Bearing with sensor module

An antifriction bearing (A) that enables a shaft (4) to rotate with minimum friction in a housing (2) includes a generally cylindrical outer race (46) located in an opening (12) in the housing, an inner race (48) located around the shaft, and rolling elements (50) arranged in rows between raceways on the outer and inner races. The outer race has a cylindrical exterior surface (56), whereas the opening in which the bearing is located has a flat wall (14, 16). A stabilizing block (C) may be attached to the outer race against its cylindrical surface, and this block lies along the flat surface of the housing opening to prevent the outer race from turning in the housing opening. A sensor module (B) is located within the environs of the bearing, and it contains a plurality of sensors (110, 112, 114) which produce signals that reflect conditions under which the bearing operates. Among the conditions monitored are speed, temperature and vibrations.

BACKGROUND ART 
This invention relates in general to antifriction bearings and more 
particularly to a bearing having sensors which monitor conditions under 
which the bearing operates. 
Antifriction bearings have rolling elements which roll along raceways on 
races to significantly reduce friction between a shaft and a housing or 
between similar components, one of which rotates relative to the other. 
The rolling elements and raceways require lubrication which often takes 
the form of grease, and of course, they should be isolated from 
contaminants such as dirt and water. Seals fitted to the ends of the 
bearings serve this purpose. Thus, the critical surfaces of antifriction 
bearings are not exposed and cannot be inspected without removing the 
bearing from its installation and disassembling it. Indeed, some bearings, 
such as those used for journals on railcars and those used on mill rolls, 
are disassembled at periodic intervals for inspection, cleaning and 
relubrication. 
To be sure, devices exist which are designed to monitor operating 
conditions of bearings. Most sense temperature. For example, railroads use 
track-side infrared sensors to detect overheated journal bearings in 
passing trains. Some bearings even come equipped with temperature sensors. 
In this regard, the absence of adequate lubrication will cause the 
temperature of a bearing to rise. Also, where a bearing race slips within 
a housing or on a shaft, the temperature in the bearing will rise owing to 
the high friction where the slippage occurs. Seizure, as when a rolling 
element becomes wedged between races, produces an extreme form of 
slippage. While heat may signal or mark a bearing failure, its presence 
often does not provide adequate time to avoid a failure. 
Apart from the problems identified with detecting bearing failure, bearing 
races tend to rotate or creep in the structures in which they are mounted, 
particularly when subjected to shocks. Typical are the outer races of 
railcar journal bearings which tend to creep in the adaptors for the truck 
side frames in which they are located. But sometimes creep should be 
avoided. For example, a refurbished bearing may have a slightly fatigued 
area in its stationary race and that area should be kept out of the load 
zone. Also, a bearing equipped with a wired sensor cannot tolerate creep 
in the race that actually carries the sensor, since creep will eventually 
sever the electrical leads that connect the sensor with a device for 
processing the signal generated by the sensor. 
The present invention resides in a bearing having a sensor module 
containing multiple sensors which produce signals that reflect various 
operating conditions of the bearing, such as angular velocity, temperature 
and acceleration. The sensor module fits into or adjacent to one of the 
races. In addition. the invention resides in a bearing having a round 
outer race equipped with blocks that prevent it from rotating in a housing 
.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring now to the drawings, an antifriction bearing A (FIG. 1) fits 
between a housing and a shaft and enables the shaft to rotate in the 
housing about an axis X with minimum friction. In the construction 
illustrated the housing takes the form of a side frame 2 for a railcar 
truck, while the shaft is an axle 4 on which flanged railcar wheels 6 are 
mounted. The bearing A, which has a generally cylindrical outer surface, 
carries a sensor module B (FIG. 3) which contains multiple sensors that 
monitor the operation and physical condition or "health" of the bearing A. 
The bearing A also has antirotation or stabilizing blocks C (FIGS. 2 and 
3) which prevent it from rotating in the side frame 2. 
The side frame 2 is conventional. At each end it has a pedestal 10 (FIGS. 2 
and 3) provided with an opening 12 that opens downwardly. The opening 12 
has flat side faces 14 and a flat upper surface 16. 
