GB2033789A - Assembling Hooke's type universal joint - Google Patents

Abstract

A kit of tools for removing and replacing the cross (10) and bearing units (13) (14) of a Hooke's type universal joint comprises two gauge devices each comprising an internally screw-threaded ring (30) containing a screw (31), a gauge block, two drifts of different diameters, a broaching tool and a staking tool of the same length as the gauge block. The screws of the gauge devices are set to reference positions according to the axial positions of the respective trunnions (11), (12) of a pair relative to the associated yoke arms (17), (18), the ring of each device being placed against the corresponding arm with the gauge block between the screw and the associated bearing unit. The trunnions and bearing units are removed using the two drifts. The stakes are removed from the bore in each yoke arm by drawing the broaching tool through the bore. New trunnions and bearing units are fitted and secured by stakes formed in the bores of the yoke arms at positions determined by the gauge devices using the staking tool which is driven into each bore by the corresponding gauge device with the tool positioned between the screw and the bearing unit. <IMAGE>

Description

SPECIFICATION Improvements relating to Hooke's type Universal Joints This invention relates to Hooke's type universal joints which comprise a cross having two pairs of axially aligned trunnions arranged with the axis of one pair at right angles to the axis of the other pair and the two axes disposed in a common plane and intersecting the central axis of the cross, the cross drivingly connecting together two yokes the two arms of each of which are formed with axially aligned bores accommodating bearing units which receive a respective pair of trunnions.

Hooke's type joints are commonly used to transmit drive from a propellor shaft to a rear wheel differential gearing of a road vehicle, and it is common practice with such a joint permanently to secure one of the yokes to the propellor shaft with the result that when the joint becomes worn and requires replacement, the whole assembly of shaft and joint has to be replaced, which is expensive. The other yoke is usually provided with a flange which is bolted to a flange on the input shaft of the gearing.

It is also common practice to secure the bearing units in the bores in the yoke arms and thereby locate the trunnions axially in relation to the yokes, by deforming or staking the bores to provide a series of small inwardly extending projections or stakes which engage the outer end faces of the bearing units. As a result, to replace merely the cross and the bearing units, it would be necessary to use special machinery which is expensive, and it is for this reason that it is the practice to replace the whole assembly of the shaft and joint.

A further problem which would be encountered in replacing the cross and bearing units only is that of ensuring that each pair of trunnions of the replacement cross is in precisely the same axial position in relation to the yoke in which they are located, as the pair of trunnions of the old cross which were located in said yoke, otherwise the propeller shaft assembly might be out of balance.

The object of the present invention is to provide simple and comparatively inexpensive means to facilitate the removal and replacement of the cross and bearing units of a staked Hooke's type joint, without the aforementioned problem.

According to a first aspect of the invention, there is provided a kit of tools to facilitate the removal and replacement of the cross and the bearing units of a Hooke's type universal joint, the kit comprising (a) two adjustable gauge devices settable to reference positions according to the axial positions of the respective trunnions of a pair relative to the associated yoke, (b) means to facilitate the removal of the said pair of trunnions and the associated bearing units from the said yoke, (c) a cutting tool for removing the projections or stakes from the bores in the arms of said yoke after removal of the trunnions and bearing units, and (d) a staking tool for forming in said bores, after insertion of a pair of trunnions of a replacement cross and replacement bearing units into said bores, projections or stakes which engage the outer end faces of the bearing units thereby to secure the units in said bores and axially locate the trunnions, the disposition of the projections or stakes in each bore and hence the axial location of the associated trunnion being determined by cooperation of the staking tool with the corresponding gauge device according to the reference position of the latter.

This kit is relatively inexpensive and simple so that it can be bought and used by a motorist without incurring high garage repair costs.

