Method and apparatus for dismounting trunnion bearings

A method and apparatus for dismounting a trunnion bearing from a universal joint utilizes a plate that is secured to the proximal arm of one yoke of the joint through which dismounting bolts are threaded into contact with the other joint yoke. Further threading of the dismounting bolts into the plate causes the one yoke secured to the plate to move along a pin of a crossed-pin member of the universal joint, bringing a pin end into contact with the trunnion bearing in the distal arm of the one yoke, thereby urging it out from its press-fitted position in that arm.

TECHNICAL FIELD 
This invention relates to methods and apparatuses for dismounting trunnion 
bearings from univeral joints. 
BACKGROUND OF THE INVENTION 
Universal joints, such as the yoke and spider type, typically have two 
forked coupling halves or yokes which are pivotably mounted to a 
crossed-pin member or spider for rotation about two axes oriented at right 
angles to each other. Each arm of each yoke is pivotably mounted to an end 
of the crossed-pin member by trunnion bearings that have a generally 
cup-shaped outer race press-fitted within a recess of the yoke arm about 
the pin end, with a set of needle or roller bearings arranged annularly 
about the pin end within the race. In order to service the joint, or 
replace or repair a bearing, it is necessary to remove it from its 
press-fitted placement within the yoke arms. Heretofore, this has 
typically been done by unthreading the bolts from both trunnion bearings 
mounted to the arms of one yoke and then striking that yoke as with a 
sledgehammer to move it axially along one pin of the crossed-pin member. 
As this is done the cup-shaped outer race of the bearing is brought into 
engagement with an end of the pin whereby further movement of the yoke 
causes that pin end to push the bearing outer race out of its press-fitted 
location within the yoke arm. 
The just-described procedure has had pronounced disadvantages and 
limitations. For example, the use of a sledgehammer is often limited by 
spacial restrictions about the universal joint. For instance, with 
automobiles and trucks its location is often difficult to access and 
spacially restricted which limits hammer travel distance and direction. 
The striking of a joint yoke also tends to place a torque upon the 
crossed-pin member or spider which can itself damage one or both of the 
trunnion bearings or a bearing seal. 
Heretofore, apparatuses or tools have been devised to aid in the removal of 
trunnion bearings from universal joints. These devices, however, often 
have been designed merely to insure that the force of a sledgehammer is 
imparted substantially coaxially with respect to one of the pins of the 
universal joint's crossed-pin member. Furthermore, the devices have 
typically been of a configuration such as to require their being mounted 
completely about a universal joint. For example, U.S. Pat. No. 4,120,082 
disclosed a universal drive shaft service kit of such a type which is 
mounted about opposite sides of a joint and which has an impact knob for 
communicating a shock force resulting from the impact of a hammer onto a 
trunnion bearing. Again, spacial restrictions often found to be present 
within the environs of a universal joint render the use of such devices 
impractical and cumbersome. 
It therefore would be advantageous to devise an apparatus and method for 
removing trunnion bearings from universal joints in a manner that would 
overcome these disadvantages and limitations of the prior art. It is this 
task to which the present invention is primarily directed. 
SUMMARY OF THE INVENTION 
In one preferred form of the invention a method is provided for dismounting 
a trunnion bearing from a universal joint of the type having a crossed-pin 
member or spider to each pin of which a yoke is mounted for pivotal 
movement by means of trunnion bearings having outer races press-fitted and 
bolted to the arms of each yoke overlaying the pin ends. The method 
comprises the steps of unbolting the trunnion bearing races from the arms 
of one yoke, bolting to a proximal arm of the one yoke a plate so as to 
position threaded holes in the plate in alignment with the arms of the 
other yoke, threading dismounting bolts into the plate threaded holes and 
into contact with the other yoke arms, and continuing to thread the 
dismounting bolts into the plate threaded holes thereby forcing the plate 
and the one yoke secured thereto to slide upon a pin until an end of that 
pin has engaged and urged the trunnion bearing race in the one yoke arm 
distal the plate at least partially therefrom. 
In another preferred form of the invention, apparatus is provided for 
dismounting a trunnion bearing from a universal joint of the type having a 
crossed-pin member or spider, to each pin of which member a yoke is 
mounted for pivotal movement by means of trunnion bearings having outer 
races secured to the arms of each yoke overlaying the ends of the pins, 
and with each yoke arm having a pair of threaded holes straddling a pin of 
the crossed-pin member in which bolts may be threaded in securing the 
trunnion bearing race thereto. The apparatus comprises a plate adapted to 
be placed against a proximal trunnion bearing of one yoke with an inner 
pair of plate holes sized and located for bolts to be passed therethrough 
and threaded into the pair of threaded holes of the proximal arm of the 
one yoke and with a pair of outer threaded plate holes located so as to be 
aligned with the arms of the other yoke. The apparatus further comprises a 
pair of threaded dismounting bolts of a length more than sufficient to be 
threaded into the plate outer threaded holes, with the plate placed 
against the proximal trunnion bearing, and into engagement with the other 
yoke arms. So constructed, the apparatus need only be mounted to one side 
of a universal joint in dismounting a trunnion bearing from the other 
joint side by threading the dismounting bolts into the plate against the 
other yoke arms until the trunnion bearing on the one yoke arm distal the 
plate has been urged at least partially therefrom.

