Patent Publication Number: US-7716782-B2

Title: Mobile unit for cleaning a sewer network

Description:
BACKGROUND OF THE INVENTION 
   The term mobile unit covers both a self-propelled assembly such as a wheeled vehicle of the truck type, and an assembly that itself towed, such as a trailer, a wagon, or indeed an assembly suitable for mounting on a trailer or on the chassis of a vehicle. 
   There exists trucks, known as jetter-trucks, that can be used for applying both a water-jet and suction to sewer networks, i.e. for enabling the deposits that accumulate in manholes and the adjacent channels to be removed by means of a cleaner hose having a cleaner head that delivers a high-pressure water-jet, and by means of a suction hose for sucking up the liquid residue and sludge. 
   It will be understood that equipment of that type must enable the operator, who remains close to the manhole situated in a roadway, to place the cleaner hose with the cleaner head at its end in the manhole in the desired location(s), to hold it in position throughout the high-pressure cleaning operation while causing water to be delivered at high pressure, and then to raise it back onto the truck. Thereafter, the operator needs to perform the same positioning, control, retention, and raising operations using the suction hose. 
   From the above, it can thus be understood that the operator needs to perform a large amount of handling while not having a good view of the position inside the manhole, and thus while not guaranteeing that cleaning will be performed properly and that no zones will be left unwashed and/or with debris that has not been sucked up. 
   Furthermore, in particular when raising the hoses, and more particularly the cleaner hose, splashing can arise outside the manhole that, combined with possible dirtying of the hoses, can lead to situations and to handling difficulties that can sometimes be most uncomfortable for the operator. 
   Document DE 102 46 041 discloses a cleaning vehicle having an arm mounted on the vehicle that is movable relative to the vehicle to swivel about a vertical axis and to move in horizontal translation, the arm carrying a suction hose and a cleaner hose. 
   Document EP 0 698 696 also discloses a cleaning vehicle fitted with a high-pressure cleaner hose and a suction hose mounted on a horizontal-swiveling telescopic boom. 
   Nevertheless, it is desirable to achieve greater accuracy in the positioning of the suction and cleaner hoses, in particular over the manhole, and in particular close to the manhole, and in the manhole, both vertically (height/depth) and in a radial direction about a vertical axis running along the manhole. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a mobile unit for cleaning a sewer network that enables the drawbacks of the prior art to be overcome, and in particular that makes it possible to facilitate accurately positioning the working ends of the suction and cleaner hoses at each step, i.e. while putting the hoses into place, while the hoses are working, and then while extracting the hoses from the manhole. 
   To this end, the present invention provides a mobile unit for cleaning a sewer network from a manhole, the unit comprising:
         a suction hose mounted on a reel and connected to a collection tank and to a suction pump;   a high-pressure cleaner hose mounted on a reel and connected to a water tank, to a high-pressure pump, and to a cleaner head;   a support and guide arm for supporting and guiding the suction hose and the cleaner hose, said arm comprising a horizontal portion connected to the mobile unit and being movable to swivel about a vertical axis and in horizontal translation relative to the mobile unit so as to enable the working ends of the suction and cleaner hoses to be positioned above the sewer manhole, said arm further comprising a vertical portion connected to the horizontal portion and presenting a bottom module that is movable in swiveling and in vertical translation relative to said horizontal portion;
 
the suction and cleaner hoses being connected to said bottom module, whereby the positioning of the bottom module corresponds substantially to the positioning of the working ends of the suction and cleaner hoses.
       

   In this way, it will be understood that the various degrees of freedom of the support and guide arm make it possible to obtain great accuracy in the positioning of the suction hose and of the cleaner hose carried by said support and guide arm. 
   Because of the equipment provided in the horizontal portion of the arm, the entire arm can be pivoted about a vertical axis and its entire vertical portion can move in horizontal translation relative to the mobile unit. 
   In addition, in a manner specific to the invention, the vertical portion of the arm includes arrangements that enable the bottom module at its bottom end to move both in swiveling about its vertical axis and in vertical translation. 
   In this way, it will be understood that it is easy to move the bottom module into the desired position, and thus to move the working ends of the suction and cleaner hoses into position inside the manhole. 
