GB2090781A - Brake liner truing device - Google Patents

Abstract

The device comprises a clamping cylinder 2 adapted to receive the brake liner 5 to be turned or trued and a rotary frame 7 adapted to be driven in rotation by a drive motor and supporting a rotary arm 9 carrying a cutting tool 12. Dust removing means 15 mounted in the frame exhausts and collects from the vicinity of said cutting tool the dust particles and chips produced during a brake liner truing or turning operation. The drive motor and a motor 23 for a suction impeller 22 may be separate or one and the same. Filters 19, 20 lie between a suction duct 15 and the impeller. <IMAGE>

Description

SPECIFICATION Brake lining truing device This invention relates to a brake lining turning or truing device.

The brake linings of shoe-and-drum brakes are conventionally turned to size or trued by means of turning devices comprising rotary cutting tools.

According to one known method, the truing device is directly mounted on the wheel axle and rigidly clamped thereto whereupon the freely accessible brake liners are turned to size by means of a rotary cutting tool as described, for example, in German Patent Specification No. 12 32 032; according to another known method, the brake liners to be turned to size or trued are removed from the wheel, clamped and centered by means of a clamping attachment and then turned to the desired diameter by means of a rotating cutting tool supported by a truing device which is mounted in a fixed position.

During the truing operation, it is necessary to remove by suction the chips and, particularly, the dust produced by this operation. Particularly in the case of brake liners containing asbestos, the fibreshaped asbestos dust particles are extremely detrimental to health. In German Laid-Open Specification No. 2837 873, there is disclosed a dust protection device for brake lining truing devices which has the shape of a dust containing bell which is adapted to receive the entire brake lining truing device; this dust collecting bell is connected to exhausting means, e.g. a vacuum cleaner, which is adapted to remove by suction the chips and dust particles produced by the turning operation and to filter the exhausted air so as to retain the chips and dust particles.Since the dust collecting bell has a large volume and since it is impossible to provide a hermetic seal between the bell and the truing device, it is necessary in this case to provide for a high suction capacity so as to ensure that actually all chips and dust particles produced during the truing operation are removed.

It has further been proposed only to provide an exhaust line in the vicinity of the cutting tool, said suction line being guided along the frame of the device and connected to stationary dust removing means by a slip ring arrangement. However, this arrangement requires the provision of suction flow paths of great length, the result being that a considerable part of the suction energy is dissipated by friction. In addition to this, the efficiency of the device is reduced by the slip ring arrangement. Thus, this known dust removing device also requires the provision of high-capacity suction means.

In order practically to ensure dust-free operation, it would be necessary, with either of the two abovementioned known devices, to employ dust removal equipment having so large dimensions and being so expensive that efficient operation would no longer be possible. Thus, there exists a demand for small high-capacity dust removal means whose efficiency nevertheless suffices to provide the required dust removal during the turning operation.

In view of the foregoing, it is an object of this invention to provide a truing or turning device of the kind named which comprises dust removal means which are adapted to combine a strong suction effect with short flow paths and a small volume of air drawn in per unit time.

According to the invention, this object is attained by the provision of an arrangement in which the dust removal means are directly mounted on a supporting frame for rotation therewith. The dust removal means may be disposed in such a position that is constitutes a counterweight either for a supporting arm or for a drive motor, if any, which is mounted on said frame.

Since the dust removing means are directly mounted on the rotary support, the air aspirating paths are only of small length so that the power employed to create a vacuum is not reduced by large frictional losses. Besides, it is possible with this arrangement to draw off the chips and dust particles produced during the turning operation at a point in the direct vicinity of the cutting tool, the result being that only a small quantity of air has to be drawn in per unit time. Thus, the entire amount of power serving to produce suction is practically utilized completely.

The invention and further particulars will be described more specifically hereinafter with reference to preferred embodiments shown in the drawings, in which: Figure 1 is a longitudinal cross-section of a brake liner truing device comprising dust removing means according to the invention; Figure 2 is a plan view of the truing or turning device shown in Figure 1; Figure 3 is an elevation, partly sectioned, of a second embodiment of dust removing means according to the invention; Figure 4 is a partly sectional elevation of a third embodiment of dust removing means according to the invention; and Figure 5 is a partly sectioned elevation of still another dust removing means according to the invention.

The brake liner truing device 1 shown in Figure 1 comprises a supporting tube 2 which is supported by means of adapter rings 3 from a stub axle 4 carrying freely accessible brake liners 5 belonging, for example, to a truck or lorry, the supporting tube 2 being held in position by means of a clamping ring 6.

