US3915383A

US3915383A - Sprinkler with sealed magnetic rotary motion transmitting mechanism

Info

Publication number: US3915383A
Application number: US467555A
Authority: US
Inventors: James P King
Original assignee: LR Nelson Corp
Current assignee: LR Nelson Corp
Priority date: 1974-05-06
Filing date: 1974-05-06
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28
Also published as: ZA752298B; CA1031012A

Abstract

A sprinkler having a drive shaft and reduction gearing therefor operatively connected to a water flow powered motor by a permanent magnet coupling. By utilizing a magnetic coupling, the reduction gearing can be completely sealed from the water flow and all foreign materials carried thereby without any impairment of the rotation of the turbine of the water motor. Also, the utilization of planetary reduction gearing is facilitated. The drive shaft may drive both an oscillating fluid delivery tube and the wheels of a travelling sprinkler.

Description

United States Patent King Oct. 28, 1975 [54] SPRINKLER WITH SEALED MAGNETIC 3,128,047 4/1964 Rogers 239/191 ROT MOTION TRANSMITTING 3,169,398 2/1965 Sparling et a1... 310/103 X MECHANISM 3,261,553 7/1966 Kooi et a1. 239/242 Inventor! James King, Glen Ellyn, Primary ExaminerJohn J. Love [73] Assignee: L. R. Nelson Corporation, Peoria, Attorney Agent or Firm cushman* Darby &

L Cushman PP 467,555 A sprinkler having a drive shaft and reduction gearing therefor operatively connected to a water flow pow- [52] CL 239/242 ered motor by a permanent magnet coupling. By uti- [511 Int 75 3/04 lizing a magnetic coupling, the reduction gearing can [58] Field of Search 240 241 be completely sealed from the water flow and all for- 239/242 2 6 eign materials carried thereby without any impairment of the rotation of the turbine of the water motor. Also, he utilization of lanetar reduction earin is facili- [56] References Cited t p y g g tated. The drive shaft may drive both an oscillating I UNITED STATES PATENTS fluid delivery tube andvthe wheels of a travelling sprin- 2,132,314 10/1938 Needler 239/242 klen 2,770,131 11/1956 Sparling 310/103 UX 2,914,255 11/1959 Jepson 239 242 12 Clalms, 10 Drawmg Flgul'es U.S. Patent Oct. 28, 1975 Sheet 1 of6 US. Patent Oct. 28, 1975 Sheet 2 of6 3,915,383

Sheet 4 of6 3,915,383

US. Patent Oct. 28, 1975 sheet 5 of6 3,915,383

U.S. Patent Oct. 28, 1975 wN Amm U.S. Patant Oct. 28, 1975 Sheet60f6 3,915,383

1 SPRINKLER WITH SEALED MAGNETIC ROTARY MOTION TRANSMITTING MECHANISM BACKGROUND OF THE INVENTION The invention relates generally to the art of lawn sprinklers, and more particularly to water flow responsive drive means for varying the ground area receiving water from a lawn sprinkler. In the past, it has been common practice to provide a water flow responsive motor unit that through a series of reduction gears drives some sort of means for varying the ground area receiving water from the sprinkler, such as an oscillating linkage as shown in US. Pat. No. 3,430,860. There have been a number of hitherto unsolved problems associated with such motor and drive means however. The reduction gearing utilized has generally been cumbersome, taking up a great deal of valuable space within the sprinkler housing. Also, the gearing and drive mechanism have been subject to deterioration when exposed to the water flow and the grit and impurities carried thereby. Attempts have been made to seal the gear reduction unit by utilizing special bearings, as shown by US. Pat. No. 3,286,929, or by including water-repellant grease in the gear reduction unit housing, as shown by US. Pat. No. 3,107,056, but such means have not been completely effective in preventing fouling and deterioration of the reduction gears and drive mechanism over long periods of use, and/or have impaired the movement of the turbine thereby reducing the efficiency, power, and reliability of the unit.

Also, in the past a unit for powering a sprinkler has not been demonstrated that both powers a mechanical means for moving a fluid-distributing mechanism while at the same time providing power for driving the sprinkler unit as a whole. Prior devices related to this aspect are shown in US. Pat. Nos. 2,249,211, 2,788,241, and 3,128,047.

