Semi-unitized shaft seal and method

A two-part, separable, semi-unitized shaft seal for sealing between a housing bore and a relatively rotatable shaft extending through the bore and comprising a metal wear sleeve member and a sealing member assembled onto the wear sleeve member for transportation, shipping and installation of the seal as a unitized seal. However, when the housing and shaft are disassembled, one of the two seal parts remains with the housing and the other part remains with the shaft, whereby each part can be examined and replaced, if necessary, without discarding the entire seal. One seal part press-fits onto one of the housing and shaft and the other seal part forms an elastomeric interference fit on the other of the housing and the shaft.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to shaft seals and in particular to an improved, 
semi-unitized hub seal. 
2. Description of the Prior art 
Shaft seals, including unitized hub seals are well-known in the prior art. 
Such prior art unitized hub-type shaft seals include a wear sleeve 
assembly and a sealing element, the two pieces being unitized and one 
piece press-fitting onto the shaft and the other piece having a ridged 
elastomeric O.D. interference fit into the housing. Such prior art 
unitized seals are installed by, for example, press-fitting it onto the 
axle and then installing the wheel hub onto the axle and seal with the 
elastomeric ridges of the seal sliding into the wheel hub bore. Upon 
removal of the wheel, the entire unitized seal stays on the axle and can 
be removed from the axle and the entire seal can be replaced if necessary. 
The interference fit between the wheel hub and the seal O.D. resists 
removal of the hub therefrom and additional force must be used in removal 
of the hub. Other prior art unitized seals are pressed into the wheel hub 
bore and the entire unitized seal remains in that bore when the wheel is 
removed from the axle. 
Such prior art unitized hub shaft seals are subject to a variety of 
disadvantages and problems. It is a primary object of the present 
invention to provide an improved hub-type shaft seal that overcomes 
problems in the prior art. 
It is a further object of the present invention to provide a semi-unitized 
shaft seal which is installed as a unit but which, when the wheel hub is 
removed from the shaft, one seal part stays with the wheel hub and the 
other part stays on the axle, allowing the wheel hub to be removed from 
the axle without resistance from the seal. It is a still further object of 
the present invention to provide a two-part semi-unitized shaft seal that 
can be disassembled and each part examined for damage and wear, and 
replaced separately if necessary, in contrast to the prior art unitized 
seal which cannot be disassembled for inspection and which must be 
completely discarded and replaced if one part is damaged or worn. 
It is a still further object of the present invention to provide a shaft 
seal having a sealing lip that runs on a smaller diameter wear surface 
whereby it will have a longer life than prior art shaft seals having a 
sealing lip that must run on a larger diameter wear surface. 
It is another object of the present invention to provide a semi-unitized 
shaft seal with a sealing lip that more easily dissipates heat. It is a 
further object of the present invention to provide a semi-unitized shaft 
seal with a wear surface which is more accurately concentric than in the 
prior art shaft seals. It is a still further object of the present 
invention to provide a semi-unitized shaft seal that does not require an 
internal gasket, which gaskets are susceptable to being cut or damaged 
during manufacture and installation. It is another object of the present 
invention to provide, in certain embodiments, a semiunitized shaft seal 
having positive and constant lubrication at the lip without requiring 
lubricant to go through, for example, holes or passageways to lubricate 
the sealing lip. It is a still further object of the present invention to 
provide a semi-unitized shaft seal that does not have metal parts that can 
interfere with each other during rotation. 
It is another object of this invention to provide a semi-unitized shaft 
seal: that has fewer metal parts, that allows the area directly over where 
the sealing lip contacts the wear sleeve to be continually flooded with 
oil to dissipate heat, and that has no area where dirt and water can 
become lodged or trapped. 