The supporting tube 2 carries a rotary support or frame 7 which is adapted to be driven in rotation about the supporting tube by means of a drive motor 8 shown in Figure 2 through the medium of a per se known driving chain (not shown).

The rotary frame 7 is additionally provided with a radially extending rotary arm 9 serving to support a tool holder 10 extending parallel to the axis of rotation. Mounted on the free end of the tool holder facing the brake liners 5 is a cutting tool 11 carrying a tool bit 12 made of steel. The distance between the tool bit 12 and the axis of rotation can be adjusted by adjusting means (not shown) permitting the desired depth of cut to be selected. The tool holder 10 is of hollow construction and defines an open duct 13, the suction aperture 14 of which is disposed in the immediate vicinity of cutting bit 12.

The rear end of tool holder 10 is inserted into a flexible or rigid connecting tube 15 which extends to dust removing means 16 which are also mounted on rotary frame 7.

These dust removing means may be constructed in a variety of ways; in Figure 1 dust removing means resembling a vacuum cleaner are shown.

This vacuum cleaner comprises a cylindrical housing 17 whose longitudinal axis extends parallel to the rotary axis of rotary frame 7, the end of said housing connected to tube 15 being closed by means of a cover 18. The connecting tube 15 extends through cover 18 and is rigidly attached to said cover by any suitable means. Provided within housing 17 is a preliminary or primary filter 19 made of paper and adapted to retain the coarse chips produced during brake linerturning operations, there being disposed downstream of this filter a fine or secondary filter 20 also made of paper and designed to retain the fine dust particles produced during said turning operations. The two filters are rigidly mounted in a per se known manner within housing 17, for example by means of clamping rings 21 orthe like.Disposed downstream of secondary filter 20 in housing 17 is an impeller 22 which is adapted to be driven in rotation by a high-speed electric motor 23 supported within housing 17 by means of flanges 24.

On its side facing away from the brake liners to be trued rotary frame 7 is provided with a sleeve 25 surrounding supporting tube 2 and extending beyond the rear end of said tube, the sleeve portion 25 being adapted to be rotated together with rotary frame 7. Mounted on the rear end of sleeve portion 25 is a slip ring carrier 26 surrounding the sleeve portion and having three slip rings 27 embedded therein. Thus the slip ring carrier also rotates together with rotary frame 7. Extending through the bottom of sleeve portion 25 is a screw 28 which is rigidly attached to the adjacent bottom of supporting tube 2 and carries an adjusting nut 29 which bears againstthe bottom of sleeve portion 25. Mounted on the stationary periphery of adjusting nut 29 is a cover 30 behind which slip ring carrier 26 is disposed.Extending into the cavity defined by cover 30 there is a supply cable 31 comprising three leads, each of which is connected to one of a plurality of sliding contacts 32 cooperating with their associated slip rings 27. The supply cable 31 is provided in a per se known manner with a switch 33. In this embodiment, the three slip rings are connected, by means of wires (not shown), to the drive motor 8 and the electric motor 23 driving the dust removing means 16, the said two units being connected in parallel, this making it possible, by means of a simple monitoring relay provided within switch 33, to prevent one orthe other of the two units from being operated alone. This ensures in a reliable manner that it is impossible, for example, to turn brake liners without the dust removing means having been put into operation.

Prior to truing of the brake liners, the cutting tool is adjusted for the necessary depth of cut whereupon the turning ortruing operation is performed. During the truing or grinding operation, rotary frame 7 is displaced axially in the direction of arrow P until the brake liners have been turned to size throughout their entire width. The chips and dust particles produced during the turning operation are drawn into the aspirating aperture 14 and conducted, via duct 13 of the tool holder and the connecting tube 15, to dust removing means 16 in which the material is filtered out of the air stream by means of preliminary filter 20 and downstream filter 21, respectively.

Figures 3 to 5 illustrate a variety of embodiments of the dust removing means. Identical or identically operating components corresponding to comparable components shown in Figures 1 and 2 are identified by similar reference numbers having added thereto index numbers corresponding to the numbers of the figures in which they are shown.

Figure 3 shows dust removing means 163 forming an integral unit together with drive motor 83. The ventilating impeller with which drive member 83 would otherwise be provided has been replaced by a high-speed turbine impeller 223 mounted on the shaft of the motor. The housing of the drive motor is extended in a rearward direction; the extended portion contains in the manner shown in Figure 1 dust removing means comprising a preliminary filter 193 and a downstream filter 203. The housing which is closed by means of a cover 183 is connected to the tool holder by means of a connecting tube 153 in the manner shown in Figure 1.

