FIELD OF APPLICATION
The present invention relates to an improved three-piece bogie assembly for a railway
freight car. More specifically the invention relates to a resilient pad introduced
between bearing pedestal roof crown of a bogie assembly and a bearing adaptor for
overcoming the relative metal-to-metal movement of components and the resultant
wear.
BACKGROUND OF THE INVENTION
The known freight car bogie assembly, comprises a pair of wheels and axle assembly,
a pair of side frames, a bogie bolster, secondary suspension between side frame and
bolster, cartridge bearing and adaptor at each axle end. Each side frame is provided
with a pedestal opening at each end, with two jaws and a roof crown. A bearing
assembly is provided including an adaptor on each end of each axle positioned in a
corresponding side frame pedestal opening for mounting of the frame on each end of
the axle.

In this known arrangement of bogie assembly for a railway freight car, there is
considerable wear on the pedestal crown, pedestal jaws and the adaptor due to the
relative movement between the side frame and the adaptor. Riding of these bogies is
also found to be inferior with biased wheel flange wear.
In order to overcome this problem a metal bonded rubber pad was introduced
between the bearing adaptor and the pedestal roof crown.
This arrangement generates a cushioning effect in the primary mode and eliminates
metal-to-metal contact of the components that is between the side frame and the
bearing adaptor. Though such a metal bonded elastomeric shear pad in general may
contribute only about a millimeter deflection in the vertical mode, they may deflect
considerably in the lateral and longitudinal mode during bogie running service.
Excessive lateral and longitudinal deflection results in premature failure of the
elastomeric shear pad. This also results in excessive wear in the pedestal and the
bearing adaptor calling for premature repair, re-claimation and / or replacement.

In a known freight car with a three-piece bogie of American or similar refrigaration
excessive wear is caused particularly in the pedestal area where the journal bearing
and the bearing adaptor are loosely housed with clearances all over in the side frame.
This is because of the relative movement between metal-to-metal contact surfaces
and failure of metal bonded elastomeric shear pads.
A need therefore, exists for an improved three-piece bogie assembly for a railway
freight car which will eliminate metal to metal contact at this location under all
circumstances.
SUMMARY OF THE INVENTION
The main object of the present invention therefore is to provide an improved bogie
assembly for a railway freight car where excessive wear on the pedestal crown,
pedestal jaws and the adaptor due to relative metal-to-metal movement of
components can be eliminated.

This and other objects of the present invention can be achieved by inserting a resilient
bearing pad between the pedestal roof crown and the bearing adapted which fits
snugly against the roof crown, thus restricting lateral and longitudinal movement of
the adaptor. The resilient pad can be made of polyurethane designed with optimal
strength.
Rubber being highly elastic deflects enormously in lateral and longitudinal modes
during working of the bogies. Polyurethane on the other hand shears far too less
compared to rubber enabling very little lateral or longitudinal movements. This not
only assists the stability of the components itself, but also prevents contact between
the relative surfaces preventing wear. This extends the life of the system
substantially.
Thus the present invention provides an improved three-piece bogie assembly for a
railway freight car, comprising a pair of side frames for carrying a pair of wheels and
axles at each end thereof; a bolster extending between the side frames; and four
bearing assemblies provided at four pedestal portions of said side frames, said

bearing assemblies each comprising a bearing adaptor and a bearing pad disposed
between said adaptor and roof crown of said pedestal; wherein said bearing pad
made of suitable resilient material is designed to fit snugly against said pedestal roof
crown; thereby restricting any excessive lateral and longitudinal movement of said
bearing adaptor with respect to said pedestal.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be explained with the reference to the accompanying drawings
where
Figure 1 shows the pictorial view of the existing three-piece bogie.
Figure 2 shows the perspective view of a three-piece freight car bogie assembly
of Figure 1 including the bearing pad in accordance with the present
invention.

Figures 3 show exploded perspective views of pedestal opening of a side frame
and assembly of bearing adaptor and bearing pad.

Figures 4 show in plan and elevation of a portion of the rearing adaptor
assembled in the pedestal opening with the bearing pad positioned
between the roof of the pedestal opening and the top of the bearing
adaptor.
Figures 5 show sectional views on A-A and B-B of Figure 4.
Figure 6 shows a schematic, exploded, perspective view showing a bearing pad
constructed in accordance with the present invention.
Figure 7 shows a top plan view of the bearing pad constructed in accordance
with the present invention.
Figure 8 shows an end elevation view of the bearing pad of Figure 7.
Figure 9 shows a side elevation view of the bearing pad of Figure 7.

DETAILED DESCRIPTION OF THE INVENTION
Figures 1 and 2 in pictorial and perspective forms respectively illustrate a three-piece
bogie on which the present invention is applied.
Figure 2 shows a three-piece bogie assembly 10 including a pair of axles 12 and 14, a
pair of side frames 16 and 18, four wheels 20, 22, 24 and 26, a bolster 30 which
extends between the side frames 16, 18 with its opposed ends projecting into
openings in the side frames to be supported on spring assemblies shown at 30' and a
spring plank 32 which connects the two side frame rigidly. The bogie assembly 10
further includes four bearings 34, each having an adaptor 36 and a resilient pad
(bearing pad) 38 disposed between the bearings and the underside / crown of a
pedestal 40 of the side frame 16,18.

