FR2551318A1 - IMPACT DRIVING WATERING APPARATUS - Google Patents

Abstract

THE INVENTION RELATES TO AN IMPACT DRIVEN WATERING APPARATUS FOR PROJECTING A CURRENT OF WATER GENERALLY UPWARD AND OUTWARD FROM A WATER SUPPLY PIPE. ACCORDING TO THE INVENTION, IT INCLUDES A SHAPED BODY OF A TUBE LENGTH 12 MOUNTED FOR ROTATION ON THE RISING PIPE 16, THE TUBE BEING BENT AT A SELECTED ANGLE TO DEFINE A REGULAR AND SENSITIVELY UNINTERRUPTED FLOW PATH FROM RISE 16 TO AN EXHAUST ADJUSTMENT 18; A 20 IMPACT DRIVE ASSEMBLY IS MOUNTED ON TUBE 12 AND INCLUDES A 22 SPRING DRIVE ARM TO INTERRUPT THE FLOW OF PROJECTED WATER AT REGULAR INTERVALS AND TO IMPACT TUBE 12 TO ROTATE THE TUBE BY INCREMENTS AROUND THE PIPE 16; THE DRIVE ASSEMBLY IS MOUNTED ON TUBE 12 IN A POSITION DOWNSTREAM OF ELBOW 28. THE INVENTION APPLIES IN PARTICULAR TO THE WATERING OF CROPS OR TURF.

Description

1 22551318

  The present invention generally relates to impingement sprinklers, and more particularly to a simplified impact sprinkler constructed with relatively inexpensive components and having improved hydraulic flow characteristics. Impaction drive sprinklers are generally known for use in applying irrigation water to crops, turf surfaces and the like. Such sprinklers typically include a body mounted at the top end. of a water supply tube or riser pipe in a manner permitting rotation of the body about the axis of the riser pipe A water flow path is formed in the body of the apparatus watering to guide a stream of pressurized water upwardly from the riser pipe and then to rotate the stream of water in a generally outward and upwardly sloping direction for projection through a nozzle A spring-loaded drive arm mounted on the body of the watering apparatus is oscillatingly entrained by the flow of water projected to impact the body of the watering apparatus at a regular frequency To rotate this body in small angular increments about the axis of the riser pipe, the projected water stream is swept over a circular region of the ground for irrigation. With the entire circle of the sprinkler body, the impingement drive assembly may include a conventional reversing mechanism to periodically reverse the direction of rotation to thereby permit use of a sprinkler for

  an irrigation on a chosen arcuate region.

  According to conventional methods of manufacture, the body of the sprinkler is formed of a rust-resistant or stainless material such as brass or plastic by a casting or molding process where the material is poured or injected into a closed mold having an internal cavity conforming to the geometry of the desired body of the sprinkler This type of manufacturing process, however, tends to be relatively expensive, particularly with regard to the formation of different molds for each configuration

watering device body.

  In a sprinkler body formed by casting or molding, the internal water flow path 10 is typically defined by two generally linear passages which intersect each other at an angle in the body. These generally linear passages can be formed using internal cores which are placed in the mold cavity before sinking and are then removed from the body of the mold.

  the watering apparatus after separation from the mold.

  Alternatively, these generally linear passages may be formed by a drilling process. In each case, the intersecting passages form a relatively steep angular bend in the water flow path and the bend is not routinely contoured for In contrast, the bend is defined by a wide variety of surface irregularities, discontinuities, and interrupts which are inherent in the process of forming the intersecting passages. when watering apparatus bodies of this general type are used, the water undergoes substantial turbulence as it flows through the elbow which significantly reduces the kinetic energy of the water flow projected by the evacuation nozzle, thereby correspondingly reducing the range of the water flow and the soil surface that can be irrigated While this loss of energy can be partially relieved by using straightening fins placed along the flow path immediately upstream of the nozzle, such straightening fins increase the price of the sprinkler and do not prevent at least some energy losses. Another disadvantage with conventional sprinkler casings is that the spring-biased drive arm has a size and shape that is uniquely chosen to correspond to a particular configuration of an apparatus body. In particular, the drive arm is typically mounted on the body of the watering apparatus 10 for oscillating movement about the axis of the water supply riser and includes a deflection spoon configured to appropriate interaction

  with a stream of water having a particular trajectory.