DETAILED DESCRIPTION 
With reference next to the drawing, there is shown a universal joint of the 
type having a crossed-pin member or spider 15 from which pins 16 and 17 
coaxially extend and from which pins 18 and 19 coaxially extend at right 
angles to the pins 16 and 17. For clarity, coaxial pins 16 and 17 are 
considered as separate pins, as are coaxial pins 18 and 19. However, 
elsewhere in this specification and in the claims pins 16/17 and 18/19 are 
considered as single pins of the crossed-pin member. 
A generally U-shaped yoke 20 is pivotably mounted to the pins 18 and 19 
while another U-shaped yoke 22 is pivotably mounted to the pins 16 and 17. 
The yoke 20 has an opening 21 to which a shaft may be connected while the 
yoke 22 has an opening 23 to which another shaft may be connected, as by a 
weld formed between the shafts and the openings 21 and 23. As is well 
known, once shafts have been so mounted to the two yokes, the universal 
joint serves as a coupling for transmitting force between the two shafts 
even though they may be rotatably driven about axes that are offset from 
each other. It thus should be understood that while the universal joint, 
as illustrated in FIGS. 2 and 3 has been described as being shown in a 
side-elevational view, these views could just as easily be considered plan 
or bottom views since the yokes may be mounted at many different 
orientations both relative to each other and with respect to the joint 
environment. 
Each of the U-shaped yokes 20 and 22 has a pair of yoke arms, with those of 
yokes 22 being shown at 25. Each yoke arm is pivotably mounted to one of 
the pins of the crossed-pin member 15 by a trunnion bearing 30 that has a 
hollow cylindrical outer race 32 closed at one end by an end plate 33 
having flanges 34 which are provided with holes through which bearing 
mounting screws 35 may be passed in mounting the trunnion bearing to a 
yoke arm. A set of roller or needle bearings 37 is located in annular 
arrangement within the trunnion bearing race about one of the pins of the 
cross-pin member. Each trunnion bearing may also have an annular seal to 
inhibit lubricant in the bearing from escaping inwardly into the yoke. 
Thus described, the universal joint is of conventional construction such 
as those joints found today in large trucks. 
To dismount a trunnion bearing from an arm 25 of the yoke 22, the four 
bolts 35 which secure the bearing to the two arms of that yoke are first 
removed. As shown in FIG. 2., the plate 9 is then placed against the 
trunnion bearing located on the opposite arm of yoke 22 to that arm from 
which a bearing is to be dismounted. In this position a pair of plate 
inner holes 10, 10', 10" or 10'" are located in register with the holes in 
the trunnion bearing race flanges 34. Which particular pair of plate inner 
holes will be placed in register will, of course, depend on the size of 
the particular universal joint being serviced. Bolts 35 are then threaded 
into the plate inner holes and back into one of the yoke arms. 
Next, two dismounting bolts 40 are threaded into a pair of the plate outer 
threaded holes 12, 12' 12" or 12'" and into contact with yoke 20, still as 
shown in FIG. 2. It should be noted at this point that the apparatus has 
been mounted to but one side of the universal joint, namely that side 
opposite from the trunnion bearing to be dismounted, with no part of the 
apparatus located about the other yoke 20. 
Next, the screws 40 are together threaded further into the plate 9 causing 
the plate to pull yoke 22 to the left as shown in FIG. 3 upon the coaxial 
pins 16 and 17 of the crossed-pin member 15. This occurs since the other 
yoke 20, that is in contact with the ends of the screws 40, cannot move on 
coaxial pins 18 and 19 since the force being applied to that yoke is at 
right angles to the pins upon which it pivots. As screws 40 are continued 
to be threaded into the plate end 17' of pin 17 contacts the plate element 
33 of the trunnion bearing 30 mounted to pin 17 causing it to urge the 
trunnion bearing out from its press-fitted location or seat within yoke 
22. At this point the flanges 34 of the trunnion bearing may be gripped as 
with a wrench and pulled out. Alternatively, the dismounting bolts 40 may 
be further threaded into the plate until the bearing 30 has been freed 
completely from the yoke. At this point the needle or roller bearings 37 
will also come free. 
If it is desired to dismount the other trunnion bearing on pin 16 the plate 
9 and dismounting bolts 40 may be removed from the position illustrated in 
the drawing and remounted flush against the pin end 17 as with bolts 
somewhat longer than bolts 35 threaded to the other arm of yoke 22. The 
dismounting bolts 40 are threaded into the plate 9 up against the yoke 20 
until the trunnion bearing about pin 16 has been dismounted from the other 
yoke arm 25. Following this, the bearings mounted within the other yoke 20 
may also be dismounted in a similar manner. 
It thus is seen that a method and apparatus is provided for dismounting 
trunnion bearings from a universal joint with relative ease in restricted 
space and without the use of a sledgehammer or the like. The provision of 
several sets of plate hole pairs enables the same plate member to be used 
in dismounting trunnion bearings from universal joints of several 
different sizes. One particularly advantageous use is in dismounting 
bearings from universal joints from under the fifth wheel of large trucks 
where there is very little room in which to maneuver and to swing a 
sledgehammer. 
Finally, it should be understood that the just-described embodiment merely 
illustrates principles of the invention in a preferred form. Many 
modifications, additions and deletions may, of course, be made thereto 
without departure from the spirit and scope of the invention as set forth 
in the following claims.