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Nov. 12, ‘1946.
Filed April 8, 1940
6 Sheets-Sheet 1
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Nov.‘ 12, 1946. '
Filed April 8, 1940
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Nov. 12, 1946.
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Filed April 8, 1940
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Patented Nov. 12, 1946
Walter C. Barnes, Lake Bluff, and Henry W.
Keevil, Highland Park, Ill.
Application April s, 1949, Serial No. 328,516 ‘
27 Claims. (Cl. 175-183)
This invention relates to rail ?aw detector cars
for locating ?aws in track. This application is
a continuation-in-part of application Serial No.
25,586 which has been abandoned and of appli
cation Serial No. 330,210.
To provide a'?aw detecting unit which,though
normally operating underneath the rail head, has
the ability to automatically move into the ?ange
way provided adjacent to the rail head when
ever an obstruction makes it impossible to test
In the past, it ‘has always been‘ assumed that
indications recorded by ?aw detecting appara
tus at the exact point where the rail surface
under ‘the rail head;
the former passing a uni-directional electric cur
To provide means for testing the gauge side
of the rail head'and to automatically move to
shows an obvious imperfection, such as a driver
a position clear of track obstructions whenever
burn, shelly spot, ?owed rail; or‘the like, were 10 they are encountered by the detecting unit;
caused by the ‘surface defect, and the car oper
To provide a detecting unit which is so mount
ator would pass the rail without further inspec
ed and controlled that it is automatically moved
tion. This has applied to rail flaw detector cars
out of the way .of track obstructions but is yield
using the electro-inductive system of testing as
ingly urged into normal operating position so
well as to cars employing the residual magnetism 15 that, after the obstruction has been passed by
system of testing. In both systems protesting
the car, it will resume its normaloperating po
rent through the rail and then detecting varia
To provide novel ways for setting up charac
tions in the magnetic ?eld surrounding the rail.
teristic magnetic conditions‘ in the vicinity of
and the latter passing a strong magnetic ?ux 20 ?aws and for detecting their presence; and
through the rail and then detecting the presence
To otherwise provide ?aw detecting apparatus
of residual magnetism in the vicinity of ?aws
that is more accurate and reliable for locating
flaws in rail.
the sensitivity of the detecting apparatus is nec
Other objects and advantages will become ap
essarily limited by the surface condition of the
rail, for it has been found by experience that 25 parent as the disclosure proceeds and the de
scription is read in conjunction with the ac
certain surface conditions, such asdriver burns,
corrugations, shelly spots, and the like, cause
disturbances'in the magnetic field in their vi
cinity which result in an indication being made
companying drawings,'in which
Fig. 1 is a. diagrammatic side, elevational view
of a rail ?aw detector car employing the residual
on the ?aw recording device.
30 magnetism method of testing, showing the im
As a consequence, the ampli?ers associated
proved detecting unit mounted on the detector
with the recording apparatus are set so that the
record is comparatively clean, except for rela
tively large surface imperfections; and in-some
Fig. 2~is a. vertical sectional view'taken on the
line 2—2 of Fig‘; 3, showing a'form of the inven
instances it is even impossible to cut down' the 35 tion in whichthe detecting unit cooperates with
sensitivity of the ampli?ers to the extent neces
sary for this purpose without destroying their
the gauge side of the rail head;
Fig. 3 is a side elevational view of the detecting .
required sensitivity for the detection and indica
unit shown in Fig. 2;
tion of ?aws.
Fig. 4 is a sectional view taken on the line 4-4
It has been found that ?aws are in some in
stances located directly beneath such surface im
perfections as burns, shelly rail, and the like.
It is for that reason that one of the principal
objects of this invention is to provide ?aw de
of Fig. 3;
Fig. 5 is a view taken from the rear of the
detector car showing the preferred mounting for
the detector carriage;
Fig. v6 is a side elevational view of the detector
tecting equipment that is capable of indicating 45 carriage mount, the detecting unit for the gauge
the presence of ?ssures‘beneath surface imper
side of the rail head being shown mounted on
the customary pick-up box; ‘
‘ fections of this kind.
Broadly stated, other objects of the invention
Fig. '7 is a side elevational view showing one
form of mounting the detecting unit for coopera
To provide flaw detecting equipment which will 60 tion with the under surface of the rail head;
accurately and reliably indicate the presence of
Fig. -8 is an end elevational view of the mount '
?aws but will not be responsive to magnetic con
shown in Fig. 7;
ditions created by surfaceimperfections on the
, Fig. 9 is a horizontal sectional view taken on.
are as follows: _
top surface of the rail head;
the line 9-8 of Fig. '7 ;‘
To provide a detecting unit that normally op 55 ‘Fig. 10 is a ‘side elevational'view showing a de
erates either underneath the rail head or adja
tecting unit mount which is movable in response
cent to the gauge side of the rail head, where
to a‘ feeler arm ‘to avoid vobstructions along the‘
there are relatively few, if any, surface impre
i _
fectionsof a nature which can produce false in
Fig. 11 is a fragmentary vertical ‘sectional view
60 taken on theline ll-ll of Fig. 14;
Fig. ‘12 is a horizontal sectional view taken on
theline |2—|2 ofFig. 10;
» -;
tion 50 of the record line 44), it is usually nec
essary to cut‘down the sensitivity of the ampli?er
.42 until the record line 44 is substantially devoid
~ _
Figs. 13 and 14 are vertical sectional ‘views
taken on the line l3—l3 ‘of Fig. 10, the former
of these ragged portions. Even then, indications.
?gure showing the detecting unit in operative '
showing the detecting unit; in the position which
such as the one shown at 5|, corresponding in all
respects to a flaw indication, are produced on the
record tape by such surface defects as driver
it assumes within the, ?ange way whenever the
.feeler strikes an obstruction; suchas a switch,
~ever-present danger that a true ?ssure will be
position below the rail head and ‘the latter, ?gure
angle bar, or the like;
burns, shelly rail, and the like; and there is the
10 missed 'when the sensitivity to the ampli?er is
Fig. .15 is a. sectional view taken ‘on the line
15-15 ofFig. 10;
cut down tothe extent necessary to produce a
Fig. 16 is a diagrammatic view showing how
relatively “clean” record.