In the embodiment shown in Figure 4, a high speed turbine impeller 224 has been substituted for the ventilating rotor of drive motor 84. In a separate housing 174 which is again attached to the rotary frame 74 there are disposed, in the manner described with reference to Figure 1, a preliminary filter 194 and a secondary filter 204. The housing of drive motor 84 and turbine impeller 224 is connected by means of a tube or hose 34 to housing 174 containing said filters. In the manner shown in Figure 1, a connecting hose 154 extends between housing 174 and the tool holder.

Figure 5 shows another embodiment of the invention in which drive motor 85 is constructed in the manner described above; the only modification provided in this case relates to the shaft supporting the ventilating rotor, this shaft extending from the housing of the drive motor. The dust removing means 165 only comprise a housing 175 containing filters 195 and 205 as well as a turbine impeller 225 disposed to the rear of the filters, the shaft carrying the impeller also extending from the housing. The shafts of the drive motor and of the turbine impeller are interconnected by suitable power transmission means such as a toothed belt 35; thus the turbine impeller is directly driven from the drive motor. The housing 175 of the dust removing means 165 is connected to the hollow tool holder by means of a flexible tube 155 in the manner shown in Figure 1.

Each of the embodiments shown in Figures 3 to 5 comprises a single electric motor which serves to drive the rotatable frame as well as the dust removing means. As a result of this arrangement, the two units can only be operated simultaneously.

Forthe purpose of ensuring operational safety twill be necessary only to provide a single overload protection means which is adapted simultaneously to stop the two units for example upon the filters having been fillted with chips and dust particles, respectively.

In the embodiments shown in the drawings, the dust removing means are disposed in a straight cylindrical tube. It is, of course, possible to provide housing structures of different shape, for example, housings of arcuate shape which at least partially surround the rotary frame. Such arcuate or circular housings are adapted also to accommodate additional components, for example the paper filters described. According to the foregoing description, this invention provides dust removing means for use with a turning ortruing device which means, due to their arrangement on a rotary frame, permit short suction ducts to be employed with the result that only small frictional losses occur. With the aid of the arrangements described it is possible, in comparison to conventional dust removal equipment, considerably to increase the suction capacity. Moreover, operation and handling of the inventive means are particularly simple and due to the compact design of the rotary frame such means require only a minimum of space. Dust removing means according to this invention may be employed not only in combination with mobile turning devices such as have been described with reference to the drawings but also in combination with stationary turning devices.

Claims (11)

1. A brake liner turning or truing device comprising means for clamping the brake liners to be turned or trued, a rotary frame adapted to be driven by a drive motor, said rotary frame supporting a rotatable arm provided with a cutting tool and dust removing means adapted to exhaust and collect from the vicinity of the cutting tool the chips and dust particles produced during truing of the brake liners, characterized in that said dust removing means are directly mounted on said rotary frame for rotation therewith.

2. The device of claim 1, characterized in that said dust removing means are connected to a suction line terminating in the immediate vicinity of said cutting tool and provided with a suction aperture adjacent to said cutting tool.

3. The device of claim 1 or claim 2, characterized in that said drive motor for said rotary frame is mounted in a per se known manner on said rotary frame for rotation therewith.

4. The device of any of the preceding claims, characterized in that said dust removing means are provided with one or more filters to provide an arrangement resembling a vacuum cleaner.

5. A device as claimed in any of the preceding claims, characterized in that said dust removing means are provided with a separate drive motor, such as an electric motor, said motor comprising a turbine impeller adapted to exhaust the dust particles and chips produced during a truing operation from the immediate vicinity of said cutting tool.

6. The device of claim 3, characterized in that the high-speed shaft of said drive motor is provided with a turbine impeller adapted to exhaust the dust particles and chips produced during a truing or turning operation.

7. The device of claim 6, characterized in that there are provided, in the housing accommodating said drive motor and said turbine impeller, a plurality of filters adapted to retain the dust particles and chips exhausted from the vicinity of said cutting tool.

8. The device of claim 6, characterized in that the end of the housing of the drive motor facing said turbine impeller is connected by means of a flexible tube to another housing containing one filter or a plurality of filters and that said filter housing is provided on its inlet end with a connecting tube adapted to exhaust the dust particles and chips produced during a turning operation.

9. The device claimed in claim 3 or claim 4, characterized in that said drive motor is adapted to drive in rotation a turbine impeller of said dust removing means through the medium of power transmission means, for example, a toothed belt.

10. A device as claimed in any of the preceding claims, characterized in that said dust removing means are mounted on said rotary frame in such a position as to constitute a counterweight for said rotary arm and said drive motor.

11. A brake liner turning or truing device, substantially as described herein with reference to the accompanying drawings.