SUMMARY OF THE INVENTION The present invention teaches the use of a water flow responsive turbine in a sprinkler that is magnetically coupled to reduction gearing and drive means thereby allowing the reduction gearing to be completely, effectively, and reliably sealed from the water flow by a unitary housing without impairing the movement of the turbine and the power delivered thereby. While fluid motors with magnetic couplings per se are known, such as shown by US. Pat. No. 2,466,468, they are not known in sprinklers. Use of such a unit in a sprinkler effectively sealing the reduction gearing while not impairing turbine movement also allows planetary reduction gears to be used. The use of planetary reduction gears in a sprinkler is advantageous because of their efficiency and because of their compactness and small size for a given reduction, but in the past their use in sprinklers has been excluded for all practical purposes since they are very susceptible to fouling in a contaminated environment such as a sprinkler housing.

The present invention also teaches the use of mechanical drive means powered by the output shaft from the planetary reduction gear unit of the invention that operates both an oscillating linkage for a water delivery tube and drive wheels for the sprinkler unit as a whole to move it along the ground. Through the use of accessory reduction gearing and speed selecting means, the motor output shaft-of the present invention is able to power both such units.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an improved motor unit for a lawn sprinkler.

It is a further object of the present invention to completely seal the reduction gearing unit of a lawn sprinkler motor unit from the water flow through the sprinkler.

It is a further object of the present invention to provide a turbine magnetically coupled to reduction gearing and an output shaft in a lawn sprinkler motor unit.

It is a further object of the present invention to utilize planetary reduction gears for reducing the speed of an output shaft relative to a water flow responsive turbine.

It is a further object of the present invention to provide means for driving means for moving a sprinkler itself while also driving water delivery means on the sprinkler.

It is a still further object of the present invention to provide a sprinkler that is automatically movable with respect to the ground while also having a water delivery tube that is oscillatable.

These and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of the travelling oscillating sprinkler according to the teachings of the present invention;

FIG. 2 is a side elevational view of the travelling oscillating sprinkler according to the teachings of the present invention;

FIG. 3 is a sectional view taken along lines 33 of FIG. 1 showing the oscillator linkage according to the teachings of the present invention;

FIG. 4 is a cross-sectional view partly in elevation taken along lines 44 of FIG. 8 showing the interrelationships of the motor, oscillating gearing, water delivery system, and drive gearing according to the teachings of the present invention;

FIG. 5 is a cross-sectional view taken along lines 5-5 of FIG. 6 showing a planetary reduction gear arrangement according to the teachings of the present invention;

FIG. 6 is a cross-sectional view of the water motor unit according to the teachings of the present invention;

FIG. 7a is a view taken along lines 7a7a of FIG. 6 showing the turbine and magnetic coupling means according to the teachings of the present invention, while FIG. 7b is a fragmentary development of the turbine and associated structures according to the teachings of the present invention;

FIG. 8 is a cross-sectional view taken along lines 8-8 of FIG. 4 showing the drive gearing for the sprinkler wheels according to the teachings of the present invention;

FIG. 9 is a sectional view taken along lines 99 of FIG. 1 showing the speed selector knob in solid line and the speed selecting means in dotted line according to the teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION A travelling oscillating sprinkler according to the present invention is shown generally at 10 in FIG. 1. A conventional oscillating fluid distributing tube 11 is supplied with fluid through hose 12, inlet connection 13, and outlet connection 14. The complete assembly is mounted on a frame shown generally at 15, comprising tubular rod side frame members 16, cross-portion 17 having an aperture 18 therein, and tube supporting bracket 19. The oscillating linkage, shown generally at 20, the motor-housing sector, shown generally at 30, and the gearing housing sector, shown generally at 50, are supported by drive'shaft 81 of wheels 80. Frame members 16 rest on bushings 68 of shaft 81, and supportively engage plates 51 of gearing housing sector 50 (as most clearly shown in FIGS. 3, 8, and 9.) The front part of frame is supported by small wheel 82, which may be of the type adapted to be guided by a hose, and which is rotatable about axle 84 connected to crossmember 17 by bracket 83.