Figure 3 shows an adaptor 36 and a bearing pad 38 constructed in accordance with
the present invention for mounting on each of the four bearing assemblies 34 shown
in Figure 2. The adaptor 36 fits snugly in contact with the underside of a bearing pad
38, as shown more clearly in Figures 3 and 5. The snug fitting contacts are shown
against reference X in Figure 5.
Figures 6 to 9 show the bearing pad 38 provided with a flat horizontal seat 44. The
seat 44 is designed to fit snugly against roof 46 of the opening of pedestal 40 as
shown in Figure 5. The bearing pad 38 is provided with another seating surface 42
opposed to seat 44 which fits closely against the adaptor 36.
The bearing pad 38 further includes a pair of parallel, upright longitudinal walls 48
and 50 that are designed to fit axially opposed sides of the roof 46 of the pedestal
opening as shown in Figure 5.

The bearing pad 38 is also provided with two pairs of longitudinally spaced depending
end lugs 52, 54 which when assembled depend down adjacent to the opposed end
surfaces 58 on the adaptor 36 for a snug fitting as shown in Figure 5. The end lugs
52, 54 also extend to reach the ends of the crown of pedestal 40 and help in
restricting longitudinal movements.
Four lugs 60, 62; 64, 66 are provided on the bearing pad 38 which snugly fit on to
roof 46 of the pedestal 40 for restricting lateral movement of the adaptor 36.
The material specification of the bearing pad 38 is of polyurethane and the design is
wear resistant. The bearing pad 38 is able to provide resilience in all three directions,
longitudinal, lateral and vertical.
The bearing pad 38 can also be made from rubber and / or steel bonded to
polyurethane. The bearing pad 38 can be made with or without recesses and voids
and can be appropriately shaped to minimize lateral and longitudinal deflections.

WE CLAIM
1. An improved three-piece bogie assembly (10) for a railway freight car
comprising:
- a pair of side frames (16, 18) for carrying a pair of wheels (20, 22) and
axles (12,14) at each end thereof;
- a bolster (30) extending between the side frames; and
- four bearing assemblies (34) provided at four pedestal portions (40) of
said side frames (16, 18) said bearing assemblies (34) each comprising
a bearing adaptor (36) and a bearing pad (38) disposed between said
adaptor (36) and roof crown (46) of said pedestal (40); wherein said
bearing pad (38) made of suitable resilient material is designed to fit
snugly against said roof crown (46) of pedestal (40) thereby restricting
any excessive lateral and longitudinal movement of said bearing adaptor
(36) with respect to said pedestal (40).

2. The bogie assembly as claimed in claim 1, wherein said bearing pad (38) is
made from poly eurethane designed with optimum strength.
3. The bogie assembly as claimed in claim 1, wherein said bearing pad (38) is
made from rubber and / or steel bonded to polyurethane with or without
recesses and voids appropriately shaped to minimize lateral and longitudinal
deflection.
4. The bogie assembly as claimed in claim 1, wherein lugs (60, 62; 64, 66) are
provided on the bearing pad (38) for snug fitting on to roof (46) of the
pedestal (40) to restrict lateral movements.
5. The bogie assembly as claimed in claim 1, wherein two pairs of depending end
lugs (52, 54) are provided on the bearing pad for snug fitting on to opposed
end surfaces (58) of adaptor (36) and to the ends of the crown of pedestal
(40) to restrict longitudinal movement.

6. The bogie assembly as claimed in claim 5, wherein a pair of upright longutudinal
walls (48, 50) are further provided in the bearing pad (38) for sriug fitting on to
axially opposed sides of roof (46) of the pedestal (40).
7. An improved three-piece bogie assembly (10) for a railway freight car,
substantially as herein described and illustrated in the accompanying drawings.

The main object of the present invention therefore is to provide an improved bogie
assembly for a railway freight car where excessive wear on the pedestal crown,
pedestal jaws and the adaptor due to relative metal-to-metal movement of
components can be eliminated.
This and other objects of the present invention can be achieved by inserting a resilient
bearing pad between the pedestal roof crown and the bearing adapted which fits
snugly against the roof crown, thus restricting lateral and longitudinal movement of
the adaptor. The resilient pad can be made of polyurethane designed with optimal
strength.
Rubber being highly elastic deflects enormously in lateral and longitudinal modes
during working of the bogies. Polyurethane on the other hand shears far too less
compared to rubber enabling very little lateral or longitudinal movements. This not
only assists the stability of the components itself, but also prevents contact between
the relative surfaces preventing wear. This extends the life of the system
substantially.
Thus the present invention provides an improved three-piece bogie assembly for a
railway freight car, comprising a pair of side frames for carrying a pair of wheels and
axles at each end thereof; a bolster extending between the side frames; and four
bearing assemblies provided at four pedestal portions of said side frames, said
bearing assemblies each comprising a bearing adaptor and a bearing pad disposed
between said adaptor and roof crown of said pedestal; wherein said bearing pad
made of suitable resilient material is designed to fit snugly against said pedestal roof
crown; thereby restricting any excessive lateral and longitudinal movement of said
bearing adaptor with respect to said pedestal.