FIELD OF INVENTION:
This invention relates to novel axle box assembly having improved cartridge cylindrical roller bearing unit with inbuilt axial float used for locomotive wheel application.
BACKGROUND:
One of the many uses for the cylindrical roller bearings is for locomotive wheel application. In locomotives, the axle box provides the connection between the wheel set and the bogie frame. It also transmits vertical and horizontal loads between the locomotive body and wheel set. Modern locomotives are equipped with roller bearing axle boxes as they offer a number of advantages over plain bearings including significant reduction in friction, operation at higher speeds and pulling of heavier train loads.
These cylindrical roller bearings are housed in axle box housing which is then mounted on axle journals of locomotives. To better explain the context of this invention, there are two bogies in the said locomotive. Each bogie has three axle journals on which the axle boxes are mounted. Therefore there are three pairs of wheel sets in a bogie with corresponding axle boxes mounted on both sides of each axle journal. The axle box in the centre of each bogie is the middle axle box while the axle boxes mounted on the first and third axle journals of each bogie are referred to as the end axle boxes.
While running on a curved or a turning track, the locomotive experiences a pull directed towards the curvature of the track due to the centrifugal force. Therefore some kind of balancing force is required to maintain the locomotive from tipping over or derailing from the tracks. This balancing force is provided by the axial float which is enabled because of the said cylindrical roller bearings.
The existing state-of-art axle box mounted on the axle journal of locomotives has a pair of single row cylindrical roller bearings and a good number of axle box components for clamping purposes which are essential for the smooth running of the locomotive especially while on curved tracks. The said cylindrical bearing on the wheel facilitates the outer assembly to float in the axial direction with rotation while the locomotive is running on the curved track.
This existing design uses two single row cylindrical roller bearings which are separated by two distance pieces called inner distance piece and outer distance

piece, which occupy more space and increasing the maintenance time thereby increasing locomotive downtime.
It is also to be noted that the state of the art cylindrical roller bearings being multiple in nature cannot be sealed efficiently along with the axle housing which is also not a completely sealed unit resulting in the bearing being more exposed to dirt and dust and reduced life. Instead a thrower is provided which is used at the extreme end near the wheel while the in-built portion of the housing is used for preventing dust and dirt from the side opposite to the wheel side of the assembly using labyrinth sealing principle but it is rather ineffective in preventing contamination of the assembly. At the other end, loose lip and the thrust collar are used and this axle box assembly is covered by the end cover which is again an integrated part of the axle box assembly.
As mentioned above, these bearings are not sealed. Therefore, every four months or so, the assembly is topped up with grease to replenish the loss while every two years or so, the entire axle assembly has to be cleared of dust and replenished with grease, thereby increasing the grease cost, manpower cost and locomotive down time.
There is a need to minimize the maintenance costs and locomotive down time while providing a cylindrical roller bearing which can provide inbuilt flexible axial float and that which is low on maintenance.
Also in the existing state of the art mounting of multiple bearings is in itself a maintenance drawback and also more time and manpower consuming. It also amounts to more number of parts. Also maximum speed rating is less because of the inner race slack where bearing width is detrimental.
OBJECT AND SUMMARY OF THE INVENTION:
The object of the present invention is to provide an axle box having a double row cylindrical roller unit bearing as a single cartridge that can be easily mounted as an integral unit on the axle journal with at least one easily accessible external grease hole.
Another object of the invention is to provide a pre-lubricated cartridge cylindrical roller bearing unit having adequate grease inside and sealed from both ends to improve grease retention and reduce contamination of the greased bearings.

Another object of the invention is to provide a novel axle box to enable flexible axial float without effecting any changes in the bogie design.
Another object of the instant invention is to provide an axle box housing that has fewer parts thereby occupying lesser space and mass.
Yet another objective of the proposed invention is to provide novel axle boxes which can still be mounted in the existing state of the art axle journals without having to modify the axle journal or wheel set design and yet be able to handle higher speed loads.
Yet another object is to mount the axle box as a complete assembled unit, thereby reducing the time for assembling, overhauling and maintenance.
The instant invention obviates the drawbacks of existing prior art. The invention provides for a double row single cylindrical roller bearing unit sealed as a cartridge and mounted as a complete assembled unit on axle journal of a locomotive. These bearings have been designed to provide adaptive axial float for a locomotive as required under different operational conditions on various axle journals. These bearings are sealed after lubricating with good quality grease. However, external grease holes are provided for maintenance and replenishment of grease from time to time.
This assembly is easy to mount, more reliable, while the sealed ends provide for improved grease retention thereby preventing contamination of grease within the bearings. This leads to lower maintenance costs, reduced downtime of locomotive and improved life of bearings. This improved design also makes it suitable for use in higher speeds, higher capacity within same boundary conditions and eliminates the thrower biting problem.
STATEMENT OF INVENTION:
Accordingly the instant invention provides a novel axle box assembly comprising of axle box housing, thrower, thrower end cover and cylindrical roller unit bearing wherein the said bearing comprises of modified double row outer race assembly, lipped inner race, plain inner race and a loose lip. The said outer race assembly has outer race, at least a pair of cages, multiple rollers and a pair of metallic seals, arranged in such a manner that the said pair of cages having multiple rollers arranged therein, are encased by outer race to form double row outer race assembly

