After a 
predetermined period of time, the RUN timer times out, causing 
de-energization of the valve actuators 45, switching the FEED/BLEED valves 
to the FEED position, and de-energizing the tower motors, thereby 
terminating the P1 mode of operation and re-initiating the P2 mode of 
operation. The described process of intermittent pivotal motion and fluid 
discharge continues for points D through L. The intermittent motion 
between points B and L, comprising the second and following P1 modes and 
all the P2 modes, defines the P3 mode of operation. 
Between the points L and M, the system 10 operates in the P1 mode; 
thereafter and until point A is again reached on the next pivotal cycle, 
the system 10 operates in the NORMAL mode of operation. 
Having described the general modes of operation of the center pivot 
irrigation system 10, the details of the control systems 32, 48 as shown 
in FIGS. 3a-3c and 4a-4b are more easily introduced. 
Referring now to FIGS. 3a-3c, the control system 32 includes a plurality of 
manually operated input switches, dials, and mechanisms for allowing the 
operator of the system to program desired operation of the main pipeline 
sprinkler system 12. A switch 58 is provided for initializing system 
operation. A PERCENTAGE TIMER is provided having contacts 62 which open 
and close at a rate which controls the rate at which the boom 22 pivots 
about stand 20. Typical pivotal rates for a standard system having a boom 
22 of about a 1/4 mile length are 18.8 hours to 188 hours per pivotal 
cycle. A FWD-AUTO-REV switch 60 is provided for specifying whether the 
boom 22 rotates in the forward only or reverse only directions, or whether 
it operates first in one direction and then in another direction for 
successive pivotal cycles. An OFF-DRY-WET switch 64 is provided for 
enabling operation of the main pipeline sprinkler system 12 in either a 
WET or a DRY mode whereby irrigation fluid is either delivered or not 
delivered respectively during the pivotal motion of the boom 22. 
The control options are shown in FIG. 3a as follows: Low PRESSURE/TEMP 
switch contacts are shown at reference numeral 66; the OVERWATERING TIMER 
at 68, its TR1 contacts at 70; and the preselected stop switch at 72. 
Briefly, operation of the control system 32 for the main pipeline sprinkler 
system 12 is as follows. A step down transformer 76 provides 120 VAC to 
the OFF-DRY-WET switch 64 and the START switch 58 via a line 78. Actuation 
of the START switch 58 provides energization to the OVER-WATERING TIMER 68 
so that, upon motion of the boom 22 inadvertently stopping, such as the 
wheels of the towers becoming stuck, the timer 68 can terminate further 
operation of the irrigation system 10 if irrigation at one orientation 
about the pivot stand assembly 20 should proceed beyond a predetermined 
period of time. A clutch contact 80 is provided for selectively disabling 
operation of the timer 68. 
Concurrent operation of the start switch 58 and of the OFF-DRY-WET switch 
64 provides energization to the FWD-AUTO-REV switch 60 when the switch 64 
is in either the DRY or WET position. Depending upon the position of the 
FWD-AUTO-REV switch 60, the 120 VAC is applied to either a REV line 82 or 
to a FOR line 84 coupled to a set of control circuits 88 for the tower 
motors. Operation of the remaining circuitry shown in FIG. 3a is obvious 
and accordingly will not be explained in further detail, as its operation 
is unchanged from that of the Model 2200 Center Pivot Irrigation System 
marketed by Lockwood Corporation. 
Referring now to FIGS. 3b and 3c, control circuits 88 of the control system 
48 for operating the tower motors is shown in detail. The tower closest to 
the pivot stand assembly 20 is denoted by the reference numeral 90 and 
will be referred to as the first tower motor. The motor corresponding to 
an intermediate tower is denoted by the reference numeral 92 and will be 
referred to as the intermediate motor. The motor for the next to end tower 
is denoted by the reference numeral 94 and will be referred to as the 
next-to-end motor; and the end tower motor is denoted by the reference 
numeral 96. 
Each of the tower motor control circuits 88 includes: a disconnect switch 
98 to which 480 VAC is applied by a set of lines 100; a contactor 102 
coupling the respective disconnect switch 98 to its tower motor; a coil 
104 for each of the contactors 102; and a terminal strip 106. The FOR wire 
84 and the REV wire 82 are respectively coupled to the third and second 
terminals on each of the terminal strips 106. 
