Rolling bearing cage

A rolling bearing cage having a through slit at one point of its periphery, characterized in that at least one projection extends from one of the cage ends defining the slit and engages in recesses at the other cage end so that the two cage ends are fixed relative to each other in both radial directions as well as in both axial directions but are able to move relative to each other in the peripheral direction.

STATE OF THE ART 
Rolling bearing cages, particularly made of polymeric material, having a 
through slit at one point of its periphery are known and are frequently 
used for the mounting of gearwheels on shafts in gear boxes of automative 
vehicles. When not under load, these gearwheels rotate relative to the 
shafts, whereas in another operational state, in which they transmit a 
torque, they are rigidly coupled with the shaft. In this latter 
operational state, in which the rolling elements lodged in the cage do not 
execute a rolling movement, there exists the danger that the rolling 
elements get pressed into their raceways, thus damaging them and leading 
to premature failure of the bearing. This danger can be eliminated by 
rolling bearing cages provided with a slit because they can expand 
slightly under the action of centrifugal force and bear without play 
against the rolling elements. This achieves, that even in this operational 
state, the rolling elements can execute a, even though slight, rolling 
movement. 
In recent times, problems have been occurring now and then with such cages 
due to the fact that these cages are assembled by means of robots. If 
these cages have been somewhat deformed during transport or storage which 
happens occasionally, particularly with cages made of polymeric material, 
so that the cage ends defining the slit are not positioned directly 
opposite each other, it is possible that the robot is not able to grip the 
cage properly and this leads to disturbances in the assembly process. In 
known cage described in DE-GM 8,715,732, an attempt was made to eliminate 
this problem by providing connecting elements in the form of elastic bars 
in the region of the slit to prevent a mutual offset of the cage ends. 
Since these elastic bars have to have extremely small wall thicknesses in 
order not to have a detrimental effect on the cage, there exists the 
danger that they break off and can, if they remain in the bearing, lead to 
its destruction. 
OBJECTS OF THE INVENTION 
It is an object of the invention to design a cage of this type with simple 
means, and particularly without additional manufacture steps, so that on 
the one hand the cage ends defining the slit are positioned exactly 
opposite each other and on the other, are able to move freely relative to 
each other in the peripheral direction, that is to say, that the diameter 
of the cage can be enlarged. 
This and other objects and advantages of the invention will become obvious 
from the following detailed description. 
THE INVENTION 
The rolling bearing cage of the invention having a through slit at one 
point of its periphery, is characterized in that at least one projection 
extends from one of the cage ends defining the slit and engages in 
recesses at the other cage end so that the two cage ends are fixed 
relative to each other in both radial directions as well as in both axial 
directions but are able to move relative to each other in the peripheral 
direction. 
In a preferred embodiment of the invention, ledges projecting in the 
peripheral direction are integrally formed adjacent to the end faces at 
one cage end, opposite which ledges corresponding sparings are situated at 
the other cage end, and on the end faces of the ledges and sparings facing 
each other are provided on the one hand, projections and on the other, 
recesses in the form of grooves extending in the peripheral direction 
which interlock with each other, the grooves being longer in the 
peripheral direction than the projections. 
In certain cases, it is required that when the cage is gripped by the 
gripper of the robot, it be at first in an expanded position from which it 
is later brought by pressing together by the grippers of the robot, into a 
second position in which it has a smaller but variable diameter. This 
porblem is solved by the invention because the grooves are divided into 
two sections of different length by transverse bars of smaller height than 
the groove depth.

FIG. 1 shows the shaft 1 on which the gearwheel 2 is mounted by the 
intermediary of cylindrical rolling elements 3 which are lodged in the 
cage 4 provided with the through slit 5 at one point of its periphery. 
FIG. 2 shows that at one cage end 6, adjacent to the end faces 7, ledges 8 
projecting in the peripheral direction are integrally formed opposite 
which corresponding sparings 9 are situated at the other cage end 10. At 
the end faces of the ledges 8 and the sparings 9, there are provided on 
the one hand, projections 11 at the ledges 8 and on the other, recesses in 
the form of grooves 12 extending in the peripheral direction at the 
sparings 9, the projections 11 interlocking with the grooves 12 in the 
assembled condition. Since the grooves 12 are longer in the peripheral 
direction than the projections 11, the two cage ends 6 and 10 can move 
freely relative to each other in the peripheral direction. 
Furthermore, transverse bars 13 are provided in the grooves 12 which have a 
smaller height than the depth of the groove 12 and which divide the groove 
12 into two sections of different length. The projections 11 can at first, 
in the delivery condition, engage into the shorter region of the groove 12 
and later be snapped into the longer region of the groove 12 over the 
transverse bars 13 by a pressure exerted by the gripper of the robot. 
Further, the cage pockets 14 in FIG. 2 can be seen which serve for lodging 
cylindrical rolling elements, particularly bearing needles, and in which 
the rolling elements are prevented from falling out radially inwards and 
outwards by retaining projections 15. 
Various modifications of the cage of the invention may be made without 
departing from spirit or scope thereof and it is to be understood that the 
invention is intended to be limited only as defined in the appended claims 
.