Maintenance Manual for BG Coaches of ICF Design - Air Brake System PDF

Maintenance Manual for BG coaches of ICF design Air Brake System CHAPTER 4 AIR BRAKE SYSTEM 401 INTRODUCTION 403a Charging t...

Maintenance Manual for BG coaches of ICF design Air Brake System CHAPTER 4 AIR BRAKE SYSTEM 401 INTRODUCTION 403a Charging the brake system In Air Brake system compressed air is § Brake pipe throughout the length of used for operating the brake system. The train is charged with compressed air locomotive compressor charges the feed at 5 Kg/cm2. pipe and the brake pipes throughout the § Feed pipe throughout the length of length of the train. The feed pipe is train is charged with compressed air connected to the auxiliary reservoir and at 6 Kg/cm2. the brake pipe is connected to the brake § Control reservoir is charged to cylinder through the distributor valve. 5 Kg/cm2. Brake application takes place by § Auxiliary reservoir is charged to 6 dropping the pressure in the brake pipe. Kg/cm2. 402 CLASSIFICATION OF AIR BRAKE 403b Brake application stage SYSTEM § For brake application the brake pipe The schematic layout shown in figure 4.1 pressure is dropped by venting air illustrates the underframe mounted twin from the driver’s brake valve. pipe graduated release air brake system on Subsequently the following actions main line coaches. The components and take place their relative location is indicated in the schematic layout. § The control reservoir is disconnected from the brake 403 PRINCIPLE OF OPERATION OF pipe. TWIN PIPE GRADUATED RELEASE AIR BRAKE SYSTEM (See figure 4.1) vent type vent type Figure 4.1 SCHEMATIC LAYOUT OF TWIN PIPE GRADUATED REL EASE AIR BRAKE SYSTEM Note: Pressure gauges are installed only in guard’s brake van. Chapter 4, Page 1 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System § The distributor valve connects The brief details of the air brake the auxiliary reservoir to the components and it’s maintenance and test brake cylinder and the brake procedure is described below: cylinder piston is pushed outwards for application of 405 COMMON PIPE BRACKET brakes. § The auxiliary reservoir is Common pipe bracket is mounted on the however continuously charged coach under frame and is suitable for use from feed pipe at 6 Kg/cm2. with all type of distributor valves presently in use on main line coaches. Table 4.1 406 INTERMEDIATE PIECE Description Reduction in B. P. (SANDWICH PIECE) Pressure Minimum Brake 0.5 to 0.8Kg/cm2 An intermediate piece is mounted on the common pipe bracket to fit the distributor Application valve on the common pipe bracket. The Service Brake 0.8 to 1.0Kg/cm2 intermediate piece serves the purpose of Application blanking all the other ports on the Full Service Brake 1.0 to 1.5Kg/cm2 common pipe bracket other than required Application for a particular make of distributor valve. Emergency Brake Brake pipe is fully Each type of distributor valve is mounted Application exhausted and its on the common pipe bracket with its own pressure reduces to intermediate piece. almost zero. 407 AIR BRAKE HOSES 403c Brake release stage: 407a Brake Pipe & Feed Pipe Hoses § Brakes are released by recharging (see figure 4.2) brake pipe to 5 Kg/cm2 pressure through the driver’s brake valve. To maintain continuity through out the § The distributor valve isolates the length of train, the brake pipe (BP) and brake cylinder from the auxiliary feed pipe (FP) are fitted with flexible reservoirs. hoses. Each hose is provided with palm § The brake cylinder pressure is vented end coupling. For easy identification, to atmosphere through DV and the coupling heads are painted with green Brake cylinder piston moves colour for B.P and white colour for F.P. inwards. Also raised letters 'BP' and 'FP' are 404 AIR BRAKE SUB ASSEMBLIES embossed on coupling heads representing Brake Pipe and Feed Pipe respectively. The various Air Brake sub-assemblies and Hose couplings must be checked for components are: leakage of air as per the test procedure given below: i) Common pipe bracket ii) Intermediate piece iii) Brake pipe and feed pipe iv) Brake pipe coupling v) Cut-off angle cock vi) Brake cylinder vii) Dirt collector viii) Auxiliary reservoir ix) Slack adjuster x) Distributor valve xi) isolating cock xii) PEASD xiii) PEAV xiv) Check valve Figure 4.2 - AIR BRAKE HOSES Chapter 4, Page 2 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 407b Test Procedure (see figure 4.3) § Observe leakage, if any from all parts of the hose coupling. For testing the hose coupling the steps § Close the isolating cock 1(b). given below should be followed: § Disconnect the hose coupling from § Use a dummy coupling head to test bed. block the outlet port of the hose § If the leakage is observed through the coupling head, replace the coupling. § Connect to hose coupling under gasket and test again. test to the end of flexible hose. § If leakage persist even after change of gasket the coupling head is § Open isolating cock 1(a) § Adjust pressure regulator (2) so unserviceable and complete assembly shall be rejected. that pressure