Each of the circuits 88, except the end tower circuit which is controlled 
by the percentage contacts 62, further includes the microswitch, denoted 
at 108, which was earlier mentioned with respect to the alignment system. 
The switch 108 is connectable to either the FOR line 84 or to the REV line 
82 according to the direction of rotation of the boom 22 and controls 
energization of the coil 104 for each respective motor. 
Operation of the tower motor control circuits 88 will be described 
subsequently in connection with the overall control system 48. 
Referring now to the control system 48 shown in FIG. 4a, a TIMER circuit 
107 which is disposed at the pivot stand assembly 20 is shown in detail in 
connection with the control system 32. A wire 110 is connected to the 
OFF-DRY-WET switch 64, and a wire 112 is connected to the PRESELECTED STOP 
switch 72. Via the wires 110 and 112, 120 VAC is provided respectively 
when the switch 64 is in the WET position and during all of the NORMAL, 
P1, and P3 modes of operation. A pair of contacts 114, 116 are commonly 
coupled to the wire 110 and are actuated by the angle sensor 34. As 
earlier indicated, the angle sensor 34 is a cam operated switch which 
mechanically opens and closes the contacts 114, 116 respectively according 
to travel of lobes on a cam at the pivot stand assembly 20. The contact 
114 is associated with operation of the lower volume auxiliary nozzle 40 
and will be referred to as the P1 contact. The contact 116 corresponds to 
operation of the system during the P3 mode of operation, and will be 
referred to as the P3 contact. Closure of the P1 contact 114 provides 120 
VAC to an input terminal 120 during the P1 mode of operation. Closure of 
the P3 contact 116 provides 120 VAC an input terminal 122. During the P3 
mode of operation, both the P1 and P3 contacts 114, 116 are rendered 
closed, providing 120 VAC to both of the terminals 120, 122. 
A step down transformer 124 is coupled to circuit ground by a line 126 and 
to the input terminal 120 via an isolation switch 128. Closure of the 
switch 128 provides 12 VAC on a line 130 whenever the contacts P1, is 
closed. A diode D1 has its cathode connected to a normally closed R6 
contact 131a, and the series connection couples the line 130 to a P1/P2 
line 132. Whenever the system is operating in the P1 mode, -12 volts is 
applied to the P1/P2 line 132 via the normally closed contacts R6 and 
diode D1 for controlling the valve 45. 
The P1/P2 line 132 is also coupled to the line 130 by a series connection 
of a normally open set of R6 contact 131b and a diode D2 having its anode 
closest to the contacts R6. Whenever the system is operating in the P2 
mode, +12 VDC is thereby applied to the P1/P2 line 132. 
The line 132 is coupled to an end tower valve control circuit 152 and to 
the fifth terminals of the terminal strips 106 of the tower control 
circuits 88 for the first tower and for the tower carrying the second 
FEED/BLEED valve which is denoted by the numeral 162b. The valve 162b is 
controlled by a set of normally open R9 contacts 135 corresponding to an 
R9 coil 135b connected to line 132. Only when +12 VDC is applied to the 
line 132 is the coil R9 energized, thereby allowing the switching of the 
valve 162b into the FEED state for closing the primary nozzles 26. The +12 
signal VDC on the line 132 also controls the valve actuator 46 of the 
second auxiliary nozzle 42 via the control circuit 152. 
An R5 coil 134 is connected between circuit ground and the terminal 122 via 
another set of contacts of the isolation switch 128. During the P3 mode of 
operation, the 120 VAC applied to the terminal 122 energizes the R5 coil 
134. 
The R5 coil 134 has two sets of normally open contacts R5 which are 
designated by the numerals 136, 138 and one set of normally closed 
contacts R5 which are designated by the numeral 140. The normally open R5 
contacts 136 and the normally closed R5 contacts 140 are commonly 
connected to the wire 112 at a terminal 142 for receiving 120 VAC during 
all modes of operation. The normally closed R5 contact 140 has its other 
terminal coupled to an output terminal 144 which in turn is connected to 
the contacts 62 of the PERCENTAGE TIMER by a line 146. 