The axle 4 and wheel 6 are also conventional. As such the axle 4 projects 
beyond each of its wheels 6 in the form of a journal 20 (FIG. 1) that 
emerges from a fillet 22. The bearing A fits over the journal 20 where it 
is clamped between two wear rings 24 which are in turn clamped between a 
backing ring 26 that is against the fillet 22, and an end cap 28 that 
extends over the free end of the journal 20 and is held against the 
journal 20 with machine bolts 30. The clamping force is provided by the 
bolts 30 and is resisted at the fillet 22. 
The bearing A also lies within the pedestal opening 12 at one end of the 
side frame 2. To accommodate the cylindrical outer surface of the bearing 
A to the flat side faces 14 and upper surface 16 of the pedestal opening 
12, the pedestal 10 is further fitted with an adaptor 34 (FIGS. 2-4) which 
is also conventional. Basically, the adaptor 34 has flat surfaces that lie 
against the side faces 14 and upper surface 16 of the pedestal opening 12. 
It also has an arcuate surface or seat 36 which is presented downwardly 
and conforms in contour to the cylindrical exterior surface of the bearing 
A. At each of the ends of the arcuate seat 36 the adaptor 34 has lips 38 
which project inwardly past the seat 36 so that the bearing A will not 
slide out of the adaptor 34. Similarly, the adaptor 34 engages the 
pedestal 10 on the side frame 2 so that it will not slide out of the 
pedestal opening 12. 
The pedestal 10 is fitted with a side frame key 40 (FIGS. 2 and 3) which 
projects beyond one of the side faces 14 of the opening 12 where it lies 
generally below the cylindrical exterior surface of the bearing A. This 
prevents the bearing A from dropping out of opening 12, and that of course 
retains the journal 20 in the side frame 2. 
Preferably, the bearing A is a double row tapered roller bearing. As such 
it includes (FIG. 1) an outer race in the form of a double cup 46, an 
inner race in the form of two cones 48, rolling elements in the form of 
tapered rollers 50 arranged in two rows between the cup 46 and cones 48. 
It also has a spacer ring 52 which fits between the two cones 48 and 
maintains the proper spacing between the cones 48.. The cup 46 fits into 
the adaptor 34, whereas the two cones 48 and the spacer ring 52 fit over 
the journal 20. 
The cup 46 has a cylindrical exterior surface 56 which extends between its 
two ends and conforms to the arcuate seat 36 of the adaptor 34. Indeed, 
the exterior surface 56 of the cup 46 lies against the seat 36 so that the 
two lips 38 at the end of the seat 36 are presented at the ends of the cup 
46. The lips 38 thus prevent the cup 46 from shifting axially in the 
adaptor 34. Internally, the cup 46 has two tapered raceways 58 (FIG. 1) 
which taper downwardly to a cylindrical intervening surface 60 that 
separates them. The raceways 58 open out of the cup 46 through short end 
bores 62, and the end bores 62 receive seals 64 which project out of the 
bearing A and establish live fluid barriers along the wear rings 24. 
Whereas the cup 46 has raceways 58 that are presented inwardly toward the 
axis X, the cones 48 have raceways 66 (FIG. 1) that are presented 
outwardly--indeed, toward the raceways 58 of the cup 46. Each cup raceway 
58 surrounds one of the cones 48 and its raceway 66. In addition, each 
cone 48 has a thrust rib 68 at the large end of its raceway 66. 
The tapered rollers 50 lie in two rows between the opposed raceways 58 and 
66 on the cup 46 and cones 48, respectively (FIG. 1). Along their tapered 
side faces, the rollers 50 contact the raceways 58 and 66. The large 
diameter ends of the rollers 50 lie along the thrust ribs 68 of the cones 
48, and the rollers 50 are thus retained in the annular spaces between the 
cup 46 and the two cones 48. In other words, the thrust ribs 68 prevent 
the rollers 50 from being expelled from the bearing A. The spacer ring 52 
fits between the ends of the two cones 48 and lies immediately inwardly 
from the cylindrical intervening surface 60 of the cup 46. Its length 
determines the axial distance between the raceways 66 of the cones 48 and 
hence establishes the setting for the bearing A. 
