Orientation ring with bearings

An orientation bearing ring for resisting radial loads, axial loads, and inclined moments. The ring includes first and second races each of unitary construction, opposed thrust faces of the races have roller thrust bearings between them with the axes of the bearings perpendicular to the axis of the ring. An additional row of bearings is disposed in opposed bearing tracks in the respective races, these bearings engaging their tracks at an oblique angle to the axis of the ring.

The present invention pertains to a turning or orientation ring with 
bearings supporting axial and radial forces as well as inclination 
moments. 
Such orientation rings are used, for example, on cranes, public works 
machines and generally whenever a member of great diameter is rotatably 
mounted on another member. In the case for example of a crane, it is not 
possible to balance the weight of the load and of the boom completely at 
every instant by a counterweight. The crane is thus submitted to a rocking 
motion which manifests itself on the orientation ring by a moment of 
"inclination" trying to make one of the rings or races of the orientation 
ring rock or tilt in relation to the other. It is necessary then that the 
orientation rings be able to support such moments in addition to axial and 
radial forces. 
At the present time different types of orientation rings with bearings are 
known. The oldest rings have two rows of ball bearings making oblique 
contact. But, it is well known that ball bearings have a limited ability 
to handle dynamic loads. In order to increase this load capacity 
orientation rings with rollers have been proposed. The most well-known 
types are the orientation rings with crossed rollers with two one-piece 
races, the orientation rings with two rows of rollers in oblique contact 
at 45.degree. with two one-piece races, as well as the orientation rings 
with three rows of rollers of which two support solely axial loads, and 
the third supports the radial loads, but for this third type, at least one 
of the races must be made in several parts. 
It is understood that the two first types are technically more 
satisfactory, both from the point of view of manufacturing and use. They 
require however, for the same axial load capacity, rollers of much greater 
diameter than the rings with three rows of rollers. However, the latter in 
which at least one of the races must be in several parts are obviously 
more complex to make and particular precautions are necessary to mitigate 
the disadvantages of the presence of the joint plane in the multi-piece 
races; moreover, the rigidity of a multipiece race is not satisfactory. 
The present invention has as an object an orientation ring with bearings 
combining the advantages of the different types of rings enumerated above 
without having the disadvantages. In other words, the orientation ring 
conforming to the invention can be manufactured with two one-piece races 
and has a good load capacity. 
The orientation ring with bearings conforming to the invention comprises in 
combination at least one row of rollers forming a thrust bearing and one 
row of rolling elements forming a bearing with oblique contact. The 
rollers of the row forming the thrust bearing, which are preferably 
cylindrical rollers, have their axes essentially perpendicular to the axis 
of the orienting ring. Thus, these rollers support axial forces, while the 
rolling elements forming the bearing with oblique contact support the 
radial forces as well as certain axial forces due to the inclination 
moments. The mutual arrangement of the rollers constituting the thrust 
bearing, and of the rolling elements constituting the bearings with 
oblique contact, is such that the circle passing through the centers of 
the lines of contact of the rollers of the thrust bearing with the track 
for these rollers on one of the rings, and the circle passing through the 
centers of the areas or lines of contact of the rolling elements making 
oblique contact with the track for these elements on the same ring, are 
situated with respect to the axis of the orientation ring, on opposite 
sides of the corresponding circles on the other ring.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
One can see in the drawing that the orientation ring, intended for example 
to be mounted between a fixed chassis and a turret or rotatable chassis of 
a machine, comprises a single exterior race 1 and a single interior race 2 
each of which is made in a single piece. The two races 1 and 2 have axial 
holes 3, 4 for fastening the races 1 and 2 onto the corresponding chassis 
of the machine, for example by using bolts. The outer race 1 has an 
exterior set of gear teeth 5. 
The two races 1 and 2 are concentric rings and have between them a row of 
cylindrical rollers 6 and a row of ball bearings 7. The profiles of the 
two races 1 and 2 are such that the two races can be fit one into the 
other axially, which enables them each to be manufactured in a single 
piece, with great rigidity. 
Rollers 6 are positioned so that their axes are perpendicular to the axis 
of rotation of the orientation ring. These rollers 6, in the form of 
cylindrical rollers, thus form an axial thrust bearing resistant to axial 
forces applied to the orienting ring. Rollers 6 move on a circular ring 
roller track 8, constituting in the present case one of the flanks of a 
recess 9 made in the inner upper corner of the outer race 1. The other 
flank 10 of this recess is at a right angle in relation to flank 8 and 
thus constitutes a cylindrical surface. 