During the P1 mode of operation, the normally closed R5 contacts 140 
provide 120 VAC to the contacts 62 for intermittently running the end 
tower. The contacts 62 open and close according to the setting of the 
PERCENTAGE TIMER, thereby controlling the speed of rotation of the boom 22 
about the pivot stand assembly 20. This intermittent 120 VAC signal is 
sent to the end tower motor control circuit 88 for driving the end tower 
motor 96 via a line 148. 
The line 148 is connected to the fourth terminal of the terminal strip 106 
in the motor control circuit 88. From this terminal, a wire selectively 
energizes, through the disconnect switch 98, coil 104 for the contactor 
102 according to whether the system mode of operation is the normal mode, 
P1 mode or the P2 mode, during the normal and P1 modes of operation, 120 
VAC, as controlled by the percentage timer contact 62, is intermittently 
applied to the coil 104 for energizing the end tower motor 96. Thus, the 
boom 22 can pivot about the pivot stand assembly 20 during either the 
normal or P1 modes of operation. 
The other terminal of the normally open R5 contact 136 is connected to the 
RUN TIMER, denoted by the numeral 154, and to the STOP timer which is 
denoted by the numeral 156. The RUN TIMER 154 has a primary input terminal 
A, a set of output terminals Z, X, T and secondary input terminals for 
each of the respective Z, X, T output terminals. The STOP TIMER 156 has 
its primary input terminal A, a pair of output terminals X, S, and 
secondary input terminals for the respective output terminals X, S. The 
other terminal of the normally open R5 contact 136 is connected via a line 
158 to all the secondary input terminals of the RUN TIMER 154 and to the 
secondary input terminal for the S output terminal of the STOP TIMER 156. 
The output terminal 144 is coupled to the Z output terminal of the RUN 
TIMER 154 by the normally open R5 contacts 138. 
The X output terminal of RUN TIMER 154 is connected by a line 160 to the 
first FEED/BLEED valves, denoted by numeral 162a. The X output terminal is 
also coupled to an output terminal 164 via a normally open R6 pair of 
contacts 166. At the output terminals 164, a 120 VAC signal is applied via 
a line 168 to the terminal 80 for maintaining the clutch of the 
OVERWATERING TIMER 68 energized so that the timer does not time down and 
disable the system when the machine is in the P2 mode. 
The T mode terminal of the RUN TIMER 154 is connected by a wire 170 to the 
primary input terminal of the STOP TIMER 156. 
The X output of the STOP TIMER 156 is coupled to an R6 coil 172. The R6 
coil 172 has its normally closed R6 contact 131a coupled to the diode D1, 
has normally open R6 contacts 131b coupled to the diode D2, has the 
normally open R6 contacts 166 coupled to the X output of the RUN TIMER 
154, and has a normally closed R6 contact 174 coupling the output terminal 
164 to an input terminal 176. A line 178 connects the input terminal 176 
to the tower motor control circuit 88 corresponding to the next to end 
tower for providing 120 VAC through the normally closed R6 contacts 174 to 
the line 168 for maintaining energization of the OVER-WATERING TIMER 
clutch during the intermittently "on" portions of the normal mode and P1 
mode. 
The S output of the STOP TIMER 156 is connected by a line 180 to the 
primary input of the RUN TIMER 154. 
The states of the RUN and STOP timers 154, 156 are given by Tables I and 
II. 
TABLE I 
______________________________________ 
RUN TIMER LOGIC 
Output Before During End of 
Terminal Start Timing Cycle 
______________________________________ 
Z 0 1 0 
X 1 0 1 
T 1 0 1 
______________________________________ 
TABLE II 
______________________________________ 
STOP TIMER LOGIC 
Output Before During End of 
Terminal Start Timing Cycle 
______________________________________ 
X 0 1 0 
S 0 0 1 
______________________________________ 
where "0" represents open contacts and "1" represents closed contacts. 