   This solution also presents an additional advantage of avoiding untimely movement of the suction and cleaner hoses, and in particular of avoiding the end of the cleaner hose fitted with the cleaner head rising and striking the operator, or indeed of avoiding the cleaner hose suffering wear by rubbing against the wall of the manhole or of the channels leading thereto. 
   Overall, because of the solution of the present invention, the work of the operator can be made much easier so as to become more accurate and less tiring, thereby providing greater effectiveness in cleaning operations. 
   The connection between the horizontal portion and the vertical portion of the arm preferably forms a bend hinged by means of a ball joint that accommodates relative angular movement between the horizontal portion and the vertical portion up to a maximum of 5°, and preferably of 3°. 
   Advantageously, the horizontal portion of the arm includes first drive means and a first swivel joint enabling said swiveling movement about a vertical axis relative to the mobile unit, the horizontal portion of the arm further including second drive means and a plurality of beams nested in one another and suitable for performing said horizontal translation movement of the horizontal portion of the arm by telescopic displacement between the beams, under drive from said second drive means. For example, the second drive means may comprise a hydraulic actuator situated in a central position within the set of nested beams. 
   In a preferred disposition, the vertical portion of the horizontal arm further includes a top module that is connected to the horizontal portion and that presents third drive means suitable for driving the vertical translation movement of the bottom module. These third drive means may comprise, for example, an electric winch associated with a cable and capable of being declutched so as to make manual control possible. Other embodiments could be provided for the third drive means, such as using a control actuator. 
   Under such circumstances, and advantageously, the vertical portion of the arm further includes a second swivel joint having a ring and fourth drive means for driving swiveling movement about a vertical axis of the bottom module. By way of example, these fourth drive means comprise a motor controlling the second swivel joint so as to enable the vertical arm to turn, the ring possibly taking a variety of forms including a ring with rolling bearings, with segments, . . . . 
   Furthermore, under such circumstances, it is preferable to provide for the vertical portion of the arm to further include an intermediate module situated between the bottom module and the top module, being connected to the ring of the second swivel joint, and comprising a plurality of beams nested in one another and suitable for performing said vertical translation movement of the vertical portion of the arm by telescopic movement between the beams driven by said third drive means of the top portion, whereby the bottom module is driven with the same vertical translation movement, one of the beams of the intermediate module being fastened to the ring of the second swivel joint. 
   In another preferred disposition, the suction hose is detachably connected to said vertical portion of the arm. For example, the free end of the suction hose can be housed telescopically in a sheath connected to the vertical portion of the arm. 
   Thus, and preferably, the bottom module is provided with a ring enabling the suction hose to be held so that it follows the movements of the bottom module. 
   In general, provision is advantageously made for the bottom module to enable the suction hose to be offset about the cleaner hose with radial indexing. Such a disposition makes it possible, for example, to clean zones adjacent to the invert (flow channel) and facing the manhole, such as sidewalks. 
   In an embodiment, the suction hose can be turned in rotation with indexing by a ring relative to an extension of the beams of the intermediate module. 
   According to another preferred characteristic, the horizontal and vertical portions of the arm are provided with a system for guiding the suction hose and/or the cleaner hose via roller elements. 
   Advantageously, the bottom module further includes a camera module making it possible from the bottom module to view the inside of the manhole and the adjacent channel zones. Such a disposition makes it easier to carry out diagnosis before performing treatment by water-jetting, and/or to inspect the state of the installation after the water-jetting treatment. Under such circumstances, and advantageously, said camera module is connected to a data acquisition and/or display system by means of a cable running along the support and guide arm. It is thus possible to transmit the information picked up by the camera to the data acquisition and/or display system so as to make it possible to perform inspections and verifications remotely or at a later time, and in particular for them to be performed by a different operator. 
   Alternatively, or in addition to the camera module that remains connected to the bottom module, the bottom module may further include a support suitable for receiving an autonomous carriage fitted with a mobile camera. Under such circumstances, the mobile camera can move within the network and pick up visual information relating to zones other than those situated directly vertically in line with or close to the manhole. 
   Preferably, the bottom module further includes a deployable presser member suitable for coming into contact with the structure of the manhole. Such a member serves to make it easier to position the suction and cleaner hoses accurately and to avoid any untimely movement caused by the water pressure when water is ejected under high pressure for cleaning purposes. By way of example, this member is constituted by a deployable sleeve within which the working end of the cleaner hose carrying the cleaner head is guided. 