  If, however, it is desired to manufacture another body of watering apparatus where the trajectory of the projected water current has a different angle of inclination, it is also necessary to manufacture another driving arm configured to correspond to the new trajectory As these drive arms are normally manufactured by a casting or molding process, additional molds of unique shape are required which thus further contribute significantly to the final price.

of the watering device.

  The present invention overcomes the problems and disadvantages of the prior art by providing an improved impact sprinkler apparatus wherein the sprinkler body is formed of an inexpensive length of tube which is bent At a chosen angle for projecting a stream of water to a desired trajectory Furthermore, the tubular body is adapted for use with a drive arm of substantially universal shape, whatever the

  trajectory of the projected water stream, o the drive arm can advantageously be formed of pressed metal parts little curling.

  According to the invention, an impingement sprinkling apparatus is provided having a body formed of a certain length of tube bent at a selected angle to project a stream of water in a generally outward direction and inclined towards water, in

  from a rising water supply pipe.

  An impact drive assembly is mounted on the tubular body and includes a drive arm for interrupting the flow of water and impacting the body of the sprinkler apparatus to rotate the

  body in increments relative to the riser pipe.

  According to a preferred form of the invention, the body of the watering apparatus is defined by a length of a metal tube having a relatively regularly contoured bend formed therein at an angle generally selected from an intermediate portion of its One end of the curved tube forms a water inlet which extends downwardly through a trunnion bearing assembly adapted to connect the water inlet end to the water supply riser pipe. a way for rotation of the body of the watering apparatus around the axis of the riser pipe The water inlet end tube ends in the riser pipe by a flange

  flared outwardly to facilitate a relatively steady inflow of riser water into the tube.

  The tube defines a regularly contoured flow path of substantially uniform cross-section to guide the flow of water upward to the bend of the tube and to guide the flow of water through the bend, relatively regularly, with minimum flow turbulence From the bend, the water flows substantially linearly in a generally outward direction and slopes upwardly to a discharge end of the projection tube through

a nozzle.

  The impact drive assembly is mounted at the top of the tubular body of the sprinkler at a position which is at least slightly downstream of the tube bend. This drive assembly includes a generally upright pivot coupled by a torsion spring at the drive arm which, in turn, is supported for rotation about the pivot axis The pivot and the drive arm are oriented for movement of the drive arm in a generally parallel plane at the upwardly and upwardly inclined portion of the tube so that the drive arm is positioned independently of the magnitude of the tube elbow The drive arm is biased by the torsion spring to rotate in a direction an impact engagement tab with one side of the tube for rotating the tube on a relatively small angular increment around the axis of the riser pipe When this impact occurs, a unit for The deflecting spoon carried by the drive arm interrupts the flow of water which produces a driving force to rotate the drive arm against the torsion spring away from the water flow, then the spring. of torsion possibly reverses the rotation of the drive arm 20 back to the tube and again for an impact of

tube with the stopper.

  According to a preferred construction of the impact drive assembly, the drive arm having the deflection spoon unit and the stopper tab 25 are formed of relatively smooth surface metal parts. The pivot mounted on the tube protrudes upward through a central opening in the drive arm and supports a sleeve which is attached to the drive arm to thereby define an axis for the rotation of the arm. several branches that support one end of a helical torsion spring, and the opposite end of the torsion spring is supported by a number of upwardly located locating tabs from the drive arm. The opposite ends of the torsion spring. torsion spring are rotated radially inwards, towards the pivot for respective engagement with one of the arms of the spider and one of the legs so that the the magnitude of the force of the torsion spring can be adjusted by selecting the particular branch of the spider or the tab engaged by the ends of the spring A protective cover is fixed on the pivot, the spider and the torsion spring, the cover having a certain number of locking fingers that can be received in the holes of the drive arm created by

  the formation of the legs turned upwards.

  The invention will be better understood, and others

  The objects, features, details and advantages thereof will become more apparent in the following explanatory description with reference to the accompanying schematic drawings given by way of example only, illustrating an embodiment of the invention and in

  which: Figure 1 is a perspective view illustrating an impulse sprinkler apparatus according to the invention; Figure 2 is an enlarged elevational view showing the watering apparatus mainly in vertical section; Fig. 3 is a generally vertical sectional view of the watering apparatus, looking along line 3-3 of Fig. 2; Fig. 4 is a generally vertical sectional view of the watering apparatus looking along the line 4-4 of Fig. 2; and FIG. 5 is a plan view generally from above of the watering apparatus, shown partially in section, looking along the line 5-5 of FIG.

figure 2.