According to a second aspect of the invention, there is provided a staking tool for forming in a bore of a yoke of a Hooke's type universal joint projections or stakes which engage the outer end face of a bearing unit in said bore, the staking tool comprising a body having a longitudinal axis and formed around its periphery with a number of corners which constitute the radially outermost portions of the tool and extend parallel to said axis to an end face of the body, the body being cut away at the junctions of the corners and said end face to provide formations which are shaped so that on advancement of the tool along a bore in the direction of said axis with the corners in contact with the surface of the bore, the formations move material of said surface forwards in said direction and thereby form inwardly extending projections or stakes in the bore.

According to a third aspect of the invention, there is provided a method of removing and replacing the cross and the bearing units of Hooke's type universal joint, said method comprising the steps of (a) setting two adjustable gauge devices to reference positions according to the axial positions of the respective trunnions of a pair relative to the associated yoke, (b) removing the said pair of trunnions and the associated bearing units from said yoke, (c) removing the projections or stakes from the bores in the arms of said yoke, (d) inserting a pair of trunnions of a replacement cross and replacement bearing units into said bores and (e) forming in said bores projections or stakes which engage the outer end faces of the bearing units thereby to secure the units in said bores and axially locate the trunnions, the disposition of the projections or stakes in each bore and hence the axially locate the trunnions, the disposition of the projections or stakes in each bore and hence the axial location of the associated trunnion being determined by co-operation of the staking tool with the corresponding gauge device according to the reference position of the latter.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 to 7show successive stages in one method of removing and replacing the cross and bearing units of a Hooke's type universal joint using one form of kit of tools embodying the invention, Figures 8 and 9 show the staking tool of the kit in detail, and Figure 10 shows one of the stages of another method according to the invention.

Referring particularly to Fig. 10, a typical Hooke's type universal joint comprises a cross 10 having two pairs of diametrically opposed trunnions, the trunnions of one pair designated 11, 1 2 being received in bearing units 13, 14 which are fitted in bores 15, 16 in the respective arms 17, 1 8 of a yoke 19, and the trunnions of the other pair, one of which is seen at 20 being similarly received in bearing units in bores in the arms of the other yoke (not shown).

Each bearing unit comprises a cap 21 having a cylindrical side wall with an inner inwardly extending end flange and an outer end wall formed with a central projection and a peripheral annular projection. The cap houses an annular series of needle bearings 22 which are in contact with the associated trunnion.

Each bore is formed with eight inwardly extending projections or stakes engaged with the peripheral annular projection of the outer end of the cap of the associated bearing unit.

The cross 10 has an annular shoulder 23 between each trunnion and the centre part of the cross, and a rubber seal 24 surrounding the trunnion is interposed between this shoulder and the inner end flange of the associated cap.

The yoke 1 9 has a flange 25 formed with bolt holes enabling it to be secured to a flange on an input shaft of a rear wheel gearing of a vehicle, and the other yoke is secured to a propeller shaft (not shown).

The kit of tools for use in removing and replacing the cross and bearing units of a Hooke's type universal joint comprises: 1. Two adjustable gauge devices (see particularly Fig. 10) each comprising a metal ring 30, the ring having a bore of which a part is screw threaded and a part is plain and of an enlarged diameter, and a metal screw 31 which is received in the screw-threaded part of the bore in the ring. One of the rings has two circumferential grooves 30a and the other ring has only one such groove 30b.

2. A metal block 32 (Fig. 1), this block having a recessed end to accommodate the central projection of the outer end wall of a bearing unit. The bock is formed so as to be a loose fit in the plain part of the bore in the ring 30 of each gauge device.

3. A support 33 (Figs. 2 and 6), this support comprising a hollow cylindrical metal component having an inwardly directed annular flange at one end.

4. Two metal drifts 34 and 35 of different diameters (Figs. 2 and 3).

5. Four metal collet segments 36 (Fig. 4), these being parts of the aforementioned means to facilitate removal of the trunnions and the associated bearing units. The segments are curved so that when fitted end-toend around a trunnion they together form a sleeve embracing the trunnion.

