FIELD OF INVENTION
The invention generally relates to a disc brake caliper unit, used within the braking system of high speed passenger coaches. Said disc brake caliper unit involves novel structural and constructional features which are suitable to be used in the braking device of railway coach; and which are particularly characterized in the pneumatically controlled mechanism to meet the requirements of braking and also actuates automatic slack adjustment in railway Coach.
PRIOR ART
Disc brakes are frequently being used in high speed vehicles. Application of disc brakes in railway coaches is conventionally known, wherein brake caliper unit with one or another constructional features, is employed.
As per the US patent no 5813499A (Figure 1), the brake caliper unit has two caliper levers whose one ends are linked to brake pads and whose other ends are linked to a slack adjusting device extending between them. The central regions of the caliper levers are coupled to a housing, in which case the coupling point of one caliper lever is constructed as a simple rotary bearing. The coupling point of the other caliper lever is constructed as an eccentric transmission, which can be operated by a brake cylinder held in the housing by a crank arm in the direction of the approach of the two caliper levers. The eccentric transmission has a shaft, which is rotatable in the housing about an axis and which, with an eccentricity directed diagonally away from

the brake disc carries a pin with the axis on which the caliper lever is disposed. The eccentric transmission permits a high power transmission ratio with relatively short caliper levers.
As per the US patent no 4473136A (Figure 2 & 3), rail vehicle disc brake arrangement includes a yoke (1) with a brake cylinder (11) and a slack adjuster (16). In order to obtain advantages as regards design, function and space requirements the yoke (1) comprises two telescoping yoke parts: a fixed part (4) and a movable part (5). The slack adjuster (16) is arranged to act between these two parts. The brake cylinder (11) on the movable yoke part is connected to a yoke lever (6), which is pivotally attached to the movable part, has a pad holder (8) with a brake pad (9), and controls the slack adjuster (16).
As per the US patent no 4497392A (Figure 4), rail vehicle disc brake caliper has a base frame (1) with a pivotally attached brake lever (3). Brake pads are provided on these parts in the vicinity of a disc to be braked. A brake cylinder (16) for acting on the brake lever is attached to the base frame. In order to obtain a space saving, simple and sturdy design with a required internal leverage and with a slack adjusting function a slack adjuster (15) of the rotary, lever type is arranged with its rotary part on a shaft (14) pivotally arranged in the base frame and its free arm connected to the piston rod (16') of the brake cylinder (16). This shaft is provided with a cam (17), preferably connected to the brake lever (3) by way of connecting links (18).
OBJECTS OF THE INVENTION
• Prime object of the instant invention is to provide a novel disc brake caliper unit, suitable to be used within the braking system of high speed passenger

coaches; wherein it is particularly a pneumatically controlled system to meet the requirements of braking and automatic slack adjustment in railway Coach.
• Another object of the invention is to provide a novel disc brake caliper unit, to be used in the braking system of railway coaches, which is more abrasion resistant, have longer working life and which involves lesser maintenance.
• Another object of the invention is to provide a novel disc brake caliper unit, which includes several advantageous features in terms of inventiveness and industrial applications, namely: (i) economical; (ii) lighter in weight in comparison to conventional disc brake caliper units; (iii) easy to handle; (iv) compact in size; (v) more reliable and user friendly etc.
• Another object of the invention is to provide a novel disc brake caliper unit, to be used in the braking system of railway coaches, which will ensure safe and comfortable journey to the passengers.
SUMMARY OF THE INVENTION:
Few of the advantages of disc brake caliper unit , as disclosed in the present invention, are as under:
i). Economical.
ii). Lighter in weight.
iii). Easy to handle.
iv). Compact in size.
v). More reliable. Indian railways have started using disc brake caliper unit in the high-speed passenger coaches. These high-speed passenger coaches consist of 2 No's Brake discs per axle. For each Brake Disc, one Disc Brake Caliper Unit acts as a braking

device. During the brake application by the driver, the BP pressure is reduced. Due to the reduction in BP pressure distributor valve gets actuated and generates the output pressure. This output pressure enters to the brake caliper unit, which actuates the brake caliper & brake is applied immediately. This reduce the speed of the train as Brake Pads fitted to the Disc Brake Caliper Unit start rubbing against the Brake Disc fitted to the Axle and ultimately bring the train to a standstill position.
Short description of the drawings, indicating certain prior arts as well as illustrating the novel and inventive features of the instant invention:
Figure 1: An illustrative representation of the invention disclosed in Prior art
US5813499, dated 29th Sept. 1998.
Figure 2: An illustrative representation of the invention disclosed in Prior art
US4473136, dated 25th Sept. 1984.
Figure 3: Another illustrative representation of the invention disclosed in Prior
art US4473136, dated 25th Sept. 1984.
Figure 4: An illustrative representation of the invention disclosed in Prior art
US patent no 4497392A.
Figure 5: View of a conventionally available Brake Caliper Unit, being used in
various types of railway coaches (source: http://www.knorr-
bremse.com/media/documents/railvehicles/product broschures/brake system
s/Brake Caliper Units P 1265 EN.pdf).
Figure 6: It represents the schematic view of the sectional view of brake
cylinder, as disclosed in the instant invention.
Figure 7: Top schematic view of the disc brake caliper unit, as disclosed in the
instant invention.