  As can be seen from the drawings, the present invention relates to a novel, improved impact sprinkler, generally designated by reference numeral 10, of the type designed primarily for use in the irrigation of crops, lawn surfaces and the like The watering apparatus 10 comprises a simplified body which is formed of a length of a bent tube 12 to define a regular and substantially uninterrupted hydraulic flow path 14 for the flow of water from a water supply pipe or riser pipe 16 to a discharge nozzle 18 Water is thrown into a stream by the nozzle 18 in a direction generally inclined towards the An impingement training assembly 20 is mounted on the tubular body of the sprinkler apparatus and includes a simplified drive arm 22 for the purpose of infusing a prescribed area of the ground. interacting with the projected water stream and the body of the watering apparatus 15 to rotate the body in a series of small angular increments around the riser pipe to thereby substantially increase the surface of the ground covered

by the projected water flow.

  The impingement sprinkler apparatus according to the invention offers significant advantages when compared to conventional impact sprinkler apparatus available. More particularly, the impingement sprinkler apparatus It is constructed of inexpensive components which are bent or stamped to the desired configuration and then quickly and easily assembled to produce a very economical sprinkler. The invention thus avoids the use of relatively expensive cast or molded components for the apparatus. watering of the type commonly used in the prior art, in particular with regard to

  relates to the body of the apparatus and the drive arm.

  On the other hand, the tubular body of the watering apparatus defines a smooth-walled hydraulic flow path having a substantially uninterrupted uniform cross section to guide the flow of water with minimum turbulence of the riser pipe by the elbow in the tube 12 towards the inclined direction towards the outside and

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  This steady flow of water through the flow path 14 results in measurable increases in the kinetic energy of the water stream to the evacuation tubing, thus resulting in additional appreciable increases in the projected range of the water flow in comparison with molded or cast bodies according to the prior art The specific angle of inclination, or trajectory, of the projected water stream can be chosen during the manufacturing process by an adjustment simple of the device to bend the tube (not shown), and the drive arm 22 is mounted on the tube in a way to use a single geometry of the drive arm with tubular bodies

  sprinkler apparatus having a wide range of angular bends.

  Referring to FIGS. 1 and 2, the exemplary impingement sprinkler apparatus 10 includes a body formed of a length of a hollow tube 12 through which the fluid path 20 is formed. According to a preferred form of the invention, the tube 12 comprises a metal material which can be bent or bent to a selected angular configuration, for example stainless steel, using a conventional tube bending device ( The tube is curved to a shape generally having linear lower and upper portions 24 and 26 typically disposed at an obtuse angle to each other and which are separated by a regularly contoured bend, indicated on FIG. Figure 2 by an arrow 28 Importantly, after bending, the flow path 14 of the tube has a substantially uniform cross-sectional shape which is delimited by the diameter surface

  internal wall of the tube and, in the illustrated embodiment, which is substantially uninterrupted over the entire length of the tube.

  The bent tube 12 is mounted at the upper end of the upright water supply pipe or riser pipe 16 where pressurized water is supplied to the watering apparatus. From this point of view, this assembly is accomplished. by a trunnion bearing assembly 30 which is

  worn around the lower part 24 of the tube 12.

  This assembly 30 supports the tube at a position where the upper portion 26 extends generally outwardly and upwardly relative to the riser pipe 16, and retains the lower portion 24 for a movement of

  substantially leak-free rotation about the vertical axis 10 of the riser pipe 16.

  The trunnion bearing assembly 30 is illustrated in detail in FIG. 2 and comprises a cylindrical brass clutch 32 or similar which is carried around the lower portion 24 of the tube 12. male threaded threaded engagement thread 34 with a female threaded upper end 36 of the riser pipe 16 and a hexagonal head section 38 for convenient engagement by a suitable key (not shown) to facilitate installation and removal of the Alternatively, the male-female relationship of the threads on the coupling 32 and the riser pipe 16 may be reversed, if desired. The cylindrical coupling 32 is biased downwards by a helical compression spring 40 which is received around the lower part 24 of the tube 12 at a position below the bend 28. This spring 40 reacts against a radially enlarged rib 42 such that a washer which is attached to the tube by brazing or the like, to apply an axially downward force to a wear washer 44 at the upper axial end of the coupling 32 Advantageously, as can be seen in Figure 2 the spring 40 and the upper end 35 of the coupling 32 are protected from contamination by contact with dust, abrasive particles or the like by an inverted protective cut which is received around the tube 12 and which has a base 46 trapped by the spring 40 against the underside of the fixed rib 42 and a skirt 48 which hangs from the base 46 to

contain the spring substantially.