SUMMARY OF THE INVENTION 
A two-part, separable, semi-unitized hub-type shaft seal for sealing 
between a housing bore and a relatively rotatable shaft and including a 
metal wear sleeve member including a cylindrical wear sleeve flange and a 
radial flange, with the cylindrical flange adapted to press-fit onto one 
of a shaft and a bore, and a sealing member assembled onto the wear sleeve 
member. The sealing member includes a metal reinforcing ring, a sealing 
element connected to the reinforcing ring and having an annular sealing 
lip forced by a resilient biasing means such as a garter spring into 
sealing contact with the wear surface of the cylindrical flange of the 
wear sleeve member, an elastomeric layer bonded to the reinforcing ring 
and adapted to provide an interference fit in the other of the bore and 
shaft, and at least one annular elastomeric bumper ring bonded to the 
reinforcing ring and extending axially into contact with a radial face of 
a radial flange of the wear sleeve member. 
This seal can be assembled, transported and installed as a unitized seal, 
however, it can be disassembled for inspection and replacement of either 
or both parts. Upon removal of the housing from the shaft, one seal part 
stays with the housing while the other part stays with the shaft, whereby 
the seal of the present invention does not resist removal of the housing 
from the shaft. The term "semi-unitized" is hereby defined for use in the 
present specification and claims with respect to a two-part separable 
shaft seal including a wear sleeve and an elastomeric member having a 
sealing element with a sealing lip in sealing contact with a wear surface 
of the wear sleeve, as meaning such a seal that is not permanently, 
structurally unitized but rather such a shaft seal which, when assembled 
together, will remain assembled for transportation, shipping, and 
installation but which can be disassembled by axially pulling the two 
members apart.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference now to the drawings, FIG. 1 shows one preferred embodiment 
of the present invention including a semi-unitized shaft seal 10 for 
sealing between a bore 12 of a housing 14 and a shaft 16. In a particular 
application the housing 14 is a truck sheel hub and the shaft 16 is a 
truck axle or spindle. Also located between the housing 14 and shaft 16 is 
a bearing assembly including a bearing cup 18, bearing rollers 20 and a 
bearing cone 22. 
The seal 10 comprises a metal wear sleeve member 24 and a sealing member 26 
assembled together to form the two-part, separable, semi-unitized seal 10. 
The wear sleeve member 24 includes a cylindrical flange 28 and a radial 
flange (or deflector ring) 30. The I.D. of the cylindrical flange 28 is 
designed to provide a press-fit on the shaft 16. The radial flange 30 
extends radially outwardly from the axially outer end of the cylindrical 
flange 28. The axially outer direction being the direction to the right as 
shown in FIG. 1; the term "outer" is with reference to the volume being 
sealed. The wheel hub or housing 14 is removed from the shaft 16 by 
pulling the housing off of the shaft to the left as viewed in FIG. 1. 
The sealing member 26 includes a metal reinforcing ring 32, an elastomeric 
sealing element 34, an elastomeric O.D. 40 and an elastomeric bumper 
member 42. The elastomeric O.D. is bonded to the reinforcing ring 32 and 
has an annular sealing lip 36 in sealing contact with the O.D. wear 
surface 38 of the cylindrical flange 28 of the wear sleeve member 24. The 
elastomeric O.D. 40 is designed to provide an interference fit in the bore 
12. The bumper member 42 includes at least one annular ring (two or more 
such rings are preferred and two are shown in FIG. 1) bonded to the 
reinforcing ring 32 and extending axially into contact with the inner 
radial face 44 of the radial flange 30 of the wear sleeve member 24. Thus, 
the sealing member 26 is properly located axially with respect to the wear 
sleeve member 24. The sealing member 26 also includes an inner metal ring 
46 connected (as by press fitting) to the reinforcing ring 32. A garter 
spring 48 is preferably employed for urging the sealing lip 36 into 
contact with the wear surface 38 in a manner well-known to those skilled 
in the art. The elastomer of the sealing element 34, the elastomeric O.D. 
40, and the bumper ring 42 is preferably one integral piece molded at the 
same time onto the reinforcing ring 32. 