FIG. 3 shows in detail the oscillating linkage 20 for oscillating the fluid distributing tube 11 according to the teachings of the present invention. Linkage arm 21 has terminating collar portions 22, 23, for respectively engaging fluid distributing tube 11 and pin shaft 24. Pin shaft 24 is received in a hole in linkage arm 25, which is pivotally attached to arm 26. Arm 26, is in turn connected to right angle terminating portion 28 of arm 27. The other right angle terminating portion, 29, of arm 27 is fixed to drive shaft 29, shown in dotted line in FIG. 3. As can be clearly seen in FIGS. 1 and 3, the oscillating linkage is supported in front of motor housing sector 30.

The novel motor structure according to the teachings of the present invention is shown generally at 30. As is clearly shown in FIGS. 47, the motor is comprised generally of two distinct sections; (1) a turbine, 31, 32, 32, magnetically coupled via permanent magnets 33, to (2) a sealed output shaft-gear reduction arrangement, 36-41, 48, sealed within a housing 34. The turbine is composed of shaft portion 31 rotatably supported by a tubular end extension of housing 34, arm and support portion 32, and turbine blades 32'. Outer coupling magnet 33 is attached to support portions 32. As shown most clearly in FIGS. 7a and 7b, the turbine is preferably formed of eight turbine blades 32 responsive to water flowing in an axial direction.

Outer and inner

magnetic coupling members

33, 35, are coupled through housing wall 34. The

permanent magnets

33, 35, are preferably formed of sintered barium-ferrite, the outer magnet 33 magnetized with multiple poles on its inner diameter, and the inner magnet 35 magnetized with multiple poles on its outer diameter. As with all magnetic couplings,

magnetic coupling

33, 35 has a break-away feature so that should turbine 32 turn too fast, it will break the magnetic coupling between it and the planetary gear train 38, thereby preventing damage to the gear train.

Inner magnetic coupling member 35 is rigidly attached to support shaft 36, which is rotatable about shaft 37. Support shaft 36 has a sun gear 36' formed thereon. Sun gear 36' is the drive gear for the planetary reduction gearing system, shown generally at 38 in FIGS. 5 and 6. Sun gear 36' drives planetary gears 39, which are attached to support segment 39 and are also in engagement with inner-toothed sector of 34 of casing 34. Since planetary gears 39' are rotatable about portions of support member 39, they drive gear 39" formed on the upper portion of support member 39. Gear 39" then in turn drives planetary gears 40' on support member 40 which gears are in engagement with toothed sector 34" of housing 34 thus driving gear 40" formed from support member 40. Gear 40" in turn drives planetary gears 41' of support member 41 which gears are in engagement with inner toothed sector 34 of housing 34. Formed on the upper extremity of support member 41 is motor output shaft 48 which drives both the oscillating linkage and the rear wheels, as will be further explained below. The preferred reduction of the planetary gear train 38 is 81.4-1.

The center shaft, 37, supports the planetary gear sets and locates the output shaft 48 axially and radially due to a press fit with the rotary output shaft 48. Shaft 37 is preferably formed of stainless steel, while rotary output shaft 48 is preferably formed of acetyl plastic. A high friction sealing element, O-ring 46, is fitted between housing 34 and output shaft 48 to prevent entry of any water or gritty material carried therewith into the housing 34. O-ring 46 provides a sufficient seal here since housing sector with which it communicates is essentially free of water and since shaft 48 is a lowspeed, high torque component.

As can be clearly seen, a completely sealed gear reduction unit driven by a turbine is provided through the utilization of a magnetic coupling. Thus, the high-speed low-torque turbine can turn reliably at any flow rate desired, while a compact planetary gearing arrangement can be sealingly separated therefrom so that no water or grit can affect the operation thereof, thus resulting in a more reliable, more efficient, and more compact motor for a sprinkler.

Gearing arrangements by which the output shaft 48 drives the rear wheels 80 and the oscillating linkage 20 are shown most clearly in FIGS. 4 and 8. Collar 44 is keyed to shaft 48, and has spur gear 42 and worm gear 49 formed thereon. The drive for the oscillating linkage is shown in dotted line in FIG. 4. Reduction spur gear 43 is driven by gear 42, thereby rotating shaft 29' and operating oscillating linkage 20.

