Title:
OIL TANK WASHING MACHINE
United States Patent 3584790


Abstract:
The machine for washing the interior surface of a hollow structure includes a head assembly mounted for rotation about a first axis. A wash fluid discharge head is mounted on head assembly for rotation with respect thereto about a second axis at an angle to said first axis. The head assembly has a passage for receiving and transferring wash fluid to the wash fluid discharge head. A wash fluid actuated rotary drive means is mounted on the head assembly externally of the passage. A fluid feed passage extends from the first passage to the drive means. Transmission means is connected to the drive means to effect simultaneous rotational movement of the head assembly about the first axis and the wash fluid discharge head about the second axis. The transmission means includes means for effecting intermittent accelerations or decelerations in the rotational speed of the wash fluid discharge head relative to the rotational speed of the head assembly.



Inventors:
BONFIELD ROBERT BENHAM
Application Number:
04/788421
Publication Date:
06/15/1971
Filing Date:
01/02/1969
Assignee:
DASIC EQUIPMENT LTD.
Primary Class:
International Classes:
B08B9/093; B05B3/04; B08B9/08; B05B3/02; B05B15/00; (IPC1-7): B05B3/00
Field of Search:
239/240,227
View Patent Images:
US Patent References:



Primary Examiner:
King, Lloyd L.
Claims:
I claim

1. A machine for washing the interior surface of a hollow structure comprising a head assembly, means for mounting the head assembly for rotation about a first axis, a wash fluid discharge head mounted on said head assembly for rotation with respect thereto about a second axis at an angle to said first axis, a passage in said head assembly for receiving and transfering wash fluid to said wash fluid discharge head, wash fluid actuated rotary drive means mounted on said head assembly externally of said passage, a fluid feed passage extending from said first passage to said drive means, and transmission means connected to said drive means to effect simultaneous rotational movement of said head assembly about said first axis, and said wash fluid discharge head about said second axis, said transmission means including means for effecting intermittent accelerations or decelerations in the rotational speed of said wash fluid discharge head relative to the rotational speed of said head assembly.

2. A machine as claimed in claim 1, wherein said transmission means comprise a static shaft, a first gear mounted for rotation on said shaft, a second gear mounted for driving said wash fluid discharge head and meshing with said first gear, a third gear secured on said shaft, reduction gear means connecting said drive means to said third gear for causing rotation of said head assembly around said shaft, means resisting rotation of said first gear by said second gear so that said second gear is driven inconsequence of the rotation of said head assembly, a rotary lobed element connected for driving said first gear, and striker means mounted in said head assembly for repeated engagement with said lobed element during rotation of the assembly whereby intermittent accelerations or decelerations of said first and second gears are effected.

3. A machine as claimed in claim 2, wherein the means resisting the rotation of the first gear comprises a friction clutch.

4. A machine as claimed in claim 2, wherein the means resisting the rotation of the first gear comprises a worm meshed with a worm wheel mounted for rotation with the first gear.

5. A machine as claimed in claim 4, wherein the worm is mounted on a spindle connected through a gear train to a further spindle carrying said lobed element, said further spindle being disposed radially with respect to said static shaft.

6. A machine as claimed in claim 2 in which the means mounting the head assembly for rotation comprises a pipe having a flange at one end adapted to bolted to a flange of a wash fluid supply pipe, said pipe comprising at its other end an internal support member to which the upper end of said static shaft is coaxially secured, said other end being received within a tubular inlet portion of said head assembly.

7. A machine as claimed in claim 6, wherein said pipe is divided into two annular portions and wherein said annular portions are connected by a friction clutch.

