JPH0364191B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an impact-driven sprinkler;
More specifically, the present invention relates to a simplified impulse-driven sprinkler constructed from relatively inexpensive components and having improved hydrodynamic flow characteristics.

Impulse-driven sprinklers are generally known for use in applying water for irrigation to areas planted with crops, turf, and the like. Typically, such sprinklers include a sprinkler body mounted to the upper end of a water supply pipe or standpipe such that the sprinkler body is rotatable about the axis of the standpipe. Inside the sprinkler body,
Directs the flow of pressurized water upward from the standpipe,
Then, in order to spray the water stream through the discharge nozzle,
A water channel is formed that bends in a generally outward and upwardly inclined direction. A spring-biased drive arm attached to the sprinkler body is driven in an oscillatory manner by the ejected water flow, applying an impact to the sprinkler body at a regular frequency, causing the axis of the standpipe to change. By rotating the sprinkler body around a small angular range, the water jet is swept over a circular area of soil for irrigation.
If it is not desired to rotate the sprinkler body through a complete circle, the impulse drive assembly can be provided with a conventional reversal mechanism that periodically reverses the direction of rotation, thus rotating the sprinkler body within the selected arcuate region. Sprinklers can be used for irrigation.

In conventional manufacturing methods, the sprinkler body is formed by casting or molding a rust-free or rust-resistant material, such as brass or plastic, with an internal mold cavity of the same shape as the desired shape of the sprinkler body. The material is injected or injected into a closed mold with a space. However, this type of manufacturing process tends to be relatively expensive, especially in that a different mold is formed for each shape of the sprinkler body.

In cast or molded sprinkler bodies, the internal water flow path is defined by a pair of generally straight passageways that intersect each other at an angle within the sprinkler body. Typical. Such a generally straight path allows the inner core to be positioned in the mold cavity prior to casting and removed from the sprinkler body after the sprinkler body is separated from the mold. Therefore, it can be formed. Alternatively, a generally straight passageway can also be formed by a drilling process. In either case, the intersecting passages form relatively steep angled bends in the water flow path that are shaped into smooth contours that minimize turbulence and optimize hydrodynamic flow. Not blooming. Rather, the bends are constituted by various surface irregularities, discontinuities, and breaks inherent in the manner in which the intersecting passages are formed. As a result, generally when using this type of sprinkler body, the water will experience considerable turbulence as it flows through the bends, significantly reducing the kinetic energy of the water stream projected from the discharge nozzle, thus reducing water flow and irrigation. The extent of the soil area obtained is correspondingly smaller. Such energy losses can be partially alleviated by placing so-called baffles along the flow path immediately upstream of the nozzle, but such baffles increase the cost of the sprinkler. At least some energy loss cannot be prevented.

Another drawback with conventional cast sprinkler bodies is that the spring biased drive arm has a size and shape uniquely chosen to match the particular shape of the sprinkler body. To be more specific,
The drive arm is typically attached to the sprinkler body so that it can oscillate about the axis of the water standpipe, and includes a deflector spoon shaped to suitably interact with the water flow having a specific trajectory. There is.
However, if another sprinkler body is to be manufactured in which the trajectory of the water jet has a different angle of inclination, it will be necessary to manufacture another drive arm shaped to match this trajectory. Since such drive arms are typically manufactured by casting or molding, additional uniquely shaped molds are required, thus ultimately adding to the cost of the sprinkler.

The present invention overcomes the problems and disadvantages of the prior art by providing an improved impact driven sprinkler. In this invention, the sprinkler body is formed from a certain flow of inexpensive tubing. The tube is bent to a selected angle to direct the water stream in the desired trajectory. Furthermore, the tubular sprinkler body is suitable for use with a drive arm having a generally universal shape that is independent of the trajectory of the water jet. Advantageously, the drive arm is formed from an inexpensive metal part produced by stamping.

The invention includes a sprinkler body formed by a length of tubing bent at a selected angle to direct a stream of water in a generally outward and upwardly sloping direction from the water supply standpipe. To provide an impact-driven sprinkler body with An impact drive assembly is mounted to the tubular sprinkler body and includes a drive arm for impacting the sprinkler body to interrupt water flow and rotate the sprinkler body through small angular ranges relative to the standpipe.