Figure 8: Isometric view disc brake caliper unit, as disclosed in the instant invention.
DETAILED DESCRIPTION OF THE INVENTION WITH THE HELP OF ILLUSTRATIVE DRAWINGS (mainly with the help of Figures 6 to 8):
The schematic drawings included in the instant specification towards illustrating the present invention, particularly drawings 6 to 8 are suitably labelled with numeric references. Said numeric references are chosen corresponding to following structural/functional features of the herein disclosed Disc Brake Caliper Unit:

Working principle of the instant disc brake caliper unit:
The working principle of Disc Brake Caliper Unit is to apply the brakes as and when required. During the brake application by the driver, the BP pressure is reduced. Due to the reduction in BP pressure Distributor Valve fitted on each coach gets actuated and generates the output brake cylinder pressure. The Disc Brake Caliper Unit mainly consists of: -
1. Brake Cylinder (2) with inbuilt automatic slack adjuster.
2. Caliper
3. Brake Pads (11)
Brake Cylinder consists of inbuilt automatic slack adjuster for taking up the excess slack during brake rigging on the release of the brake after the braking operation at which the travel of the piston in the brake cylinder exceeds a normal brake application stroke.
Caliper consists of a middle bracket, LH & RH arm, two brake pad holders and two hangers for mounting the caliper. The caliper transmits power from the brake cylinder to the brake disc during brake application.
Each disc brake caliper unit consists of 4 brake pads 200cm square each. Two brake pads are fitted on each brake pad holder. The brake pads rubs against the brake disc during brake application.
Brake application:- During the brake application, the output brake cylinder pressure from the Distributor Valve enters the Brake Cylinder Body (2). This pressure acts on the Piston (1). Due to this pressure, the Piston (1) inside the Brake Cylinder Body (2) moves to forward direction against the force of Return Spring (3) fitted inside the Brake Cylinder Body (2). Inside the Piston Tube (4) a Threaded Spindle (5), with the help of two rotatable Nuts (6, 7), is fitted.

The forward movement of Piston (1) applies the force on the Load Piece (12) and to the First Rotatable Nuts (6). From the First Rotatable Nuts (6) the force is then transferred to the Threaded Spindle (5). At the end of the Threaded Spindle (5) a Yoke (8) is fitted which is also connected to the Caliper Arms (9). Thus, through Yoke (8) the force from the Threaded Spindle (5) is transferred to the Caliper Arms (9). At the end of the Caliper Arms (9) there are Brake Pad Holders (10) on which Brake Pads (11) are fitted and locked. Hence the force from the Caliper Arms (9) are transferred to the Brake Pads (11).
This reduces the speed of the train as Brake Pads (11) fitted to the Disc Brake Caliper Unit start rubbing against the Brake Disc fitted to the axle and ultimately bring the train to a standstill position.
Brake release:- During the release of the brake, the input pressure to the Brake Cylinder (2) gets exhausted due to which the Return Spring (3) causes the Piston (1) to move back. Along with the Piston (1), Piston Tube (4) and Load Piece (12) moves back to its initial position causing the First Rotatable Nut (6) to rotate in relation with the spindle & in turn automatically correcting the excessive gap. The excessive gap is corrected until the Load Piece (12) touches the Second rotatable nut (7). When the Load Piece (12) touches the Second rotatable nut (7), this causes the complete arrangement along with the Threaded Spindle (5), Yoke (8), Caliper Arms (9), Brake Pads (11) to move to the required position creating a uniform gap required between the Brake Pads (11) and the Brake Disc. The Piston (1) travel is completed until the Piston Tube (4) touches the Brake Cylinder Body (2). During the brake application due to the rubbing of the brake pads and brake disc the gap is increased. This excessive gap is automatically corrected by the slack adjuster

on the release of the brake after the braking operation at which the travel of the piston in the brake cylinder exceeds a normal brake application stroke.
ADVANTAGES OF DISC BRAKE CALIPER UNIT OF THE INSTANT INVENTION
In comparison to available brake caliper unit, the disc brake caliper unit of the instant invention is characterized in:
• Brake Cylinder with inbuilt automatic slack adjuster.
• The axis of the brake cylinder as well as piston extends in perpendicular to the longitudinal direction of caliper arms which results in effective brake force.
• Weight distribution is uniform as the brake cylinder is aligned to the centre axis of the disc brake caliper unit.
• Less number of moving parts resulting in less wear and tear of the disc brake caliper unit.
• Compact in size.
It will be apparent to those skilled in the art that various modifications and variations can be made in the dimensional and structural arrangements within the disc brake caliper unit of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the description, illustrations, drawings, appended claims and their equivalents.