   Advantageously, the mobile unit further includes a protection bell movable in vertical translation about the vertical portion of the arm and suitable for surrounding the arm over the manhole. 
   In this way, the bell closes the manhole for the operator, thereby protecting the operator from any splashing and possible additional odors generated by the cleaning operations using water-jetting and suction, while also making it possible to move the arm (in particular in vertical translation for the vertical portion of the arm). It will be understood that the bell, which preferably forms part of the intermediate module, provides the operator with protection both in terms of hygiene and reducing health risks, and also more generally in terms of safety. Furthermore, provision may advantageously be made for the up/down movement of the bell to be servo-controlled to the movement of the cleaner hose. 
   In another preferred possibility, the protection bell further includes a camera module movable at least vertically relative to the support and guide arm and enabling the inside of the manhole and adjacent channel zones to be viewed. Under such circumstances, it should be understood that the camera module of the bell acts as the above-mentioned optional camera module of the bottom module. In this way, by means of the camera module that is housed at rest in the bell, means are made available for exploring and viewing the manhole and its surroundings. The camera module is preferably independent of the support and guide arm in terms of control and movement, for example by using a system that enables it to move with reversible vertical telescopic movement. 
   The present invention also provides a vehicle including a mobile cleaner unit as set out above. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages and characteristics of the invention appear on reading the following description made by way of example and with reference to the accompanying drawings, in which: 
       FIG. 1  is a general perspective view of a vehicle carrying a mobile unit in accordance with the present invention; 
       FIG. 2  is an enlarged perspective view of the rear portion of the vehicle visible in  FIG. 1 ; 
       FIG. 3  again shows the rear portion of the vehicle and of the mobile unit, but with the horizontal portion of the telescopic arm being shown deployed; 
       FIG. 4  is a section view in perspective of the zone connecting the horizontal portion to the vertical portion of the support and guide arm; 
       FIG. 5  is a section view showing the top end of the vertical portion of the support and guide arm; 
       FIG. 6  is a section view showing the bottom end of the vertical portion of the support and guide arm; 
       FIGS. 7 and 8  show the bottom module of the vertical portion of the support and guide arm; and 
       FIGS. 9 and 10 , in a manner similar to  FIG. 8 , show the bottom module of the vertical portion of the support and guide arm, in a position in which the bottom module is situated in the bottom of a manhole, and shown in two different configurations. 
   

   MORE DETAILED DESCRIPTION 
   In  FIG. 1 , a vehicle  100  carries on its rear chassis  102  cleaning equipment including one (or more) tank(s)  110  together with a mobile unit  200 . 
   The mobile unit  200  comprises a support and guide arm  202  constituted by a horizontal portion  210  that extends horizontally over the top portion of the rear of the vehicle  100 , and a vertical portion  220  that extends vertically to form the rear end of the vehicle  100 . 
   In  FIG. 1 , the mobile unit  200  is shown in its rest position that allows the vehicle  100  to move, since all of the mobile portions, as described below, are retracted. 
   The mobile unit  200  is more clearly visible in  FIG. 2  where all of the component parts of the horizontal portion  210  and of the vertical portion  220  of the support and guide arm  202  can be seen more clearly. 
   To perform water-jet cleaning, the mobile unit  200  is fitted firstly with a cleaner hose  230  having a cleaner head  234  at its terminal working end  232 , and secondly a suction hose  240  formed with a cylinder  242  (see  FIGS. 2 and 6 ) at its terminal working end. 
   The cleaner hose  230  and the suction hose  240  are supported by the arm  202 , along the horizontal portion  210  and along the vertical portion  220  by a guide system  204  having roller elements  206 , preferably constituted by grooved wheels (see  FIGS. 4 and 5 ). Some of the roller elements  206  are drive elements suitable for driving the hoses  230  and  240  in either direction. In particular, provision can be made for the drive elements to be wheels that apply varying amounts of pressure so as to ensure that the hose  230  and/or  240  that is being driven is properly held. 
   The horizontal portion  210  comprises a base  211  generally fixed to the vehicle  100 , and in particular the chassis  102  of the vehicle  100 , or as, in the embodiment shown in  FIG. 2 , the base  211  is fastened on the shell of the tank  110 . 