In a preferred form of the invention, the sprinkler body comprises a length of metal tubing having a relatively smooth contoured bend at a selected angle generally midway through the length of the tubing. It is formed.
One end of the bent tube constitutes a water inlet end, which extends downwardly into the journal bearing assembly. The assembly is adapted to connect the water inlet end to the water supply standpipe in a manner that allows rotation of the sprinkler body about the standpipe. The water inlet end tube terminates in an outwardly flared flange within the standpipe to allow water from the standpipe to enter the tube relatively smoothly. The tube forms a smoothly contoured channel with a substantially uniform cross-section to guide the water flow upward to the bend in the tube and to minimize flow turbulence and direct the water flow relatively smoothly into the bend. I will guide you. The water stream flows in a generally straight line from the bend in a generally outwardly and upwardly sloping direction to the discharge end of the tube and is disposed through the nozzle.

An impact drive assembly is mounted at the top of the tubular sprinkler body at least slightly downstream of the bend in the tube. The drive assembly has a generally upright fulcrum pin coupled to a drive arm via a torsion spring, and the drive arm is supported for rotation about an axis of the fulcrum pin. The fulcrum pin and drive arm are oriented such that the drive arm can move in a plane generally parallel to the outwardly and upwardly sloping portions of the tube, so that the drive arm can move regardless of the size of the tube bend. is located. a drive arm is urged by a torsion spring to rotate the stopper projection into impact engagement with one side of the tube;
The tube is rotated through a relatively small angular range about the axis of the standpipe. When this shock occurs,
The deflection spoon device supported by the drive arm interrupts the water flow, creating a driving force that rotates the drive arm away from the water flow against the torsion spring, which ultimately causes the drive arm to rotate. is reversed and rotated toward the tube, and the stopper protrusion applies an impact to the tube again.

In a preferred construction of the percussion drive assembly, the drive arm, including the deflector spoon device and stopper lug, is formed from a stamped metal component having relatively smooth surfaces. A fulcrum pin mounted on the tube projects upwardly through the central opening of the drive arm to support a bearing sleeve secured to the drive arm, thus defining an axis around which the drive arm rotates. The upper end of the fulcrum pin has a spider with several legs that supports one end of the helical torsion spring. The other end of the torsion spring is supported by a plurality of positioning pieces cut upwardly from the drive arm. The ends of the torsion spring are bent radially inward toward the support pin and engage one spider leg and one locating piece, respectively, so that the end of the spring engages the particular spider leg or locating piece. By selecting the pieces, the magnitude of the force of the torsion spring can be adjusted. A protective hood is placed over the fulcrum pin, spider and torsion spring. The hood has a plurality of locking fingers that form raised locating pieces that fit into holes in the drive arm.

Other features and advantages of the invention will become apparent from the following detailed description of the drawings.

The new and improved impact-driven sprinkler 10 embodying the present invention is designed for use primarily in irrigating grain, turf, and the like. Sprinkler 10 includes a simple sprinkler body formed by a length of bent tube 12 which directs water from a water supply or standpipe 16 to a discharge nozzle 1
8 defines a smooth, substantially continuous hydrodynamic flow path 14 for flow to 8. Water is ejected as a stream from nozzle 18 in a generally outward and upwardly sloping direction to irrigate a given soil area. An impact drive assembly 20 is mounted to the tubular sprinkler body and includes a simplified drive arm 22. The drive arm 22 interacts with the jetted water stream as well as the sprinkler body to rotate the sprinkler body around the standpipe through a series of small angular ranges so that it is covered by the jetted water stream. Substantially increases soil area.

The impact-driven sprinkler 10 of the present invention has significant advantages when compared to conventional impact-driven sprinklers previously available. Specifically, the impact-driven sprinkler 10 is constructed from inexpensive components that can be bent or stamped into the desired shape and then quickly and easily assembled to provide a very economical sprinkler. The invention thus eliminates the relatively expensive cast or molded sprinkler parts commonly used in the past, particularly the sprinkler body and drive arm.
Additionally, the tubular sprinkler body provides a substantially unbroken line to guide the water flow through the bends in the pipe 12 in an outwardly and upwardly sloping direction with minimal disturbance to the standpipe flow. It constitutes a hydrodynamic flow channel composed of smooth walls with various cross sections. As a result of water flowing smoothly through the channel 14,
The kinetic energy of the water stream at the discharge nozzle is significantly increased, resulting in a substantial increase in the dispersion area of the water stream when compared to conventional cast or molded sprinkler bodies. The particular angle of inclination or trajectory of the water stream to be injected can be selected during the manufacturing process by simple adjustment of the tube bending device (not shown), and the drive arm 22 can be A tubular sprinkler body having an angle of bend is attached to the tube in such a manner that one type of drive arm is used.

