Speed governor for irrigation system

In a system including, for example, an irrigation line supported by towers and rotatable about a central pivot, one tower thereof, for example, the outermost tower, includes a governor system for providing that increased water flow is provided to the water motor driving that tower as that tower is driven up a grade, and decreased water flow is provided to the water motor driving that tower as that tower is driven down a grade, as compared to the water flow to such water motor as the tower is driven over generally level ground.

BACKGROUND OF THE INVENTION 
This invention relates to drive apparatus for an irrigation line, and more 
particularly, to a drive apparatus including governor means for providing 
proper driving of the irrigation line over uneven terrain. 
In, for example, a rotary-type irrigation system, an elongated irrigation 
line is supported at intervals by towers on wheels and water is supplied 
from the irrigation line to individual water motors associated with the 
towers to drive them over the ground, the entire irrigation line rotating 
about a central pivot axis. Generally, the outermost tower is provided 
with a valve so as to supply water of a certain pressure to the outermost 
drive motor, and means are included adjacent each tower for providing 
proper operation of each other water motor so that the irrigation line 
stays substantially in alignment as it rotates. With constant water 
pressure being applied to the outermost water motor, the entire irrigation 
line will be transported at a substantially constant speed over level 
ground. However, as the line is driven up a grade, the torque applied to 
the outermost water motor remains the same but with the necessity of such 
torque not only driving that portion of the irrigation line over the 
ground, but actually lifting it up the grade. Likewise, as the line is 
driven down a grade, the torque applied to the outermost water motor 
remains the same. 
It will be understood that the overall speed of the outermost tower, and 
thus, the overall rotative speed of the irrigation line, changes 
substantially during either of these conditions. Yet the overall amount of 
water flowing from the irrigation line to irrigate the ground remains 
constant for a given period of time. This is a highly undesirable state 
since it will be seen that the uphill ground will be much more heavily 
irrigated, and downhill ground will be much more lightly irrigated than 
level ground being irrigated, when it is to be understood that 
substantially constant and even irrigation throughout the entire rotative 
cycle of the irrigation line is highly desirable. 
SUMMARY OF THE INVENTION 
It is accordingly an object of this invention to provide a drive apparatus 
for an irrigation line which compensates for unevenness in terrain to be 
irrigated so as to insure substantially even irrigation of the land. 
It is a further object of this invention to provide drive apparatus which, 
while fulfilling the above object, is extremely simple in design and 
efficient in use. 
Broadly stated, the invention comprises a drive apparatus for a pivot 
irrigation line comprising frame means on which an irrigation line is 
supported, and rotatable support means mounted to said frame means and on 
which the frame means are supported with the rotatable support means on 
the ground. Motor means are operatively coupled with said rotatable 
support means to apply driving torque to said rotatable support means. 
Means are included for providing a motor drive torque to rotate the 
rotatable support means to drive said frame means over generally level 
ground. Means are included for varying motor drive torque to maintain a 
generally constant speed of rotation of the rotatable support means as the 
frame means is driven up or down a grade.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Generally shown in FIG. 1 is an irrigation system 11 of the pivot type, 
including a line 14, an end 15 of which is pivotally secured relative to 
the ground. The line 14 is supported by tower 17 positioned at spaced 
intervals along its length, and an end tower 10 in association with the 
extended end 19 of the line 13. 
Generally shown in FIG. 1A is the tower 10 including frame means 12 on 
which the irrigation line 14 is supported generally transversely thereof. 
The frame means 12 include a lower frame member 16, and upwardly and 
inwardly extending frame members 18,20 forming an overall triangulated 
structure. The lower frame member 16 has rollingly fixed thereto rotatable 
support means in the form of wheels 22. 
In such a system, it is well known to provide that the irrigation line 14 
is made up of a plurality of individual sections with each tower including 
water motor means for driving the wheels which support that tower. In 
order to maintain the line 14 in an aligned condition, it is known to 
actuate and deactuate appropriate water motors upon a certain bending of 
the line 14 taking place, through, for example, a linkage system 
interconnecting two sections of line. 
The particular drive system of the outermost or end tower 10 is shown in 
FIG. 1A. As shown therein, and also in FIGS. 2 and 3, water under pressure 
is supplied from the irrigation line 14 through conduit means 24 to rotary 
means 26, including a vertically disposed shaft 28, and tubular arms 30 
fixed thereto, through which the water may exit. It will be seen that 
water supply from the line 14 through the conduit 24 and exiting from the 
ends of the arms 30 tends to turn the shaft 28 about its longitudinal 
axis. The bottom portion of the shaft 28 connects with a gear box 32, 
through which are driven forwardly and rearwardly extending shafts 34, in 
driving engagement with the respective wheels 22. Through such water motor 
means, driving torque is applied to the wheels 22, to drive the tower 10. 
Fixed to the lower end of the elongated shaft 28 is a generally T-shaped 
member 36. The extended ends 38,40 of the T-shaped member 36 have 
pivotally secured thereto links 42,44, the lower ends of the links 42,44 
having weights 46,48 secured thereto. The upper ends of the links 42,44 
have pivotally secured thereto respective links 50,52. A collar 54 is 
slidably mounted on the shaft 28, and has flanges 56,58 extending from 
opposite sides thereof to which are pivotally mounted the upper ends of 
links 50,52. Referring to FIGS. 4 and 5, secured to the collar 54 are disc 
means 60 having bearing surfaces defining an annular channel 62 
thereabout. A ring 61 is slidably disposed in the channel 62, and defines 
bores 63,65 on the opposite sides thereof. A bar 64 is pivotally mounted 
to the frame member 18, being made up of spaced plates 66,68 defining an 
enlarged opening 70 which extends about the disc means 60. The plates 
66,68 have bolts 72,74 respectively secured thereto with the inner ends 
76,78 thereof extending inwardly thereof. The inner ends 76,78 thereof are 
smooth in configuration and fit within the bores 63,65 as shown in FIG. 5. 
