EP0082619A1

EP0082619A1 - Tool for grinding brake discs or drums

Info

Publication number: EP0082619A1
Application number: EP82306399A
Authority: EP
Inventors: John Fulton Kenny
Original assignee: JFK ENGINEERING FIFE Ltd
Current assignee: JFK ENGINEERING FIFE Ltd
Priority date: 1981-12-03
Filing date: 1982-12-01
Publication date: 1983-06-29
Also published as: DK535582A

Abstract

his invention relates to a disc or drum grinding apparatus 4 for use in in situ grinding of a brake disc 1 or drum on a wheel hub 2 on a vehicle 3. The apparatus 4 is securely mountable on the hub 2 so as to be supported substantially wholly by the hub and connected substantially rigidly thereto. A first drive transmission means 9,10,12,13 is drivingly engaged with at least one of said disc 1 or drum and hub 2 for rotating said disc 1 or drum about the hub axis, the apparatus 4 being provided with a stop means 15 for engagement with a fixed body 17 so as to prevent rotation of the apparatus 4 with the disc 1 or drum. A second drive transmission means 23,24 is arranged for driving a grinding wheel 25 disposable in contact with the brake disc 1 or drum for grinding a braking surface 29,30 thereof. At least one motor 8,22 is provided for driving said first and second drive transmission means

The invention also provides a method of grinding a brake disc 1 or drum comprising the steps of removing a wheel from the hub 2, attaching a grinding apparatus 4 of the invention to the hub 2 so as to support the apparatus 4 wholly on the hub 2 in rigid connection therewith, operating the first drive transmission means 9,10,12,13 to rotate the hub 2 and disc 1 or drum, operating the second drive transmission means 23, 24 and bring the gnnding means 25 into engagement with the disc 1.

Description

The present invention relates to the grinding of vehicle brake discs and/or drums for restoring damaged or worn braking surfaces thereof.
Known methods involve removal of the discs and drums from the vehicle and grinding them on relatively complex and expensive equipment in order to achieve the required accuracy and precision in the finished surface, followed by reassembly on the vehicle. It has been previously proposed to simplify this procedure somewhat by removing a brake disc together with the associated hub as a single unit and securing this to the grinding appar-. atus. Nevertheless most of the above disadvantages remain.
A number of attempts have also previously been made to process the braking surfaces of brake discs in situ. One approach has been to simply replace the brake pads with abrasive material. A similar approach has been to mount grinding wheel means on the brake calliper mounting. Whilst theoretically attractive these methods are in practice unsatisfactory because by the time that the brake disc surfaces have become worn i.e. after some 30 to 40,000 Kms, the wheel hub bearings have also become significantly worn resulting in a corresponding degree of play between the hub together with the disc secured thereto and the main body of the car on which the brake calliper is mounted. Although this degree of relative movement may not be enough to interfere with the normal running of the vehicle it is large enough to produce unacceptable inaccuracies in the finishing of the braking surfaces which in practice have to be finished to extremely high tolerances of the order of as little as 0.025mm.
It is an object of the present invention to avoid or minimize one or more of the above disadvantages.
The present invention provides a disc or drum grinding apparatus for use in in situ grinding of a brake disc or drum on a wheel hub on a vehicle, said apparatus being securely mountable on said hub so as to be supported substantially wholly by said hub and connected substantially rigidly thereto with a first drive transmission means drivingly engaged with at least one of said disc or drum and hub for rotating said disc or drum about the hub axis, said apparatus being provided with a stop means for engagement, in use of the apparatus, with a fixed body so as to prevent rotation of said apparatus with said disc or drum, and said apparatus having a second drive transmission means arranged for driving a grinding wheel disposable in contact, in use of the apparatus, with the brake disc or drum for grinding a braking surface thereof, and at least one motor for driving said first and second transmission means.
The present invention also extends to a method of grinding a brake disc or drum of a vehicle comprising the steps of removing a corresponding wheel from the wheel support means on the associated hub of the vehicle, attaching a grinding apparatus of the invention to said hub with the aid of said wheel support means so as to support said apparatus substantially wholly on said hub in substantially rigid connection therewith, operating the first drive transmission means to rotate said hub and its associated disc or drum around the hub axis while restraining said apparatus against rotation together with said disc or drum, operating the second drive transmission means to rotate the grinding means of said apparatus, and bringing said grinding means into grinding engagement with a braking surface of said disc or drum so as to traverse said braking surface with the rotating grinding means, while said apparatus is maintained substantially wholly supported on said hub.
In the case of brake drum grinding it should be noted that it will normally be necessary to first withdraw the brake drum (only) from the hub and then remount it on the hub in a reversed position prior to attachment of the grinding apparatus of the invention to the hub. Similarly this procedure will need to be reversed after completion of the grinding operation.
By means of the present invention it is possible to dispsense with the relatively time-consuming assembly and disassembly of the brake disc or drum from the vehicle and to carry out grinding of the braking surfaces in a simple manner using relatively uncomplicated and economic apparatus.
Moreover by supporting the apparatus including the grinding means substantially wholly on the hub and rigidly connected thereto the grinding means is aligned as accurately as possible with the braking surface of the brake disc and any distortions or inaccuracies resulting from wheel hub bearing play and/or the weight of the vehicle on the apparatus, are substantially avoided.
Further preferred features and advantages of the invention will appear from the following description given by way of example of some preferred embodiments illustrated with reference to the accompanying drawings in which:

Fig. 1 is a schematic plan view of a first grinding device of the invention in use on a vehicle hub with a brake disc;
_Fig. 2 is a side view of the device of Fig. 1;
Fig. 3 is a plan view of the device of Fig. 1 in use on a brake drum;
Fig. 4 is a side view of a second device of the invention;
Fig. 5 is a plan view of a third device of the invention; and
Fig. 6 is a side view of a further device of the invention.

Figs. 1 and 2 show a grinding device of the invention in use in in situ grinding of a brake disc 1 on a wheel hub 2 on a vehicle 3. As may be seen in the drawings the vehicle wheel has been removed from the wheel hub 2 and the grinding device 4 secured to the wheel hub 2 with the aid of the wheel support means comprising wheel mounting studs 5 and nuts 6.
In more detail the grinding device 4 comprises a body 7 provided with a main drive motor 8 and a first drive transmission means in the form of a drive belt 9, and a drive shaft 10 projecting axially from one side 11,of the body 7 and terminating in a drive connection plate 12 provided with a plurality of apertures 13 arranged for receiving therethrough the wheel mounting studs 5. The drive shaft 10 is supported on the body 7 via suitable heavy duty precision bearing means 14 to provide a stable mounting of the body 7 when the drive shaft 10 is secured to the wheel hub 2.
The main drive motor 8 has a relatively low speed but powerful output for rotating the wheel hub 2 together with the brake disc 1 mounted at a rate of the order of 80 r.p.m., the body 7 being held against rotation by a telescopic support leg 15 disposed remote from said drive shaft 10 with its foot 16 in engagement with the ground 17 below the vehicle 3.
The body 7 is also provided with a grinding table 18 mounted on suitable support means such as runners 19 on the body 7 for movement relative to the body 7 in a direction parallel to the drive shaft.(10).axis i.e. at right angles to the principal plane of the brake disc 1 and in a direction at right angles to the drive shaft.(10). axis i.e. parallel to the principal plane of the brake disc 1, under the control of drive means such as screw means with control knobs 20, 21.
A grinder drive motor 22 is mounted on the grinding table 18 and connected via a drive transmission means comprising a drive belt 23 and grinder drive shaft 24 to a grinding means in the form of a hollow grinding cup 25. The grinder drive shaft 24 is rotatably mounted 26 in a support member 27 so as to extend substantially parallel to the hub 2 axis. The support member 27 is pivotally mounted 28 on the grinding table 18 so as to be movable between inner and outer grinding positions (shown in full and in dashed outline respectively) for grinding of the axially inner and axially outer braking surfaces 29, 30 respectively of the brake disc 1 which surfaces are engaged by pressure pads 31 of the main brake mechanism 32 in use of the brake disc 1. The support member 27 is locked securely in the desired grinding position by suitable locking means such as a screw means 33.
As shown in Fig. 1 the grinder drive motor 22 is made double ended so that the drive belt 23 can be relocated for driving the grinding cup 25 and drive shaft 24 in the alternative position of the latter. It will of course be appreciated that the grinding drive motor 22 is generally of lower power but higher speed than the main drive motor in order to achieve optimum grinding performance. In general the grinding cup 25 will be rotated at around 6000 r.p.m.
Once the device has been mounted on the wheel hub 2 as explained above, the grinding table position on the body 7 is adjusted in a direction parallel to the disc plane to bring the grinding cup 25 opposite the braking surface 29 and then in a direction at right_"angles thereto to bring grinding into engagement with said braking surface 29. Since the wheel hub 2 and brake disc 1 are being rotated by the main drive motor 8 the grinding cup 25 which is held in a fixed position effectively traverses the whole of the braking surface 29 around the disc 1. As shown in the drawings this can at least in some cases be carried out without removing the main brake mechanism 32 at all thereby still further simplifying the operating procedure. In such cases it will be noted that the only disassembly of the vehicle that is required is the removal of the wheel which can be done very quickly indeed. In order to treat the other braking surface 30 it is simply necessary to stop the grinding motor 22, disconnect the drive belt, swing round the support member to the new position having released it first and then locking it in position again, reconnect the drive belt and adjust the table position as before to bring the grinding cup 25 into grinding engagement with the other braking surface 30. Naturally if desired the grinding drive motor 22 could be arranged to move together with the support member 27 as.a single unit, thereby still further simplifying the procedure.
The application of the present invention to the grinding of brake drums is illustrated in Fig. 3 which is a simplified view corresponding generally to Fig. 1. The device and operating procedure are essentially similar to that described above except that the grinding cup is replaced by a grinding wheel 34, the brake drum 35 has only one, generally cylindrical, braking surface 36 therefore obviating the need for reversing the disposition of the grinding means, and the fact that it will normally be necessary to remove the brake drum 35 from the hub 2 and replace it thereon in a reversed position to provide sufficient access to the braking surface 36 clear of the brake pads and associated operating mechanism 37. Of course once the grinding operation has been completed and the grinding apparatus removed from the hub 2 it will then be necessary to remove the drum 35 and restore it back to its original position on the hub 2.
If desired it is also possible to use a grinding apparatus of the invention away from a vehicle if still more access is required, in a manner as illustrated in Fig. 4. In this case the brake drum 35 or disc 1 is removed from the vehicle hub and is remounted using a locking cone 41 on a support hub 38 rotatably mounted via a slider outrigging bearing 39 on a stand 40. The disc or drum may then be treated as if it were still mounted on the vehicle hub. Alternatively though the support hub 38 is provided with a mounting plate 42 at its outboard end 43 and the grinding apparatus secured to the mounting plate 42 in similar manner to that described above. Thereafter the operating procedure is substantially the same as already described above. This latter type of arrangement is particularly suitable for use with heavy and commercial vehicle brake drums and discs.
Finally Fig. 5 illustrates a device generally similar to that of Figs. 1 and 2 but with a slightly different grinding drive shaft (24) support member 38 in the form of a swing head. Whilst Fig. 6 shows another generally similar device provided with a plurality of legs 15 enabling the device to stand up on its own when not in use, although during use only the leg(s) at one end will normally contact the ground for preventing rotation of the device together with the hub. This is of course because in accordance with the present invention the device is substantially wholly supported on the hub and not on the ground or any other body.