‘ the detecting unit may .be adapted to the electro
The above condition did not exist on all types
of rail, but there is at least a su?‘lcient amount
inductive system of testing, in which the pick-up
isgplaced either between the current brushes or
, behind them, in which latter?case the detector
make the problem one of real concern. It is
‘present to even a greater. extent in the electro
of rail in track which produces this di?ioulty to
inductive system of testing,,where the vdetection
' . coils respond to the residual magnetism left in
the rail;
of ?aws is accomplished by a detector, coil re
Fig. 17 shows an application of this invention 20 sponsive to variations in the magnetic ?ux around
that portion of the, rail through which a strong
to a method of testing inwliich electric current
is passed transversely through the rail; I
uni-directional electric currentis ?owing.
Fig. 18 is a transverse view through a rail head
The‘present invention overcomes the need for '
reducing the sensitivity of the ampli?ers by test
whichiis being tested by'ethe'lsystem shown in
25 ing that portion of the rail head which lies below
acte'ristic distribution of residual magnetism in
the top surface thereof, which suriace is the only
portion of the rail ‘head that, by and large, has
the vicinity of ?aws;
surface imperfections causing false indications.
‘ Fig. 19 shows what may be considered a char
Figs. 20-23, inclusive, show‘ various ways in
which the detecting coils may be positioned with
respect to the'rail head in order to locate; the
As a result, the sensitivity of the ampli?er may
characteristic magnetic conditions‘in the vicinity
of‘ flaws, whether thatcondition be produced by
The detecting unit may be mounted in coop
eration either with the gauge side of the rail
head, as shown in Figs. 1-4, inclusive, or with
the electro-inductive or by the residual magnet
ism systems;
the under surface of the rail head, as shown in
Figs. 7-15, inclusive; and preferably, when the
detecting unit is mounted below the rail head,
_ Fig. 24 shows. a modi?ed-mounting for a de~
tecting .unit intended to cooperate with the under
surfaceof the rail head; and
I Fig. 25 shows still anothermodi?cation of such
means are provided so that it automatically as
40 sumes a testing position adjacent to the gauge
It will be understood thatthe disclosure of‘ cer
tain preferred forms of this invention is vmadein I
compliance with Section. 4888v of the Revised
Statutes and that the appended claims are to be
construed as broadly as the ‘prior art will permit. 45
German. Oaoamzarrox
‘be greatly increased, thereby increasing by a
proportional amount the ability of the detecting
apparatus to locate ?ssures.
side of the rail head whenever track obstructions
prevent continuedtestlng along the under sur
face of the head.
Daracron CARRIAGE AND ITS Suspension mom
1m: CAR
Referring now to Figs. 5 and 6 particularly, it
The invention has been shown applied to a de
will be seen that the detector 36 is suspended
tector car, consisting ofa towsection 3| and a . from the car underframe, generally indicated
trailer section 32, the former carrying rail ener
at 52, by ‘means ofthe trailing arm 40, this arm
gizing. magnets 33 and 34 vand the latter carrying
being vertically pivoted at 53 to a block 54
a third rail energizing magnet 35.‘ These magnets
mounted on a horizontal shaft 55 that is adapted
pass a strong magnetic ?ux longitudinally
to be‘ moved laterally from the position shown
through the rail, causing characteristic magnetic
in full lines to the position shown in dotted lines,
, conditions tov be set up in the vicinity 101' trans
verse ?ssures; and these characteristic magnetic
conditions are adapted to be picked up by alde
65 and vice versa.
The arm 40 is normally held at
right angles to the shaft 55 by‘ equalizing springs
56 adjustably attached to the yoke frame 51.
tector, generally designated 36, which comprises
. .The carriage 36 is raised and lowered , with
a detector carriage 31'adapted to travel along the
respect to the rail by an _air cylinder 58, and the
rail,‘ guided bygauge runners, 38.; A yoke 39, 60 operation of this cylinder is so coordinated with
‘ straddling the carriage 31 is horizontally and ver
ticallyypinned to an arm 40, carried by the trailer
car»_32. 4' The usual pick-up consists of a longitudi
the operation of a transverse cylinder 59 that,
when the carriage is lowered to the rail, it moves
in a substantially vertical plane, as shown by
dotted .lines in Fig. 5, to a position in which the‘
turn operates a recording pen 43_that traces a 65 gauge runner 38 is well inside the gauge edge of
line 44 on a record tape‘ 45. The present inven
. the rail, after which, the cylinder 59 functions
tion associates with the pickl-upyan additional coil
through a lever 80 to move the shaft 55, block 54,
and arm 40 laterally to the left (Fig. 5) until the
45 (or the pick-up 46 may be'used alone) which
feeds toan ampli?er 41, operating a recording.
gauge runner 38 is against the gauge side of
' pen 48 that traces a record line49 on the tape 45, 70 the rail head. The normal operating position of
the carriage is shown in full lines in Fig. 5.
the ‘latter being continuously moved at a speed
nal coil '4] feeding' to an ampli?er 42, which. in
proportional to car speed.‘
Inasmuch as surface defects on ‘the. rail cause
what are known as falseiindioations' (indicated, '
When the carriage 36 is moved laterally into
operative positiveafter striking the rail head, as
above described, a‘ spring 6|, attached to the
byway of example,rby the bracketed ‘lagged por 76 upper end of the arm 40, is placed in tension,
" 2,410,808
thereby yieldingly holding the carriage 39 in its
proper lateral position with're'spect to the rail
with the gauge runners 3‘8 riding on the gauge
this may beaccomplished by providing solenoids
94 and '85 and operatively connecting them to
operating arms, onthe valves 19 and TI respec
side of the rail head.
tively. .The solenoids 94 and95 are connected
The yoke 39 is‘vertically pinned at 62 to the‘
arm and hori'zontallypivoted at‘93to a connect
ing-clevis 64, so that theyoke may align itself
.the'circuit which controls the two solenoids. ;
in'all directions with respect to any irregularities
'in the surface of the rail.’ The yoke ‘extends’
The action of the solenoid 85 is also dependent
; upon the position of an electromagnetic switch 99
across a source of E. M. F., such as a generator
99, and-a hand switch 81 is provided for closing
around the carriage 31 and has inwardly extend 10 which, whenenergized, closes thecircuit through
ing lugs 95, which cooperate with'centering plates c the > solenoid valve 85. The electromagnetic
66' to lift the carriage from the rail whenever the
switch“. includes a solenoid 8'9,lwhich is in
arm 49'isvraisved-by the cylinder 58. In normal
series, with a safety switch 99 and a hand switch
running position; the rear lug 95 merely pushes. . 9!, the circuit receiving its E. M. F. from a small
the carriage along the rail, and downwardly ex 15, battery .92} Obviously, whenever either the safe
tending ‘studs 61, engaging vertical pockets 68
ty switch 99 or hand switch 9|. arevopened, the
solenoidyvalve 85 is tie-energized, thereby moving
in the carriage, transmit the inwardly directed
-' force produced by the spring 6| to the detector
carriage'to hold it in‘the' desired, position on the
rail head. _ The weight of thecarrlage itself, to
gether with the weight of the arm 49 and‘ yoke
39 that is transmitted‘ to the carriage through
rollers 89, is su?icient to give the carriage good
riding qualities on the rail.