6. A broaching tool 37 (Fig. 6). This tool comprises a generally cylindrical metal body having an axial bore with a screw-threaded part and an enlarged diameter plain part. In use, the screw-threaded part receives a bolt 38 which passes through the support 33 disposed between the head of the bolt and the leading end of the tool. The tool has a circumferential groove 39 and tapers slightly from this groove towards the leading end to provide a "lead" on insertion of the tool into a bore. The broaching action is effected, on advancement of the tool axially along a bore, by the sharp corner 39a at the trailing side of the groove 39. Swarf produced in the broaching operation passes into the groove. The part of the tool from the groove to the trailing end is truly cylindrical. If desired, the tool may have more than one groove with a broaching corner.

7. A metal staking tool 40 seen in Figs. 7 and 10 and shown in detail in Figs. 8 and 9.

This tool may be of any suitable polygonal shape but in the embodiment shown is formed from a length of drawn hexagon bar, of YEN 1 A mild steel case hardened to a depth of .003 to .005 inches, which is turned to the shape illustrated. The tool has six longitudinally extending corners 41 parallel to its longitudinal axis A and each slightly flattened.

These corners extend to an end face 42 and the tool is cut away on a radius at the junction of each corner and this end face to provide a sharp corner 43. The end face has a central recess 44 to accommodate the central projection of the outer end wall of a bearing unit.

The tool has a circumferential groove and is of exactly the same length as the gauge block 32.

Figs. 1 to 7 show the method of removing and replacing the cross and the bearing units of a joint utilising the kit described above. In these Figs. the joint is shown in the same position throughout the various stages but in practice the user of the kit will put the joint in different positions to suit the different operations.

The method comprises the following steps: 1. Remove any dirt and rust from the joint and apply a suitable penetrating or release oil to the joint.

2. Mark the flange 25 of the yoke 1 9 and the propellor shaft attached to the other yoke to indicate the relative angular positions of the yokes.

The new cross must be fitted with the yokes in the same relative positions otherwise the shaft and joint assembly is likely to be out of balance and cause vibration.

3. Put one marking, e.g. a file nick, on one of the arms of the yoke 19, say arm 17, and put two markings, e.g. two file nicks, on the other arm, 1 8. These markings correspond to the one and two circumferential grooves 30b, 30a in the respective gauge devices 30.

4. Referring to Fig. 1, place the gauge block 32 on the outer end face of the bearing unit 1 3 of the arm 1 7 with one marking and place over the block the gauge device 30 with one circumferential groove. Adjust the screw 31 of the gauge device until it presses the gauge against the outer end face of the bearing unit, whilst maintaining the gauge ring in contact with the outer face 26 of the yoke arm. Repeat the gauging operation for the bearing unit 14 of the other arm of the yoke which has two markings, using the gauge device 30 with two circumferential grooves and the same gauge block. The two gauge devices are thereby to reference positions according to the axial positions of the respective bearing units and hence their associated trunnions relative to the yoke.The markings on the yoke arms enable the device corresponding to each arm to be identified at a later stage. Put the two gauge devices on one side without disturbing their screws. Pencil markings may be made on the gauge rings in line with the screw driver slots in the screws in case the screws are inadvertently turned slightly.

5. Referring to Fig. 2, with the arm 1 8 of the yoke 1 9 supported by the support 33, place the large diameter drift 34 on the outer end face of the bearing unit 1 3 of the other arm 1 7 and by hammering the drift drive the trunnions 11, 12 of the cross downwardly as far as possible relative to the yoke arms.

6. The outer end of the cap of the bearing unit 1 4 having thus been exposed, remove the outer wail from the cap by means of a sharp chisel. Such removal is assisted by the fact that the cap has been weakened by the stakes in the bore adjacent the junction of the end wall and the cylindrical side wall of the cap as its outer end was driven past the stakes.

7. Invert the yoke and using the support and the small diameter drift 35, drive the trunnions 11, 12 and the bearing unit 1 3 back approximately 4 It (Fig. 3).