sealed at both ends by said pair of metallic seals, and thereafter greased using good quality grease. The lipped inner race along with said plain inner race on which the said loose lip is fitted is assembled into the said greased outer race assembly to form the said cylindrical roller unit bearing. The said cylindrical roller unit bearing is mounted on the axle journal after the mounting of the thrower on the axle followed by sliding of the thrower end cover on to the said thrower thereby facilitating the mounting of the cylindrical roller unit bearing as a single integrated unit with other required components to form said axle box assembly which is sealed against dust and grime and has at least one externally accessible grease hole for periodic maintenance and replenishment of grease.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figure la: depicts the axle box assembly of the existing prior art. The entire axle box housing (H) encompasses the end cover (EC) and a pair of bearings (Bl, B2) separated by a pair of distance pieces namely inner distance piece (ID) and outer distance piece (OD) with a thrower (T) at the end nearer to the wheel side. On the outer side that is away from the wheel also known as the road side, a thrust collar (TC) and loose lip (LL) are provided to facilitate axial float. The plain inner (PI1 and PI2) is used to mount the assembly on the axle.
Figure lb: depicts the front half sectional view of axle box housing of the existing prior art. There are twelve axle boxes with housing per locomotive.
Figures 2a to 6 illustrate the different aspects of the invention.
Figure 2a: shows the cross sectional view of the invention's axle box assembly with plain end cover depicting cartridge cylindrical roller double row bearing with seals at both ends with at least one grease hole,.
Figure 2b: shows the front half sections view of centre axle box with plain end cover.
Figure 2c: depicts the components of the CRU (5) of the invention in detail.
Figure 3: shows the end axle box with the hassler speedometer end cover. This is attached on side that is, the left as well as the right sides of the locomotive.
Figure 4: depicts the middle axle box with plain end cover. There are three such axle boxes per locomotive.

Figure 5a and 5b: depicts the position of the bogie on straight and curved track respectively.
Figure 6a: depicts general view of the loose lip arrangement.
Figure 6b: depicts the detailed view of the axial float in end axle box
Figure 6c: depicts the detailed view of the axial float in middle axle box
The legend for the diagrams of the invention: The axle box housing (1), grease hole (2), thrower (3), thrower end cover (4), cylindrical roller unit bearing (5), metallic seal (6), outer spacing piece (7), thrust collar assembly (8), end cover (9), grease hole (10), cage (11), roller (12), outer race (13), plain inner race (14), lipped inner race (15), loose lip (16), sealing ring (17).
DETAILED DESCRIPTION OF THE INVENTION WITH RESPECT TO DRAWINGS AND EXAMPLES:
The invention provides for a novel axle box assembly with single cartridge double row cylindrical roller bearing unit (5) with metallic seals (6) at both ends to seal against dust and grime. This cylindrical roller bearing unit (5) is novel in the absence of conventional distance pieces (ID, OD) between the two Single Row cylindrical roller Bearings (Bl & B2). Further the rollers (12), which are in the range of 15-20, preferably 17 in number, are longer in length and bigger in diameter than the conventional rollers. The length and diameter of the said rollers are in the range of 50 mm to 55 mm, preferably 53 mm and in the range of 30 mm to 36 mm respectively. The rollers are arranged in a pair of cages that are covered with an outer race and are covered in grease to form an outer race assembly, which is put together into the said cylindrical roller bearing unit (5) by fitting in the plain inner race (14) having width in the range of 80-85 mm, preferably 83 mm tipped with the loose lip (16) of diameter in the range of 190 mm to 200 mm on the one side and the lipped inner race (15), whose width is in the range of 95 mm to 110 mm, preferably 102 mm, on the other side to facilitate easy mounting on the axle journal.
The cylindrical roller unit bearing is mounted on the axle journal as a single integrated unit since it is effectively sealed on either end by a pair of metallic seals (6) to protect against dust and grime. In order to facilitate maintenance and replenishment of grease, there is at least one grease hole (10).