‘ ‘
the valve 'I‘i to a position inwhich the chamber
19 of the time-delay device is connected'to at
va ,‘The safety
1 I
; mosphere.
99. is
- carried
v .
. at
. upper
end of thearrn 49, and-‘it consistsof almetal
plate 93, which is in contactv with an electrical
‘contact 94 carried by the block 54 as long as the
- The pick-up box 10, which has'been used in v25
arm-“cremains within given limits of angular
the past to ‘house the coil 4| '(Fig. ‘1), cooperati
. movement about pivot'y53. ‘_ If- for any reason the
ing with the top surface of the rail, is supported
fromthe carriage -3‘l by'bolts 19a; The housing
forthe gauge coil 46 is generally indicated at ‘H.
,‘tcarriagevshould become derailed, as for example
by erroneously following a'switch rail or the 1
like, the angular movement of the ‘arm 49 about
the pivot 53 will cause the plate 99 to move away
Contact AND OPnriArroN or Dnfracroapsaamcr: to from‘ the contact 94, whereupon the solenoid 99
The coordination between the cylinders 59 and
99 is accomplished by a control'system, ‘generally
indicated in -Fig.',6.
It consists ofa compressor .
12, which maintains an air storage tank ‘13 under 35
' desired pressures through a check valve-‘l4. The
air line 15 from the storage tankv 13 passes
through a main- valve 19, and then branches out
to auxiliary valves, controlling the detector‘c'ar
riages on each side ofthe car. Only one of these
auxiliary valves is shown at ‘H, it being under
stood that the branch air conduit -‘l9 extends to
similar equipment on the other sidel'of the car.’
Whenever the valves 16 and" are opened to
permit air under pressure to‘ enter the chamber
‘I9 of a time-delay device 89, the air under pres
sure immediately enters the cylinder 59‘ to lower
the detector carriage to the rail; and, inasmuch
as a spring 83 normally holds the piston in the
of the electromagnetic switch 98 is de-energized
. to, cause the solenoid valve 11 to release the air
from the cylindersBB and 59. . The springs with
in these cylinders automatically lift the carriage,
whereupon theequalizing springs 56 bring. the
arm .49 back itolynormal position in alignment
.with thezrail and close'the contact between the
plate 93 ‘and the contact 94.vv .Preferablyt .the
electromagnetic switch 89 is of the slow-make,
quick-break type, so that the switch '88 does not
actually close until a few seconds have elapsed
.after the solenoid 89 is energized, thus giving
‘the carriage time to steady itself before being
lowered again to the rail. Thespring 95,v ex
tending between thetyoke 99 and the block 54,
assists ‘in _ aligning the carriage preparatory to
again being lowered.
cylinder 59 (Fig. 5) in such a position that the 50
'’ .Da'mcrnvdU‘mr':
‘shaft 59 is ‘in its dotted line position,’ the car
vGauge mount (Figs. 1-6,v inclusive)
riage in its downward movement travels in a
vertical plane downwardly until it strikes the
Afsimple form‘of mountinga detecting unit
rail. After. a predetermined time interval; de
for cooperation with the'gauge side I99 of'the
termined by the bleeding of air' through a re 65 rail head IN is shown, in Figs. 1-6,. inclusive.
’stricted channel 8i. in- the seat of‘j'ball'evalve‘ 92
The pick-up box ‘l9,v cooperating vwith the top
that is normally held closedbyia' spring 83, the
surface I921of the rail head, has mounted within
air pressure in the ~cylinder 59 increases sum
it the‘eonventional longitudinal coil 4| operating
cientlyso that it overcomes the‘ pressure of the
the pen 43 to produce the'record'line 44. The
spring '83 and causes the lever 69 to be rocked co gauge‘ pick-up 46' may be supported from the box
to- move the detector carriage with its supporting
'I9.or some other portion'of the carriage in vari
arm to the full line position'vshown in ‘Fig. 5.
ous-ways; and, as here shown, the coil is mounted
When the valve 11 ‘is rotated‘ to‘ connect the
in a housing ‘H pivotally supported at I93 from
chamber 19 with atmosphere, the'ball valve 92 v
a- bracket I94 adjustably'secured at 195 to the
is unseated, and both cylinders operate by means 65 pick-up box 19."-,The’-housing"ll is preferably
of the springs associated with the incased pistons
vmade‘ as lightas possible so that it can 'be‘easily
to lift the carriage to aposition in which both
lmovedpby obstructions to a‘position' that will
carriage and arm 49 are positioned inwardly of
clear them, and preferably it is, made ‘of- light
the plane which they normally occupy when the ‘ .gaugecopper sheeting bent to form a box-like
carriage is in running position. Subsequent 70 enclosure 496 at its lowerrendvwhich receives
opening of the valves/.16- and ‘I1 produces- the
same sequence of operation as previously’ dee
the detector coil 49. The box is ?anged asshown
at I 91. to receive van‘ insulating closure plate I98
scribed for the: lowering of the carriage.
' The ‘main valve 16 and'auxiliary valvefl'l are
upon which terminals I99 are mounted. The
preferably controlled by electrical means; ‘and
of the housing, either by ?lling the housing with
coil ‘as may be held rigidly in'place at the bottom
wax afterv the~ coil has been placed in position ~
‘ Underneath mount (Figs. ?;9, inclusive)
'with the core legs‘v H0 ‘facing the gauge edge 7
"Hill of the rail,"o_r a small piece of sponge rubber
Ht'may becompressed against * the coil 46 by
[obstacles is, more. complicated with an under
neath mount, such as shown in Figs. ‘7-9, in
clusive, than a gauge mount such as shown in
‘forcing ‘the closure plate lnljagainst the ?anges
_ I01 by attaching screws III.‘ ~
Although the problem of getting past track
upwardly to form the arm H3 of-‘the pendulum
Figs. 1-6, inclusiveLthere are certain inherent
advantages in havingthe detector coil beneath
' provided in-thearm 'I I3. Hence, the position'of '
created byimperfections on the top surface of
The upper portion of the housing ‘|_I ‘extends
. mounting of the coil 46,'the pin lll3’being insert- , the rail head. In, the first place,‘ it islfarther
. able "selectively in any one of several holes H4 10 away from the magnetic conditions which are
therail. In the second ‘Place, the detectorcoil is
positioned-closerto the center line ‘of the rail,
where it hasa better opportunityof locating ‘?s
The housing is; free to’ swing rearwardly about
the‘p'in M3 in the‘ event that it ‘strikes. an ob 15 sures in the outer portion of the rail head.