8. Remove the rubber seal 24 around trunnion 1 2 and insert the four collet segments 36 into the gap comprising the space left by the seal and the space formed by moving the cross relative to the cap 1 4. The collet segments are thus located between the shoulder 23 of the cross and the inner end flange of the cap (Fig. 4).

9. Referring to Fig. 4, using the support 33 and the large diameter drift 34, drive the remaining cylindrical part of the bearing unit 14 completely out of its bore and then remove the collet segments. The part of the bearing unit is driven out by the action of the shoulder 23 on the segments which in turn act on said part.

10. Again using the support and the large or small diameter drift, drive the remaining bearing unit 1 3 back as far as possible.

11. Remove the cross from the yoke (Fig.

5).

1 2. Using the large diameter drift 34, drive out the remaining bearing unit from its bore.

1 3. Referring to Fig 6, position the broaching tool 37 at the inner side of the yoke arm 1 7 with the support 33 at the outer side and the bolt 38 passing through the bore in the arm. Turn the bolt to draw the tool through the bore thereby removing the projections or stakes and truing the bore, the latter being achieved by the broaching corner 39 of the tool being in a trailing position in relation to the centre of the pulling action of the bolt.

Repeat the broaching process for the bore of the arm 18.

1 4. Having ensured that all surfaces are clean and free from fraze, insert a replacement bearing unit into the bore of one of the yoke arms, say 18, if necessary using a vice, the large drift or a mallet so that the outer end face of the unit is flush with the outer face 26 of the arm.

1 5. Fit new rubber seals to the replacement cross and locate the trunnions of one pair in the fitted bearing unit and in the bore of the other arm 17.

1 6. Insert a replacement bearing unit into the bore in the arm 1 7 so that the trunnions are then located within the two bearing units.

1 7. Referring to Fig. 7, locate the staking tool 40 on the outer end face of the bearing unit in the arm 1 7 which carries one marking and place the corresponding gauge device 30 with a single groove over the tool. Position the whole assembly between the jaws J of a vice and close the jaws until the gauge device is in full contact with the outer face 26 of the yoke arm. The staking tool is thus forced into the bore and forms six projections or stakes in contact with the outer end of the bearing unit.

The radius formations at the leading end of the tool move metal of the bore forwards to form the stakes, and the inner edges of the formations locate the tool concentrically in the bore.

1 8. Using a screw driver engaged in the circumferential groove of the staking tool 40, remove the tool.

1 9. Re-position the gauge device on the arm 1 7 but with the gauge block 32 instead of the staking tool, and position the staking tool with the gauge device having two grooves against the other arm 1 8. Position the assembly in a vice again and close the jaws until both gauge rings are in full contact with the outer faces of the respective yoke flanges. The staking tool thus forms stakes in the bore of arm 1 8 to abut the bearing unit in this bore.

20. Repeat this procedure to remove the old cross from the yoke attached to the propeller shaft and to secure the new cross to the yoke. The new cross is first fitted to the flanged yoke since this yoke is easier to handle and the user of the kit can more readily learn the technique before fitting the cross to the more cumbersome assembly of the propeller shaft and other yoke.

Fig. 10 of the drawings shows one stage of a method which can be used for larger joints.

In this case the kit additionally comprises a spacer bar 44 of an appropriate length to fit between the two arms of each yoke of the joint.

The method comprises the same steps as steps 1 to 1 6 of the method described above.

Instead of then staking the bores in the yoke arms in two separate operations, the projections or stakes are formed in one operation, using two staking tools 40. Thus, the staking tools are positioned on the outer end faces of the respective bearing units and the corresponding gauge devices are placed over the tools The whole assembly is then positioned between the jaws J of a vice. The jaws are closed until the gauge devices are in full contact with the outer faces 26 of the yoke arms. After removal of the assembly from the vice the staking tools are removed.