1 and 2, the impact-driven sprinkler 10 shown as an example has a flow path 1
4 has a sprinkler body formed with a length of hollow tube 12 formed therein. In a preferred form of the invention, tube 12 is constructed of a metallic material, such as stainless steel, that can be bent to a selected angle using conventional tube bending equipment (not shown). The tube has generally straight lower and upper portions 24, 2 typically arranged at obtuse angles to each other and separated by a smoothly contoured bend shown by arrow 28 in FIG.
It can be bent into a shape with a 6. What is important is that, after bending, the tube flow path 14 has a substantially uniform cross-sectional shape. This cross-sectional shape is bounded by an inner diameter defined by the smooth wall of the tube, which in the illustrated embodiment is substantially unbroken over the length of the tube.

A bent tube 12 is attached to the upper end of an upright supply tube or standpipe 16 for supplying pressurized water to the sprinkler. This attachment includes a journal bearing assembly 3 supported around the lower portion 24 of the tube 12.
This is done by 0. The journal bearing assembly 30 supports the tube in a position such that the upper portion 26 extends generally outwardly relative to the standpipe 16 and supports the lower portion 24 substantially around the vertical axis of the standpipe 16. restraint to allow rotational movement without leakage.

A journal bearing assembly 30 is shown in detail in FIG. 2 and is comprised of a cylindrical fitting 32, such as turned brass, supported around the lower portion 24 of the tube 12. Fitting 32 has external threads 34 that threadably engage the internally threaded upper end 36 of standpipe 16 and a suitable wrench (not shown) to facilitate installation and removal of the sprinkler from the standpipe.
It has a hexagonal head 38 adapted to conveniently engage. Alternatively, the relationship between the male and female threads of the fitting 32 and the standpipe 16 may be reversed, if desired.

Cylindrical fitting 32 is forced downwardly by a helical compression spring 40 fitted around lower portion 24 of tube 12 at a location below bend 28 . A spring 40 acts against a radially enlarged rib 42, such as a washer, secured to the tube by brazing or the like, and against a fatigue-resistant washer 44 at the axial upper end of the fitting 32. Apply downward force. As shown in FIG. 2, the upper ends of spring 40 and fitting 32 are conveniently protected from contamination by contact with dirt, grit, etc. by an inverted protective cup. The cup is fitted around the tube 12 and has a bottom portion 46 which is secured to the underside of a rib 42 secured by a spring 40, and a skirt portion 48 depending from the bottom portion 46 so as to substantially surround the spring. have.

For this purpose, the helical compression spring 40 connects the axially lower end of the joint 32 to a relatively hard nylon washer 50 sandwiched between a pair of elastomer washers 52.
Press into bearing engagement with a stack of sealing washers such as. As shown, sealing washers 50, 52
is located around the bottom end of the lower tube section 24 and is retained by a radially enlarged or flared flange 54 at the inlet end of the sprinkler body. Therefore, the joint 32 is connected to the standpipe 16.
When threaded into engagement, the compression spring 40 holds the stack of sealing washers 50, 52 in a compressed state between the end of the fitting 32 and the top surface of the flared flange 54. Seal washers 50 and 52 on standpipe 1
By sizing the standpipe for sealing engagement with the inner diameter of the standpipe 6, water flow from the standpipe is restricted into the channel 14 and is substantially leak-free. Importantly, however, this leak-tight connection allows rotation of the lower section 24 of the tube about the vertical axis of the standpipe.

Accordingly, the flared flange 54 of the tube 12 is positioned directly within the upper end of the standpipe 16 to guide pressurized water upwardly into the flow path 14 with minimal flow turbulence. Make the water inlet shape with smooth contours. Flow path 14 passes upwardly through journal bearing assembly 30 toward tube bend 28 with substantially no surface breaks or discontinuities. For this reason, the water flows relatively smoothly through bend 2.
8 and flowing through bend 28,
There is no significant flow disturbance or resultant loss of flow energy. The water thus passes through the bend 28, passes through the upper section 26 of the tube with relatively high kinetic energy, and is ejected from the sprinkler nozzle 18.