The bearing A permits the journal 20 to rotate with minimum friction within 
the pedestal 10 of the side frame 2. Being clamped tightly on the journal 
20, the cones 48 and spacer ring 52 rotate with the journal 20. The cup 
46, on the other hand, remains stationary in the pedestal 10 of the side 
frame 2. Actually, the rotating cones 48, acting through the rollers 50, 
exert a slight torque on the cup 46. In conventional bearings this torque 
often causes the cup to turn slightly or creep, particularly when the 
bearing is subjected to shocks which tend to momentarily lessen the 
friction between the cup and the arcuate seat of the adaptor in which it 
fits. But the stabilizing blocks C which are attached to the cup 46 of the 
bearing A, lie along the side faces 14 of the pedestal opening 12 and 
prevent the cup 46 from rotating in the opening 12. Two stabilizing blocks 
C are attached to the cup 46 at 120.degree. intervals, and each may serve 
as a mount for a sensor module B (FIGS. 3 and 4). The blocks C, while 
securely attached to the cup 46, may be removed and repositioned so as to 
change the position of the load zone in the cup 46. In this regard, the 
load zone for the bearing A, when it is set in end play, extends for about 
120.degree., or 60.degree. on either side of top center. From time to time 
the cup 46 may be rotated 120.degree., so that different 120.degree. 
segments of its raceway 58 lie within the load zone where stresses are 
greatest. This ability to index the cup 46 is in a sense beneficial. For 
example, it changes the portion of the cup raceways 58 that experience 
cyclic rolling stresses. Also. it enables one to move a known fatigued 
region on one of the cup raceways 58 out of the load zone and keep it out 
of the load zone. 
In order to accommodate the stabilizing blocks C and the sensor module B, 
the double cup 46, at each of three locations, is provided with a module 
hole 74, smaller threaded holes 76, one at each side of the module hole 
74, and pin holes 78 located beyond the threaded holes 76. All of the 
holes 74, 76 and 78 extend radially with respect to the cup 46 and are 
arranged one after the other along the exterior surface of the cup 46, 
that is to say, in an axially directed line (FIGS. 1 and 4). The module 
hole 74 extends completely through the wall of the cup 46. opening into 
the interior of the cup 46 through the cylindrical intervening surface 60 
midway between the ends of the two cup raceways 58. It is also the largest 
in diameter of the five holes 74, 76 and 78, and indeed, it is large 
enough to receive the sensor module B. The holes 74, 76 and 78 are 
arranged in three sets, with the sets being located at 120.degree. 
intervals around the cup 46 (FIG. 1). One set of holes 74, 76, 78 is 
presented directly upwardly and as such is covered by the adaptor 34. 
Nevertheless, within this set, the hole 74, which passes completely 
through the cup 46, is plugged to insure that contaminants do not enter 
the interior of the bearing A through it. The other two sets of holes 74, 
76 and 78 lie below the adaptor 34 where they are presented generally 
downwardly. The stabilizing blocks C extend over the holes 74, 76 and 78 
of the two lower sets. 
The two stabilizing blocks C are identical. Each is generally triangular in 
cross-section and long enough to cover all of the holes 74, 76 and 78 of a 
set. Each has (FIGS. 3-5) an arcuate surface 84, the curvature of which 
conforms to that of the exterior surface 56 on the cup 46, and two planar 
side surfaces 86 which are oriented at 120.degree. with respect to each 
other. The apex formed by the intersection of the two planar surfaces 86 
is relieved midway between its ends in the form of a recess 88 having a 
flat base. At the recess 88 the stabilizing block C is provided with a 
large module hole 90 and smaller screw holes 92 (FIG. 5). The block C also 
has pin holes 94 which open out of its arcuate surface 84. 
When the block C is properly fitted to the cup 46, the arcuate surface 84 
of the block C lies against the cylindrical exterior surface 56 of the cup 
46 and the module holes 74 and 90 of the cup 46 and block C, respectively, 
align. Moreover the screw holes 92 in the block C align with the threaded 
holes 76 in cup 46, while the pin holes 78 and 94 in the cup 46 and block 
C also align. Indeed, the pin holes 78 and 94 receive pins 96 (FIG. 4) 
which are pressed into one or the other and prevent the block C from 
moving over the exterior surface 56 of the cup 46. Keyways and keys may be 
substituted for the holes 78 and 94 and the pins 96. 