The reinforcing ring 32 includes a cylindrical flange 50 and a radial 
flange 52 extending radially inwardly from the axially outer end of the 
cylindrical flange 50. The elastomeric O.D. 40 is bonded to the O.D. of 
the cylindrical flange 50 and is adapted to provide an interference fit in 
the bore 12. The surface of the elastomeric O.D. 40 is preferably provided 
with a plurality of circumferential, axially spaced-apart ridges 54 (the 
ridges 54 are also shown in FIG. 1 in their uncompressed state by dotted 
lines) with a valley 56 therebetween to accommodate the material of the 
ridges when the ridges are compressed during installation. Preferably 
these ridges are designed so as to be compressed more than 50% of their 
height when installed. The elastomeric sealing element 34 includes, in 
addition to the sealing lip 36, a dust lip 58 on the opposite side of the 
radial flange 52 from the sealing lip 36. 
The inner ring 46 is connected, as by press fitting, to the reinforcing 
ring 32 on the opposite side thereof from the radial flange 30 of the wear 
sleeve member 24. The inner ring 46 includes a first cylindrical portion 
60, a first radial portion 62 extending radially inwardly from the axially 
outer end of the first cylindrical portion, a second cylindrical portion 
64 extending axially inwardly from the radially inner end of the first 
radial portion 62, and a second radial portion 66 extending radially 
inwardly from the axially inner end of the second cylindrical portion 64. 
The second radial portion 66 of the inner ring 46 is a protective flange 
spaced axially inwardly from the sealing lip 36 for protecting the sealing 
lip from damage and also to aid in retention of the garter spring 48. 
In installing the seal of the present invention, the seal is installed as a 
unitary seal by a single tool. The metal wear sleeve forming the press-fit 
is provided on either the I.D. or the O.D. of the seal, depending on 
whether or not the seal is to be installed first on the shaft or in the 
bore. The other sealing joint provided by the elastomeric interference fit 
is provided on the other of the I.D. or O.D. of the seal. In the 
embodiment shown in FIG. 1, the I.D. of the seal is a press fit and the 
O.D. is the elastomeric interference fit. The seal 10 is installed onto 
the shaft 16 using a single tool with the seal 10 being treated as a 
unitary or unitized seal. The wheel hub or housing 14 is then installed on 
the shaft 16 with the bore 12 sliding onto the elastomeric O.D. 40 and 
forming an interference fit therewith. When the housing or hub 14 is 
removed from the shaft 16, the sealing member 26 stays with the hub while 
the wear sleeve member 24 stays with the shaft. Thus, the seal 10 is 
automatically disassembled. The sealing member 26 can then be inspected 
for wear and damage and can be replaced, if necessary, without affecting 
the wear sleeve member 24. Similarly, the wear sleeve 24 can be inspected 
and can be replaced, if necessary, without replacing the sealing member 
26. The two parts of the seal 10 can thus be inspected and replaced, if 
necessary, without discarding the entire seal. 
FIGS. 2 and 3 show another embodiment of the present invention comprising a 
seal 70 including a wear sleeve member 72 and a sealing member 74. The 
wear sleeve member 72 includes a first cylindrical flange 76, a first 
radial flange 78 extending radially inwardly from the axially outer end of 
the first cylindrical flange 76, a second cylindrical flange 80 extending 
axially inwardly from the radially inner end of the first radial flange 
78, and a second radial flange 82 extending radially inwardly from the 
axially inner end of the second cylindrical flange 80. The wear sleeve 
member 72 includes an abutting flange 84 extending radially inwardly from 
the axially inner end of the first cylindrical flange 76 for properly 
positioning the wear sleeve member 72 in a bore 86 of a housing 88 (such 
as a truck wheel hub). The first cylindrical flange 76 includes a radially 
outer stepped portion 90 and a radially inner stepped portion 92. 