Rear wheels 80 are driven by the gearing arrangement shown generally in housing sector 50. Worm gear 49 drives gear 52 formed on sleeve 57 rotatably supported by shaft 53. Gear 54, also formed on sleeve 57, drives gear 59, which is splined at 62 to sleeve 61 rotatably supported by rear wheels shaft 81. Rotation of gear 59 also results in rotation of gear 63 formed on sleeve 61, which in turn rotates gear 64, which gear is rotatably supported by shaft 53. Gear 64 is connected to gear 65, so that rotation of gear 64 rotates gear 65 which in turn drives gear 66. Since gear 66 is keyed to shaft 81 at 67, rotation of gear 66 drives shaft 81, thereby driving rear wheels 80. Note that shaft 81 is supported by bearings 68.

The gearing arrangement above described is for driving the sprinkler at a relatively high speed. For driving the sprinkler at a relatively low speed, gears and are utilized in place of gears 54 and 59. Gear 55 is keyed to sleeve 57 at 58, while gear 60 is rigidly attached to gear 59. FIG. 8 shows the gears arranged to drive the sprinkler at the relatively high speed. To change to neutral or low speed, the selecting means shown generally at 70 in FIGS. 8 and 9 is used. Selecting means 70 is composed of a selector knob 71 located on the outside of the gear housing sector, and rotatable about shaft 72. Shaft 72 extends into the interior of the housing, and is rigidly attached to selector member 73 having arms 74 and 75, formed thereon. A detent means 76, 77, may be utilized to hold the selector knob in one of the three positions, and the positions may be indicated by raised lettering on the housing.

To change from high to low speed, selector knob 71 is rotated to the right (as shown in FIG. 9) thereby moving arm 74 of selecting member 73 against the side of gear'59. Since gear 59 is splined to shaft 61, it slides to the left (as viewed in FIGS. 8 and 9) passingthrough a neutral position to the low position wherein gears 60 and 55 engage. Engagement of gears 55 and 60 will result'in rearwheels 80 being driven at a slower speed than when gears 54 and 59 are utilized. Thus it will be seen that a compact, efficient, powerful reduction gear driving arrangement has been disclosed.

Water flow for the sprinkler is provided through inlet l3,'con'd uits 90, 91, and flow-directing motor mounting member 93, as'shown in FIG. 4. Conduit 90 is affixed to the interior of the gearing housing sector 50 at the water inlet 13, and is attached through O-ring 92 to conduit 91. Conduit 91 directs flow from the inlet to flow directing member 93. Flow directing member 93 has a plate portion 100. Extending from the plate portion 100 of member 93 are concentric generally tubular flow-directing

portions

96, 97. Water flowing from conduit 91 flows through hole 98 in portion 96, .and holes 99 'in connecting members between

portions

96 and 97, and is then axially directed against turbine blades 32 for driving them.

In addition to directing the flow of water from the inlet l3 through the turbine blades 32', and then into the outlet 14, member 93 also supports the motor gearreduction housing 34, and sealingly separates the driving gears in housing sector 50 from the water. Plate 100 of member 93 is shaped to generally conform to the insideof housing sector 50, having peripheral holes for receiving conduit 91 and oscillating linkage driving shaft 29 formed therein. The extremities of plate 100 engage gasket 95 on housing extension 94 to seal housing sector 50 from the water flow. A large aperture in the center of plate 100, defined by tubular member 97, receives motor gear-reduction housing 34 therein. The

' housing 34 may be affixed to the plate 100, or may be held in contact therewith by the forces applied through shaft 48 in holding the shaft in place within the

housing sectors

30,50. It will thus be seen that member 93 performs the functions of sealing the gear housing sector from the water flow, mounting the motor gearreduction assembly, and directing the water flow through the turbine.