A nozzle 18 is suitably secured to the discharge end of the upper portion 26 of the tube 12 and defines an outlet orifice of selected size and shape for dispensing water as a stream 56 for irrigation. Although a variety of configurations are available for securing the nozzle 18 to the pipe, one preferred form is shown in FIG. It is advantageous to use compatible standardized nozzles with external threads that fit easily. To receive this type of nozzle, the sprinkler 10 of the present invention has a cylindrical mounting collar 58 with internal female threads 60 at one end to receive the nozzle 18 and an inner diameter forming a smooth wall at the other end. It has a surface 62 which is the upper part 26 of the tube.
It is a relatively tight sliding fit on the discharge end of the Mounting collar 58 is secured to the tube, such as by brazing, and provides a permanently attached receptacle for the nozzle.

By rotating the tube 12 about the axis of the standpipe 16, the jetted water stream 56 is swept over a relatively large soil surface area, maximizing the irrigation coverage of the sprinkler. This rotation is
This is accomplished by the action of an impulse drive assembly 20 mounted on top of the upper portion 26 of the tube 12, generally at a location intermediate the bend 28 and the nozzle 18. As shown in detail in FIGS. 2-5, the drive assembly 20 includes a fulcrum pin 64 secured, such as by brazing, to a generally U-shaped inverted mounting bracket 66. A bracket 66 is secured to the tube 12 by brazing or the like. A fulcrum pin 64 projects upwardly from a mounting bracket 66, generally perpendicular to the sloped upper portion 26 of the tube, and passes through the drive arm 22, the upper end of which is provided with a knurled tip 6.
It ends at 8.

A spider 70 with several legs is snugly fitted to the knurled tip 68 and the spider 70
is fixed so as not to rotate relative to the fulcrum pin 64. As shown, the spider 70 has a plurality of radially outwardly projecting legs 72, each extending a short distance downwardly toward the drive arm 22, and the upper side of the helical torsion spring 76. It has an outward facing recess 74 for receiving the turn. For this reason,
Spider legs 72 provide centering means for the upper portion of torsion spring 76. The torsion spring 76 projects downwardly therefrom and its upper portion is centered around a plurality of small projections 78 cut upwardly from the drive arm 22. the important thing is,
The upper end and lower end 80, 82 of the torsion spring 76 are connected to the fifth
bent radially inward toward the fulcrum pin 64 to engage one leg 72 and one lug 78 of the spider, respectively, as best shown in the figure;
Spider 70 and drive arm 22 are oriented to rotate the drive arm into impact engagement with the upper portion of the tube.
The spring 76 transmits rotational torque between the two. This will be explained in more detail later.

The amount of spring torque can be determined by manually separating spring 76 from spider 70, winding or unwinding spring 76 appropriately about its own axis, and then reconnecting spring 76 to the spider. , which is easy to adjust. When the desired torque is set, the protective hood 84, such as lightweight plastic, is torsioned to release the spring 76 and fulcrum pin 64.
on the top of the container so that it does not come into substantial contact with dirt, sand particles, etc. Conveniently, hood 84 is coupled to drive arm 22 by a plurality of depending locking fingers 86. The finger 86 passes through the hole 88 made by the cut protrusion 78,
Engages with the underside of the drive arm.

The illustrated drive arm 22 is advantageously constructed of an inexpensive, lightweight material such as stamped sheet metal, and is supported for relatively smooth rotation relative to a fulcrum pin 64. This rotational movement is facilitated by the use of a bearing spacer sleeve 90 supported about the fulcrum pin and secured to the drive arm by brazing or the like. If desired, a fatigue washer 92 is interposed between spacer sleeve 90 and mounting bracket 66. The drive arm 22 extends generally forwardly from the fulcrum pin 64 to be connected to the deflector spoon device 94 and extends generally rearwardly to form an enlarged counterweight section generally indicated by arrow 96 in FIG. terminate. Importantly, the torque applied to the drive arm 22 by the torsion spring 76 causes the drive arm to move in a direction that moves the deflector spoon device 94 to a position forward of the nozzle 18 and blocking the jetted water stream 56. The front end is biased so as to pivot around the fulcrum pin 64.