A ‘simple mount for an underneath coil is
' 's’tacle, and it is yieldingly urged forwardly against
shown in Figs. 7-9,}inclusive, and it consists of
' astop Hiby meansof'a spring H6. 1
> »
‘the 0611 ll with respect to the top'surface of the
rail head may bechosen to suit conditions; ‘
a tightlycoiled spring . I ll fastened at its upper
width of‘ the box enclosure I06 ‘and its
end to a vrod H8, which has aballand socket
spacing from the gaugesside of thefrail head‘ are
‘such that" the gauge coil- will normally ride 20 connection, I 19 with the carriage 31. The lower
end of the. spring H1 is secured to a cam-‘shaped
through all track obstructions, such as highway
crossings, switches, frogs, and the like, in the casting 120,. preferably of manganese steel,
'st'ainlesssteel, or someother wear-resistant ma
i?ange-way'thatis provided in standard track to
terial. The. horizontal sectional shape of the
receive the wheel ?anges of the rolling stock
casting m is shown in Fig. 9, thecam .face m
traveling' over ‘the ‘rail. " Occasionally, 'however,'-a 26 serving
forcethe body 120 inwardly away from
stone-or some’ foreign object will become caught they rail‘towhenever
a track obstacle, such as a
‘ '"in the ?ange Way?and the pendulum mounting
joint bar, frog, .or the like, is encountered. The
. "of the detector coil avoids any damage being done
spring" Ill readily‘ accommodates this movement,
to the coil by‘ reason of’its striking such ‘as ob
and‘the cam face I22 causes'the body I20 to
Preferably, the coil 46 is'wound with 7500 turns a . move upwardly a su?lcient distance to ride in
the ?ange‘ way adjacent to the gauge side of the
' of~No.~ 36 enameled wire; and the core, by way of
qraillheadruntil the obstacle is passed, whereupon
example, may be one-‘quarter inch inv crosssec
, the spring, Ill moves the body In back to its
tion‘with the legs‘! I0 having ‘a total depth, vtop
to bottom. of three-eighths'of-an' inch.
~=§The record-produced-by alccil'positioned ad-:
~ -jacent to they gauge sideopghe rail head‘ is ex
adjustment H9 permits the mounting to be ad
justed so that the detecting .unit is normally
spaced a slight distance fromthe under surface
I23 of the rail head, or, if desired, it may be
adjusted so that there'is a light running con
~ ceptionally clean and free. from "false indications.
it having been determined by actual test that the
‘surface imperfections which ordinarily cause
--false indications do not affect a pick-up locat
ed on the gauge side'of the rail head.
normal running position. The ball and socket
40 _‘ tact with this surface of the rail head.’
The detector coil I724 -is-housed within the body
V120, and it ‘may have the samev operating char
a re-,
sult, the sensitivity of the ampli?er 4Tm'ay be
stepped up considerably,- and it'is therefore pos~
acteristicsthat were described for the- coil 40.
sible to locate ?ssuresfsome of which‘may not 45 The. legs, “0 of. the core are turned upwardly, as
be indicated at‘all by the 0011 ll, due to the lower ' shown in Fig. 8, and the coil is enclosed by a
stainless steel tube 125, which, after being ?lled
sensitivity of' its ampli?er, and others which,
though‘ indicatedmnthe record line 44, would
‘ normally be passed by as caused by ‘some sur
face imperfectiOnon'the topsurface of the rail.
Hence, in reading ‘a record of the type shown -
in Fig. l, ‘the operator will interpret the indica
1 , tions made by the pen ‘3 in the same manner
‘ as always, ,but whenever a corresponding indica
with wax I25 to hold the .coil I!‘ in place, is
‘closed by a plate I21 and soldered to-the tube III,
as indicated at 128.‘ The tube I25 may be secured
to .the body I20 by screws Or rivets 129, as shown
in Figs. 8 and 9. Again, the regular pick-up ll
on the topsurface of thelrail may ,be used, or not,
r as desired.
tion is made in the record 49, or whenever an in 55 .It. should be noted that the manner in which
the vdetector carriage, is raised and lowered with
dication ofany kindpis made on the reoordline 7
respect to the rail ,(as shown in Figs. 5 and 6 and
t9, the operatoriwill hand-check the rail tower
ify the ?nding of a?ssure.
In vother words,
heretofore described) permits the inwardly ex
tending portion of the detecting unit mount (1. e.,
,every indication,‘ on‘the record line" will ‘nor
mally indicatethe presence of a ?ssure, whereas 60 .the coill“ with its housing I25) to clear the '
rail head as the carriage islowered to ‘the rail,
certain indications-on line “,where there is '
after which the lateral movement of the carriage
no corresponding indicationon line 49,v would be
outwardly, bringingrthe gauge runners “into
' ,interpretefd'as caused by surface imperfections in
contact with the rail head, moves the detecting
unit into operative position, on the under surface
.V_ be Possible
u to I dispense
‘cases. r it may.
with ,the top "Pick-up 4|, abut preferably‘v this I‘ 7' iof-the railhead.
pick-unis retained ‘in order to‘ be more certain
Underneath. modnt-‘feele'r type’ (Figs. 10-15, m
rail. .
10fv detecting'?ssures located near the outer side I
vof-theraii head. [Of course, detectingscoils may
, Another way in which the detecting unit that
:be located along this margin of the rail head‘or 70 is being carriedunderneath the rail head may
adjacent to the under ‘surface thereof, 'as ‘shown
be moved to a position of safety while it is pass- ,
in'Fig. 20'; but,‘ the problemof avoiding obstruc
ing track obstacles is shown in Figs. ll-1_5, in
tions in the rail is much more'fcomplic'ated on the
clusive. Here, the detector coil, indicated-at I",
outer side‘ of the rail head than it is on the, gauge ’
,is carried inn small box housing I36 formed of _
stainless steel or other wear-resistant material
and secured by screws. I31 .to a small pivotblock
carriage 31, the pivot I65 vlying'on anaxis I61,
I38 hinged‘at I39 to the lower end of a vertical
which is substantially normal “to the plane which
includes the under surface I23 of the rail head.