Although the housing can be formed in any suitable manner, and assembly of components likewise may be effected by any suitable means, preferably, the housing is formed in two parts 1 10, 112, divided generally along lines 88 in FIG. 4. Part 112 contains motorcontaining housing sector 30 and a substantial portion of gear housing sector 50, while part 110 contains the remaining portion of sector 50 including the selector knob 71 and the raised lettering associated therewith. The parts 1 10, 1 12 may be held together after insertion of all the parts into them by bolts passed through

holes

114 and 116 formed in extensions of the outer housing periphery. Note that bushings for the

shafts

53, 81 are formed half way in each of the parts 1 10, 112, thereby facilitating assembly of the components.

ing sprinkleraccording to the present invention having been described, theoperation will now be set forth. A hose 12 is connected to inlet 13 of the sprinkler 10, and water under pressure is provided thereby. The water enters conduit 91, and passes throughflow-directing member 93 to exert an axial force on turbine blades 32, thereby rotating

turbine

31, 32. The water then continues flowing through the housing to outlet 14. From outlet 14 it is supplied to oscillating waterdistributing tube 11 to be supplied to the ground.

Rotation of the turbine also rotates outer magnetic member 33 attached thereto. Magnet 33 is magnetically coupled to inner magnet 35 in sealed housing 34, and rotation of sun gear 36' on support shaft 36 at the same speed as the turbine is thereby effected. The speed of the motor output shaft 48 is reduced through planetary reduction gear train 38. The output shaft then drives both the oscillating linkage 20 for oscillating the fluid-delivery tube 11, and the rear wheels for moving the sprinkler along.

The oscillating linkage 20 is driven by motor output shaft 48 via gear 42, reduction gear 43, and drive shaft 29'. Rear wheels 80 are driven by shaft 48 via worm gear 49, spur gear 52, either high-speed gear train.54, 59, or low-speed gear train 55, 60, reduction gears 63, 64, 65, and 66, and rear-wheel drive shaft 81. After the area to be watered has been sufficiently sprinkled, or the travelling sprinkler has completed its travel, the sprinkler may be shut down by turning off the water power to hose 12, or by any suitable conventional automatic shut-off means.

Many modifications of the sprinkler according to the teachings of the present invention are possible. For instance, instead of driving an oscillator and travelling wheels, the output shaft of the magnetically coupled motor according to the teachings of the present invention could instead drive a rotary spinkler head and/or a hose windup drum or a cable windup wheel. A gear train other than a planetary reduction gear train could be used in the motor to reduce the speed of the output shaft, although planetary gears are preferred because of their compactness, efiiciency, reliability, and the large reduction possible within a small area. Many other modifications are also possible.

It is thus apparent that a sprinkler with an improved drive means therefore accomplishing all the objectives of the invention has been clearly set forth. Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention which is not to be limited to details disclosed but is to be accorded the full scope of the claims so as to embrace any and all equivalent structures and devices.

What I claim is: I

1. A sprinkler comprising:

a. a water inlet for supplying water under pressure from a hose to the sprinkler,

b. delivery means for delivering water from said inlet to a ground area,

0. a rotary output shaft rotatable about a first axis of rotation,

d. means operable in response to the movement of said rotary output shaft for changing the ground area receiving the water from said delivery means, and

e. means for converting the flow of water from said inlet to said delivery means to rotary motion of said output shaft including (i) a turbine having turbine blades responsive to said water flow, said turbine blades being rotatable about said first axis of rotation, (ii) planetary gear reduction means operatively connected to said rotary output shaft for reducing the speed of said shaft relative to the speed of said turbine, said planetary gear reduction means comprising a first gear member rotatable about said first axis of rotation, a pair of second gear members, said second gear members being operatively connected to said output shaft and said second gear members being rotatable about second and third axes of rotation respectively, said second and third axes of rotation being spaced from but parallel to said first axis of rotation, an inner housing toothed annular sector, said sector being concentric with said first axis of rotation, said second gear members being disposed on opposite sides of said first gear member and each simultaneously cooperating with said sector and said first gear member for providing gear reduction of said output shaft, whereby a compact arrangement is provided, (iii) housing means for completely sealing said gear reduction means from said water flow, said housing means having said inner toothed sector formed thereon, and (iv) permanent magnet coupling means for coupling said gear reduction means to said turbine through said housing means, said magnet coupling means including a first permanent magnet ring operatively connected to said turbine blades and being rotatable about said first axis, and a second permanent magnet ring operatively connected to said first gear member of said gear reduction means, whereby said gear reduction means will be permanently and efficiently sealed from said water flow without any impairment of the movement of said turbine.

2. A sprinkler as recited in claim 1 wherein said turbine blades are responsive to water flow in a direction generally parallel to the axis of rotation of said turbine.

