Reversible gear oscillating sprinkler

A gear driven oscillating sprinkler head includes a reversible gear train for transmitting drive from a drive motor to the oscillating sprinkler head with a shifting mechanism, including a shiftable carrier on which a pair of driving pinions are mounted for shifting alternately into driving engagement with an internal ring gear, with a lost motion connection between a shifting arm and the carrier with separate over-center spring units for separately biasing the carrier and shifting arm to the alternate driving engagement positions.

BACKGROUND OF THE INVENTION 
The present invention relates to sprinkler units and pertains particularly 
to a special reversible drive gear system for oscillating sprinklers. 
In my prior U.S. Pat. No. 3,107,056, issued October 15, 1963, entitled 
"Sprinkler", I disclose a gear driven oscillating pop-up type sprinkler. 
In that patent, the drive train includes a shifting mechanism that 
alternately shifts a pair of terminal gears carried on a shifting plate 
into and out of engagement with an internal gear at the ends of the 
oscillating stroke. In adapting that drive system to more compact higher 
pop-up stroke higher volume sprinklers, certain problems with the shifting 
mechanism were encountered. 
The chief difficulty encountered was the different engaging and shifting 
forces present in the shifting mechanism. The shifting mechanism has a 
very strong self-engaging force when turning in the same direction as the 
input drive. A great deal of force is required to disengage the drive and 
shift to the opposite direction. This problem was solved in my U.S. Pat. 
No. 4,568,024, issued Feb. 4, 1986, entitled "Oscillating sprinkler". 
However, a new problem has been discovered, namely when the sprinkler unit 
stops while in the process of shifting from one direction to the opposite 
direction, the terminal gear becomes disengaged from the ring gear. When 
the water is again turned on, the drive remains disengaged and will not 
function. The sprinkler unit is then considered defective and is typically 
discarded or returned to the vendor for replacement. 
It has been discovered that the lost motion connection between the shifting 
arm and the carrier allows the shifting arm to be biased to a position 
short of the over center position, such that the carrier allows the 
terminal gear to become disengaged. This condition can occur when the 
sprinkler head is turned manually to check or adjust the coverage. 
It is, therefore, desirable that an improved gear drive be available for 
sprinkler units that overcomes this problem. 
SUMMARY AND OBJECTS OF THE INVENTION 
It is, therefore, the primary object of the present invention to provide an 
improved reversible driver for an oscillating sprinkler unit. 
In accordance with the primary aspect of the present invention, an 
oscillating gear drive train for an oscillating sprinkler head includes a 
first pinion shiftable into engagement with an internal gear for driving 
in one direction, and a second pinion shiftable into engagement with the 
gear for driving in the opposite direction, with first and second pinions 
mounted on a shiftable carrier and having over-center means acting 
directly on the shiftable carrier for maintaining the first and second 
pinions in positive drive engagement.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Turning to FIG. 1 of the drawing, a sprinkler unit, designated generally by 
the numeral 10, includes a generally cylindrical housing 12 having an 
inlet opening at the bottom, not shown, which is connectable to a source 
of water such as a fixed water line or the like 14. The sprinkler unit 
includes a typical drive motor 16, such as a water turbine or the like, 
which is drivingly coupled through a gear train 18, the details of which 
are not shown, for driving a reversible drive gear train, as will be 
subsequently disclosed and discussed, which is contained within an 
oscillating drive unit 20. The oscillating drive unit 20 is in the form of 
a generally cylindrical housing mounted in the upper end of the 
cylindrical housing 12 and is coupled through a hollow or tubular drive 
shaft 22 to a sprinkler head or nozzle unit 24. The nozzle unit 24 is 
mounted for rotation with the shaft 22 for rotating about the axis 
thereof. The shaft 22 is also tubular and serves as a water flow conduit 
for conveying water to the nozzle unit 24 from the lower portion of the 
housing. 
The basic drive arrangement is substantially like that disclosed in my 
prior U.S. Pat. Nos. 3,107,056, issued Oct. 15, 1963, entitled 
"sprinkler", and 4,568,024, issued Feb. 4, 1986, entitled "Oscillating 
sprinkler". The contents of these patents are incorporated herein by 
reference as though fully set forth. 
The oscillating head 24 is driven in alternate directions by a reversible 
drive assembly, which is best illustrated in FIGS. 2-4. The drive assembly 
comprises a reversible gear train and includes an input shaft 28, which is 
driven by a suitable motor or turbine 16 powered by the water flowing 
through the unit. The shaft 28 is mounted for rotation about an axis 
positioned paralle and to one side of the central axis of the rotatable 
member 22. The input shaft 28 carries an input pinion gear 34 positioned 
between the central axis, and an internal gear 30 formed on the downwardly 
turned skirt portion 32 of the output drive unit 20. The input pinion gear 
34 is mounted on the shaft 28 for rotating therewith and for driving a 
pair of shiftable gear trains that alternately shift into driving 
engagement with the internal gear 30, as will be described. 