The rotational movement of the drive arm 22 described above is limited by a stop lug 98 depending from the drive arm and engaging or impacting one side of the sprinkler. Specifically speaking, the stopper protrusion 9
8 is formed of a stamped sheet metal or the like so that it can be conveniently connected to the drive arm by spot welding or the like, and projects downward from the drive arm so as to be impact-engaged with one side of the nozzle mounting collar 58. It's summery.
When this impact occurs, a lateral force is applied to the discharge end of the tube 12, causing the tube to rotate about the axis of the standpipe 16 over a relatively small range of angles.
This rotation slightly changes the direction of the water flow.

The deflection spoon device 94 is also formed of stamped sheet metal for convenient connection to the drive arm, such as by spot welding, but when the stop tab 98 engages the mounting collar 58, the entire nozzle 18 move to a position in front of and interact with the water flow. Specifically, in FIGS. 2 and 5, the deflecting spoon device 9
4 moves the upright vane 100 in front of the nozzle 18. The vanes are set at a slight angle to the direction of the jet of water. Feather 100
passes through the water stream, the water stream engages the rear surface 102 of the vane, causing the stopper projection 98 to engage the mounting collar 58.
The entire deflector spoon device 94 is pushed further into the water stream until it is impacted. When this impact occurs, the water stream passes behind the vane 100 and impinges on the oppositely angled spoon 104 at the front end of the deflector spoon device 94 in the line shown in FIG. The water stream thus exerts a substantial lateral force on the spoon 104, causing the drive arm 22 to rotate out of the water stream, against the force of the torsion spring 76. Torsion spring 76
finally dissipates the fluid force applied to the drive arm, then reverses the rotation of the drive arm to interrupt the water flow, and attaches the stopper lug 98 to the collar 98.
impact engagement. In this way, the tube 12 rotates through a complete circle around the axis of the standpipe 16, successively over a relatively small angular range. However, if desired, a suitable inversion mechanism of the type typically used in impulse driven sprinklers can be used to confine the rotation of tube 12 within a selected arcuate path.

As one feature of the present invention, the above-described attachment system for the impulse drive assembly 20 is independent of the size of the angular bends 28 in the tube, so that a range of tube bends 28 having different angles may be used. For any of the sprinklers, the drive assembly can be used without modification to give the water flow different trajectories. More specifically, the impact drive assembly 2
0 is mounted on top of the upper portion 26 of the tube 12,
Regardless of the particular angle of inclination of the upper section 26, the drive arm 22 is positioned to oscillate substantially parallel to the upper section 26. Furthermore, by mounting the fulcrum pin 64 at least slightly downstream of the tube bend 28, the total moment arm acting about the axis of the standpipe 16 is increased so that the stopper lug 98 The effective rotational force applied to 12 increases correspondingly. This increase in effective force has the advantage that the sprinkler rotation time is relatively faster and it moves over a larger range of rotation angles, which is particularly desirable when the feed water pressure is relatively low. .

The impact-driven sprinkler of the present invention allows water to flow into the sprinkler and how it flows within the sprinkler.
This is a significant improvement over conventional sprinklers having cast or molded sprinkler bodies in that the flow is substantially smoother with substantially reduced turbulence, particularly at bend 28. Channel 14
has a smooth inlet end defined by a flared flange 54 and the journal bearing assembly 3 has a smooth inlet end defined by a flared flange 54.
0 and through the bend 28 to the discharge nozzle 18;
It extends without any noticeable breaks on the surface. The cross-sectional size and shape of the flow path and the texture of the surface of the tube wall defining the flow path are substantially uniform throughout.
As a result, the water stream has more kinetic energy when it reaches the discharge nozzle 18, and this higher level of kinetic energy results in a greater amount of kinetic energy than with a conventional sprinkler body of cast brass or molded plastic. The direct effect is that the area of water flow is expanded by about 10% or more.

The invention is further advantageous in that its major components can be constructed from inexpensive components that are easily fabricated into the desired final shape by using economical, high-volume manufacturing methods. In particular, the tube 12 can be bent to the desired final shape, and the stamping-formed drive arm 22, including the deflector spoon device 94, can be bent quickly and in large quantities to tight tolerances without the use of expensive molds or the like. It can be manufactured. When assembled, the resulting sprinklers are highly reproducible to each other, as well as being reliable and low cost.

