FIELD OF THE INVENTION
The present invention generally relates to auxiliary generators of traction
alternator for application on diesel electric locomotives. More particularly, the
present invention relates to an improved oil sealing device adaptable to auxiliary
generators of a traction alternator.
BACKGROUND OF THE INVENTION
In a locomotive, the traction alternator is coupled to the diesel engine. The
electrical power generated by the traction alternator is fed to traction motors
through several control means. In order to meet the additional power
requirement such as, for starting the diesel engine, exciting the field of the
alternator, lighting of the locomotive, and charging battery, a plurality of
auxiliary generators are mounted on the traction alternators. These auxiliary
generators get its drive from a gear train arrangement. The lubrication of the
gear train along with the drive end bearing of the auxiliary generator is arranged
by the oil contained in an oil sump of a gearcase of the gear train. After
lubrication of the drive end bearing of the auxiliary generator, the lubricant
sometimes enters inside the auxiliary generator and cause a problem of low
insulation resistance of windings.
In the prior art, a felt is used in a space between the rotating and stationary
parts to prevent the flow of oil through the gap (Arrangement of fitment of felt

seal in the auxiliary generator is as shown in the Figure 1). According to the
arrangement, a strip of felt (13) is wrapped in a groove provided on a wiper ring
(12). The ends of the felt (13) are cut at approx. 45 degrees for making a butt
joint and RTV (Room temperature vulcanisation silicon rubber paste) is applied
on the three mating faces of the wiper ring (12) for example, two vertical sides
and the bottom surface and the felt is fitted into the wiper ring (12). The felt
(13), rotating along with the wiper ring (12) (mounted on an armature shaft by a
shrink fitting) touches the stationary part i.e. the end shield (14), and prevents
any leakage of oil inside the auxiliary generator (1). The disadvantages of the
felt seals (13) are (a) the seals get damaged / cut easily during mounting of the
end shield (14) on the wiper ring (12), (b) the condition of the felt assembly of
the felt seal after assembly of the wiper (12) and the end shield (14) can not be
monitored in respect of minor oil leakage during the initial stages of auxiliary
generator testing, (c) during operation of the felt seal (13), the seal gets harder
and wears out easily resulting in insufficient sealing (d) Oil pockets provided in
the end shield (14) for oil drainage often get blocked by dust including the felt
pieces resulting in oil leakage through the felt seal.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an improved oil
sealing device adaptable to auxiliary generators of traction alternator, which
eliminates the disadvantages of the prior art.
Another object of the present invention is to propose an improved oil sealing
device adaptable to auxiliary generators of a traction alternator, which is efficient

and capable of sealing the gap between the rotary and stationary components in
a positive and reliable manner.
A still another object of the present invention is to propose an improved oil
sealing device adaptable to auxiliary generators of a traction alternator, which is
substantially maintenance-free, and fail-safe.
Yet another object of the present invention is to propose an improved oil sealing
device adaptable to auxiliary generators of a traction alternator, which prevents
ingress of oil into auxiliary generators to avoid reduction in insulation resistance
of its windings which leads to failure of the loco.
A further object of the present invention is to propose an improved oil sealing
device adaptable to auxiliary generators of a traction alternator, which is simple,
cost-effective, and enables the lubricant oil in the auxiliary generators to remain
free form environmental or foreign materials contamination.
SUMMARY OF THE INVENTION
The present invention provides an improved oil seal device adaptable to auxiliary
generators of traction alternator in which a spring loaded oil seal is provided
between a rotary shaft and the stationary end shield. The oil seal comprising: an
annular supporting member supported in the fixed structure of the end shield,
and an annular elastic sealing member disposed in contact with the outer