8. A machine for washing the interior surface of a hollow structure, comprising, in combination, a head assembly having a body member having an inlet passage, an outlet passage defining a bore a passage interconnecting said inlet and outlet passages, a first inner wall dividing said passages from a gear chamber, a second inner wall dividing said gear chamber from a Pelton wheel compartment having an exhaust part therein, an inlet pipe received at one end in said inlet chamber for rotation of said body with respect thereto, a flange on the other end of said inlet pipe for secural to a flange of a wash fluid supply pipe, a thrust bearing located at a transverse wall of said body member beneath said first inner wall, a sealing gland mounted in said first inner wall in axial alignment with said, thrust bearing, a static shaft carrying at its lower end the weight of said body through said thrust bearing and extending upwardly through said sealing gland, means supporting the upper end of said shaft coaxially in said inlet pipe, a first gear mounted for rotation on said static shaft a second gear meshing with said first gear and operatively connected through sealing means in said first inner wall with a wash fluid discharge head mounted for rotation in said outlet bore, a third gear secured on said static shaft, a Pelton wheel mounted for rotation in said Pelton Wheel compartment, reduction gear means connecting said Pelton wheel to said third gear for causing rotation of said head assembly around said shaft means resisting rotation of the first gear by said second gear, so that said second gear is driven in consequence of the rotation of said head assembly, a rotary lobed element connected for driving said first gear, striker means mounted in said head assembly for repeated engagement with said lobed element whereby intermittent accelerations or decelerations of said first and second gears are effected, and means defining a fluid feed passage extending between one of said first mentioned passages and said Pelton Wheel compartment and terminating in a nozzle or nozzles disposed for directing impulse jets at the buckets of the wheel.

9. A machine as claimed in claim 8, wherein the means resisting the rotation of the first gear comprises a friction clutch.

10. A machine as claimed in claim 8, wherein the means for resisting the rotation of the first gear comprises a worm meshed with a worm wheel mounted for rotation with the first gear.

11. A machine as claimed in claim 8, wherein said Pelton wheel compartment is mounted at the lower end of the head assembly and wherein the third gear is driven by a pinion connected to said Pelton wheel through a two stage worm and wheel reduction gear train located in a compartment intermediate said transverse wall and second inner wall.

12. A machine as claimed in claim 8, wherein said wash fluid discharge head is connected to said second gear through means comprising a friction clutch.

Description:
DESCRIPTION OF THE INVENTION

The invention relates to machines for washing the interior surfaces of hollow structures, and particularly to machines for washing the interiors of the tanks of marine oil tanks with high pressure fluid jets.

The invention provides a machine for washing the interior surface of a hollow structure comprising a head assembly, means for mounting the head assembly for rotation about a first axis, a wash fluid discharge head mounted on said head assembly for rotation with respect thereto about a second axis at an angle to said first axis, a passage in said head assembly for receiving and transferring wash fluid to said wash fluid discharge head, wash fluid actuated rotary drive means mounted on said head assembly externally of said passage, a fluid feed passage extending from said passage to said drive means, and transmission means connected to said drive means to effect simultaneous rotational movement of said head assembly about said first axis and said wash fluid discharge head about said second axis, said transmission means including means for effecting intermittent accelerations or decelerations in the rotational speed of said wash fluid discharge head relative to the rotational speed of said head assembly.

In consequence of the accelerations or decelerations, jets of wash fluid from said wash fluid discharge head are precessed slightly at each passage around the interior surface of the hollow structure washed by the machine so that the whole of said interior surface can be effectively washed.

The invention may further comprise the features hereinafter described with reference to the accompanying drawing in which:

FIG. 1 is a perspective view of a machine according to the invention,

FIG. 2 is a sectional side elevation on the line II-II of FIG. 1,

FIG. 3 is a sectional plan view on the line III-III of FIG. 2,

FIG. 4 is a sectional side elevation on the line IV-IV of FIG. 3,

FIG. 5 is a sectional side elevation of a modified embodiment of the invention, the Pelton wheel and transmission system being omitted from the drawing in order to illustrate the modifications with greater clarity,

FIG. 6 is a sectional side elevation of a further modified embodiment of the invention,

FIG. 7 is a sectional plan view on the line VII-VII of FIG. 6, and

FIG. 8 is a sectional plan view on the line VIII-VIII of FIG. 6.

Referring first to FIG. 1, the machine comprises a wash head body portion 1 having a wash fluid discharge head 2 mounted thereon for rotation about a horizontal axis. The discharge head 2 comprises two oppositely directed nozzles 3. The body portion 1 is mounted for rotation at the lower end of a wash fluid supply tube 4 terminating in a flange 5.