Whenever the detecting unit. I63 strikes an ob
stacle beneaththe rail head-the rotation of the
arm I64 about the pivot vI65 will always, insure
that‘ it can get out from under the rail head with
‘ arm‘ I40. The housing I36 is yieldingly urged to
its normal operating position (Fig, 13) by means .7
of a spring MI, and the exact anglewhich the
housing makes with respect to the arm_I40 is .con
trolled by an adjustable stop I42 cooperating
.with a lug I43, formed on the pivot block I38.
The. arm I40 is- carried by parallel links I44
After, the unit I63 has been rotated about the
and I 45, which are pivotally secured to the car 10 pivot I65 until it is clear of the rail head, it may
riage 31 at I46 and I41 respectively. The arm‘ ' be moved upwardly by'the track obstacle about a
I40 is yieldingly urged downwardly by a spring
horizontal pivot "I68 and against the tension of
I48 extending from the top of the arm I40 .to an “ spring I69, which normally holds the Jointed arm
I64 ‘in the position shown in Fig. 24 againsta stop
adjacent portion of the carriage.
I10. The arm is yieldingly urged forwardly
A feeler plate I49 is keyed to a horizontal shaft
.against a stop (not shown) by‘ a spring "I exI50 which extends between the two legs I5I and
tending from the arm I64 to a ?xed portion of
I52 of the detector carriage, andwthe plate is so
shaped that it projects around the rail head and
Instead of using a dashpot, such as shown at I58
has the trailing portion I53 of its cam face I54
positioned in advance of and directly in the path 20 in Figs. 13 and 14, the return vof the arm I40 in
' of the detecting unit while traveling adjacent to
the embodiment of the invention shown in Figs.
the bracket'l66.
. 10-15, inclusive, to normal running position, as
the under surface of the. rail head. .
shown in Fig. 13, may be delayed-by a second .
As shown in Fig. 10, the cam face I54 is curved
upwardly in side elevation so that its forward
feeler I12, ‘which. continues'to ride on the ob
face I55 rides high in the ?ange way which exists,
in all track; This ?ange way is normally at least
‘two inches in width, and ordinarily extends at
least to the lower corner I56 of the gauge side
of the rail head. Whenever the feeler I49 strikes
an obstacle, such as _a rail joint, frog, or the
like, the cam face I54 causesthe feeler to move
stacle,—in this instance, a joint bar I13-after the
front feeler I49 has passed over the obstacle.
Whenitfinally clears the obstacle, it is perfectly
safe for. the arm I40 to be again lowered. -
Oman Monmcarrons
1 30
upwardly about its pivot shaft I50, and the upper
surface of the feeler I49 (see Fig. 15) strikes
The invention is notlimited to use with the
residual magnetism system of testing, for it may
be used with the electro-inductive system as well.
For example, in Fig. 16 there is diagrammatically
an adjustable stop I51, carried by the lower link
I45 supporting-the arm I40, The link I45 is 35 shown a pair of spaced current brushes I 14 and
I15,- which deliver uni-directional direct current
thereby moved upwardly, carrying withv it the arm
to the portion of the rail between the brushes I14
1 I40 against the tension of the spring I48; and,
and I15 by a generator I16. ‘ The detector care.
since the rail head prevents the coil I35 from
riage in the electro-inductive system is mounted
moving directly upwardly, the housing I36 is
caused to rotate about the pivot I39 to' the posi 40 between the current brushes and may carry any of
tion shown in Fig. 14, in which position it is not
only within the flange way that is clear of'ob
stacles but is in testing position during the en
tire time that it-has been moved from its normal
position beneath the rail head.
As soon as the trailing portion I53 of the feeler
I49 has cleared the obstacle,v it tends to fall by
its own weight to its normal position beneath the
mil head, but its action is retarded by a dash- '
pot I58, so that the varm I40 is not lowered until 50
it also has had an opportunity to clear the ob
the types of detecting units that are shown in the
drawings and are herein described, although it is
necessary with the electro-inductive system to
employ two detector coils I11 connected in series
opposition in order to balance out the variations
in the strength of the current passing through the
rail. The coils may be placed on the gauge-side of
the rail head or underneath the rail head, and
they maybe positioned vertically, as shown by the
coils‘ I11, or horizontally, as indicated‘ by the coils
I18. Likewise, the detecting coils, instead of be
ing placed between the current-brushes I14 and
I15, where they are responsive to variations in the
ered suiilciently to enable the housing I36 for the
magnetic ?eld around the rail, may be placed be
detecting. unit to rotate in a clockwise direction
about the pivot I39, it will do so, again setting 55 hind the rear‘current brush I15, where they pick
up residual magnetism in the vicinity of ?aws.
itself to the position shown in Fig. 13.
The coils I18 are shown in this position in Fig, 16.
The dashpot I58 may be of any suitable form,
It should also be understood that both vertical
the one here- shown consisting of a cylinder I59
and horizontal coils, positioned along the gauge
provided with a restricted opening I60 at its end
for slowly releasing air from the cylinder when 60 side of the rail head'or beneath the rail'head, may
be used between the current brushes or in rear of
the piston I6I is moved to the right (Fig. 14) as
the current brushes, as desired.
the arm I62, integral with the feeler I49, is moved
When residualmagnetism is to be established
in that direction. If desired, the dashpot may
by passing electrical current through the rail, it is
provide for unrestrained movement of the piston
I6I to the left, although this is not necessary be 65 sometimes best to pass the current transversely
through the rail head, as shown in Figs. 1'1 and 18,
cause the feeler I49 is always lifted to its upper
in order that the lines of ?ux set ‘up by the cur
position by a, positive force which readily over
rent will be in the right direction'to polarize the
. comes the resistance of the dashpot.
faces of transverse ?ssures, one of which is shown
stacle. Obviously, as soon as the arm I40 is low
Underneath mounts (Figs. 24 and 25)
The underneath mount of the detecting unit
I63, shown in Fig. 24, is somewhat similar to the
one shown in Figs. 7-9, inclusive; but, here, the
at I19 in Fig. 1'1. Obviously, the pick-up coil I80
may be positioned on the top surface of the rail,
along the gauge edge or underneath the rail head,
as may be desired.
detecting unit is mounted on an arm I64, which
The distribution of magnetic flux around a
is pivoted at‘ I65 to a bracket I66 carried by the
transverse ?ssure is indicated generally in Fig, 19,
‘ 2,410,808
i' and Figs. 26-23, inclusive, showv various ways in
which the characteristicmagnetic?ux conditions
around the ?ssure-may. be located by induction
5. Apparatus for progressively detecting ?aw
inv rail comprising means for s'ettingup charac
teristic magnetic conditions in the vicinity of
coils used in accordance with this invention. For
?aws, a detecting unit responsive to said con
ditions movable along the rail, and means for
A , example',-they may be longitudinal coils, as shown
' at IBI in
20, and they may be adjacent to the
gauge side, the outer‘side, or underneath one or
the other of the under surfaces of the rail head.