peripheral surface of the rotary shaft in such a manner so as to allow a
sliding rotation between the shaft and the oil seal. This provides an
sealing arrangement to prevent ingress of oil inside the auxiliary
the end shield the locating diameter for fitment of oil seal and in the
peripheral surface where the elastic sealing member of the oil seal
contact are maintained within very close tolerance.
By virtue of the arrangement of the spring loaded oil seal in accordance
present invention, the use of wiper ring (12) of the prior art is eliminate
provides an additional space for collection of the oil and passage for
unrestricted drainage of the oil through the drainage holes provided
endshield. The easy drainage of the oil results in reduced pressure of
spring loaded oil seal. This further increases the life and the effectiveness
oil seal to completely prevent the ingress of oil inside the auxiliary
According to the invention, the device comprises a spring loaded
supported in a housing for sealing a space between a stationary end shield
rotating shaft to prevent loss of lubricant inside the auxiliary generator.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure - 1 shows a sectional view of a prior art oil sealing arrangement
felt (13), wiper ring (12), end shield (14) including the
oil flow in the auxiliary generator (1).
Figure-2 shows a schematic diagram showing a typical gear
traction alternator with gear case (7) and oil lubricant (9)

Figure-3 shows a schematic diagram of typical assembly of engine and
alternator.
Figure - 4 shows a sectional view of an improved oil seal device adaptable to
auxiliary generators according to the invention.
DETAIL DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Figure 1,2,3, the auxiliary generators (1) are mounted on a.
gearcase (7) of the traction alternator. The gearcase (7) contains a geartraln
mechanism consisting of a bull gear (4) mounted on the main alternator shaft
(3), wherein the pinions (5) are mounted on the shafts (2) of the auxiliary
generators. When the traction alternator is in running condition, the bull gear (4)
rotates and transmits the rotary motion to the pinions (5) of the auxiliaries,
During this operation lubrication of the gear train is achieved by splash
lubrication. At the bottom of the gear case (7), a sump (8) is provided which
contains gear oil (9) up to a predetermined level and monitored periodically by
means of a dip stick (16). Teeths of an idler gear (6) are partially dipped Inside
the oil (9) and when the gear train operates, this oil (9) is passed on the teeths
of the bull gear (4) and pinions (5) thus providing on effective lubrication of the
gear and pinion (4,5).
The lubrication of a driving end bearing (25) in the auxiliary generator (1) is also
achieved by means of this gear oil (9). After lubrication of the bearing (25), the

excess oil is drained out through a plurality of drainage holes (26) provided in
the end shield (14). If the flow of oil by splash lubrication is more than the
drainage rate the leftover oil attempts an entry inside the auxiliary generator (1)
through a space between the end shield (14) and the wiper ring (12) mounted
on shaft (2) as shown in figure-1.
According to the invention, and as shown in figure - 4, a spring loaded oil seal
(22) is provided for the purpose of sealing the gaps between the end shield (14)
and the shaft (2) of the auxiliary generator (1). The use of wiper ring (12)
mounted on shaft along with felt (13) of the prior art (as shown in figure-1) are
eliminated. The endshield (14) has a stepped opening (23,24) formed at one end
thereof in such a manner allowing the endshield (14) to open in the axial
direction. In the larger diameter opening (23), the roller bearing (25) is disposed.
In the smaller-diameter opening portion (24) which is concentrically formed
axially inside the larger-diameter opening portion (23) of the end shield (14), this
spring loaded oil seal (22) is disposed. The shaft (2) is supported by the bearing
(25) and extends from the smaller opening (24) to the inside of the endshield
(14). The plurality of oil drainage holes (26) are provided in the end shield (14)
that extend from the shaft (2) to the outside opening in the gearcase sump (8).
The oil seal (22) has an annular supporting member (27) formed of metal, and
an annular elastic sealing member (28) supported by the supporting member
(27). The elastic sealing member (28) is formed of an elastic material such as
rubber. A spring ring (29) is fitted on a radially outer surface of a tip (30) which
applies a radially inward pressure on the tip (30) and brings the tip (30) into
close contact with the outer peripheral surface of the shaft (2), thus providing a
liquid-tight sealing enabling however, a relative sliding rotation between the
shaft (2) and the oil seal (22).