When the two blocks C are so located, one of the planar surfaces 86 on each 
is oriented vertically, and those vertical surfaces 86 lie in planes that 
are slightly beyond the exterior surface 56 of the cup 46 where the 
surface 56 has its greatest lateral projection, that is 90.degree. from 
top center. This presents the vertical planar surfaces 86 along the flat 
side faces 14 of the pedestal openings 12 in the side frame 2. The blocks 
C thus prevent the cup 46 from turning in the adaptor 34 and pedestal 
opening 12. 
Each block C is held in place and further secured against rotation by 
machine screws 98 (FIG. 4) which pass through the screw holes 92 in the 
block C and thread into the threaded holes 76 in the cup 46. Actually, the 
machine screws 98 also secure a retaining plate 100 against the base of 
the recess 88 in the block C. The retaining plate 100 for one block C 
holds the sensor module B in the downwardly presented module hole 74 over 
which the block C extends. The retaining plate 100 for the other block C 
may hold another sensor B or it may hold a plug 102 in that hole 74. 
Another plug 102 fits int he upwardly presented hole 74. 
Both the sensor module B and the plug 102 in the blocks C have (FIGS. 4 and 
5) a somewhat elongated shank 104 and a flange 106 at one end of the shank 
104. The shank 104 fits into the module hole 74 in the cup 46, but the 
flange 106 is too large to pass into that hole. It does however fit into 
the somewhat larger module hole 90 of the block C, lying completely within 
that hole. The retaining plate 100 overlies the flange 106 and captures it 
within the module hole 90 of the block C. Thus, the sensor module B and 
the plug 102 are retained firmly in their respective module holes 74 in 
the cup 46. The fit is snug enough to effect a fluid-tight seal, so 
contaminants do not enter the interior of the bearing B through either of 
the downwardly presented module holes 74. 
The shank 104 of the sensor module B is hollow and long enough to extend 
into the interior of the bearing A between the two rows of rollers 50. 
Within its hollow interior, the shank 104 of the module B contains sensors 
for detecting the operating conditions and physical characteristics or 
"health" of the bearing A. For example, the module B may contain a speed 
sensor 110, a temperature sensor 112 and an acceleration sensor 114 (FIG. 
5). All three sensors 110, 112 and 114 are retained in the hollow shank 
104 of the module B in the proper orientation with a potting compound. On 
the other hand, the shank 104 could be injection molded with the sensors 
110, 112 and 114 embedded in it, or it could have machined recesses for 
receiving the sensors 110, 112 and 114. 
The speed sensor 110 lies at the inner end shank 104 where it is presented 
toward the spacer ring 52 that separates the two cones 48. The spacer ring 
52 carries a target wheel 118 (FIG. 3) which is configured or otherwise 
constructed to excite the speed sensor 110, causing the sensor 110 to 
produce a signal that reflects the angular velocity of the cones 48 which 
is normally the angular velocity of journal 20 and axle 4. To this end, 
the target wheel 118 may have teeth arranged at equal circumferential 
intervals along its periphery or alternating magnetic poles. Irrespective 
of its construction, the speed sensor 110 produces a pulsating signal when 
the target wheel 118 rotates, and that signal reflects angular velocity. 
The temperature sensor 112 detects the temperature in the interior of the 
bearing A and may provide a digital or analog output. The acceleration 
sensor 114 senses acceleration along an axis and is oriented such that its 
sensitive axis preferably extends vertically in a plane parallel to the 
radial load transferred by the bearing A, although practically any 
orientation is available. It may provide a digital or analog output 
signal. 
The sensor module B may contain additional sensors as well to detect other 
operating conditions and physical characteristics of the bearing A. Such 
other sensors may take the form of acoustic emission sensor or a sensor 
capable of detecting material strain. If a single sensor module B does not 
have enough space to accommodate all of the sensors desired, another 
sensor module B, extended through the other downwardly presented module 
hole 74 in the cup 46 and through the other stabilizing block C, may be 
used to hold some of the sensors. Still more sensors may be housed in a 
sensor module B that extends through the uppermost hole 90 in cup 46, with 
the adaptor 34 modified to accommodate that module B. 