More. thanone coil may, of course, :be employed, if
- desired, located in'these positions. or transverse
coils‘ i82‘may be employed in anyone or more of
thesepositions, . as‘ shown in Fig. 21; In Figs. 22
and 23, a detectorcoil is shown which is positioned
~at-an inclined angle with respect to all‘ three axes
JOE,‘ YY, and ZZ of the rail.’
. .
' a It willbe understood that in all ‘formsof the
invention the regularpick-up 4H, may be used with
the gauge or underneath pick-upsif desired.
supporting'said unit where the unit will'have
- its strongest magnetic coupling with the rail
through a surface of the rail- head lower than the
top surface of the rail, thereby producing an
indication when the device traverses said field
whereby the unit is relatively unresponsive to
magnetic conditions set up by surface imperfec
tions on“ the top surface of the rail head, said
supporting means including a carriage adapted
15 to travelalong the rail, and means engaging the
~gauge side of the rail head for maintaining the
carriage in uniform lateral position with respect
to the rail head.
6. Apparatus for progressively detecting ?aws
1. Apparatus for progressively‘: detecting flaws 20 ‘in rail comprising means for setting up charac
in rail comprisingrmeans for setting up v‘charac
teristic magnetic conditions in the vicinity ‘of
teristic magnetic conditions in thetvicinity of
?aws, a detecting unit responsive to said :condi
" flaws, a detectingunit responsiveito said'con
tions movable along the rail, means for support
‘ditions movable alongthe railpand means for
ing said unit adjacent to the rail head, but below
supporting said unit where the'unit will have its 25 the top surface thereof, whereby the unit is un
strongest magnetic coupling‘ with‘ the-.rail
responsive to magnetic conditions, set up by sur
through a surface of ,the rail head; lowerthan
face imperfections on the top surface of the rail
the top surface of the, rail, thereby producing an
118811,‘.58-1011 supporting means including a car
indication when the device traverses said ?eld
I riage adapted to travel along the rail, and means
unit including afcore having poles lying adjacent
‘unit and gauge-engaging means being shaped,
whereby the unit is relatively unresponsive to 30 engaging the ‘gauge side of the rail head for
magnetic conditions set up by surface imperfec
maintaining the carriage in uniform lateral posi
tions on theetop surface of the rail‘head, .said
tion with respect to the rail head, said detecting
to the rail head.
, ‘ 2.»~Apparatus for progressively detecting ?aws.
in rail comprising means for setting up charac
teristic magnetic . conditions in ‘ the vicinity ,of
vsized, and positioned so" that they may ride
through all track obstructions in the ?ange way
necessarily provided on-the gauge side of stand
ard track.
7. Apparatus for progressively detecting flaws
news, a detecting unit responsive to‘ said con
ditions movable. along the rail, and‘means for
in rail comprising means for setting up charac
supporting said "unit on the gauge side of the 40 teristic magnetic conditions in the vicinity of ~
rail head where the [unit will‘have itsstrongest
flaws, a detecting unit responsive to said condi
magnetic coupling with the rail through ‘a sur
tions movable along the rail, and means for sup
face of the rail'head ‘lower than the top surface
porting said unit on-the gauge side of the rail
of the rail, thereby producing an indication when
head where the unit will have its strongest mag
the device traversessaid?eld whereby the ,unit 45 netic coupling with the rail through- a surface
is relatively unresponsive to magnetic conditions
of the rail head lower than the top surface of
set up by surface imperfections on the top sur
the rail, thereby producing an indication when
face of the rail head.v
- .
. 3. Apparatus for progressively detecting flaws
in rail comprisingv means for setting up charac
teristic magnetic conditions in the vicinity of
?aws, a detectingunit responsive to said condi
, tions movable along theirail, and means for sup
porting said unit where the ‘unit will have the
strongest magnetic coupling with the rail through
an under surface of the» rail head whereby the
,unit'isunresponsive to magneticconditions set
up by-surface imperfections on the top surface
‘the device traverses said ?eld whereby the unit
is relatively unresponsive to magneticconditions
set up by surface imperfections on the top sur
.face of the rail head, said supporting means in
cluding .a pendulum mounting for the detecting
unit, resilient means urging the pendulum mount
ing in one direction, and astop limiting move
55 ment of the pendulum mounting in said direction.
8. Apparatus for detecting flaws in rail com
prising a carriage‘ adapted to travel along the
rail, means for maintaining the carriage in uni
form. lateral position with respect to the gauge
- 4. Apparatus for progressively detecting flaws 60 side of the rail head, and'a detecting unit mount
in rail comprising means for setting up charac
ed on the carriage for cooperation with the un
teristic magnetic conditions in the'vicinity of
der surface of the rail head, the mounting for
?aws, ‘a detecting unit v‘responsive to said condi
said detecting ‘unit including a tightly coiled
tions movablealong the rail, said detecting unit
spring yleldable, in all directions in which the
including an induction coil positioned with its 65 spring may be subjected to forces caused by the
longitudinal axis substantially parallel to the
detecting unit striking track obstructions.
rail, and means for- supporting said unit where
_9. Apparatus for detecting flaws in rail com
the unit will have its strongest magnetic coupling
prising a carriage adapted to travel along the.
7 with the rail through a surface of the rail head
rail, means for maintaining the carriage in uni
lower than the top surface of the rail, thereby 70 form lateral position with respect to the gauge
producing airindication when the device trav
side of the ‘rail head, and a detecting unit mount
erses said ?eld whereby the unit is relatively
ed on the carriage for cooperation with the under
unresponsive to magnetic conditions set up by
surface of the rail head, the mounting for said
ofthe rail head.
- '
surface imperfections on the top surface of the
detecting unit including a tightly coiled spring
75 yieldable in all directions in which the spring
ing the carriage with respectto the rail, a de
‘maybe subjected to ‘forces caused by the de
> tecting unit mounted on the‘carriage normally
tecting unit striking track obstructions. said
positioned adjacent to the under surface or the
rail head when testing. for ?aws in the ra?, a
spring being inclined upwardly and forwardly
and having its upper endmounted in ‘anad
horizontal shaft on the carriage, a feeler mount- -
justable socket whereby the positionof the de- .