  The helical compression spring 40 thus urges the lower axial end of the coupling 32 into a bearing engagement with a stack of sealing washers, such as a relatively rigid nylon washer.

  sandwiched between two elastomer washers 52.

  As can be seen, these sealing washers 50 and 52 are placed around the lower end of the lower part 24 of the tube and they are retained by a radially enlarged or flared flange 54 at the inlet end of the tube. Thus, when the coupling 32 is screwed into the riser pipe 16, the compression spring 40 holds the stack of the sealing washers 50 and 52 in a very compressed relation between end of coupling 32 and the upper face of the flange 54 By sizing 20 the sealing washers 50 and 52 for sealing engagement with the inner diameter surface of the riser pipe 16, the water flow of the pipe The riser is confined to a flow in the flow path 14 within the tube, substantially leak-free. Significantly, however, this leak-free connection allows rotation of the lower portion 24 of the tube.

  around the vertical axis of the riser pipe.

  Flared flange 54 on tube 12 is therefore placed directly in the upper end of riser 16 and provides a regularly contoured water inlet geometry for guiding water under pressure with minimal flow turbulence. upwardly in the flow path 14 The flow path 14 extends without interruption or substantial surface discontinuity, upward, through the trunnion bearing assembly 30 to the elbow 28 of the tube L Water is thus guided relatively regularly for a flow to 1 1 and through the elbow 28 without significant turbulence or resulting energy losses. The water thus passes through the elbow 28 into and through the upper portion 26.

  of the tube at a relatively high kinetic energy for spraying the watering apparatus through the discharge pipe 18.

  The tubing 18 is attached to the discharge end of the upper portion 26 of the tube 12 in an appropriate manner and defines an outlet port of a size and shape selected by the water being projected under A preferred form is shown in FIG. 2 to form a stream 56 for irrigation purposes. While there is a wide variety of constructions for attaching the tubing 18 to the tube, a preferred form is illustrated in FIG. standardized interchangeable nozzles having male threads for quick and easy receipt in complementary shaped female threads at the discharge end of the sprinkler apparatus For receiving such a nozzle, the sprinkler apparatus 10 according to the invention comprises a cylindrical mounting collar 58 having internal female threads 60 at one end for receiving the nozzle 18 and a smooth wall internal diameter surface 62 at its opposite end for sliding reception e relatively accurate on the discharge end of the upper portion 26 of the tube The mounting collar 58 is attached to the tube by soldering or the like to produce a receptacle

  permanently mounted for the nozzle.

  The projected water stream 56 is swept over a relatively large area of the soil to maximize irrigation coverage of the watering apparatus by rotating the pipe 12 about the axis of the riser pipe 16. is achieved by the operation of the impact driver assembly 35 which is mounted at the top of the upper portion 26 of the tube 12 at a position generally between the elbow 28 and the exhaust nozzle 18 This drive assembly 20, as can be seen in detail in FIGS. 2 to 5, comprises a pivot 64 fastened, for example by soldering, to a generally U-shaped mounting lug 66 which, in turn, is fixed, for example, 5 of the mounting lug 66, the pivot 64 protrudes upwardly generally perpendicular to the inclined upper portion 26 of the tube to pass through the drive arm 22 and terminates therein.

  at its upper end by a gadrooned tip 68.

  A multi-branched brace 70 is tightly received on the dovetail 68, so the brace 70 is secured against rotation relative to the pivot 64. As illustrated, the brace 70 includes a number of radially projecting arms 72. outwardly, each extending downwardly a short distance to the drive arm 22 and including a recess 74 shown outwardly to receive the upper turn of a torsion coil spring 76 The branches 72 form Thus a centering means for the upper extent of the spring 76 which in turn projects downwardly and whose bottom extent is centered around a number of small tabs 78 extending upwardly from the arm In a major way, the upper and lower extremities 80 and 82 of the spring 76 are turned radially inwards towards the pivot 64 as can be seen more clearly on FIG. 5, for respectively engaging a leg 72 of the journal and a tab 78 so that the spring 76 transmits a rotational torque between the pin 70 and the drive arm 22 in a direction urging the drive arm to turn into position. impact engagement with the upper portion 26 of the tube, as will be described in

more details.