Referring now to FIG. 2 to 4, the machine comprises a stub pipe 6 having a flange 6a at the upper end thereof for facilitating bolted connection to the flange 5 of the supply tube 4. At its lower end, the stub pipe 6 is provided internally with a spider 7 from which depends a static shaft 8 coaxial with the stub pipe 6.

Between the flange 6a and the spider 7, the stub pipe 6 carries a graduated filter structure 6b. The comprises a series of spaced gauges, the mesh sizes of which decrease in a direction from the flange 6a towards the spider 7.

The body portion 1 comprises a neck portion 9 dimensioned for rotation on the lower end the stub pipe 6 and provided with a labyrinth gland 10. The body portion 1 is divided into two chambers by an internal wall, namely a wash fluid chamber 12 and a precess and drive gear chamber 13. The shaft 8 extends through a gland structure 14 in the wall which is vented from a central position by a vent 15.

The chamber 12 is defined in part by the neck portion 9 and comprises an inclined passage 16 which terminates in a horizontal bore 17. At the inner end of the bore 17, a small concentric bore 18 is provided into the chamber 13. Journaled for rotation in the bores 17 and 18 respectively are a hollow cylindrical body 19, forming part of the discharge head 2, and a stub shaft 20 extending therefrom, the bores 17 and 18 being provided with labyrinth glands 21 and 22, and O-ring seals at 21a.

The end of the stub shaft 20 extending into the chamber 13 has a bevel crown wheel 23 keyed thereon and retained by a nut.

The cylindrical body 19 has an inner end wall 25, an outer end wall 26 an apertures 24 in the cylindrical wall thereof which apertures 24 sweep across the end of the passageway 16 during rotation of the cylindrical body 19. At its outer end, the cylindrical body 19 extends beyond the body portion 1 and carries the two nozzles 3 which extend in diametrically opposite directions. If desired the nozzles may be slightly offset on opposite sides of the diametric centerline of the cylindrical body 19 so as to provide an assisting torque during rotation of the discharge head 2.

At its lower end, the static shaft 8 is journaled in a thrust bearing 27 set in a lower cover 28 of the body portion 1 and adapted to transfer the full weight of the body portion 1 and discharge head 2 machine onto the shaft 8. The thrust bearing 27 may comprise a ball race generally as shown in FIG. 2 or a dry lubricated bearing may be used, for example utilizing sintered bronze/polytetrafluoroethylene/lead bearing surfaces. A bearing cover 27a is provided to protect the bearing.

A worm wheel 29 is secured by a shear pin 30 on the shaft 8 at a position within the chamber 13 just above the bearing 27. The worm wheel 29 carries an upwardly extending stepped sleeve bushing 31 on which is keyed a quadrant plate 32.

Mounted for rotation on the shaft 8 above the quadrant plate 32 is a pinion 33 having an upwardly extending sleeve bushing 34 formed as a bevel pinion 35 at its upper end, the bevel pinion 35 meshing with the crown wheel 23 mounted on the stub shaft 20.

At a position spaced radially from the shaft 8, the quadrant plate 32 is bored to receive a sleeve bearing 36 in which a spindle 37 is journaled. At its lower end the spindle 37 carries a pinion 39 which meshes with a pinion 40 (FIGS. 3 and 4). The pinion 40 is mounted for rotation on a spindle 41 set in the quadrant plate 32 and is formed integrally at the lower surface thereof with a star wheel 42 having four lobes 43.

Mounted in the body portion 1 in horizontal alignment with the star wheel 42 is a strike pin 74 which extends inwardly to such a position that upon rotation the body portion 1 about the spindle 8 (as described below), the pin 74 strikes one of the lobes 43 and causes partial rotation of the star wheel 42, this partial rotation being transmitted through the gears 40, 39, 38, 33, 35 and 23 to the head 19, the overall reduction being 9:1 to effect an acceleration of deceleration of the gear 35, the gear 23 and thus of the rotational speed of the wash fluid discharge head.