The sealing member 74 includes a reinforcing ring 94, an elastomeric 
sealing element 96, an elastomeric I.D. 98 and an annular elastomeric 
bumper member 100. The reinforcing ring 94 includes a cylindrical flange 
102 and a radial flange 104 extending radially outwardly from the axially 
outer end of the cyldindrical flange 102. The sealing element 96, the 
elastomeric I.D. 98 and the elastomeric bumper member 100 are all one 
integral body of elastomeric material bonded onto the reinforcing ring 94 
all at the same time. A garter spring 106 is used for forcing or urging a 
sealing lip 108 of the sealing element 96 into contact with a wear surface 
110 of the wear sleeve member 72. The wear surface 110 is the I.D. surface 
of the second cylindrical flange 80. The sealing element 96 also includes 
a dust lip 112 in contact with the wear surface 110. The bumper member 100 
includes a plurality of radial lubricant passageways 114 (also shown in 
FIG. 3) extending therethrough to provide lubrication to the sealing lip 
108. The distal or radially inner end of the second radial flange 82 is 
spaced-apart from a shaft 116 to provide a lubricating passage 
therebetween. The bumper member 100 contacts the radial flange 82 and thus 
properly axially locates the sealing member 74 with respect to the wear 
sleeve member 72. The elastomeric I.D. 98 is preferably formed as a 
plurality of circumferential, spaced-apart ridges 118 (the ridges 118 are 
also shown in FIG. 2 in their uncompressed state by dotted lines). The 
rubber in the ridges is displaced into adjacent valleys, such as a valley 
120, on either side of the ridges 118 when the ridges are compressed. 
Preferably the ridges are designed to be compressed more than 50% of their 
height when installed on a shaft. 
Circulation of sealed fluid around the O.D. surface of cylindrical flange 
80 also helps to carry away heat generated at wear surface 110. 
FIG. 3 is a view looking at the sealing member 74 from the left as viewed 
in FIG. 2 (with the second radial flange 82 of the wear sleeve member 72 
removed), and shows more clearly the lubricating passageways 114 through 
the bumper member 100. The bumper member 100 includes a plurality of 
identical, equally spaced-apart, axially extending ridges 122 between 
which are located the passageways 114. The particular design of the 
passageways 114 and ridges 122 of FIGS. 2 and 3 is not critical; other 
designs can be used. 
Providing the passageways 114 also serves to reduce the contact area 
between the bumper member 100 and the flange 82 and thus, also reduces the 
rotary friction therebetween. 
FIGS. 4 and 5 show another hub shaft seal according to the present 
invention comprising a seal 130 for sealing the space between a bore 132 
of a housing 134 and a shaft 136. The seal 130 includes a wear sleeve 
member 138 and a sealing member 140. The wear sleeve member 138 includes a 
first radial flange 142, a first cylindrical flange 144 extending axially 
inwardly from the radially inner end of the first radial flange 142, a 
second radial flange 146 extending radially inwardly from the axially 
inner end of the first cylindrical flange 144, a second cylindrical flange 
148 extending axially outwardly from the radially inner end of the second 
radial flange 146, and a third radial flange 150 extending radially 
inwardly from the axially outer end of the second cylindrical flange 148. 
The first radial flange 142 is an abutting flange designed to abut a 
radial surface of the wheel hub or housing 134 to locate the seal 130 
properly axially in the application. The O.D. of the first cylindrical 
flange 144 is designed to press-fit in the bore 132. The third radial 
flange 150 is designed to contact the sealing member 140 to position the 
sealing member 140 properly axially in the application. 
The sealing member 140 comprises a reinforcing ring 152, an elastomeric 
sealing element 154 having a sealing lip 156, an elastomeric I.D. 158 and 
an elastomeric bumper member 160. The reinforcing ring 152 includes a 
cylindrical flange 162 and a radial flange 164 extending radially 
outwardly from the axially outer end of the cylindrical flange 162. It is 
noted that the bumper member 160 is contacted by the third radial flange 
150. Lubricating passageways 166 are provided through the bumper member 
160 (as is also shown in FIG. 5). The elastomeric I.D. 158 preferably 
includes a plurality of circumferential, axially spaced-apart ridges 168 
(the ridges 168 are also shown in FIG. 4 in their uncompressed state by 
dotted lines) with valleys 170 therebetween, into which the material of 
the ridges is displaced when the ridges are compressed. Preferably the 
ridges are designed so as to be compressed more than 50% of their height 
(as measured from the bottom of the valley to the top of the ridges in 
their uncompressed state). The sealing element 154 also includes a dust 
lip 172 extending into contact with the wear surface 174. 