  The magnitude of the spring torque is chosen and easily adjusted by releasing, by hand, the spring 76 of the spider 70 to allow winding or proper unwinding of the spring 76 around its own

  axis before reconnecting the spring 76 to the cross.

  When the desired torque is established, a protective cover 84 of lightweight plastics material or the like is attached to the torsion spring 76 and the pivot 64 to prevent their sensitive contact with dust, abrasive particles or the like. Advantageously, the hood 84 is attached to the drive arm 22 by a number of interlocking locking fingers 86 which pass through openings 88 left empty by the upwardly pushed tabs 78 for engagement with

the underside of the drive arm.

  The illustrated drive arm 22 is advantageously constructed of an inexpensive and lightweight material such as a stamped sheet or the like, and is supported for relatively regular rotational movement relative to the pivot 64. This rotational movement is facilitated by using a sleeve. bearing spacer 90 which is carried around the pivot and which is attached to the drive arm by soldering or the like, with a wear washer 92 interposed between the spacer sleeve 90 and the mounting bracket 62, if desired Pivot 64, the drive arm 22 generally extends forwardly for connection to a deflection spoon unit 94 and 25 in a generally rearward direction terminating in an enlarged counterweight portion

  generally designated by the arrow 96 in FIG.

  Importantly, the torque applied to the drive arm 22 by the torsion spring 76 urges the forward end of the drive arm to pivot about the pivot 64 in a direction moving the deflection spoon unit 94 to a front position

  of the nozzle 18, interrupting the flow of projected water 56.

  The above-described rotational movement of the drive arm 22 is limited by a stop tab 98 which hangs from the drive arm to engage or impact one side of the watering apparatus. Retaining tab 98 is formed of a stamped sheet or the like for easy connection with the drive arm, for example by spot welding, to protrude downwardly from the drive arm for impact engagement with When this impact occurs, a side force is imparted to the discharge end of the tube 12 to rotate the tube on a relatively small angular increment about the axis of the tubing pipe. climb 16. 10 Such a rotation thus slightly redirects the azimuth of the

projected water flow.

  The deflection spoon unit 94, which is also formed of pressed sheet metal for easy connection to the drive arm, for example by spot welding or the like, moves to the position generally at the front of the nozzle 18 for interaction. with the stream of water while the stop tab 98 moves in engagement with the mounting collar 58. More particularly, by looking at FIGS. 2 and 5, the unit 94 moves an upright fin 100 to the front of the the nozzle 18, this fin being placed at a slight angle relative to the projected direction of the water flow While the fin 100 passes through the stream of water, the current engages the rear surface 102 of the fin to further attracting the entire deflecting spoon unit 94 into the water stream until the stop tab 98 impacts the mounting collar 58 When this impact occurs, the flow of water flows behind the fin 100 and done i Spacecraft 104 on an opposite angle to the front of the unit 94, looking at FIG. 5 The stream of water thus imparts a spoon-sensitive lateral force 104 to rotate the drive arm 22. the torsion spring 76 35 eventually dissipates the hydraulic force applied to the drive arm and then reverses the rotation of the drive arm to the interruption with the current

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  In this way, the tube 12 is rotated in succession by relatively small angular increments on a full circle about the axis. However, if desired, a suitable reversing mechanism of the type particularly used in impact-sprinkler apparatus may be provided to limit the

  tube 12 to a rotation on a selected arcuate path.

  According to a feature of the invention, the above-described mounting arrangement for the impact driving assembly 20 is independent of the magnitude of the angular bend 28 in the tube, thereby allowing the drive assembly to be used without modification with all watering appliances having elbows 28 at different angles, to produce different paths for the water currents. More particularly, the entrainment assembly 20 is mounted at the top of the part. upper 26 of the tube 12 to place the drive arm 22 for an oscillating movement substantially parallel to the upper portion 26, regardless of the angle

  particular inclination of the upper portion 26.

  On the other hand, by mounting the pivot 64 at a position at least slightly downstream of the bend 28, the total moment arm which acts around the axis of the riser pipe 16 increases to correspondingly increase the effective rotational force applied. This increase in effective force advantageously results in relatively faster rotational times of the watering apparatus and greater rotational increments in motion. which may be particularly desirable when the water supply pressure is relatively low. The impact sprinkler according to the invention offers further improvements over conventional apparatus having cast or molded bodies in that the flow of water into and through the sprinkler is considerably The flow path 14 has a smooth inlet end defined by the flared flange 54 and extends without substantial surface interruption through the forming assembly. journal bearing 30,

  through the elbow 28, to the evacuation nozzle 18.