The worm wheel 29 meshes with a worm 44 keyed to one end of a shaft 45. A pinion 46 keyed to the other end of the shaft 45 meshes with an idler pinion which in turn meshes with a pinion 47 keyed to the end of a shaft 48. At the other end of the shaft 48 is keyed a pinion 49 which meshes with a pinion 50 keyed to a drive shaft 51. The shaft 51 extends through labyrinth sleeve bearings 52 in the outer wall of the body portion 1 and has keyed to the other end thereof a Pelton wheel 53. The bearings 52 are vented from a midposition by a vent 54.

The Pelton wheel 53 is enclosed in a cover 55 bolted to the body portion 1. The cover 55 carries a pipe union 56 in one wall thereof to which a nozzle 57 is secured for operation of the Pelton wheel. A pipe 58 extends from the other end of the pipe union 56 to a second pipe union 59 mounted in the wall of the wash fluid chamber 12. A gauge filter 59a is provided as shown to prevent any particulate material from entering the pipe 59 that may have passed the filter 6b.

A discharge vent 60 is proved in the cover 55 for exhaust fluid from the Pelton wheel.

In operation, the machine is advantageously mounted as a permanent installation in a tank to be washed with the flange 6a being connected to the flange 5 of the wash fluid supply pipe 4.

As soon as wash fluid under pressure enters the chamber 12 from the pipe 4, a small proportion is bled off through the pipe union 59 and pipe 58 to the nozzle 57. The remainder of the wash fluid is fed down the passage 16 and through the apertures 24 into the cylindrical body 19 where it is discharged through the nozzles 3. The fluid discharged through the nozzle 57 impinges on the buckets of the Pelton wheel 53 to cause rotation thereof at a maximum speed of 2,600 r.p.m. and is then discharged through the vent 60 in the cover 55.

The rotation of the Pelton wheel is transmitted through the gear train 50, 49, 47 and 46 to the worm 44 so as to preferably provide a 100:1 reduction from the speed of the Pelton wheel. Since the worm wheel 29 is fixed by the shear pin 30 of the shaft 8, the rotation of the worm causes the body 1 to rotate about the shaft 8.

The initial rotation of the body 1 causes rotational movement to be imparted to the crown wheel 23 due to its engagement with the level pinion 35.

A friction pad 32a is set into the lower side of the quadrant plate 32 so as to bear on the pinion 39 and prevent slip and consequent rotation of the gears 38 and 33 which would check this rotational movement. The pad 32a is loaded by springs 32b set in bores in the quadrant plate and adjustable by grub screws.

As the body continues to move round the shaft 8, the striker pin 74, strikes one of the lobes 43 of the star wheel 42 and causes, through the gear train 40, 39, 38, 33, 35 and 23 a momentary acceleration of the cylindrical body 19. The frequency with which this acceleration occurs can be varied by increasing or decreasing the number of lobes 43 on the star wheel and/or the number of striker pins 44 set in the body 1. The striker pin 44 and/or the lobes 43 may also be longitudinally and/or radially adjustable respectively so as to regulate the frequency of striking and length of contact (and therefore extent of movement of the star wheel. The acceleration can also be varied by changing the gear ratios between the star wheel 42 and the crown wheel 23.

In a preferred embodiment, the body portion 1 rotates about the vertical shaft 8 at a speed of 5 revolutions per minute or less and the wash fluid discharge head 2 rotates at a speed approximately one-third of but variable in respect of, the speed of the body portion 1.

The paths of impingement of the jets from the nozzles 3 on the walls of the tank are thus precessed slightly at each passage so that eventually the whole of the tank surface is washed.

Furthermore, by arranging the wash fluid discharge head 2 to rotate more slowly than the body portion 1, the paths if impingement have a moderate slope and the jets are more effective in removing residues from horizontal surfaces in the tank.

The pinion 40 and star wheel 42 may be arranged for easy removal from the machine after removal of the cover 28 so that the star wheel 42 or the gear train between the star wheel and the crown wheel 23 may be changed to provide a ratio of rational speeds between the body portion 1 and the wash fluid discharge head to suit particular operating requirements.

In the embodiment described above, the number of teeth on the various gears were as follows. ##SPC1##

In the modified embodiment of FIG. 5, the parts which are analogous to the construction of FIGS. 1 to 4 are given the same reference numerals, (the Pelton wheel, transmission and precess gearing being omitted for clarity).