WE CLAIM
1. An improved oil sealing device adaptable to auxiliary generators of a traction
alternator of diesel electric locomotives, the traction alternator connected to
the diesel engine such that the electrical power produced being fed to tha
traction motors for the loco drive, wherein a plurality of auxiliary generators
mounted on a gear case of the traction alternator to generate power for
alternator field excitation as well as lightening, fan & battery charging load of
locomotive, the gearcase comprising a geartrain having one bull gear and a
plurality of pinions, the bull gear mounted on a main shaft of the traction
alternator, the pinions being mounted on a shaft of the auxiliary generators,
the gearcase further having an oil sump containing gear oil for providing
lubrication to the bull gear, the pinions, and the drive end bearing, the
auxiliary generators having non-orbitable end shields, and a rotating shaft,
the lubricating oil after lubrication of the bearing if not fully drained out
manages an entry inside the auxiliary generator through a gap between the
end shield and the shaft of the auxiliary generator, the sealing device
comprising:-
- a spring loaded oil seal between an end shield and the shaft of the auxiliary
generator, the shaft extending inside the end shield and supported by the
drive end bearing, the end shield having stepped openings comprising a
larger diameter opening and a smaller diameter opening in the axial direction,
the spring loaded oil seal concentrically disposed in the smaller diamete
opening which is formed axially inside the larger diameter opening;
- a plurality of oil drainage holes provided in the end shield to extend from the
shaft to an external opening formed on the gearcase sump;

- the spring-loaded oil seal comprising an annular support member, and an
annular elastic sealing member supporting said annular supporting member
and
- a spring ring attached radially on the outer surface of the annular elastic
sealing member forming a tip, the spring ring forces the tip to shift radially
inwardly to be in close contract with the shaft to prevent oil leakage.

2. The device as claimed in claim 1, wherein the annular supporting member
formed of a metal, and wherein the annular elastic sealing member is formed
of an elastic material for example, rubber.
3. An improved oil sealing device adaptable to auxiliary generators of a
alternators of diesel electric locomotives as substantially described and
illustrated herein with reference to the accompanying drawings.

An improved oil sealing device adaptable to auxiliary generators of a traction
alternator of diesel electric locomotives, the traction alternator connected to the
diesel engine such that the electrical power produced being fed to the traction
motors for the loco drive, wherein a plurality of auxiliary generators mounted on
a gear case of the traction alternator to generate power for alternator field
excitation as well as lightening, fan & battery charging load of locomotive, the
gearcase comprising a geartrain having one bull gear and a plurality of pinions,
the bull gear mounted on a main shaft of the traction alternator, the pinions
being mounted on a shaft of the auxiliary generators, the gearcase further
having an oil sump containing gear oil for providing lubrication to the bull gear,
the pinions, and the drive end bearing, the auxiliary generators having non-
orbitable end shields, and a rotating shaft, the lubricating oil after lubrication of
the bearing if not fully drained out manages an entry inside the auxiliary
generator through a gap between the end shield and the shaft of the auxiliary
generator, the sealing device comprising a spring loaded oil seal between an end
shield and the shaft of the auxiliary generator, the shaft extending inside the end
shield and supported by the drive end bearing, the end shield having stepped
openings comprising a larger diameter opening and a smaller diameter opening
in the axial direction, the spring loaded oil seal concentrically disposed in the
smaller diameter opening which is formed axially inside the larger diameter

opening; a plurality of oil drainage holes provided in the end shield to extend
from the shaft to an external opening formed on the gearcase sump; the
springloaded oil seal comprising an annular support member, and an annular elastic
sealing member supporting said annular supporting member; and a spring ring
attached radially on the outer surface of the annular elastic sealing member
forming a tip, the spring ring forces the tip to shift radially inwardly to be in close
contract with the shaft to prevent oil leakage.