   The base  211  includes a motor  212  identified by its location in  FIG. 2 , and in particular a hydraulic motor, constituting first drive means that are connected to a first swivel joint  213  (see  FIGS. 2 to 4 ) enabling the arm  202  to turn relative to the base  211  and to the vehicle  100  about a vertical axis Z 1 -Z 1 ′. 
   The horizontal portion  210  also has a turret  214  mounted above the swivel joint  213  (see  FIGS. 2 to 4 ) and including roller elements  206  of the guide system  204  (see  FIG. 4 ) for passing the cleaner and suction hoses  230  and  240 . The turret  214  can thus be turned about the vertical axis Z 1 -Z 1 ′. 
   Above the turret  214 , there is mounted a series of beams  215 ,  216 ,  217 , and  218  having rectangular sections of different sizes, the beams being nested in one another so as to form a telescopic assembly that can move in translation in a horizontal direction (see  FIGS. 1 to 4 ). This movement is driven by a hydraulic actuator (not shown) situated inside the housing  219  defined between the four beams  215 ,  216 ,  217 , and  218 , and forming second drive means that serve to provide drive in horizontal translation (see  FIG. 4 ). 
   The beams  216 ,  217 , and  218  are connected to parts situated beneath them and that support the roller elements  206  for each of the cleaner and suction hoses  230  and  240 , with the suction hose being placed under the cleaner hose. 
   As can be seen in  FIG. 4 , the connection between the horizontal portion  210  and the vertical portion  220  is implemented in the form of a hinged bend  250  with a ball joint. More precisely, this connection  250  is a resilient hinge suitable for receiving a large radial load (e.g. of the SPHERIFLEX type) and for accommodating a limited amount of angular movement between the horizontal portion  210  and the vertical portion  220  about the two axes of these two portions  210  and  220 , through no more than  150 , and preferably through 3° or 5°. 
   This connection  250  is attached to the beams  218  of the horizontal portion  210  and to the top module  221  of the vertical portion  220 . It serves to make it possible, in particular manually, to reestablish proper positioning of the vertical portion  220  in certain situations. Thus, when the road on which the vehicle  100  is standing is on a slope, the angular movement allowed by the connection  250  enables the vertical portion  220  to be placed accurately vertically. Furthermore, if the manhole entrance is obstructed immediately below the bottom module  220 , after the vehicle  100  has been parked and the support and guide arm  202  has been deployed, the angular movement allowed by the connection  250  can then serve to tilt the vertical portion  220  a little so as to enable the bottom module  226  to enter into the sewer manhole  300 . 
   The vertical portion  220  comprises firstly a top module  221  formed essentially by a machine-welded part that houses the corresponding portion of the connection  250  in its top end, and third drive means  222  that enable this vertical portion  220  to be driven in vertical translation. For this purpose, the third drive means  222  comprise (see  FIG. 4 ) an electric winch  222   a  associated with a cable  222   b  and a motor  222   c  of the motor and stepdown gear type. Preferably, provision is made for the electric winch  222   a  to be declutchable so as to enable the cable  222   b  that is attached to the bottom portions of the vertical portion  220  that are situated beneath the top module  221  to be rewound manually so as to enable the bottom portions of the vertical portion  220  to be raised in the event of an electrical problem arising. 
   As also shown in  FIG. 4 , the top module  221  presents an opening into which the cleaner hose  230  is inserted, while the suction hose  240  remains disposed along but outside the top module  221 , under the cleaner hose  230 , with these two hoses  230  and  240  being guided in this location by other roller elements  206 , in order to bring them into a vertical direction. 
   In the bottom portion of the top module  221  of the vertical portion  220 , fourth drive means  223  are also provided that serve to enable the bottom end of the vertical portion  220  to turn about a vertical axis parallel to the vertical portion  220 . In  FIG. 5 , there can be seen a motor  223   a  associated with a ring  223   b  (e.g. of the ROLLIX type), which is thus made movable in rotation relative to the remainder of the top module  221  so as to constitute a second swivel hinge  223   c  at this point. 
   Under the top module  221 , the vertical portion  220  includes an intermediate module  224  constituted by four beams  224   a ,  224   b ,  224   c , and  224   d  of rectangular section and of different sizes, that are nested in one another so as to form a telescopic assembly that is movable in translation in the vertical direction (see  FIGS. 5 and 6 ). This movement is driven by the above-described third drive means  222 , the cable  222   b  being connected to one or more of the four beams  224   a  to  224   d  (connection not shown). 