The spacer bar 44 is located between the two yoke arms before closing of the vice jaws, the ends of the bar contacting machined inner faces of the arms, so as to prevent deflection of the arms inwardly towards one another. It is the use of the spacer bar which permits the two bores to be staked at the same time.

The method is then repeated to secure the new cross to the yoke attached to the propeller shaft.

Claims (21)

1. A kit of tools to facilitate the removal and replacement of the cross and the bearing units of a Hooke's type universal joint, the kit comprising (a) two adjustable gauge devices settable to reference positions according to the axial positions of the respective trunnions of a pair relative to the associated yoke, (b) means to facilitate the removal of the said pair of trunnions and the associated bearing units from the said yoke, (c) a cutting tool for removing the projections or stakes from the bores in the arms of said yoke after removal of the trunnions and bearing units, and (d) a staking tool for forming in said bores, after insertion of a pair of trunnions of a replacement cross and replacement bearing units into said bores, projections or stakes which engage the outer end faces of the bearing units thereby to secure the units in said bores and axially locate the trunnions, the disposition of the projections or stakes in each bore and hence the axial location of the associated trunnions being determined by co-operation of the staking tool with the corresponding gauge device according to the reference position of the latter.

2. A kit as claimed in Claim 1 wherein each gauge device comprises a first member for engagement with a part of an arm of a yoke of the joint and a second member movable relative to the first member and settable in a reference position according to the axial position of the bearing unit and hence the trunnion of said arm relative to the latter, the second being formed to cooperate with the staking tool to determine, by engagement of the first member with said part of the yoke arm, the disposition of the projections or stakes formed in the bore of the arm by the tool.

3. A kit as claimed in Claim 2 wherein the first member of each gauge device comprises a ring of which one end face is formed for engagement with the outer end face of an arm of a yoke of the joint, and the second member comprises a screw engaged with a screw thread in the bore of the ring.

4. A kit as claimed in Claim 3 which further comprises a gauge block of the same axial length as the staking tool, the bore of the ring of each gauge device having a plain portion of enlarged diameter adjacent said end face thereof to receive the gauge block or the staking tool, and a portion adjacent the other end face thereof which is formed with the screw thread engaged by the screw, whereby for setting of each gauge device the gauge block is located in the plain portion of the bore of the gauge ring and interposed between the inner end of the screw and the outer end face of the bearing unit of a yoke arm and the screw is adjusted to, and set in a position in which the gauge block is in contact with both the screw and the bearing unit and the ring is in contact with the outer end face of the yoke arm, and for the formation of projections or stakes in the bore of the arm the staking tool is located in the plain portion of the bore of the gauge ring in contact with the inner end of the screw and the ring is urged into a position in contact with the outer end face of the yoke arm so that the staking tool is driven into the bore in the arm and thereby forms projections or stakes therein.

5. A kit as claimed in any one of the preceding claims wherein the staking tool comprises a body having a longitudinal axis and formed around its periphery with a number of corners which constitute the radially outermost portions of the tool and extend parallel to said axis to an end face of the body, the body being cut away at the junctions of the corners and said end face to provide formations which are shaped so that on advancement of the tool along a bore of a yoke arm in the direction of said axis with the corners in contact with the surface of the bore, the formations move material of said surface forwards in said direction and thereby form inwardly extending projections or stakes in the bore.

6. A kit as claimed in Claim 5 wherein each corner of the body of the staking tool is slightly flattened.

7. A kit as claimed in Claim 5 or 6 wherein the body of the staking tool is cut away on a radius at the junction of each corner and the said end face of the body.

8. A kit as claimed in any one of the preceding claims wherein the means to facilitate the removal of the trunnions and the bearing units from the yoke of the joint comprise two drifts of different diameters, the larger diameter drift being engageable with a bearing unit to drive the unit and its trunnion axially relative to the bore pf their yoke arm, and the smaller diameter drift being engagable with a trunnion to drive the trunnion axially relative to its bearing unit in the bore of their yoke arm.