CLAIM:
1. The Disc Brake Caliper Unit for a braking system and automatic slack adjustment thereof, wherein said Disc Break Caliper Unit mainly comprising of Brake Cylinder (2) with inbuilt automatic slack adjuster, Caliper, and Brake Pads (11).
2. The Disc Brake Caliper Unit, as claimed in claim 1, wherein said Disc Break Caliper Unit is characterized in reduction of BP pressure during application of the Break by the driver, leading to actuation of distribution valves fitted on each coach and generation of the output break cylinder pressure.
3. The Disc Brake Caliper Unit, as claimed in claim 1, wherein Brake Cylinder (2) consists of inbuilt automatic slack adjuster for taking up the excess slack during brake rigging on the release of the brake after the braking operation at which the travel of the piston (1) in the brake cylinder (2) exceeds a normal brake application stroke.
4. The Disc Brake Caliper Unit, as claimed in claim 1, wherein said Caliper consists of a middle bracket, LH & RH arms (9), two brake pad holders (10) and two hangers for mounting the caliper., wherein said caliper is characterized in transmiting power from the brake cylinder (2) to the brake disc during brake application.
5. The Disc Brake Caliper Unit, as claimed in claim 1, wherein the preferred embodiment of said Disc Break Caliper Unit comprises of 4 brake pads (12), preferably of dimension 200cm square each, and two brake pads (12) are fitted on each brake pad holders (10) therein.

6. The Disc Brake Caliper Unit, as claimed in claim 1, wherein the said Breaking System is characterized in following steps of Brake application:-During the brake application, the output brake cylinder pressure from the Distributor Valve enters the Brake Cylinder Body (2); Such brake cylinder pressure acts on the Piston (1) and due to such pressure the Piston (1) inside the Brake Cylinder Body (2) moves to forward direction against the force of Return Spring (3) fitted inside the Brake Cylinder Body (2);
Inside the Piston Tube (4) a Threaded Spindle (5), with the help of two rotatable Nuts (6, 7), is fitted;
The forward movement of Piston (1) applies the force on the Load Piece (12) and to the First Rotatable Nuts (6);
From the First Rotatable Nuts (6) the force is then transferred to the Threaded Spindle (5);
At the end of the Threaded Spindle (5) a Yoke (8) is fitted which is also connected to the Caliper Arms (9);
Thus, through Yoke (8) the force from the Threaded Spindle (5) is transferred to the Caliper Arms (9). At the end of the Caliper Arms (9) there are Brake Pad Holders (10) on which Brake Pads (11) are fitted and locked;
Hence the force from the Caliper Arms (9) are transferred to the Brake Pads (11);
This reduces the speed of the train as Brake Pads (11) fitted to the Disc Brake Caliper Unit start rubbing against the Brake Disc fitted to the axle and ultimately bring the train to a standstill position.

The Disc Brake Caliper Unit, as claimed in claim 1, wherein the said Breaking System is characterized in following steps of Brake release:-During the release of the brake, the input pressure to the Brake Cylinder (2) gets exhausted due to which the Return Spring (3) causes the Piston (1) to move back. Along with the Piston (1), Piston Tube (4) and Load Piece (12) moves back to its initial position causing the First Rotatable Nut (6) to rotate in relation with the spindle & in turn automatically correcting the excessive gap. The excessive gap is corrected until the Load Piece (12) touches the Second rotatable nut (7).
When the Load Piece (12) touches the Second rotatable nut (7), this causes the complete arrangement along with the Threaded Spindle (5), Yoke (8), Caliper Arms (9), Brake Pads (11) to move to the required position creating a uniform gap required between the Brake Pads (11) and the Brake Disc. The Piston (1) travel is completed until the Piston Tube (4) touches the Brake Cylinder Body (2).
During the brake application due to the rubbing of the brake pads and brake disc the gap is increased. This excessive gap is automatically corrected by the slack adjuster on the release of the brake after the braking operation at which the travel of the piston in the brake cylinder exceeds a normal brake application stroke.
The Disc Brake Caliper Unit, as claimed in claim 1, wherein Disc brake caliper unit is suitable to be used within the braking system of high speed passenger coaches; wherein it is particularly a pneumatically controlled system to meet the requirements of braking and automatic slack adjustment in railway Coach.

The Disc Brake Caliper Unit, as claimed in claim 1, wherein said Disc brake caliper unit is to be used in the braking system of railway coaches and is characterized in more abrasion resistant, longer working life, lesser maintenance and in ensuring safe and comfortable journey to the passengers.
The Disc Brake Caliper Unit, as claimed in claim 1, wherein said Disc brake caliper unit is characterized in several advantageous features in terms of inventiveness and industrial applications, namely: (i) economical; (ii) lighter in weight in comparison to conventional disc brake caliper units; (iii) easy to handle; (iv) compact in size; (v) more reliable and user friendly etc.