The second roller track of rollers 6 is constituted by a circular ring 
surface 11 constituting the lower flank of an annular portion 12 of race 2 
which projects radially outwardly above recess 9 of outer race 1. Opposite 
flank 10 of race 1, the race 2 comprises a flank 13 in the form of a 
cylindrical surface, the four flanks 8, 10, 11 and 13 together defining in 
this example an annular space with essentially rectangular profile for 
circulation of the rollers 6 and possibly for a cage 6a or spacers to 
maintain the rollers spaced apart. The cylindrical surface 13 of inner 
race 2 extends downwardly to form a cylindrical surface 15 which is 
surrounded at a slight distance by an inner cylindrical surface 14 of the 
outer race 1. On a level with a row of ball bearings 7, outer race 1 has a 
recess 16 of preferably semicircular profile made in the cylindrical 
surface 14, preferably with a radius slightly greater than the radius of 
ball bearings 7. Likewise, inner race 2 comprises, on a level with ball 
bearings 7, a recess 17, preferably with semi-circular profile made in its 
cylindrical surface 15 and likewise with a radius slightly greater than 
the radius of ball bearings 7. As seen in the drawing, the center of the 
balls 7 is axially offset in the direction of the thrust rollers 6 with 
respect to the center of curvature of the profile of the first groove 16 
of said outer race and in the opposite direction with respect to the 
center of curvature of the profile of the second groove 17 of said inner 
race. The two recesses 16, 17 form, with the ball bearing 7, a bearing 
with oblique contact. In the drawing and in order to better clarify, the 
clearance has been exaggerated on both sides of the two contact points 18, 
19 of ball bearings 7 with tracks 16 and 17, between the surface of the 
ball bearings and the said roller tracks. In reality, the difference 
between the radius of the ball bearings 7 and the radius of recesses 16, 
17 corresponds to that which is customary for bearings with oblique 
contact. 
Below the row of ball bearings 7, the two races 1 and 2 continue as 
cylindrical surfaces 20, 21 which have, in this example, diameters 
preferably slightly greater than the diameters of surfaces 14, 15 
respectively. 
One can see that rollers 6 support the axial forces while radial forces as 
well as certain axial forces due to inclination moments are supported by 
ball bearings 7. When these ball bearings are acted upon by inclination 
couples tending to make the two races 1 and 2 separate from each other so 
that the part of race 1 visible in the drawing moves downwardly and the 
part of race 2 visible in the drawing moves upwardly, the angle of contact 
of ball bearings 7 with tracks 16, 17 tends of increase, which allows the 
ball bearings to better support the inclination moment. In this case a 
sufficient area of contact between the ball bearings 7 and tracks 16, 17, 
is maintained since the cylindrical surfaces 21 and 14 have similar 
diameters. The diameter of surface 14 must however be slightly greater 
than the diameter of surface 21 in order that the two races 1 and 2 can be 
assembled. 
The assembling of the orienting ring is preferably carried out in the 
following manner: first of all one places the row of rollers 6, with the 
cage 6a, on the roller track 8 of ring 1. One then fits the inner race 2 
into the outer race 1. Finally, one inserts ball bearings 7 and possibly, 
spacers for them through at least one filling opening provided in one or 
the of the two races, e.g. a radial fill hole 22 provided in the inner 
ring 2 and obtured by a plug secured by means of a check pin or the like. 
It can be seen that it is completely possible to assemble a prestressed 
assembly since it requires only choosing the diameter of the rolling 
elements accordingly. 
In addition, other assembly methods than that already described can be 
used: mounting of the rolling elements constituting the bearing with 
oblique contact can be by decentering or by a fill slot, mounting of the 
rollers of the thrust bearing can be by a fill slot, etc... 
In addition it is appropriate to observe that it is possible to make 
numerous modifications and variations of the orienting ring shown and 
described above. Thus, the toothed periphery which is not obligatory, can 
likewise be provided on the inner race. Fastening holes 3 and 4 can 
likewise be blind tapped holes. Watertight seals can be provided both for 
the row of rollers 6 and for the row of ball bearings 7 between the two 
races 1 and 2. 
Moreover the annular recess 9 can be made radially longer so as to be able 
to introduce two concentric rows of thrust rollers when axial forces will 
be very large. 
Finally, the cylindrical rollers of the thrust bearing can be replaced by 
conical rollers and the ball bearings constituting the bearing making 
oblique contact can be replaced by cylindrical rollers. The nominal angle 
of contact .alpha., that is to say, under load, of the roller elements of 
the bearing making oblique contact, in relation to the axis of the 
alignment ring, is advantageously between 30.degree. and 60.degree. for 
ball bearings, while it is 45.degree. for roller bearings.