The mounting of the axle journal by the novel cylindrical roller unit bearing is preceded by first the thrower (3) followed by the newly introduced component the thrower end cover (4) which effectively seals the housing (1) from this end. At the far end outer spacing piece (7) and thrust collar assembly (8) are used and the entire axle box assembly is covered by the end cover (9) which is not an integrated part and is mounted separately to accommodate various attachments like alternator, hassler speedometer etc. As mentioned earlier an additional part called 'thrower end cover' (4) has been designed for sealing purpose from the rear side and also to reduce thrower biting problem. A sealing ring (17) ensures that dust does not filter into the rear of the assembly.
The arrangement of the novel parts and the removal of distance pieces provides inbuilt flexible adaptive float with fewer number of axle box components.
The axle box housing (1) bore is made through to facilitate mounting of cartridge bearing on axle journal of locomotive as a single sealed unit.
The conventional axle box housing (H) has a pair of single row cylindrical roller bearings (Bl and B2) separated by a pair of distance pieces referred to as the inner distance (ID) piece and the outer distance (OD). These occupy more space and were mounted both on the middle as well as the end axles to provide greater axial movement. The greater axial movement required in the middle axle due to the curvature of the track to balance the greater centrifugal force. The proposed invention reduces the number of bearings to a single cylindrical roller bearing but with double rows and also, as it is a sealed integral cartridge unit self-enabled which can be adapted to provide flexible axial float without having to tamper with the bogey design or the axle journal.
In the existing state-of- art the entire axle box assembly is only covered on the side which is farther from the wheel by the end cover (EC). This assembly does not have a sealing at the end of the cylindrical roller bearings. Instead the thrower is used at the wheel side and the in-built portion of the housing is used to prevent dust from the opposite side by using the labyrinth sealing principle. Therefore, the other end is exposed to dust and dirt which again leads to shorter life of the bearings as they are exposed to contamination. Further due to this contamination and drying due to exposure to the elements, the bearings require to be topped up with a lubricant more often approximately every 4 months. This exposure to dust and dirt also leads to an increase in the number of maintenance visits. Every 4 month or so, the grease in the

axle boxes must be replenished thereby increasing, the grease costs, manpower costs and locomotive down time.
Further the conventional axle box housing had a number of additional parts such as multiple units of single cylindrical roller bearings, inner distance piece, outer distance piece which resulted in more space and mass and hence thereby increasing the period of overhaul as there will be more number of parts to mount, dismount and attend to thereby increasing, the grease costs, manpower costs and locomotive down time. The novel axle box assembly has fewer components thereby decreasing locomotive downtime and providing axial float within the said bearing while complying with the existing bogie design.
The invention provides for a novel assembly with single cartridge double row cylindrical roller bearing unit (5) with seals (6) at both ends to be mounted on the axle journal as a single integrated unit, a grease hole with inbuilt flexible adaptive float with fewer number of axle box components without any modification in the existing bogie design to provide said axial float. The axle box housing (1) bore is made through to facilitate mounting of cartridge bearing on axle journal of locomotive as a single sealed unit. At the road side outer spacing piece (7) and thrust collar assembly (8) are used and the entire axle box assembly is covered by the end cover (9) and is mounted separately to accommodate various attachments like alternator, hassler speedometer etc.. An additional part called 'thrower end cover' (4) has been designed for sealing purpose and also to reduce thrower biting problem.
The invention has a double row of multiple bearings rather than a single row of bearings. Besides, there are lesser number of parts occupying lesser space and mass. The maintenance costs are also reduced because of fewer parts. Further, the axle has smoother movement towards the direction of the curvature facilitated by the double row cylindrical roller bearing which provides the desired axial float to enable the movement of the said axle in a smooth manner. The axial float is also provided in the bearing unit, which facilitates outer assembly to float in axial direction with rotation while the locomotive is running on a curved track as shown in Figure 5(a) and 5(b). Since the float is given in the bearing there is no change in the bogie design. Also, since these bearings are used as a complete assembled unit in an axle box mounted on axle journal of locomotive, hence these bearings can be customized according to the axial float required on axle journal while running on curved track.