'ed on thejshaft and positioned in advance of the
detecting Zi-iinit adapted to locate and be moved
tecting unit with respect to: the rail head may '
be adjustably determined.
10. Apparatus for detecting ?aws in tracklin
which the under surface of the rail head is ob
structed at intervals by joint bars, switch points,
upwardly when it encounters obstructionsv under
.neath the rail head in the path of the detecting
unit, means responsive to the feeler for mov
ing the detecting unitfrom its position under the
highway crossings, and the like, but which always .
rail head to a position adjacent ‘to the gauge side
of’ the rail head whereby it may travel in said
‘?ange way and’ still be inoperative position to
has a ?ange'way.oiflimitedsizefprovided adja
cent to the gauge side'of the rail, thecornbination
of a car adapted to travel 'on said track, a detect
test the rail for'?aws, and means for returning
ingunit carried by thecar and mounted so that
it normally cooperateslprimarllywith ‘the under
the detecting unit to its normal operating posi
‘tion'below the rail head after the feeler returns
- surface of the rail headfon the gauge side of
to its normal position.
the rail center line; and means. associated with
14., Apparatus for detecting ?aws in rail com
- ing the detecting unit into cooperativerelation 20 prising ‘a car, a detector carriage supported from
the .car, means for raising and. lowering the car
ship withthe gauge side of the rail head when
ever the underysurface oi’ therail head is ob-y '_riage with respect to the rail, said means being
constructed and arranged so that the carriage
structed by rail joints or the like, said detecting
unit being adapted to ride in the ?ange way ad- . when lowered to v(operative *position on therail
iacent to the gauge side of the rail head whenever 25 strikes the rail while positioned laterallyin
'wardly from vitsnormal running position on the
the detecting unit is moved‘ into cooperative re
rail and'is. then movedlaterally outwardly to
iationshipwith the gauge. side, of the rail head.
said normal operating position,; a detecting unit
‘11. Apparatus for detecting ?aws intrack, in
vmounted on thei‘carriagetincludingla substan
which the under surface of the rail headlis', ob
tially vertical arm positioned when the carriage
structed at intervals by Joint/bars, switch points,
is inits nm'ning position closely adjacent to the
highway crossings, and the'like, but which, al
gauge ‘side of the rail head, and means for mount
ways has ‘a ?angeway 'of'limited size provided
ing theidetecting 'unit'on the lower end of said
adjacent to the‘gauge side of the rail, the com
arm in'position tocooperate primarily with the
bination of a car adapted to travel on said track.
under surface of the rail head. '
- ._
a detecting unit carried by the car and mounted
15. The method of‘progressively detecting ?aws
so that it normally. cooperates primarily :with
in the ‘head of a. rail- which consists in condi
the under surface. of the rail head ,on-vthe gauge
tioning the head by setting up characteristic
side of the rail center line, and-means‘mounted
magnetic conditions in the head inthevicinity '
in advance of the detecting unit for loc'atingob
the detecting unit mount for automatically rais
structions to the ‘normal path oi the detegaing
‘of ?aws, andthen locating said?aws by search
ing for the characteristic magnetic conditions by'
moving ‘a ?ux responsive device along the rail
unit and ' for thereupon raising‘ the detecting
unit from its position ‘under the ‘rail head to a
. position alongside the gauge side of the rail head.
l2.'Apparatus for detecting ?aws in track in
which theunder. surface ofthe rail, headis ob
structed at intervals by joint bars, switch points,‘
vhighway crossings, and the like, hut'whichv always
hasa ?ange way or li'mitedsize provided adja
in a path where the device will: have it strongest
magnetic coupling. with the ran through a sur
face of the rail ‘head lower' than the top sur
face of the rail, thereby producing an indication
when the device traverses'said?eld.
cent to 'thegauge side of the rail, the combina
tion of a car adapted to travel on said track, a 50
; ,
16.’ Apparatus for progressively detecting ?aws
in rail comprising means {or setting upcharac
,teristic residual'magnetic conditions inthe vi
detecting unit‘ carried by'the car and mounted
so that it normally cooperates primarily with the
under surface of the rail head'on- the gauge side
of the rail vcenter line, meansmounted in ad
cinity of ?aws, a detecting unitresponsive to
said conditions movable along the rail, and means
for thereupon raising the detecting. unit from
its ‘position under the rail head to a position
the top surface of the rail, thereby producing an ‘
for supporting said unit away from said ?rst
mentioned means and where the device will have
vance ofthe detecting‘ unit. for locating obstruc so its strongest magnetic, coupling —with the ‘rail
through a surface of the rail? head lower than
tions to thej'normal path. of‘, the detecting unit
indication'when the device/traverses said ?eld,
whereby the unit is relatively ‘unresponsive to
alongside the gauge side of the rail head, and
means yieldingly urging the detecting unit to 60 magnetic conditions 'set up by surface imperfec
tions ‘on the topsurface of the rail, and is ai-'
ward its normal operating position under the
fected only by magnetic conditions remaining in
rail head, and means for retarding the movement
the vicinity of, ?aws after‘ the removal of said
of the detecting unit to said normal operating
position after the obstruction locating means has
?rst mentionedmeans‘.
passed the obstruction.
13. Apparatus for detecting flaws in track in
which .the under surface of the rail ‘head is ob
> 17. The method of progressively detecting ?aws
in the head of a rail which consists in condition
’ ing the" head'by passing ‘along the rail means for -
passing a strong magnetic flux- through the rail,
and‘ then, after the ‘conditioning means has '
highway crossings, and the'like, ‘but which al
ways has a ?ange way of limited size provided. 70 moved along, searching the head for character
istic ?aw-indicating magnetic conditions by mov
adj went to the gauge side of the raiL'the combi
ing a ?ux responsive device along'the rail in a
nation of a car adapted to travel along said track’.
path where the device will have its strongest
a carriage suspended from the car, means for
raising and lowering the carriage with respect
magnetic coupling with the ran through a surface
to the rail, a gauge runner for laterally position 75 of the rail head lower. than the top surfaceof the
structed at intervals by Joint bars, switch points,‘
rail, thereby producingan uindicationmwhen the ‘
along-‘the rail in‘ apath where the devicewill
18.‘ The methodof progressively detecting?aws
- ‘ rail‘through the surface of the rail head at the
/_ v1.5
device traverses said ?eld.