The raw signals derived from the sensors 110, 112 and 114 in the sensor 
module B require processing and perhaps archival at a remote processing 
unit 120 (FIG. 7) which, insofar as railcar journal bearings are 
concerned, may be on the railcar of which the bearing A is part, or in the 
locomotive which pulls the railcar, or even at a track-side location. The 
sensors 110, 112 and 114 must communicate with the remote processing unit 
120, and to this end, a communication channel 122 exists between the two 
of them. Actually, the channel 122 lies between a transmitting device 124 
and a receiving device 126. The transmitting device 124 is carried by the 
sensor module B, or at least is generally fixed in position with respect 
to the sensor module B, and of course the sensors 110, 112 and 114 are 
connected to the transmitting device 124, either directly or indirectly. 
The receiving unit 126 preferably exists at the processing unit 120 and is 
connected to the processing and archival circuitry within it. 
The communication channel 122 may take the form of a cable containing 
wires, in which event the transmitting and receiving devices 124 and 126 
are simply electrical connectors. On the other hand, it may exist in the 
form of electromagnetic waves. In that form the transmitting device 124 is 
a radio transmitter and the receiving device 126 is a radio receiver. Both 
require electrical energy. 
The receiving device 126, when in the form of a radio receiver, derives its 
electrical energy from the source which powers the processing unit 120. 
That may be a battery on a railcar or other site for the processing unit 
120. In the preferred embodiment the electrical energy for the 
transmitting device 124, when it exists in the form of a radio 
transmitter, derives from a storage unit, specifically a battery 128, 
preferably located in the sensor module B. However, the battery B may be 
located elsewhere adjacent to the cup 46, such as in the block C or in the 
adaptor 34. Alternatively, the electrical energy may be supplied to the 
sensor module B by an external source other than a battery, such as a 
power supply. 
The battery 128 has a finite capacity to store electrical energy and unless 
recharged may not last long enough to adequately service the radio 
transmitter that serves as the transmitting device 124. But with the 
availability of the rotating target wheel 118, the speed sensor 110 may 
also serve as an electrical generator or a separate microgenerator may be 
housed within the sensor module B. The target wheel 118 may simply present 
a variable reluctance path, or it may possess permanent magnets. Where the 
target wheel 118 has permanent magnets, its alternating poles pass by the 
end of the sensor module B, and the fluctuating magnetic field produced by 
them induces an electrical current in a coil within the sensor 110. A 
rectifier converts that current to direct current which recharges the 
battery 128. 
Sometimes the raw signals produced in the sensor module B do not transmit 
well through the communication channel 122, but may be modified within the 
module B by a local microprocessor 130 to provide a more useful signal. 
For example, the vibrations detected by the acceleration sensor 114 may 
exist at many frequencies, some of which, owing to band width limitations, 
do not transmit well through the communication channel 122. The 
microprocessor 130 could be used to convert the signal delivered by the 
sensor 114 into a simple RMS energy level signal which is more effectively 
transmitted through the communication channel 122. Other forms of 
processing in addition to or beyond an RMS calculation are possible. By 
the same token, the pulses delivered by the speed sensor 110 may be 
converted by a microprocessor into a simple signal representing speed 
during a small increment of time, and that signal transmits quite easily 
through the communication channel 122. In that sense, signals are 
transmitted indirectly at the transmitting device 124. 
The processing unit 120 processes the signals that are delivered through 
the communication channels 122 and receiving device 126. It has the 
capacity to archive certain signals and to convert signals into real time 
signals capable of energizing displays and activating alarms. The archival 
of raw or processed signal information enables one to track the 
performance of the bearing A over an extended period of time and to detect 
trends. As an example and with regard to the signals derived from the 
three sensors 110, 112 and 114, these signals once processed and stored in 
the processing unit 120, enable one to make the following assessments with 
regard to the operation and condition of the bearing A: 
1. Speed--the instantaneous speed of the journal 20 based on pulses caused 
by the rotating target wheel 118; comparison of that speed with the speed 
of other bearings A operating under similar conditions, such as on the 
same railcar; archival of total cyclic history experienced by the bearing 
assembly; 
2. Temperature--simple level detection; comparison with the temperature of 
other bearings A operating under similar conditions, such as with bearings 
on the same railcar. 
