FIELD OF THE INVENTION
The present disclosure relates to the field of brush holders in general, more particularly to reaction type brush holders for DC machines.
BACKGROUND OF THE INVENTION
Typically, in a DC machine, rotor winding is electrically connected to carbon brushes via commutator. Current is fed to rotor winding or current is taken from rotor winding through carbon brushes.
Many times, it is observed that brush holder spring tension is not accurate in reaction type brush holders because it is not possible to adjust spring tension in this type of brush holder during/after assembly of components of brush holder. Improperly set spring tension results in inaccurate bedding of carbon brushes which in turn results in bad commutation performance and heavy shooters during commutation test of DC machine. Such types of machines with bad commutation are not acceptable to end user because this may cause flashover and eventually failure of machine during service.
To achieve required spring tension, correct bedding of carbon brushes and satisfactory commutation performance of DC machine, brush holder with spring tension adjustment arrangement is required.
OBJECTS OF THE INVENTION
An object of the invention is to provide a reaction type brush holder in which spring tension can be adjusted during/after assembly of brush holder components by overcoming the deficiencies and disadvantages of the prior art.

Another object of the invention is to eliminate commutation problem caused on account of improper spring tension in reaction type brush holders.
SUMMARY OF THE INVENTION
The present disclosure relates to a reaction type brush holder (200) with spring tension adjustment arrangement. The brush holder (200) includes a brush holder body (01); a hinge pin (02) fitted on the brush holder body (01); a pin (03) fitted on the brush holder body (01), proximal to the hinge pin (02); a male spring seat (05) provided on the hinge pin (02), the male spring seat (05) having threads on its outer side; a female spring seat (06) provided on the pin (03), the female spring seat (06) having threads, correspondingly matching with the threads of male spring seat (05), on its inner diameter; and a spring (07) disposed with the male spring seat (05) and the female spring seat (06), wherein tension of the spring (07) is adjusted by rotating the male spring seat (05) with reference to the female spring seat (06) based on an engagement of a particular number of threads of both the male spring seat (05) and the female spring seat (06).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of the exemplary embodiments and wherein:
Figure 1a-b shows: Conventional reaction type brush holder (100).
Figure 2a-b shows: New reaction type brush holder (200) in accordance with an embodiment of the present disclosure.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The present invention, now be described more specifically with reference to the following specification.
Now, reference may be made to Figs. 1a and 1b discussing conventional reaction type brush holder (100). Fig. 1a illustrates a front view, and Fig. 1b illustrates a top view of the brush holder (100).
Part details of the earlier conventional reaction type brush holder (100) as shown in Figs. 1a and 1b includes the following:


Brush holder body (01) of conventional reaction type brush holder (100) is manufactured from sand casted leaded gunmetal. Brush holder body (01) is machined using broaching process to ensure proper fitment of carbon brushes within given tolerance in broached pockets of the brush holder (100). Broaching is a machining process that uses a toothed tool, called a broach, to remove material.
Further, outer surfaces of the brush holder body (01) are machined to achieve the width and length of the brush holder (100) as per drawing / design dimensions. Next, two tapped holes are drilled for assembly of brush holder insulating stud. Further, machining and drilling operations necessary for assembly of hinge pin (02), Pin (03), Dowel Pin (04), arcing stud (10), hexagonal screw (l1), machined washer (12), dowel sleeve (13), and split pin (14) are carried out.
In DC machine, brush gear connections are provided at left hand side and right hand side of the brush holder (100). Moreover, the arcing stud (10) remains towards connection side. Hence in the prior art brush holder (100), it is required to cast the left hand side and the right hand side of the brush holder (100) separately.
The spring (07) which produces tension rests on two similar spring seats, Spring seat-1 (05) & Spring seat-2 (06), and it is not possible to adjust the spring tension in such arrangement. Pressure is transmitted from the spring (07) to carbon brushes through brush holder lever assembly (08) which consists of a press finger resting on carbon brush, a back plate to move the lever assembly (08), and hinge box assembled with the help of rivets.

Fig. 2a and 2b illustrates a new reaction type brush holder (200) in accordance with an embodiment of the present disclosure. Fig. 2a illustrates a front view, and Fig. 2b illustrates a top view of the new brush holder (200). In an example, manufacturing of the novel brush holder (200) employs conventional techniques as described earlier.
Part details of the new brush holder (200) as shown in Figs. 2a and 2b includes the following:

Manufacturing of the new brush holder (200) in reference to its various components will now be described in the foregoing description in reference to the Figs. 2a and 2b. In an embodiment, the brush holder body (01) of new reaction type brush holder (200) is manufactured from sand casted leaded

gunmetal, providing better strength, soundness and good machinability. Brush holder body (01) is machined using broaching process for fitment of carbon brushes in broached pockets of the brush holder (200). Further, machining is carried out on outer surfaces of the brush holder body (01) to maintain outer dimensions as per drawing / design. For assembly of brush holder insulating studs, two tapped holes are drilled in the brush holder body (01). Next, all other machining and drilling operations necessary for assembly of hinge pin (02), pin (03), dowel pin (04), arcing studs (10), hexagonal screw (11), machined washer (12), dowel sleeve (13) and split pin (14) are carried out.
Further, brush gear connections are provided at left hand side (LH) and right hand side (RH) of the brush holder (200) in DC traction motor. The arcing stud (10) remains towards connection side of the brush holder body (01). In prior art, as discussed earlier, it was required to cast the left hand side and the right hand side of the brush holder (100) separately as per requirement of connections. In present art, provision has been made to connect same brush holder (200) at either left hand side or right hand side. Thus, in present art separate casting of LH and RH brush holder (200) is not required.
Further, in prior art, the spring which produces tension rests on two similar spring seats and it was not possible to adjust the spring tension. In present art, spring (07) rests on set of male-female spring seats (05, 06). These male-female spring seats (05, 06) rest on hinge pin (02) and pin (03) such that during movement of lever assembly (08), spring seats (05, 06) rotates on the hinge pin (02) and the pin (03). The male spring seat (05) has suitable threads on its outer side whereas female spring seat (06) has corresponding matching threads in its inner diameter.

Whenever, it is required to adjust the spring tension during or after assembly of components of the brush holder (200), the male spring seat (05) is rotated with the help of a spanner (or the like device), such that male-female spring seats (05, 06) are engaged with particular number of threads of both the male spring seat (05) and the female spring seat (06). In an embodiment, the spring seats (05, 06) are made of brass. In other examples, the spring seats (05, 06) may be made of any suitable material.
For transmission of pressure from the spring (07) to carbon brushes, the brush holder lever assembly (08) is used which consists of press finger resting on carbon brush, and back plate to move the lever assembly (08), epoxy sleeves, and hinge box assembled with the help of rivets. Length of the back plate in present art has been increased as compared to prior art so as to increase space for proper lifting of the lever assembly (08) during service.
In prior art, it was observed that because of friction between moving parts, the lever assembly was not resting accurately on carbon brush, hence provision of application of suitable lubricant between moving parts has also been introduced with the lever assembly (08) of the new reaction type brush holder (200) of the present art. In an embodiment, the arcing stud (10) is provided with a spring washer (15) to counter problem of loosening of arcing stud, as observed.
Following are advantages of the newly developed brush holder (200) over the prior art:
- In the present art it is possible to adjust the spring tension during/after assembly of brush holder (200) components whereas prior art was with fixed spring tension.

- If brush holder spring tension is not sufficient in prior art brushes shall not be bedded correctly whereas in present art correct bedding of brushes can be achieved by adjusting the brush spring tension.
- No problem of bad commutation performance and heavy shooters in present art where as bad commutation was predominant problem with prior art.
- With the application of suitable lubricant in moving parts of brush holder assembly in newly developed brush holder (200) problem of improper resting of lever on carbon brush has been eliminated.
- Problem of loosening of arcing stud (10) observed in prior art has been resolved in present art by using a spring washer.
- Present art provides better space for movement of lever assembly (08) during service in situ condition of machine as in present art length of back plate has been increased.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims.

WE CLAIM:
1. A reaction type brush holder (200) with spring tension adjustment
arrangement, the brush holder (200) comprising:
a brush holder body (01);
a hinge pin (02) fitted on the brush holder body (01);
a pin (03) fitted on the brush holder body (01), proximal to the hinge pin (02);
a male spring seat (05) provided on the hinge pin (02), the male spring seat (05) having threads on its outer side;
a female spring seat (06) provided on the pin (03), the female spring seat (06) having threads, correspondingly matching with the threads of male spring seat (05), on its inner diameter; and
a spring (07) disposed with the male spring seat (05) and the female spring seat (06), wherein tension of the spring (07) is adjusted by rotating the male spring seat (05) with reference to the female spring seat (06) based on an engagement of a particular number of threads of both the male spring seat (05) and the female spring seat (06).
2. The reaction type brush holder (200) as claimed in claim 1 includes a dowel pin (04).
3. The reaction type brush holder (200) as claimed in claim 1 includes a brush holder lever assembly (08) for transmission of pressure from the spring (07) to carbon brushes.

4. The reaction type brush holder (200) as claimed in claim 1 includes an arcing stud (10) for connection at left hand (LH) or right hand (RH) side of the brush holder (200).
5. The reaction type brush holder (200) as claimed in claim 4, wherein the arcing stud (10) is provided with a spring washer (15) to prevent loss of the arcing stud (10).
6. The reaction type brush holder (200) as claimed in claim 1, wherein the brush holder body (01) is machined using broaching process.
7. The reaction type brush holder (200) as claimed in preceding claims, wherein during movement of the lever assembly (08), the spring seats (05, 06) rotates on the hinge pin (02) and the pin (03).
8. The reaction type brush holder (200) as claimed in claim 1, wherein the male spring seat (05) is rotated with a spanner like device.
9. The reaction type brush holder (200) as claimed in claim 1, wherein the spring seats (05, 06) are made of brass.