‘have its ‘strongest ‘magnetic coupling with the
rain‘ the head of a rail which'consists injcondi
gauge side thereof and lower than the top sur
face of the railheadQ thereby producing an in
tioning the head. by setting *up characteristic
magnetic conditions-in the» head j in the vicinity
dication when the device traverses said?eld. "
' _24. The method of progressively detecting flaws
of ‘?aws and locating said flaws and surface im- '
perfections on”the top of ‘the rail by searching
in rail which has been conditioned by the passage
for'the characteristic magnetic conditions by two _ . of a strong externally applied magnetic ?ux lon
‘separate means positioned in close ‘magnetic cou 10 ~ gitudinally‘ therethrough' and ' the removal of the
plingto the"headan'dv giving separate indications,
externally applied ?uxtoset up and leave char
acteristidresidual‘magnetic ‘conditions in thejvl
.-'cinity of ?aws, which comprises moving a lon
gitudinal' ?ux responsive, device along the rail
15 in a path'where the device will have its strong
est magnetic coupling with the rail through the
"one of said means being close to theupper sur
"face of the head,v and the other Vofsaid means
being close ‘to another surface of the‘ head lower
1 than the upper surface, whereby: ‘said'?aws and
‘said surface imperfections may bev distinguished
by di?erences in the? indications given by said
surface of the rail‘head at'the' gauge sidethereof '
and lower. than the‘ top‘surface of the rail head
19. iApparatusforprogressively detecting ?aws
' thereby producing an
in the head of a vrail comprisingmeansfor set
traverses said ?eld.‘
‘tingfup characteristic magnetic conditions in'the.
arate detecting units‘ responsive toysaid condi
ing the other of {said uni‘ts‘uadjacent ‘to another
surface of the rail head lower than the upper sur
tinguished from said surface imperfectionsjby
‘differences in the indications. given by' ' said 'lélep
20. The method of‘detectingj?aws in a ferro
through the vrail, a'ri'dthen, after the rail condi
tioning means has‘ ‘moved along, testing the rail
' upper surface ofthe'rail' head and for support
‘passing a strong magnetic ?ux longitudinally .
tions and movable together ‘along the rail, means
wfor supporting one of? said units adjacent to the
arate means,
in rail which consists ‘in conditioning therail by
progressively passing along the rail means for
in the vicinity of surface imperfections; two sep
posed records-Ito "indicate theje?ect'of‘said sep
arate detecting units whereby‘ ?aws maybe dis
‘ ~ 25.‘ The method of progressively detecting ?aws
vicinity of ?aws and: other magnetic, conditions
face,‘ and separate means" for producing iuxta~
indication when the device
for’ traces of residual‘iniagnetism byrmoving' a
longitudinal ?ux responsive device along the‘rail
in a path wherejthe device will‘havep its strong
est magnetic coupling with the rail‘ through‘ a
surface of the rail head loweruthan the top sur
face of'the rail, thereby producing an indication
' when‘ the device traverses ‘said ?eld, whereby
false indications causedvby, Shelly spots, burns.
corrugations, etc., are avoided.
' '
‘26. The method of progressively detecting ?aws
in thehead of a rail which has beencondi
tioned by setting up characteristic magnetic con
magnetic ‘rail ‘in _'track which consistslnv subject
a ing 'the' rail to .fan‘ energizingjforce which when
removed leaves 5a-residual magnetic field in the
ditions in the head in vthe vicinity of ?aws and
vicinity of such ?awsyand then locating said ?eld
which is characterized by having surface irregu
v est magnetic coupling with their-ail through the
lower surfaces ‘of ‘the railjhead which-consists, in
locating‘ said “flaws and also-some surface ir
regularities on the top of the rail by‘ searching
by moving'a ?ux vresponsive:device'along the rail
' in apath where'the' device will‘have its strong
surface of the rail head at the gauge side thereof
~ and lower than the top surface of the} rail head,
' thereby producing‘aniindicationl'when the de
.vice traverses said ?eld.
larities ‘along its top surface which are not along
.-21-. The method ofdetectingq?aw'si'in' a ferro
magnetic rail'in' track which consists in subject
ing the rail’ to an energizing force: which when 50
‘removed leaves a residual magnetic’ ?eld_ in the
‘ vicinity of such flaws, and thenilocating said ?eld
by moving; a ?ux responsive device along .the rail
ins-a path where the device will have its‘strong
“ est‘ magneticv coupling withthe rail‘ throughian
undersurface of theirfailf head,~ thereby producj-'
ing anvv indication when‘ the device traverses said
22. ‘The method of detecting flaws in ,a‘yferro
magnetic mum-momma consists in subject
ing the rail-Itolanfenergizingfforce which when
removed leaves a residual ‘magnetic ?eld. in the
I vicinity of such flaws; and then locating said
' field by moving a ?ux responsive‘ devicev along
the rail-in a path where the device will have its
strongest magnetic coupling with the rail through
a surface of the rail head-lower than the top
surface of‘ the rail, thereby producing an indica
tion when the device traverses said ?eld,
_ '
, 23. The method of progressively detecting ?aws
in ‘a rail which ‘has beenjconditioned by setting
Q ‘ up‘ characteristic ' magnetic ‘conditions in the evi
cinity of flawswhich consists} in searching'for
Said ?aws'fby" moving a flu; responsive ‘device
for the ‘characteristic magnetic conditions by »
moving ‘detector means positioned‘ in close mag
neticcoupling to the'top surface of the rail head
and responsiveyto ‘the entire cross-section of the
rail head, and simultaneously movingalong. the
rail ‘detector means in ‘close magnetic coupling
to ailower surface of the rail head whereby said
flaws and said surface‘ imperfections may be dis
tinguished by the differences "in the responsive
ness‘of the'two'detelctor means.
' v
i’ 27. Apparatus for progressively ‘detecting j?aws
in the head of arail‘which hasf'a top surface'suib
iect to certain’v surface irregularities anda lower
surface not subject .to said, irregularities vand
which‘ has been conditionedby setting up char
60 acteristic magnetic conditions in'the ‘vicinity of
flaws, includingya ‘detectingv unit substantially
responsive to ‘the entire‘ rail headand movable
along the rail head closely “coupled thereto
through the‘top "surface thereof and, an‘ addi
tional detecting unit movable. along ‘the rail
head closely coupled thereto through said lower
surface thereof, means for supporting said units
in their respective positions and for moving them
longitudinally along thefrail in such-positions
whereby said ?aws .and said surface imperfec
tions' maybe distingiushed by the di?erences in
the‘responsiv‘enessof said units.
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