   In this way, when the motor  222   c  of the third drive means  222  is activated, to drive downwards or upwards, the cable  222   b  drives the set of four beams  224   a ,  224   b ,  224   c , and  224   d  vertically, which beams deploy or retract depending on the drive direction. 
   As can also be seen in  FIGS. 5 and 6 , at the location of the intermediate module  224 , the cleaner hose  230  passes into the inner housing defined by the four beams  224   a ,  224   b ,  224   c , and  224   d , while the suction hose  240  remains disposed along but outside the intermediate module  224 , and in particular outside the beams  224   a  to  224   d , with no particular guidance being provided for these two hoses  230  and  240  at the location of the intermediate module  224 . 
   Under the intermediate module  224 , the vertical portion  220  has a bottom module  226  that is designed to be placed at the bottom of the sewer manhole  300 , sensibly at the location of the invert  304  (flow channel), and that therefore includes the equipment needed for the operations that the mobile unit  200  of the invention is capable of performing. 
   Firstly, the bottom module  226  has a flexible sleeve  226   a  of section smaller than the section of the inner beam  224   d  of the intermediate module  224  and that is received in an extension  225  of the inner beam  224   d . More precisely, the sleeve  226   a  extends inside and beneath the set of four beams  224   a ,  224   b ,  224   c , and  224   d  of the intermediate module  224 , such that the sleeve  226   a  serves as a guide for the terminal portion of the cleaner hose  230 . The sleeve  226   a  is securely connected to the set of four beams  224   a  to  224   d , so it moves together therewith. Furthermore, the sleeve  226   a  holds the terminal end of the cleaner hose  230  in such a manner that the position in the vertical direction of the cleaner hose  230  is directly associated with the position of the sleeve  226   a . The sleeve  226   a  has an opening  226   b  (see  FIGS. 6 to 10 ) into which the cleaner head  234  at the working end  232  of the cleaner hose  230  opens out. 
   Similarly, the sleeve  226   a  is hinged to pivot about a horizontal axis by means of a leg  228 , the sleeve  226   a  moving between a vertical position in which its extends the beams  224   a  to  224   d , as shown in  FIGS. 6 and 7 , to a deployed position as shown in  FIGS. 8 ,  9 , and  10 . The leg  228  comprises a first part pivotally connected to the arm  202  via the extension of the outer beam  224   d  ( FIG. 8 ) and a second part pivotally connected to the free end of the sleeve  226   a , the first and second parts of the leg  228  themselves being pivotally connected to each other about an axis that is likewise horizontal. 
   Thus, in its deployed position as shown in  FIGS. 8 to 10 , the sleeve  226   a  serves not only as a guide for positioning the cleaner head  234  in a more or less horizontal position, but also as a presser member. As shown in  FIGS. 9 and 10 , the sleeve  226   a  can press against the sidewalk  302  inside the sewer manhole  300  (see  FIG. 9 ) or against the wall of the portion of the channel or invert  304  adjacent to the sewer manhole  300  (cf.  FIG. 10 ). 
   It can thus be understood that the sleeve  226   a  makes it easier to clean by water-jetting by increasing the stability of the equipment of the bottom module  226 , and in particular of the cleaner head  234 . 
   Alternatively, and in a variant that is not shown, the presser member can be made in the form of a tilting bracket using a slideway connection made on the extension of the beam  224   d , together with retaining rods mounted on the front portion of the bracket, which front portion comes to press against the edge of the invert  304 , for example. 
   The (relatively rigid) cylinder  242  forming the working end of the suction hose  240  is connected to the (more flexible) remainder of the suction hose  240  by a quick-coupling type fastener  241 . The cylinder  242  is placed along the bottom module  226 , being retained by a ring  227  mounted on an extension  225  of the inner beam  224   d  of the bottom module  226 . 
   To enable the suction hose  240  to be detached, it will be understood that the cylinder  242  is suitable for being extracted from the sheath  243 : in this extended position, the cylinder  242 , and more generally the suction hose  240 , is held to the support and guide arm  202  solely along the horizontal portion  210  of the top module  221  and of the intermediate module  224  of the vertical portion  220  (see  FIG. 5 ), by the roller elements  206  and by the protective bell  260  inside which there passes the suction hose  240  that remains outside the beams  224   a  to  224   d.    