This embodiment provides a modified body portion 1 and discharge head 2 which incorporate a clutch and means whereby feed water for the Pelton wheel is led internally of the body.

To this end, the crown wheel 23 is mounted on one end of a shaft 61 by a nut 62. The shaft 61 extends through the bore 18 and coaxially with the bore 17 in the body 1 to a position beyond the end of the bore 17. At its outer end, one element 63 of a core clutch is mounted on the shaft 61. At a position adjacent the bore 18, a gland member 64 is keyed to the shaft 61, the member 64 incorporating a number of seals to prevent ingress of water to and through the bore 18.

The wash head 2 is mounted towards the outer end of the shaft 61 for fee rotation thereon when the core clutch is disengaged between the core clutch element 63 and the end of the bore 17. The wash head 2 has two nozzles 3 extending radially therefrom and a cylindrical boss portion 65 extending along the bore 17 as far as the passage 16. At its outer face the boss portion 65 is formed with a core clutch face 66 adapted to cooperate with the element 63. The outer surface of the boss portion 65 is provided with a ring seal 67 and sufficient clearance is provided between the clutch element 63 and the end of the bore 17 to permit limited axial sliding movement of the wash head 2 on the shaft 61.

At a position inwardly of the seal 67, the boss portion 65 is provided with an external annular recess 68 into which a series of holes 68a vent from the interior of the boss. The holes 68 also act as a strainer. A passage 69 extends from the annular zone in which the recess 68 in the boss rotates and through the body 1. The other end of the passage 69 connects with the nozzle member 57 mounted in the Pelton wheel compartment (not shown) for actuation of the Pelton wheel.

The passage 69 is preferably formed as an integral part of the body casting although an external pipe may be provided if required similar to the pipe 58 of FIG. 1.

Turning now to FIGS. 6 to 8 the embodiment shown comprises a wash head body portion 101 having a wash fluid discharge head 102 mounted thereon for rotation about a horizontal axis therein. The wash fluid discharged head 102 having two oppositely directed nozzles 103.

The body portion 101 comprises a flange 104 adapted to be bolted to a cooperating flange (not shown) provided on the end of a wash fluid supply pipe. A first element 105 of a clutch is secured on the underside of the flange 104 by set screws, the clutch face being formed by the lower surface 106 of an internal annular recess 107 formed therein. An O-ring seal 108 is also provided in the element 105 above the recess 107.

The O-ring seal 108 is engaged by the upper end of an entry pipe 109 which also has an external annular flange 110 engaging in the recess 107, the lower face 111 of the flange 110 forming the second clutch surface.

The entry pipe also has a spider 112 mounted internally therein, from which depends a static shaft 113 coaxial with the entry pipe 109.

A neck portion 114 of the body portion 1 is dimensioned for rotation on the lower end of the entry pipe 109, an O-ring seal 115 being provided between the two members.

The body portion 1 is divided by internal walls 116, 117 and 118 into a wash fluid chamber 119, a precess gear chamber 120, a transmission gear chamber 121 and a Pelton wheel compartment 122, the chambers being generally arranged in sequence one beneath the other.

The chamber 119 is defined in part by the entry pipe 109 and also comprises an inclined passage 123 which terminates in a horizontal bore 124 At the inner end of bore 124, a small concentric bore 125 is provided into the chamber 120. Journaled for rotation in the small bore 125 is a shaft 126 having a bevel crown wheel 127 keyed to the end extending into the chamber 120 and secured by a nut. The bore 125 is provided with a labyrinth gland 128 around the shaft 126. A flange member 129 keyed onto the shaft 126 adjacent the bore 125 and has an O-ring seal 130 which seals against a cylindrical surface 131 forming part of internal wall 116. The gland 128 and seal 130 prevent ingress of water through the bore 125 to the chamber 120.

The shaft 126 extends beyond the end of the bore 124 and at its outer end carries one element 132 of a core clutch secured by a nut 132a. The wash head 102 is mounted for free rotation on the shaft 126 when the clutch is disengaged between the core clutch element 132 and the end of the bore 124. The wash head has a cylindrical boss portion 133 extending into the bore 124 as far as the passage 123. At its outer face the wash head 102 has a recess coaxial with the shaft 126, the wall of the recess defining a core clutch face 134 adapted to cooperate with the clutch element 132. The outer surface of the boss portion 133 is provided with an O-ring seal 135 and sufficient clearance is provided between the clutch element 132 and the end of the bore 124 to permit limited axial sliding movement of the wash head 102 on the shaft 126.