9. A kit as claimed in Claim 8 wherein the said means further comprises a number of collet segments for fitting around a trunnion between a shoulder formed on the trunnion and the inner end of the associated bearing unit to facilitate removal of said unit from the bore in its yoke arm.

10. A kit as claimed in any one of the preceding claims which further includes a support for supporting a yoke of the joint during removal of the associated trunnions and bearing units.

11. A kit as claimed in Claim 10 wherein the support comprises a hollow cylindrical component with an inwardly directed annular flange at one end.

1 2. A kit as claimed in any one of the preceding claims wherein the cutting tool is a broaching tool to be passed through a bore in a yoke arm to remove the projections or stakes therefrom and comprising a generally cylindrical body which has at least one circumferential groove formed with a sharp outer circumferential corner at the trailing side thereof to effect a broaching action on passage of the tool through a bore, swarf produced in the broaching operation being collected in the groove.

1 3. A kit as claimed in Claim 12 wherein the body of the cutting tool tapers from the groove towards the leading end of the body to provide a "lead" on insertion of the tool into a bore, and the portion of the body between the groove and its trailing end is truly cylindrical.

14. A kit as claimed in Claim 11 and Claim 1 2 or 1 3 wherein the cutting tool is formed with an axial bore having a screw thread for engagement by a bolt forming a part of the kit, whereby in use, the cutting tool may be located at the inner end of a bore in a yoke arm and the support may be located at the outer end of the bore with an end thereof in contact with the outer end face of the yoke arm. The bolt being arranged with its head abutting the flange of the support and its shank extending through the aperture defined by the support flange and the bore in the yoke arm into the bore in the cutting tool so that the bolt may be turned to draw the cutting tool through the bore in the yoke arm.

1 5. A kit as claimed in any one of the preceding claims which further comprises a spacer bar for fitting between the two arms of a yoke of the joint to prevent distortion of the arms during the formation of projections or stakes in the bores of the arms.

1 6. A staking tool for forming in the bore of a yoke of a Hooke's type universal joint projections or stakes which engage the outer end face of a bearing unit in said bore, the staking tool comprising a body having a longitudinal axis and formed around its periphery with a number of corners which constitute the radially outermost portions of the tool and extend parallel to said axis to an end face of the body, the body being cut away at the junctions of the corners and said end face to provide formations which are shaped so that on advancement of the tool along a bore in the direction of said axis with the corners in contact with the surface of the bore, the formations move material of said surface forwards in said direction and thereby form inwardly extending projections or stakes in the bore.

1 7. A method of removing and replacing the cross and the bearing units of Hooke's type universal joint, said method comprising the steps of (a) setting two adjustable gauge devices to reference positions according to the axial positions of the respective trunnions of a pair relative to the associated yoke, (b) removing the said pair of trunnions and the associated bearing units from said yoke, (c) removing the projections or stakes from the bores in the arms of said yoke, (b) inserting a pair of trunnions of a replacement cross and replacement bearing units into said bores and (e) forming in said bores projections or stakes which engage the outer end faces of the bearing units thereby to secure the units in said bores and axially locate the trunnions, the disposition of the projections or stakes in each bore and hence the axial location of the associated trunnion being determined by cooperation of the staking tool with the corresponding gauge device according to the reference position of the latter.

18. A kit of tools to facilitate the removal and replacement of the cross and bearing units of a Hooke's type universal joint, substantially as herein described with reference to and as illustrated in the accompanying drawings.

1 9. A staking tool for forming in a bore of a yoke of a Hooke's type universal joint projections or stakes which engage the outer end face of a bearing unit in said bore, substantially as herein described with reference to and as illustrated in the accompanying drawings.

20. A method of removing and replacing the cross and the bearing units of Hooke's type universal joint, substantially as herein described with reference to Figs. 1 to 9 of the accompanying drawings.

21. A method of removing and replacing the cross and the bearing units of a Hooke's type universal joint, substantially as herein described with reference to Figs. 1 to 10 of the accompanying drawings.