FIG. 5 is a view looking at the bumper member 160 from the left as viewed 
in FIG. 4 (with the wear sleeve member 138 removed) and more clearly shows 
the lubricating passageways 166 through the bumper member. The bumper 
member 160 includes a plurality of identical, equally spaced-apart, 
radially extending ridges 176 between which are located the passageways 
166. The particular design of the passageways 166 and ridges 176 shown in 
FIGS. 4 and 5 is not critical; other designs can be used. 
In the seals shown in FIGS. 2-5, the wear sleeve members 72 and 138, 
respectively, are designed for use in truck wheel hubs where the seal 
assembly is driven into the bore of the wheel hub (the housings 88 and 
134, respectively,) and then this wheel with the seal installed is 
assembled over the axle or spindle (the shafts 116 and 136, respectively, 
in FIG. 2 and 4). One reason for this design is that a bearing cone 18 can 
be retained in the wheel hub 88 and 134, respectively, by the seal 70 and 
130, respectively, and then the bearing I.D. acts as a guide when the 
wheel is docked onto the spindle or shaft. As with the other embodiments 
of the present invention, the seals 70 and 130 are really two separate 
pieces but they can be handled and installed as a unitized assembly and 
require only one installation tool. 
FIG. 6 shows another embodiment of the present invention comprising a seal 
180 for use between a bore 182 of a wheel hub or other housing 184 and a 
shaft 186. The seal 180 includes a wear sleeve member 188 and a sealing 
member 190. The wear sleeve member 188 includes a cylindrical flange 192 
and a radial flange 194 extending radially outwardly from the axially 
outer end of the cylindrical flange 192. The I.D. of the cylindrical 
flange 192 is designed to form a press-fit onto the shaft 186. 
The sealing member 190 includes a reinforcing ring 196, a sealing element 
198 having a sealing lip 200, an elastomeric O.D. 202 for providing an 
interference fit in the bore 182, and an elastomeric bumper ring 204, 
extending axially outwardly into contact with an inner radial face of the 
radial flange 194 of the wear sleeve member 188. The sealing member 190 
also includes an inner ring 206 including a radial flange 208 and a 
radially inwardly and axially outwardly tapering flange 210. The distal 
end of the tapered flange 210 extends into holding contact with the 
sealing element 198 while the distal end of the radial flange 208 is 
positioned to retain a garter spring 212 in place behind the sealing lip 
200 and is also a protective flange for the sealing element 198. The 
reinforcing ring includes a cylindrical flange 214 and a radial flange 216 
extending radially inwardly from the axially outer end of the cylindrical 
flange 214. The axially inner end of the clyindrical flange 214 is rolled 
or bent over against the inner ring 206 to lock it in place therefore also 
locking the sealing element 198 in place. The elastomeric O.D. 202 and the 
elastomeric bumper ring 204 are preferably one integral body of 
elastomeric material bonded onto the reinforcing ring 196. The elastomeric 
O.D. preferably includes a plurality of circumferential, axially 
spaced-apart ridges 218 (the ridges 218 are also shown in FIG. 6 in their 
uncompressed state by dotted lines) with a valley 220 between each pair of 
ridges. The material of the ridges is forced into the valleys during 
compression thereof. The ridges are preferably designed so as to be 
compressed more than 50% of their height when installed. The bumper member 
204 preferably includes a plurality of concentric, radially spaced-apart 
bumper rings 222. 
It is to be noted that the phrase "shaft seal for providing a seal between 
a housing bore and a relatively rotatable shaft extending through the 
bore" means that there is relative rotation between the housing and shaft, 
for example, either one of the housing and shaft can be stationary and the 
other one will then be rotatable. 
The invention has been described in detail with particular reference to the 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention as described hereinabove and as defined in the appended claims.