Those skilled in the art will recognize various modifications and improvements to the impact-driven sprinkler described herein. It is, therefore, to be understood that the invention is limited only by the scope of the claims.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an impact-driven sprinkler embodying the present invention, Fig. 2 is an enlarged side view mainly showing a vertical section of the sprinkler, and Fig. 3 is a line 3 in Fig. 2.
- A roughly vertical cross-section of the sprinkler taken at 3;
4 is a generally vertical cross-sectional view of the sprinkler taken along line 4--4 of FIG. 2, and FIG. be. Explanation of main symbols, 12: pipe, 14: flow path, 1
6: standpipe, 20: impact drive assembly, 24: lower section, 26: upper section, 30: journal bearing assembly.

Claims (1)

[Scope of Claims] 1. In an impact-driven sprinkler connected to a water supply standpipe, separating first and second pipe sections arranged at an angle to each other approximately midway along the length thereof. a sprinkler body formed of a length of tubing with bends defining an open channel for the passage of water therethrough, and supported about the first tubing section; a journal bearing assembly connecting the first pipe section to the standpipe so that water from the standpipe flows into the flow path, the journal bearing assembly including a the first tube portion terminating in a flange extending radially outwardly through the journal bearing assembly, the flange being relatively Constructs a smooth contoured water inlet to minimize flow turbulence.
guiding the flow of water from the standpipe into the flow path, and further applying an impact at a regular frequency to one side of the second pipe section, which is attached to the second pipe section,
an impulse drive assembly for rotating the tube as a whole about a standpipe axis in small angular increments; An impact-driven sprinkler that passes through the surface without interruption. 2. In the impact-driven sprinkler according to claim 1, the flow path formed by the tube passes through the first tube section, the bend, and the second tube section substantially uniformly. An impact-driven sprinkler having a specific cross-sectional size and shape. 3. An impact-driven sprinkler according to claim 1, wherein a mounting collar is supported around the open end of the second pipe section and has means for removably supporting a discharge nozzle. Impact driven sprinkler. 4. In the impact-driven sprinkler according to claim 1, the journal bearing assembly comprises:
a generally cylindrical fitting supported about the first pipe section and at least one interposed between the flared flange and one axial end of the fitting for connection to a standpipe; a sealing ring, an outwardly projecting rib provided on the first tube section between the axially opposite ends of the bend and the fitting; and a reaction between the fitting and the rib; spring means for urging a flared flange of the first tube section into sealing engagement with the at least one sealing ring. 5. An impact-driven sprinkler as claimed in claim 4, including a bottom portion supported around the first tube section between the ribs and the spring means, and a bottom portion extending from the bottom portion in a direction surrounding the spring means. An impact-driven sprinkler having a bowl-shaped member with an extending protective annular skirt. 6. The percussion-driven sprinkler of claim 1, comprising a drive arm mounted so that the percussion drive assembly oscillates generally in a plane parallel to the second tube section; a stopper protrusion provided on the drive arm for applying an impact to one side of the second tube section; and a stopper protrusion provided on the drive arm for rotating the drive arm in a direction that brings the stopper protrusion into impact engagement with the second tube section. a torsion spring that biases the drive arm; and a deflection spoon device that is provided on the drive arm and intercepts the jet of water substantially at the same time as the impact engagement, so that the water flow twists the drive arm. An impact-driven sprinkler, wherein a force is applied to the drive arm to rotate it against a spring, and the drive arm, the stopper protrusion, and the spoon device are formed by stamping metal. 7. The percussion-driven sprinkler of claim 6, wherein the percussion drive assembly extends through a drive arm in a direction generally away from the first pipe section and toward the second pipe section. a fulcrum pin mounted on the second tube portion so as to project generally vertically therethrough, and the torsion spring connects the distal end of the fulcrum pin with a plurality of locating pieces formed on the drive arm. an impact-driven sprinkler coupled between the drive arm and the drive arm with a protective hood over the fulcrum pin and torsion spring; 8. In the impact-driven sprinkler according to claim 7, the positioning piece is cut upward from the drive arm, and the hood has a hole formed in the drive arm by the positioning piece. An impact-driven sprinkler having a locking finger that can be inserted downward into the sprinkler.