3. Vibration--simple RMS measure of energy level over a given time 
interval; comparison of that energy level with past energy levels stored 
in the processing unit; comparison with energy levels of other bearings A 
operating under similar conditions. 
The assessments have very real and useful applications insofar as the 
operation of the bearing A is concerned, for they enable one to determine 
the operating condition of the bearing A in real time, that is at any 
given instance, and to further evaluate the physical condition or "health" 
of the bearing A. Perhaps the most important objective is to recognize an 
imminent failure before it actually occurs and results in significant 
damage to the bearing A and related components as well. For example, if 
the speed sensor 110 in one of the bearings A produces a signal that 
indicates that the cones 48 of the bearing A are rotating at a velocity 
less than the cones 48 of the other bearings A, the reduced velocity 
suggests that the slower cones 48 are loose and are slipping on their 
journals 20. If the speed sensor 110 registers no angular velocity, the 
bearing A may have seized, perhaps by reason of a roller 50 being wedged 
between one of its cones 48 and the surrounding cup 46. Or it may indicate 
locked brakes, which can produce wheel flats. The signal derived from the 
speed sensor 110 may also provide the instantaneous velocity measurements 
required by antilock braking systems. 
The acceleration sensor 114 will detect vibrations. This could represent 
irregularities or other defects in the track. But when the acceleration 
sensor 114 of one bearing A registers vibrations significantly greater 
than those registered by the sensors 114 of other bearings, a cause for 
concern exists. The vibration may derive from the wheel adjacent to the 
bearing A, most likely from a flat spot on the wheel. It may also indicate 
a defect in the bearing A itself. Spalling along one of the cup raceways 
58 or along one of the cone raceways 66 represents the onset of bearing 
failure and manifests itself in vibration. A damaged roller 50 will also 
produce vibrations. An increase in the energy level of vibrations over a 
period of time suggests growing defects in the raceways 58 or 66 or the 
rollers 50. When the energy level reaches a certain threshold, the bearing 
A should be removed from service. Indeed, with many defects, vibrations 
signify the onset of bearing failure well before an elevation in 
temperature which invariably also accompanies such defects. 
All bearings A that operate under similar conditions, such as on the same 
railcar, should exist at the same temperature. A significant differential 
in temperature between one bearing A and other bearings A suggests a 
defect in the bearing A with the elevated temperature. 
The bearing A with its stabilizing blocks C fits within the pedestal 10 and 
is accommodated to the pedestal 10 by the adaptor 34. Neither the pedestal 
10 nor the adaptor 34 fully encircle the bearing A. A slightly modified 
bearing D (FIG. 8) fits into a different adaptor or housing 140 having a 
full bore 142, and accordingly the housing 140 completely encircles the 
bearing D, limiting access to it. Even so, the bearing D is quite similar 
to the bearing A. It has a cup 46, cones 48 and tapered rollers 50, as 
well as a spacer ring 52 between the cones 48. However, the cup 46 does 
not contain a module hole 74, threaded holes 76 and pin holes 78, nor does 
it receive the sensor module B. Like the bearing A, the bearing D fits 
over an axle journal 20 and is clamped on that journal 20 with an end cap 
28 and a wear ring 24 located between the end cap 28 and the outboard cone 
48. The end cap 28 on its periphery has a target wheel 118 which may take 
the form of teeth spaced at equal circumferential intervals or magnetic 
poles of alternating polarity. 
Fitted against the end of the housing 140 is a cover 144 which extends 
across the end cap 28 and completely obscures it. More importantly, the 
cover 144 isolates the outboard end of the bearing D from the surrounding 
environment so that contaminants do not enter it. The cover 144 is 
actually attached to the housing 140 with machine bolts 146 which pass 
through a flange 148 on the cover 144. In the region of the flange 148, 
the cover 144 projects into the housing 140 where it bears against the end 
of the cup 46, thus preventing the cup 46 from moving axially out of the 
housing 140. 