At a position inwardly of the seal 135, the boss portion 133 is provided with an external annular recess 136 into which a series of holes 137 vent from the interior of the boss. The holes 137 also act as a strainer. A passage 138 formed in the body 101 extends form the annular zone in which the recess 136 in the boss rotates and terminates at the internal wall 118. A removable nozzle member 139 is mounted in the Pelton wheel compartment 122 and in communication with the passage 138, by a set screw 140.

The static shaft 113 extends downwardly through a gland structure 141 incorporating two external and two internal O-ring seals 142 and 143 respectively and which is vented from a central annular recess by a vent 144. At its lower end, the static shaft 113 is journaled in a thrust bearing 145 set in the internal wall 117 and adapted to transfer the full weight of the machine onto the shaft 113. The thrust bearing 145 is enclosed by a cover plate 146 and may comprise a ball race generally as indicated in FIG. 6. Alternatively, a dry lubricated bearing may be used as described with reference to the embodiment of FIGS. 1 to 4.

A pinion 147 is keyed on the shaft 113 and secured by a nut 148 at a position within the chamber 120 immediately above the thrust bearing 145. The pinion 147 carries an upwardly extending stepped sleeve bushing 149 on which is keyed a quadrant plate 150. Mounted for rotation on the shaft 113 above the quadrant plate on a spacer washer (not shown), is a worm wheel 151 having an upwardly extending sleeve bushing 152 formed as a bevel pinion 153 at its upper end, the bevel pinion 153 meshes with the crown wheel 127.

At a position spaced radially from the shaft (see FIG. 7), the quadrant plate carries two bearing brackets 154 in which the spindle of a worm 155 is journaled, the worm meshing with the worm wheel 151. At one end, the spindle of the worm extends through the respective bracket 154 and has a pinion 156 keyed thereto. The pinion 156 meshes with a pinion 157 keyed on the end of a spindle 158, the spindle 148 being journaled in a further bearing bracket 159 on the quadrant plate 150. The other end of the spindle 148 has a six lobed star wheel 160 keyed thereto, the star wheel 160 having its axis lying on an extended radius of the shaft 113.

Mounted in the body portion 101, also on an extended radius of the shaft 113 but above the axis of the star wheel 160, is a striker pin 161. The striker pin 161 is threaded at its outer end for adjustment and extends inwardly to such a position that upon rotation of the body portion 101 about the shaft 113 (as described below) the pin 161 strikes one of the lobes of the star wheel 160 to cause partial rotation of the star wheel 160, the partial rotation being transmitted through the gears 157, 156, 155, 151, 153 and 127 to the shaft 126 and the wash head 102 to effect an acceleration or a deceleration of the rotational speed of the wash head 2.

The pinion 147 meshes with a smaller pinion 162 keyed to the upper end of a vertical shaft 163. The shaft 163 extends downwardly through a sleeve bearing 164 in the inner wall 117, the bearing 164 incorporating inner and outer seals 165.

At its lower end, (See FIG. 6 and 8) in the transmission gear chamber 121, the shaft 163 is provided with a socket 166 which envelops the end of a shaft 167 having a worm wheel 168 keyed thereto. A drive connection between the socket 166 and the shaft 167 is provided by a shear pin 169 extending transversely through both elements. The lower end of the shaft 167 is journaled in a bearing 170 formed in the wall 118. A worm 171 (FIG. 8) meshes with the worm wheel 168 and is keyed to a shaft 172 of which one end is journaled in a bearing 173 formed in the outer wall of the body 101 and the other end extends through a bearing block 174 mounted on the wall 118. A further worm wheel 175 is keyed to the other end of the shaft 172 and meshes with a worm 176. The worm 176 is keyed to a vertical shaft 177 which at its upper end is journaled in a bearing 178 in a bracket 179 bolted to the wall 118. The transmission gear chamber 121 is preferably packed with grease.