gauge (6a) shows However if leakage occurs at the 10Kg./cm2 air pressure. hose nipple or coupling end hose § Immerse the hose coupling joint the clamp should be assembly completely in the tub of attended/replaced to make the water. assembly leak proof. § Open isolating cock (1b) and see that (6b) shows 10 Kg/cm2 pressure. Kg Cm 6a MR 6b Kg Cm CHARGING PRESSURE GAUGE 11/4” BSP SOCKET TO MAIN RESERVOIR ISOLATING COCK COUPLE HOSE ISOLATING COCK PRESSURE REDUCER COUPLING NIPPLE END 6 1a 1b 4 1c FLEXIBLE HOSE 2 HIGH PRESSURE EXHAUST COCK (10 KG/CM2 CAL) figure 4.3 – TEST BENCH FOR HOSE COUPLING 408 CUT OFF ANGLE COCK on either end of each coach to facilitate (see figure 4.4) coupling and uncoupling of air hoses. When (Ref: Drg. No. WD-88123-S -01 the handle of the cut off angle cock is and WD-88123-S-01) placed in closed position it cuts off the passage of compressed air, there by Cut off angle cocks are provided facilitating coupling and uncoupling action. both on brake pipe & feed pipe Figure 4.4 - CUT OFF ANGLE COCK Chapter 4, Page 3 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System The cut off angle cock consists of two (b) Screw driver 12”/300 mm long. parts viz. cap and body which are secured (c) Vice. together by bolts. The cap and the body (d) Light hammer. together hold firmly the steel ball inside it, which seated is on nitrile rubber seat. 408c Procedure The ball has a special profile with the provision of a groove at the bottom i) Dismantling portion for venting the air to the atmosphere. § Hold the cut – off angle cock in a vice. On the top surface of the body a bore is § Unscrew the lock nut from the stem. provided for placing the stem, to which a § Take out the handle assembly (The self locking type handle is fixed. When handle assembly need not be the handle is placed parallel to the cut off dismantled further unless it is angle cock the inlet port of the cut off necessary to change the plate spring angle cock body is connected to the outlet i.e. if it is found, heavily rusted, port, through the hole provided in steel pitting crack or the spring is ball. Thus air can easily pass through the permanent set). cock. This position of the handle is known § Unscrew the four hexagonal bolts as open position. When the handle is and spring washers. placed perpendicular to the cock body the § Detach cap from the body. steel ball gets rotated and the spherical § Remove ‘O’ ring and ball seat from and groove portion of the ball presses the cap. against the sealing ring at inlet and outlet § Turn the stem in such a way that the port, there by closing the passage of inlet ball can be pulled from the stem. air and venting the outlet air through the § Slightly hammer the stem at its top vent hole. This position of the handle is and take out the stem through the known as closed position. bore of the body. With the stem one leaf spring is provided § Remove the ball seat from the body. which presses the operating handle downwards. By virtue of this, handle gets ii) Cleaning of Parts seated in deep grooves at ON / OFF position resulting in a mechanical lock. § Clean out side portion of the body and cap with wire brush. Under normal working conditions, the § Direct a jet of air to remove the dust. handle of all cut off angle cocks of BP are § Clean all metallic parts with kept open except the rear end angle cocks kerosene oil and wipe dry. (BP). This facilitates in charging the complete air brake system with iii) Replacement of Parts compressed air supplied by the compressor housed in the locomotive. Cut § Replace all rubber parts. off angle cock fitted on the brake pipe is § Replace spring-washer, nut & bolts painted green. in case they are excessively corroded or defective. 408a Overhauling of Cut Off Angle Cock § Replace handle spring if it is found heavily rusted, is having pitting The cut-off angle cock is to be completely crack or is permanently set dismantled and overhauled in every POH (Dismantle the handle assembly, and or when there is some specific trouble. fit a new spring along with a snap During overhauling, it is dismantled for head rivet). cleaning, replacement of parts and § Replace stainless steel ball if found checking for effective functioning. The with scratch marks on the outer POH kit should be as per annexure 4.3. surface or dented. 408b Tools & Equipment iv) Assembly The following tools and fixtures are required for overhauling § Insert the two ‘O’ rings in their respective grooves on the stem. (a) Single end spanner. 1) A/F 17 for M10 nut pivot screw. 