The shifting gear trains comprise a pivoting yoke or carrier, including a 
lower annular plate 36, which surrounds the central drive shaft 22 and is 
pivotally mounted on the shaft 28 for pivotal movement about the axis 
thereof. The shiftable yoke plate 36 includes a pair of oppositely driven 
terminal gears 46 and 52, which are driven by the input pinion 34 by way 
of one or more idler gears as needed. The yoke assembly includes an upper 
plate 42, between which is mounted a first gear train, comprising an idler 
gear 44 driven by the input gear 34 and an outer or terminal pinion gear 
46 for drivingly engaging the internal gear 30 for driving it in a 
counterclockwise direction. A second gear train includes the input gear 
34, drivingly engaging terminal gear 52, which in turn drivingly engages 
the internal ring gear 30 for driving the ring gear in the clockwise 
direction, as seen in FIG. 2. The yoke assembly, including the plate 36, 
pivots about the axis of shaft 28 for pivoting to alternate positions, as 
shown respectively in FIGS. 2 and 3, for alternately shifting the terminal 
gears of the drive trains selectively into driving engagement with the 
internal ring gear 30 for driving the ring gear and the sprinkler head in 
alternate directions. 
As shown in FIG. 2, the first gear train, including idler gear 44 and 
terminal drive gear 46, are in driving engagement with the internal ring 
gear 30 such that the ring gear is driven by the gear 46 in a 
counterclockwise direction. 
Referring to FIG. 3, the shifting yoke 36 has been tilted in the opposite 
direction, such that the terminal drive gear 52 is in driving engagement 
with the internal ring gear 30 for driving the ring gear in the clockwise 
direction, with the input gear 34 driven in the counterclockwise 
direction, as shown in FIG. 2. 
The shifting yoke 36 is pivoted about the axis of shaft 28 by means of a 
shifting level 54, which is rotatably mounted on the lower tubular 
extension 22a of the shaft 22. The shifting lever 54 is connected to the 
yoke by a lost-motion connection comprising a downward extension portion 
thereof to finger or arm 66 which alternately engages shoulders 38 and 40 
of the yoke. The shifting lever 54 is biased to its alternate positions by 
a pair of identical over-center springs 56 engaging notches 58 and 60 on 
opposite sides of the lever 54 and engaging notches 62 and 64 on 
extensions of the housing 12. 
The lever 54 is shifted by the ring gear 30 by the engagement of the outer 
tip 66 of the level 54 by opposing shoulders 80 and 82 for shifting it 
about its axis. This shifts it against the over-center springs 56, which 
forces the lever 54 to engage shoulders 38 and 40 of the yoke forcing yoke 
36 to pivot about its axis 28. This shifts alternate ones of the gears 46 
and 52 into driving engagement with the internal ring gear 30. 
An over-center spring 72 is mounted between a notch 74 on yoke 36 and notch 
76 on a stationary housing portion 70, for providing a positive biasing of 
the yoke 36 to its extreme positions independently of the biasing of the 
shifting lever 54. This maintains the terminal gears positively biased to 
the engaging position independently of the shifting lever 54. Thus, if the 
water should be cut off as the ring gear 30 is moving the shifting lever 
54 to the over-center position, the terminal gear 46 or 52 will remain 
engaged under the positive bias of over-center spring 72. Thus, when the 
water is turned on, the drive will be engaged and continue to drive 
internal gear 30 which will continue to shift lever 54. This eliminates 
the problem of the unit stalling in an intermediate position between 
alternate drive positions. 
At the position, as shown in FIG. 2, the lever 54 has just been forced 
over-center in a clockwise direction under engagement by shoulder 80 of 
the ring gear, thereby engaging shoulder 40 and shifting the yoke 36 to 
shift gear 46 into driving engagement with the ring gear 30. The ring gear 
30 now begins to turn in the counterclockwise direction until shoulder 82 
thereof engages the lever tip 66 of lever 54, shifting it back in the 
counterclockwise direction, as shown in FIG. 3. This shifts the gear 46 
out of engagement with the ring gear, and the gear 52 back into driving 
engagement. Continued rotation of the input gear 34 then immediately 
reverses direction of the ring gear 30, forcing it to begin rotating in 
the clockwise direction. 
The stroke of the drive and the angle of coverage of the resulting output 
will be determined by the angle or the length of the slot between 
actuating shoulders 80 and 82 on the ring gear. 
Thus, while I have illustrated and described my invention by means of 
specific embodiments, it is to be understood that numerous changes and 
modifications may be made therein without departing from the spirit and 
scope of the invention as defined in the appended claims.