fig1 and 2 show a plan view and a side elevational view , respectively , of an inspection brush assembly having a plurality of conductive brushes 101 each having a conductive base housing mounted in holes 205 around the perimeter of a hub 103 . only a few brushes 101 are shown here for clarity , however they are intended to completely encircle hub 103 . the assembly is inserted into a pipeline , preferably as part of a self - contained pipeline inspection device commonly referred to as a “ pig ”. the brushes 101 are rotated as they pass through the inside of a pipeline . a magnetic source located inside of hub 103 causes magnetic flux to pass through hub 103 , through the base housing of the brushes 101 and through their bristles . the bristles are brushed against the inner walls of the pipeline , thereby passing magnetic flux into the metal pipeline walls . prior art inspection brushes have individual bristles which were soldered , epoxied , or otherwise glued into the base housing . these do not exhibit the electrical conduction properties and strength exhibited by the present invention . these properties are very important since pieces of the inspection brushes which break off can destroy pipeline equipment , make it unusable for a period of time and may be very expensive to repair . fig3 and 4 show side and front elevational sectional views , respectively , of one embodiment of the present invention having a plurality of bristles 330 . the present invention shows a bristle 331 having three parts , a first elongated end 331 a , a second elongated end 331 b , and an intermediate securing portion 331 c . the bristles are made to fold or wrap - around a conductive retaining member 350 . therefore , the intermediate securing portion 331 c is made to partially encircle retaining member 350 , allowing first end 331 a and second end 331 b to extend away from the retaining member 350 . the ends may be made to extend substantially parallel to each other as shown in fig3 , or angle outwardly . similarly , other bristles such as bristle 333 also have a first end 333 a , a second end 333 b , and a securing portion 333 c . the bristles for the brushes may be wire that is tempered or untempered , plated , coated or uncoated in virtually any desired diameter . these wires should be electrically conductive . a number of bristles are packed into base housing 320 , thereby causing a tight fit , securing them into the base housing . the unique configuration of the base housing 320 allows it to retain the substantially straight sides desired by the end users while firmly holding the bristles in the base housing and maintaining tight contact between all of the bristles and the base housing for excellent conductivity . to further secure retaining member 350 inside base housing 320 and to further secure bristles 331 , 333 , etc . the top portion 321 of base housing 320 is “ swedged ” by crimping or compressing top portion 321 into a smaller diameter , physically pressing against the bristles . retaining member 350 may be implemented by using a rod slightly shorter than the internal diameter of base housing 320 . if the retaining member 350 is implemented in this manner , swedging base housing 320 after retaining member 350 has been inserted into base housing 320 , secures retaining member 350 inside of base housing 320 , since it is now too large to pass through the smaller opening in the top portion 321 of base housing 320 . ( fig7 d shows a reduce diameter swedged portion 340 .) retaining member 350 may be secured by other known means as long as the electrical conductivity between base portion 320 , retaining member 350 and bristles 331 , 333 are maintained . in an alternative embodiment of the present invention , the securing portion 331 c , 333 c of bristles 331 , 333 may be wound around securing device 350 several times as shown by the dashed lines shown in fig3 and 4 . securing portions 331 c and 333 c are shown in phantom as concentric circles around retaining member 350 in fig3 . these portions are also shown as circles in phantom immediately above and below retaining member 350 . winding these bristles around retaining member 350 would result in improved securing of the bristles , and a more resilient inspection brush . fig5 is a cross - sectional , plan view of the embodiment of fig3 and 4 , as viewed from the line 5 - 5 of fig4 . bristles 330 are shown as circles in phantom emanating from above and below retaining member 350 . it can be seen here that retaining member 350 extends from one side of the inner surface of base housing 320 to the other side . slightly above this level , base housing 320 is the swedging area 340 having a smaller circumference thereby preventing retaining member 350 from being pulled out of base housing 320 . ( this is shown in fig7 d .) fig6 shows a portion of another alternate embodiment of the present invention . a single wire may be folded back on itself to make a plurality of double stranded bristles 611 , 613 , 615 . a plurality of securing portions 601 c , 603 c , and 605 c are formed between each of the bristles 611 , 613 , 615 . the securing portions 601 c , 603 c , 605 c are intended to be folded back onto each other such that 601 c , 603 c and 605 c are coaxial and fit over retaining member ( 350 of fig3 and 4 ). since each securing portion would be connected to the retaining member 350 , and each bristle would be connected to an adjacent bristle , there is less chance that pieces would break off during use falling into the pipeline and creating damage . 1 . an electrically conductive base housing 320 is provided having a generally cylindrical shape , a bottom portion 325 and a top portion 321 with a recess 327 passing generally lengthwise from the top to bottom portions . 3 . the bristles 330 are positioning in a generally parallel configuration across the top of the base housing 320 such that they are generally perpendicular to the length of the recess 327 as shown in fig7 a . 4 . an elongated electrically conductive retaining member 350 is then positioned across the bristles 330 , as shown in fig7 b . 5 . the retaining member 350 is forced into the recess 327 , thereby folding the bristles 330 into the recess 327 such that they are held in place by the retaining member 350 , as shown in fig7 c . since the bristles are held in place by the retaining pin , brush integrity is maintained . in another embodiment , each of the bristles 330 are wound at least a full circle around the retaining member 350 . the wires are wound before the retaining member 350 is inserted into the base housing 320 . optionally , the top of the base housing 320 may be compressed in swedged section 340 to further hold the bristles 330 in place as shown in fig7 d . fig8 is a partially cut - away side elevational view of another embodiment of the present invention in a disassembled view . in this embodiment , there is an inner sleeve 810 which is intended to hold bristles 330 such that the first end 331 a and the second end 331 b extend out of inner sleeve 810 . inner sleeve 810 has at least one catch 811 , 813 on its outer surface which are designed to fasten easily to a corresponding groove ( s ) 861 , 863 when inner sleeve 810 is inserted into central recess 880 in base housing 860 . it can be seen that the catches are wedge - shaped moving from bottom to top , and have an abrupt shoulder 812 , 814 at the uppermost edge thereby resisting release once fastened . fig9 is a partially cut - away side elevational view of another embodiment of the present invention shown in fig8 in an assembled view . in fig9 inner sleeve 810 is shown after it has been pushed into base housing 860 . once catches 811 , 813 snap into groove 861 , 863 there is a close fit between shoulders 812 , 814 and groove upper edges 862 , 864 that does not allow release of the parts . this is a one - time fastener and is designed to fasten , but not release . during assembly of the embodiments above , a solder or thermoplastic may be placed in the bottom ( 325 of fig3 ), 825 of base housing ( 320 of fig3 ), 860 . the base housing ( 320 of fig3 ), 860 may then be heated to further hold the bristles 330 in place . other epoxies , glues , and adhesives may also be used to further strengthen the assembly .
a resilient inspection brush used in electrically inspecting pipelines for abnormalities is described which employs highly conductive metals , such as nickel . since bristles made from these metals cannot be secured firmly by soldering or epoxy , they are folded over a retaining member , or wrapped around the retaining member . the retaining member is secured inside of a base housing . the top portion of the base housing may be crimped or swedged to reduce the size of the opening , thereby physically holding the bristles . this also insures that the retaining member does not pass through the opening , securing the retaining member inside of the base housing . in another embodiment , an inner sleeve is used to further secure the bristles and simplify assembly .