Referring now to FIG. 4b, the end tower valve control circuit 152 is shown 
in detail for selectively energizing the valve actuators 45, and 46. An 
R10 coil 190 and an R11 coil 192 are respectively connected through 
oppositely poled diodes D3, D4 to a terminal 194 which in turn is 
connected to receive the P1/P2 wire 132. The other terminal of each of the 
coils 190, 192 is connected to circuit ground such that, upon application 
of the -12 VDC signal on the line 132, the coil R11 is energized; upon 
application of the +12 VDC signal on the line 132, the R10 coil 190 is 
energized. 
The R11 coil has a normally open set of R11 contacts 196 and a normally 
closed set of R11 contacts 198. The coil R10 has first and second sets of 
normally closed R10 contacts 202, and a set of normally open R10 contacts 
200. Whenever the line 132 provides a -12 VDC signal for energizing the 
R11 coil 192 during the P1 mode of operation, energization to the valve 
actuator 45 is applied thereto via the contacts 196 and a line 206. When 
the R11 coil 192 is de-energized during the P2 mode of operation, the 
normally closed R11 contacts 198 provide a signal via a line 208 for 
disabling the valve actuator 45. Whenever a +12 VDC signal is applied to 
the line 132, the R10 coil 190 is energized, applying energization to the 
valve actuator 46 via the R10 contact 200, a pair of pressure contacts 
211, and a line 210. The contacts 211 are those of a pressure switch in 
the pipe 24 and connect the line 210 and the normally open R10 contacts 
200 such that the valve actuator 46 is actuated only upon the pressure 
within the pipe 24 achieving a preselected value, indication that the 
primary nozzles 26 have sufficiently closed. In the preferred embodiment, 
this pressure value is approximately 80 PSI. As a feature, the pressure 
switch provides differential programming such that the contacts 211 do not 
reopen until pressure in the control tube falls to approximately 
fifty-five PSI. Therefore, once the valve begins to open it opens fully. 
When the +12 VDC signal disappears from the line 132 during the P1 mode of 
operation, the R10 coil de-energizes and the normally closed R10 ccontact 
202 closes to provide 120 VAC to the valve actuator 46 for closing it. 
To provide energization when desired to the actuators 45, 46, the contacts 
196, 198, 200 and 202 are commonly coupled to a FOR/REV circuit 220 at a 
common mode J1. The FOR/REV circuit 220 is connected to the lines 82, 84 
for receiving 120 VAC when the boom 20 is pivoting in either the forward 
or the reverse direction. The circuit 220 includes an R14 coil 222 and an 
R15 coil 224 respectively coupled to the lines 82, 84. The R14 coil 222 
has a pair of normally closed R14 contacts 226 respectively connected in 
series between the R15 coil 224 and between the line 84 and the mode J1. 
The R15 coil 224 similarly has a pair of normally closed R15 contacts 
serially connecting the R14 coil 222 to circuit ground and connecting the 
wire 82 to the mode J. In this manner, isolation between the wire 82, 84 
is maintained while providing 120 VAC to the common junction J1 regardless 
of the direction of pivoting of the boom 22. 
Operation of the control systems 32, 48 will now be summarized. As the boom 
22 pivots towards a corner, a lobe on the P1 cam causes the P1 contacts 
114 to close. This provides -12 volts DC on the P1/P2 line 132 which 
energizes the R11 coil 192. Energization of the R11 coil 192 closes the 
normally open R11 contacts 196 for energizing the valve actuator 45 for 
the first auxiliary nozzle 40. The primary nozzles 26 and the auxiliary 
nozzle thus both provide irrigation to the central area A and to the P1 
peripheral area. 120 VAC from the line 112 is applied through the contacts 
140 to the line 146 for maintaining movement of the boom about the pivot 
stand assembly 20. The pivotal rate of the boom 20 at this point is the 
same as during the normal mode of operation, as determined by opening and 
closing of the TR2 contacts 62 from the PERCENTAGE TIMER. That is, because 
the P3 contacts 116 are open, the R5 coil 134 is de-energized, allowing 
120 VAC to be applied through the normally closed R5 contacts 140 and the 
percentage timer contacts 62 to the coil 104 for the end tower motor 96. 