   The operations of raising (lowering) the suction hose  240  by the third drive means  222  also serve to extract (insert) the cylinder  242  of the suction hose  240  out from (into) the sheath  243 , which sheath may present a flared top segment (variant not shown). The sheath  243  is a cylinder of diameter varying between a maximum diameter allowing the cylinder  242  to be disengaged (inserted) and a minimum diameter blocking the cylinder  242  relative to the sheath  243  by clamping. 
   The relative vertical position between the cylinder  242  and the sheath  243  is identified by slideway indexing between one (or more) peg(s)  246  and one (or more) vertical groove(s)  227   a  crossing the wall of the ring (see  FIGS. 7 to 10 ). 
   Likewise, it is possible to orient the position of the suction hose  240  radially about the vertical portion  220  of the arm, and more precisely of the vertical portion of the flexible sleeve  226   a  and the vertical portion of the cleaner hose  230 . For this purpose, and as can be seen in  FIGS. 7 to 10 , the extension  225  is provided with two horizontal grooves  225   a  crossing its wall over an angle at the center of about 180° (enabling adjustment to be made between +90° and −90°), and co-operating with other projecting elements (not shown in the figures) of the ring  227 . 
   An endpiece  244  is fastened to the free end of the sheath  243  and serves as a filter for the material sucked in by the cylinder  242 . 
   Likewise, because of the second swivel hinge  223   c  between the top module  221  and the intermediate module  224 , it will be understood that it is possible to orient the position of the intermediate module  224  and thus of the bottom module  226  radially about a vertical axis, thus making it possible to obtain very great accuracy in the positioning of all of the equipment of the bottom module  226 , and in particular of the endpiece  244  of the suction hose  240  and also of the cleaner head  234  of the cleaner hose  230 . 
   It should be understood that the cleaner head  234  can be deployed beyond the bottom module  226 , in particular beyond the sleeve  226   a , since the cleaner hose  230  is associated with a motor-driven reel (not shown) situated on the vehicle  100 . 
   Finally, the mobile unit  200  also includes a mobile protection bell  260  surrounding the intermediate module  224  and that serves, when the bottom module  226  is deployed in the sewer manhole  300 , to move down onto the manhole, so as to protect the operator. Advantageously, the bell  260  has a transparent top wall portion so as to make it possible to see the operations taking place inside the manhole  300 . 
   The vertical portion  220  further comprises, in a housing (not shown) mounted inside the protection bell  260 , a camera module (not shown) suitable for leaving the above-mentioned housing to view the state of the manhole  300  before and/or after cleaning, comprising washing under a high pressure jet of water delivered through the cleaner head  234 , and then suction via the endpiece  244  of the suction hose  240 . For this purpose, such a camera module has its own control system and its own drive system enabling it to move from the bell  260  towards and into the manhole  300 , independently of the movements of the vertical portion  220  of the arm  202 . 
   In addition to the first viewing means, the mobile unit  200  may also include a retractable support (not shown) on which it is possible to place a moving camera forming a detachable vehicle of the bottom module  226  capable of going to examine and check the state of the network beyond the location of the sewer manhole  300 . 
   The mobile unit  200  includes a control system for controlling all of the moving equipment, in particular the first, second, third, and fourth drive means for the support and guide arm  202 , and also for the suction hose  240 , the cleaner hose  230 , the camera module, and the optional moving camera support. 
   From the above, it will be understood that at the support and guide arm  202 , the elements that enable the intermediate module  224  and the bottom module  226  to turn, are disposed at the top portion of the set of three modules  221 ,  224 , and  226  of the support and guide arm  202 . This avoids placing mechanical elements, and in particular moving mechanical elements that are bulky in the portion of the support and guide arm  202  that is positioned inside the manhole  300 . 
   Furthermore, the bottom module  226  of the support and guide arm  202  contains only those technical elements (and in particular mechanical elements) that are essential for this location, so as to avoid them being subjected to stresses associated with dirt, moisture, and impacts that are likely to occur when operating inside the manhole. 
   The tanks for containing firstly clean water for the high-pressure water-jet (water tank) and secondly for containing the sludge and dirty water sucked in by the suction hose (collector tank) can be constituted by a single vessel  110  having an optionally displaceable separator partition. 
   Alternatively, the water tank is separate from the collector tank, which tank may be fitted with an ejector piston to make it easier to empty.