Adjacent to the flange 148, the cover 144 is directed generally axially, 
for in this region it must clear the end cap 28. Between two of the bolts 
146 it is provided with an axially directed land 150 out of which a module 
hole 152 opens, as well as two threaded holes 154, one on each side of the 
module hole 152, the latter being designed to accommodate a retaining 
plate 100. 
The module hole 152 is located directly outwardly from the target wheel 118 
on the end cap 28 and receives the sensor module B. Indeed, it is 
counterbored at its outer end to accommodate the flange 106 on the sensor 
B. The retaining plate 100 lies against the land 150 to which it is 
fastened with machine screws 98 which thread into the threaded holes 154. 
The plate 100 lies over the flange 106 at the end of sensor module B and 
secures the sensor module B in the cover 144. While the sensor module B 
lies beyond the end of the bearing D, it still remains within the environs 
of the bearing D. 
The sensor module B contains multiple sensors which operate as previously 
described. 
A modified adaptor 160 (FIGS. 9 & 10) not only accommodates the bearing A 
to the generally orthogonal opening 12 in the side frame 2, but further 
secures the cup 46 of the bearing A against rotation or creep and provides 
a mounting for the sensor module B. To this end, the cup 46 has elongated 
holes 161 on each side of its three module holes 74, with the holes 161 
being elongated in the direction of the axis x. Like the adaptor 34, the 
adaptor 160 has an arcuate seat 36, that conforms to the exterior surface 
of the cup 46, and lips 38 at the end of the seat to confine the cup 46 
axially. The adaptor 160 also has an axial groove 162 which opens 
downwardly out of the arcuate seat 36, indeed at the very top of the seat 
36. In addition, the adaptor 160 contains a narrow circumferential groove 
164 which likewise opens out of the seat 36, but extends circumferentially 
from the axial groove 162 to the lower edge of the adaptor 160 to serve as 
a wireway. Finally, the adaptor 160 in the region of the axial groove 162 
has a module hole 166, two screw holes 168, and two pin holes 170, with 
the pin holes 170 being located beyond the screw holes 168. The pin holes 
170 contain pins 172 which are pressed into the holes 170 and project 
downwardly beyond the seat 36. 
The cup 46 of the bearing A fits against the arcuate seat 36 between the 
two lips 38, it being positioned such that one of the module holes 74 in 
its cup 46 is presented directly upwardly. That hole 74 aligns with the 
module hole 166 in the adaptor 160. The elongated holes 161in the cup 46, 
on the other hand, align with the pin holes 170 in the adaptor 160 and 
receive the pins 172 which project from the holes 170. The holes 161 in 
the cup 46 are elongated in the direction of the axis x for the cup 46, 
this being to accommodate axial displacement of the cup 46 within the 
adaptor 160. In this regard, the spacing between the lips 38 on the 
adaptor 160 is slightly greater than the length of the cup 46. 
The sensor B fits through the aligned module holes 166 and 74 in the 
adaptor 160 and cup 46 and projects into the interior of the bearing A, so 
that its inner end is located close to the target wheel 118 that is 
between the two rows of tapered rollers 50. The sensor module B effects a 
seal with the adaptor 160 and the cup 46, and a plate 174 fits over it to 
secure it in place, it being secured with screws 176 which thread into the 
screw holes 168 of the adaptor 160. Moreover, the shank 104 of the sensor 
B is encased in an elastomer which yields as the cup 46 shifts axially 
between the two lips 38 on the adaptor 160, thus enabling the sensor B to 
accommodate the axial displacement. The sensor module B contains multiple 
sensors which operate as previously described. 
The remaining module holes 74 in the cup 46 are plugged to prevent 
contaminants from entering through them. Yet they remain available to 
receive the sensor module B when the cup 46 is indexed. 
When the communication channel 122 takes the form of electromagnetic waves, 
the transmitting device 124, that is the radio transmitter, may be housed 
within the axial groove 162 of the adaptor 160. The same holds true with 
regard to the battery 128. On the other hand, when the communication 
channel 122 takes the form of wires bound together in a cable, the cable 
will extend through the circumferential groove 164.