P3 lobe on the angle sensor cam closes the P3 contacts 116 and maintains 
the P1 contacts 114 closed. This initiates the P2 mode of operation, 
energizing the R5 coil 134 which in turn closes the R5 contacts 136, 138 
and opens the R5 contacts 140. Closing of the R5 contacts 136 switches the 
FEED/BLEED valve 162a into the feed position whereby the pressure within 
the control tube begins to increase. Opening of the R5 contact 140 
disrupts the 120 VAC through the contacts 62 and prevents movement of the 
boom 22 during the P2 mode. 
Closure of the R5 contacts 136 also initiates the STOP TIMER 156 and 
energizes the R6 coil 172. Energizing of the R6 coil 172 effects 
application of a +12 VDC voltage on the P1/P2 line 132 which energizes the 
R10 coil 190 and switches the FEED/BLEED valve 162b to the feed position. 
The R10 contacts 200 close and the R10 contacts 202 open. As soon as 
pressure within the pipe 24 reaches the predetermined threshold level, the 
pressure switch 211 closes, and 120 VAC is applied to the valve actuator 
46 to inititate discharge of fluid from the second auxiliary valve 42. 
Opening of the R5 contacts 140 disconnects line 112 from the line 144 for 
de-energizing the coil 104 of the end tower motor 96. 
After the STOP TIMER 156 has timed out, the R6 coil 172 de-energizes, 
causing: (1) the R6 contacts 131a to impose a -12 VDC on the line 132 
which begins the sequence which opens the valve actuator 45, and closes 
the valve actuator 46 and (2) opening of the R6 contacts 166 and closing 
of the R6 contacts 174, imposing on the line 168 an intermittent 120 VAC 
signal to the OVERWATERING TIMER 68 whenever the next-to-end tower motor 
is energized. 
Timing out of the STOP TIMER 156 also initiates operation of the RUN TIMER 
154 via line 180. This provides energization to the terminal 144 from the 
Z output via the R5 contact 138 for providing energization to the 
PERCENTAGE TIMER contacts 62. Operation of the RUN TIMER 154 also disrupts 
energization to the FEED/BLEED valve 162a via the X output and the line 
160. Accordingly, during the P1 phase of the P3 mode of operation when the 
RUN TIMER is timing down, (1) the control tube is bled to open the primary 
nozzles 26, (2) energization to the end tower motor 96 is reapplied for 
pivoting the boom 22, and (3) the valve actuator 45 is energized for 
causing discharge through the first auxiliary nozzle 40. Also during time 
out of the RUN TIMER 154, the STOP TIMER is de-energized via the T output 
and the line 170 from the RUN TIMER 154. 
After the RUN TIMER 154 times out, and as long as the P3 mode of operation 
is commanded via the angle sensor 34, the STOP TIMER 156 is again enabled 
via the line 170 and the P2 mode of operation is again initiated. This 
sequence of P1 and P2 modes of operation continues until the P3 lobe on 
the angle sensor 34 rotates to open the P3 switch contacts 116. At this 
time, only the P1 contacts are maintained closed via the P1 lobe, and only 
the P1 mode of operation results. 
As a special feature of the invention, the first tower motor 90 is disabled 
simultaneously with each stopping of the end tower motor 96 to prevent 
false operation of the P1 or P3 contacts. This is accomplished by a 
disable circuit 230 connected to the P1/P2 line 132. The disable circuit 
230 includes an R8 coil 232 and its normally closed R8 contacts 234. 
Whenever a +12 VDC signal is applied to the line 132, for stopping 
energizing of the end tower motor 96, the R8 coil 232 is also energized 
for opening the R8 contacts 234. This breaks the connection to the coil 
104 for the first tower motor 90 from the FOR line 84 or from the REV line 
82. The disable circuit 230 assures that the alignment system for the boom 
22 does not cause a slight movement of the first tower after 
de-energization of the end tower motor 96 which could potentially cause 
the cam followers for the P1 and P3 switches to roll off their respective 
lobes. 
Although rather specific embodiments of the invention have been disclosed, 
it is understood that such description has been by way of example only. 
Numerous changes and modifications will be apparent to those of ordinary 
skill in the art without departing from the spirit and scope of the 
invention.