These bearings are sealed and filled with a good quality grease to run for longer time, thereby increasing the periodic overhauling time. This enhances tremendous direct savings in grease cost, manpower cost and locomotive downtime at the customer end. It also provides for a better service life and easy maintenance in the workshop. There is no need to change bogie design as float is given in the bearing. Further, mounting of bearing on axle is also less time consuming.
These bearings have higher load carrying capacity as compared to conventional bearings and can also run at higher speeds.
With reference to figure-6 thrower (3) is mounted on shaft by induction heating (By induction heating thermal expansion occurs in thrower bore). Then thrower end cover (4) is placed over thrower (3). Now cartridge cylindrical roller unit (5) is pressed on shaft by a hydraulic press. After this axle box housing 1 is mounted over bearing unit (5) and bolted with thrower end cover (4). Now bearing unit is clamped axially by thrust collar assembly (8). After this outer assembly and axle box housing is clamped with end cover (9).
The above invention is explained here by way of an example.
The embodiment described herein is exemplary only, and is by no means limiting.
The cylindrical roller unit bearing (5) is assembled in a step by step manner. The core of the bearing is the double row outer race assembly, which has one outer race (13), a pair of cages (11) and seventeen rollers (12) in each cage. This double row outer race assembly is sealed on both sides with a pair of metallic seals (6). Once the outer race assembly is sealed with metallic seals the grease is applied all over whereupon the said assembly is ready for the next stage in the assembly.
Thereafter the lipped inner race (15) and the plain inner race (14) are then inserted inside the greased outer assembly. The loose lip (16) is then fitted on the plain inner. This entire assembly is known as the Cylindrical Roller Unit bearing. The width of the Upped inner race has been increased to optimize the load carrying capacity.
Thereafter, the thrower is mounted on the axle with the help of pusher jig. Then the thrower end cover is slid and pushed onto the thrower to facilitate the mounting of the CRU as a single integrated unit. Thereafter the CRU Bearing is mounted on the

axle using hydraulic press. One sealing ring is placed in the groove of thrower end cover to provide the sealing against moisture and dust particles from the rear.
The axle box housing is pushed until it abuts against the thrower end cover flange. The screws with locking plate are tightened to clamp thrower end cover with the axle box housing.
Finally the front component is mounted with the end cover to complete the mounting of axle box housing in such a manner that the plain inner is facing wheel side and the loose lip is facing the road side.

We claim:
1. A novel axle box assembly comprising of axle box housing (1), thrower (3),
thrower end cover (4) and cylindrical roller unit bearing (5)
wherein the said bearing comprises of modified double row outer race assembly, lipped inner race (14), plain inner race (15) and a loose lip (16)
said outer race assembly having outer race (13), at least a pair of cages (11), multiple rollers (12) and a pair of metallic seals (6), arranged in a manner that the said pair of cages having multiple rollers arranged therein, are encased by outer race to form double row outer race assembly sealed at both ends by said pair of metallic seals, and thereafter greased using good quality grease;
said lipped inner race (14) along with said plain inner race (15) on which the said loose lip is fitted is assembled together into the said greased outer race assembly to form the said cylindrical roller unit bearing (5);
said cylindrical roller unit bearing being mounted on the axle journal after the mounting of the thrower (3) on the axle followed by sliding of the thrower end cover (4) on to the said thrower thereby facilitating the mounting of the cylindrical roller unit bearing as a single integrated unit with other required components to form said axle box assembly which is sealed against dust and grime and has at least one externally accessible grease hole for periodic maintenance and replenishment of grease;
such that the said novel axle box assembly has fewer components thereby decreasing locomotive downtime and providing axial float within the said bearing while complying with the existing bogie design.
2. A novel axle box assembly as claimed in claim 1 wherein the number of said rollers in the said bearing is in the range of 15 to 20.
3. A novel axle box assembly as claimed in claim 1 wherein the width of the plain inner race is in the range of 80 mm to 85 mm.
4. A novel axle box assembly as claimed in claim 1 wherein the width of the lipped inner race is in the range of 95 mm to 110 mm.

5. A novel axle box assembly as claimed in claim 1 wherein the length of the said roller is in the range of 50 mm to 55 mm
6. A novel axle box assembly as claimed in claim 1 wherein the diameter of the said roller is in the range of 30 mm to 36 mm
7. A novel axle box assembly as claimed in claim 1 wherein the diameter of the said loose Up is in the range of 190 mm to 200 mm.
8. A novel axle box assembly as claimed in claim 1 wherein the said CRU bearing is mounted on the axle journal such that loose lip faces the road side.