  The cross-sectional dimension and shape of the flow path, as well as the surface texture of the walls of the flow path defining the flow path, are substantially uniform over the entire length. As a result, the flow of water has a sufficient high kinetic energy when it reaches the discharge nozzle 18, where this increased level of kinetic energy is directly transformed into an increased jet range of the projected water stream of about% or more in comparison with conventional watering appliances made of cast brass or

molded plastic.

  The present invention is further advantageous in that its major components can be constructed of inexpensive components which are easy to produce at the desired final configuration using economical manufacturing processes, at a large volume. to be bent to the desired final shape and the stamped drive arm 22, including the deflection spoon unit 94, can be manufactured quickly and at high volume at precise tolerances without the use of expensive molds or the like. When assembled, the resulting watering apparatuses exhibit a high level of reproducibility with respect to each other while at the same time offering

time reliability and low price.

Claims (8)

R E V E N D I C A T IO NS   An impingement sprinkler apparatus for connection to a water supply riser pipe, characterized by comprising: a sprinkler body formed of a length of tubing (12) having a bend (28) generally on an intermediate portion of its length, separating first and second tube portions (24, 26) which are angled relative to each other, said tube defining a flow path open (14) for the passage of water therethrough; a trunnion bearing assembly (30) carried around said first tube portion for connecting said first tube portion to the riser pipe (16) with said flow path disposed for flow therethrough, water from the riser, whereby water flows through said tube for evacuation in the form of a stream of water sprayed at said second portion of the tube, said trunnion bearing assembly comprising means to allow rotation of said tube generally about the axis of said riser, said first tube portion extending through said journal bearing assembly and terminating with an outwardly radially flared flange (54), said flange defining a relatively regularly contoured water inlet to guide the flow of water from the riser into the flow path with minimal turbulence; and an impact driver assembly (20) mounted on said second tube portion for impacting the side of said second tube portion at a regular frequency to cause said tube to rotate in a succession of angular increments generally around the axis of the riser pipe; said flow path extending through said   first tube portion, said bend and said second tube portion without substantial surface interruption. 18 2551318   Apparatus according to claim 1, characterized in that the aforesaid flow path defined by the aforesaid tube has a substantially uniform cross-sectional dimension and shape extending through said first tube portion, said bend and said second part of tube.   Apparatus according to claim 1, characterized in that it comprises a mounting collar (38) carried around an open end of said second tube portion and having means for removably supporting a exhaust nozzle (18).   An apparatus according to claim 1, characterized in that the trunnion bearing assembly comprises a generally cylindrical coupling (32) carried around said first tube portion for connecting to said riser pipe, at least one bushing sealing (50, 52) interposed between said flange flare and an axial end of said coupling, an outwardly protruding rib (42) on said first tube portion between said bend and the opposite axial end of said coupling and a spring means (40) for reaction between said coupling and said rib for urging said flange flared on said first portion   tube in sealing engagement with said sealing ring.   5. Apparatus according to claim 4, characterized in that it comprises a cutter member (46, 48) having a base carried around said first tube portion between said rib and said spring means and an annular skirt. protector extending from said base in a surrounding direction said spring means.   Apparatus according to claim 1, characterized in that the aforesaid impact driving assembly comprises a driving arm (22) mounted for oscillatory movement in a plane generally parallel to the aforesaid second tube portion; a stop tab (98) on said drive arm for impacting against one side of said second tube portion; a torsion spring (76) for biasing said drive arm to rotate in a direction bringing said stop tab into impact engagement with said second tube portion; and a deflection spoon unit (94) on said drive arm for interrupting the projected water flow substantially simultaneously with the impact engagement, whereby the water flow imparts a force to said drive arm for rotate it against said torsion spring, said drive arm, said stop tab and said spoon unit of   deviation being formed of metal stampings.   An apparatus according to claim 6, characterized in that said impact drive assembly further comprises a pivot (64) mounted on said second tube portion for generally protruding perpendicularly thereto through said arm. said drive in a direction generally away from said first tube portion, said torsion spring being connected between the distal end of said pivot and a number of locating tabs (78) formed on said drive arm, and further comprising a protective cover (84) attached to said pivot and said torsion spring and connected to said drive arm. An apparatus according to claim 7, characterized in that said locating tabs are pushed upwardly from said drive arm, said hood including locking fingers (86) receivable downwardly through holes in the aforementioned drive arm emptied by said legs location.