The lower end of the shaft 177 extends downwardly through a bearing 180 in the inner wall 118 and into the Pelton wheel compartment 122, where a Pelton wheel 181 is keyed or splined on the shaft 177 and secured by a nut 182.

The lower wall of the body 101 is formed by a detachable cover 183 having a discharge port 184 for exhaust water from the Pelton wheel 181.

The machine is assembled, as indicated in FIG. 6, in tiered sections secured together by set screws 185. This arrangement enables a machine to be provided which whilst having an output sufficient to operational requirements, can be passed through the standard 12.5 inch (32 centimeter) access holes which are normally provided in the tanks of marine oil tankers.

The machine shown in FIG. 6 to 8 is advantageously secured by the flange 104 to the flange of a wash fluid supply pipe. At this stage, and during the lowering of the machine through the access hole, the wash head 102 is free to rotate with respect to its fixed clutch elements 132. This prevents damage to the internal gearing due to torque inadvertently or improperly applied to the wash head 2 and also permits orientation of the nozzles 103 to allow the wash head to pass through the access hole.

Similarly, before lowering into the tank and during positioning when in the tank, the clutch 106/111 allows rotation of the body 101 relative to the wash water supply pipe which again prevents damage to the internal gearing.

In operation, and after proper location in the tank, as soon as wash fluid under pressure enters the chamber 119, it is directed down the passage 123, through the bore 124 and boss 133, and out through the nozzles 103. The optimum water pressure is approximately 200 pounds per square inch (14,000 gm./cm.2 ) and at this pressure, the pressure loadings on the upwardly presented face of the inner wall 116 and the inner surfaces of the wash head 102 are sufficient to engage the clutches 106/111 and 132/134 and prevent relative rotation between the parts.

A proportion of the wash fluid entering the boss 133 is bled off radially through the holes 137 into the annular external recess 136 in the boss. This wash fluid is then led through the passage 138 and discharged through the nozzle 139. The fluid discharged impinges on the buckets of the Pelton wheel to cause rotation thereof and is then discharged through the port 184 in the lower cover 183.

The rotation of the Pelton wheel is transmitted through the gear train 176, 175, 171 and 168 to the pinion 162 so as to preferably provide a speed reduction of approximately 100:1 from the Pelton wheel speed. Since the pinion 147 is keyed to the static shaft 113, the pinion 162 carries out a planetary motion with respect to the pinion 147 and thereby causes the body 101 to rotate around the shaft 113.

The initial rotation of the body 101 causes the crown wheel 127 to rotate due to its engagement with the bevel pinion 153. The bevel pinion 153 is prevented from rotation by the locking action of the worm 155 on the worm gear 151 when reverse drive is applied.

As the body 101 continues to move around the shaft 113, the striker pin 161 (FIG. 7) strikes one of the lobes of the star wheel 160, and causes, through the gears 157, 156, the worm 155, the worm wheel 151, and the bevel pinion 153, a momentary acceleration of the crown wheel 127 together with the shaft 126 and the wash head 102. The frequency with which this acceleration occurs can be varied by increasing or decreasing the number of lobes on the star wheel and/or the number of striker pins set in the body 1. The acceleration can also be varied by changing the gear ratios between the star wheel 160 and the crown wheel 127.

In consequence of the momentary acceleration, the jets from the nozzles 103 are precessed slightly at each passage round the walls of the tank so that the whole zone of the tank surface covered by the machine is eventually washed.

In all of the embodiments above described, the wash fluid discharge head is preferably arranged to rotate at a speed (neglecting the momentary accelerations) slower than that of the body portion 1. The paths of impingement of the jets are then more effective in removing residues from horizontal surfaces in the tank.

In one machine having a jet range of approximately 120 feet (37 meters) the body 101 rotates about the vertical axis on the shaft 126 at 1.5 revolutions per minute whilst the wash fluid discharge head 2 rotates about the horizontal axis of the shaft 126 at 0.5 revolutions per minute. In a smaller machine having a jet range of approximately 55 feet (17 meters) the body 101 rotates at 3 revolutions per minute whilst the wash fluid discharge head 2 rotates at 1 revolution per minute.