3. A sprinkler as recited in claim 2 further comprising means for directing the water flow from said inlet through said turbine blades in said direction generally parallel to the axis of rotation of said turbine.

4. A sprinkler as recited in claim 3 further comprising means for mounting said housing means for completely sealing said gear reduction means from said water flow.

5. A sprinkler as recited in claim 4 further comprising means for sealing gear means driven by said rotary output shaft from said water flow.

6. A sprinkler as recited in claim 5 wherein said means for directing the water flow, said means for mounting said housing means, and said means for sealing gear means driven by said output shaft are all part of an integral member contained in a housing for said sprinkler.

7. A sprinkler as recited in claim 1 wherein said means for changing the ground area receiving the water from said delivery means includes means for oscillating said delivery means.

8. A sprinkler as recited in claim 7 wherein said means for changing the ground area receiving the water from said delivery means further includes means for automatically moving said sprinkler relative to the ground.

9. A sprinkler as recited in claim 8 wherein said means for automatically moving said sprinkler comprises a worm gear mounted on said output shaft, reduction gears driven by said worm gear, and a drive gear keyed to a drive axle having wheels mounted thereon, whereby said worm gear drives said reduction gears which in turn dn've said drive gear which in turn drives said drive axle thereby rotating said wheels to move said sprinkler with respect to the ground.

10. A sprinkler as recited in claim 9 wherein said means for moving said sprinkler further comprises speed selector means for selecting said reduction gears to vary the speed at which said wheels are rotated and thus the speed at which said sprinkler is driven.

11. A sprinkler as recited in claim 7 wherein said oscillating means includes a gear mounted on said output shaft, a reduction gear in operative relationship with said gear mounted on said output shaft, a drive shaft keyed to said reduction gear, and an oscillating linkage connected to said delivery means and in operative relationship with said drive shaft, whereby said output shaft drives the gear mounted thereon which in turn drives said reduction gear which in turn drives said drive shaft which in turn drives said oscillating linkage which in turn oscillates said delivery means.

12. A sprinkler as recited in claim 11 wherein said delivery means comprises an elongated fluid delivery tube mounted at both ends thereof.

Claims

1. A sprinkler comprising: a. a water inlet for supplying water under pressure from a hose to the sprinkler, b. delivery means for delivering water from said inlet to a ground area, c. a rotary output shaft rotatable about a first axis of rotation, d. means operable in response to the movement of said rotary output shaft for changing the ground area receiving the water from said delivery means, and e. means for converting the flow of water from said inlet to said delivery means to rotary motion of said output shaft including (i) a turbine having turbine blades responsive to said water flow, said turbine blades being rotatable about said first axis of rotation, (ii) planetary gear reduction means operatively connected to said rotary output shaft for reducing the speed of said shaft relative to the speed of said turbine, said planetary gear reduction means comprising a first gear member rotatable about said first axis of rotation, a pair of second gear members, said second gear members being operatively connected to said output shaft and said second gear members being rotatable about second and third axes of rotation respectively, said second and third axes of rotation being spaced from but parallel to said first axis of rotation, an inner housing toothed annular sector, said sector being concentric with said first axis of rotation, said second gear members being disposed on opposite sides of said first gear member and each simultaneously cooperating with said sector and said first gear member for providing gear reduction of said output shaft, whereby a compact arrangement is provided, (iii) housing means for completely sealing said gear reduction means from said water flow, said housing means having said inner toothed sector formed thereon, and (iv) permanent magnet coupling means for coupling said gear reduction means to said turbine through said housing means, said magnet coupling means including a first permanent magnet ring operatively connected to said turbine blades and being rotatable about said first axis, and a second permanent magnet ring operatively connected to said first gear member of said gear reduction means, whereby said gear reduction means will be permanently and efficiently sealed from said water flow without any impairment of the movement of said turbine.

9. A sprinkler as recited in claim 8 wherein said means for automatically moving said sprinkler comprises a worm gear mounted on said output shaft, reduction gears driven by said worm gear, and a drive gear keyed to a drive axle having wheels mounted thereon, whereby said worm gear drives said reduction gears which in turn drive said drive gear which in turn drives said drive axle thereby rotating said wheels to move said sprinkler with respect to the ground.