A valve 80 is disposed in the conduit 24 and is relatively openable and 
closeable upon movement of lever 82 to provide relative increase and 
decrease in water flow to rotate the shaft 28. The relatively more open 
position is shown in full in FIG. 2 and the relatively more closed 
position is shown in phantom in such FIG. 2. 
A weight 84 secured to the valve lever 82 tends to hold the valve 80 in the 
relatively open position thereof. The end of the valve lever 82 extending 
oppositely from the weight has pivotally secured thereto an elongated 
member 86, the lower end of which defines a widened portion 88 on which 
rest crossbars 90,92 extending between the plates 66,68 of the bar 64. The 
elongated member 86 actually is made up of a main portion 94, a second or 
lower portion 96, and a member 98 interconnecting the two, the lower 
portion 96 being threadably engaged with the member 98, and the main 
portion 94 being secured relative to the adjustment member 98 by means of 
a setscrew 100. 
The lower portion 96 has rotatably fixed thereto an indicator member 97 the 
position of which can readily be ascertained relative to scale markings on 
the member 98. Rotation of the portion 96 relative to member 98 changes 
this relative positioning, also changing the overall length of the member 
86. 
It will be seen that upon increase in rotational speed of the shaft 28, the 
weights 46,48 extend outwardly so as to slide the collar 54 in one 
direction downwardly along the shaft 28. Similarly, upon decrease of 
rotational speed of the shaft 28, the collar 54 will slide in the other, 
upward direction along the shaft 28. During such downward movement of the 
collar 54, the bar 64 is pivoted downwardly in one direction, and during 
movement of the collar 54 in the other, upward direction, the bar 64 
pivots in the other, upward direction. Downward movement of the bar 64 due 
to the sliding movement of the collar 54 downwardly closes the valve 80 
through movement of the elongated member 86, and movement of the bar 64 
upwardly provides relative opening of the valve 80. 
A shock damper 102 interconnects the bar 64 and frame member 18 for 
controlling pivoting movement of the bar 64 relative to the frame 12 
during the operation of the apparatus, as will now be described. 
Initially, water under pressure is supplied to the irrigation line 14, to 
rotate the rotary means 26 as above described. The valve 80 is in its 
relatively open position, supplying full flow to rotate the means 26. As 
the speed of the rotary means 26 increase, the weights 46,48 extend 
outwardly, moving the collar 54 and bar 64 downwardly to tend to close the 
valve 80, but with the valve 80 never reaching a fully closed condition. 
Assuming that the tower 10 is moving over generally level ground, a 
balanced state will be achieved wherein a generally even level of motor 
drive torque is applied to the wheels 22 to drive the tower 10 over the 
generally level ground. Overall length of the member 86 is chosen by the 
adjustment described above, to in turn determine the maximum extent of 
opening of the valve 80, in turn determining maximum speed of the motor 
wheel is available. 
Assuming that the tower 10 is then made to move up a grade, varying the 
load condition, the motor drive torque supplied to drive the wheels 22 is, 
initially, substantially the same, but is, of course, insufficient to 
maintain a drive speed of the tower 10 equal to the previous drive speed, 
since the tower 10 and portion of the irrigation line 14 must be lifted as 
well as driven over the ground. In such case, the rotary means 26 slows 
down, and the weights 46,48 move inwardly, acting as governor means which 
sense the decrease of rotational speed of the rotary means 26. The inward 
movement of the weights 46,48 slides the collar 54 upwardly along the 
shaft 28 causing the valve 80 to relatively open to provide an increase in 
water flow to the rotary shaft 28. Such increase in water flow provides 
that as the tower 10 is driven up the grade, the motor drive torque 
applied to drive the wheels of such tower 10 is greater than the motor 
drive torque which drives the tower 10 over generally level ground. This 
is done, of course, through increased water flow to the rotary means 26. 
Thus, the speed of the tower 10 picks up on the grade for more even 
distribution of irrigating water, the end result being that the rotational 
speed of the wheels 22, remains generally constant, i.e., generally equal 
to the rotational speed thereof over level ground. 
Upon the tower 10 reaching downhill ground, varying the load condition, the 
increased supply of water supplied to the rotary means 26 will rotate the 
shaft 28 faster than desirable, so that the governor means sense the 
increase in rotational speed of the shaft 28, to in turn relatively close 
the valve 80 to provide a decreased water flow to the rotary means 26. 
This in turn provides relatively less motor drive torque, so that the 
wheels 22 continue to be driven at such generally constant speed. 
The overall, steady-state rotational speed of the line 14 can be determined 
by appropriate adjustment of the length of the member 86, and the markings 
on the member 98 can be chosen in, for example, time of one complete 
rotation of the line 14. 
It is also to be noted that upon a decrease in supply pressure to the line 
14, the rotative speed of the shaft 28 decreases. The weights 46,48 move 
inwardly opening the valve to increase water flow to the rotary shaft 28, 
to in turn pick up the speed of the line 14. Likewise, an increase in 
supply pressure causes the valve to close to an extent, slowing the line 
from its too-rapid state due to such excessive supply pressure.