Claims

1. A disc or drum grinding apparatus (4).for use in in situ grinding of a brake disc.(l) or drum on a wheel hub.(2) on a vehicle.(3), said apparatus.(4).being securely mountable on said hub.(2).so as to be supported substantially wholly by said hub.(2) and connected substantially rigidly thereto with a first drive transmission means.(9, 10,12,13). drivingly engaged with at least one of said disc·(1) or drum.and hub.(2) for rotating said disc . (1) or drum about the hub axis, said apparatus· (4)·being provided with a stop means.(15) for engagement, in use of the apparatus, with a fixed body.(17) so as to prevent rotation of said apparatus.(4) with said disc.(l) or drum, and said apparatus .(4) having a second drive transmission means.(23,24)-arranged for driving a grinding wheel.(25).disposable in contact, in use of the apparatus. (4), with the brake disc .(1) or drum for grinding a braking surface.(29, 30) thereof, and at least one motor (8, 22) for driving said first and second drive transmission means.

2. Apparatus as claimed in claim 1 wherein said stop means comprises at least one leg.(15) engagable with the ground.(17) and/or vehicle body . ( 3 ) .

3. Apparatus as claimed in claim 1 or claim 2 wherein is provided a first motor.(8) for driving said first drive transmission means.(9, 10,12,13) and a second motor.(22).for driving said second drive transmission means .(23,24).

4. A method of grinding a brake disc.(1).or drum of a vehicle.(3) comprising the steps of removing a corresponding wheel from the wheel support means.(5) on the associated hub.(2) of the vehicle (3), attaching a grinding apparatus.(4) according to claim 1 to said hub (2) with the aid of said wheel support means.(5) so as to support said apparatus.(4) substantially wholly on said hub (2) in substantially rigid connection therewith, operating the first drive transmission means.(9, 10, 12, 13). to rotate said hub.(2).and its associated disc.(l) or drum around the hub axis while restraining said apparatus.(4). against rotation together with said disc.(l) or drum, operating the second drive transmission means.(23,24).to rotate the grinding means.(25).of said apparatus.(4), and bringing said grinding means.(25).into grinding engagement with a braking surface.(29, 30).of said disc.(l) or drum so as to traverse said braking surface.(29, 30).with the rotating grinding means.(25),while said apparatus.(4). is maintained substantially wholly supported on said hub.(2).

5. A method as claimed in claiml wherein said apparatus .(4) is secured to said hub.(2) by disposing the wheel support studs.(5) on said wheel hub.(2) through respective apertures.(13) in a drive connection plate.(12).of the first drive transmission means, and clamping said connection plate.(12) to said wheel hub (2) with the aid of wheel securing nuts.(6).