2) A/F 10 for M6 nut. Chapter 4, Page 4 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System § Keeping the threaded end of the § Check pressure drop in gauge (6b) stem first, insert the stem into the there should not be any leakage from body through the bore of the body. flange joints, vent and outlet port of § Place one ball seat in its groove the angle cock. inside the body. § Close cock (1c) and tighten the § Position the ball after correctly dummy plug and seal the outlet of aligning its venting slot in the bore the angle cock. of the body. § Move the handle to the open § Place the second ball seat and ‘O’ position. Open cock 1c. ring in their respective positions on § Check for leakage from body and the cap. cap joint, vent and all over the stem § Secure the body and cap by Hex. periphery using soap water. No Hd. Bolt (M6) and spring washer leakage is permissible. (for M6). § Move the handle to closed position § Place the handle assembly on the and notice a short blast of air through stem and secure it with Hex. Hd. the vent. Nut (M10). § Close cock 1c then Open cock (1d) § During assembly apply a light coat and exhaust the pressure to zero. of shell MP2 or equivalent grease on § Remove the angle cock. the external surface of the threads § Report results of the test. and the ball. iii) Safety Precautions 408d Testing of Cut Off Angle Cock § Specified tools and fixtures should be used for assembly and i) Tools and Equipment disassembly operations. § The small metal parts like leaf § Test Bench spring, nut, bolts, washers, screws § Compressor to build pressure upto etc should be kept in a safe place 10 kg/cm2. and replaced in case found § Single ended spanner as per IS 2027 defective. a) Across face 17 (for M10 lock § Inlet and outlet port of the tested nut) 1No. angle cock should be plugged with b) Across Face 13 (for M8 studs) 2 protection cap to prevent entry of No. dust and moisture inside the cut off § Screw Driver –300mm,1 No. angle cock. § 1 ¼ “ BSP dummy Plug with seal. § Dummy plug for angle cock. 409 BRAKE CYLINDER (see figure 4.5) (Refer Drg. RDSO SK-97015) ii) Test Procedure (refer figure 4.9) On every coach fitted with air brake Following test procedure sh ould be system two brake cylinders are provided adopted for performing the leakage test. for actuating the brake rigging for the application and release of brakes. During § Mount the angle cock on the base of application of brakes the brake cylinder the test bench (Part No. 7 of the develops mechanical brake power by figure 4.9 of the test bench). outward movement of its piston assembly § Move the handle to the closed after receiving air pressure from Auxiliary position. reservoir through the distributor valve. § See that cock (1e) and (1c) are in This is transmitted to the brake shoes closed position. through a combination of levers. During § Now open cock 1(a) and 1(b) till release action of brakes the compression MR indicates a pressure of 10 spring provided in the brake cylinder Kg/Cm 2. brings back the rigging to its original § If necessary, adjust pressure position. The cylinder body is made out of regulator (2) to maintain the sheet metal or cast iron and carries the pressure at 10 kg/Cm2. mounting bracket, air inlet connection, § Open cock (1c) and check the ribs and flange. To the cylinder body, a leakage with soap solution. There dome cover is fitted with the help of bolts should not be any leakage. and nuts. The dome cover encloses the spring and the passage for the piston Chapter 4, Page 5 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System Figure 4.5 – BRAKE CYLINDER trunk, which is connected to the piston by Sr. Description screws. The piston is of cast iron having No. a groove in which piston packing is 4. Socket Wrench 19 mm (For seated. Piston packing is of oil and M12) abrasion resistant rubber material and is 5. Screw Driver 12" (300 mm) snap fit to the piston head. The packing 6. Special fixture (Screw press/ has self lubricating characteristic which Pneumatic) ensures adequate lubrication over a long 7. Gauge for examining bore of the service period and extends seal life cylinder considerably 409c Dismantling of Brake Cylinder The piston packing also seals the air- flow from the pressure side to the other side Before dismantling the dome cover insert and is guided by the wear ring. The wear a bolt φ 12x25 long and secure one of the ring prevents the friction between cylinder hole in the piston trunk for the purpose of body and the piston head. The piston sub safety to prevent dome cover working out assembly incorporates a push rod, which of the piston rod due to the cylinder return can articulate and take minor var iations in spring force. alignment during fitment/operation. For preventing knocking during running, a § Unscrew the Hex. HD nut and take rubber anti rattler ring is also provided. out the spring washer on the dome cover. 409a Overhauling of Brake Cylinder § Turn the handle of the fixture to Brake cylinder has to be thoroughly release the clamp and withdraw the overhauled for efficient and reliable holding clamp of the fixture till the trouble free performance during its return spring inside the cylinder is prolonged service life. The complete fully expanded and free. overhauling of the brake cylinder is to be § Remove the dome cover and take carried out every POH of the coach. out the return spring. § Remove the piston rod sub- 409b Tools & Equipments assembly, piston ring packing, wear ring and slide out the anti Sr. Description rattler ring from the piston rod. No. § Unscrew the CSK , head screw and 1. Torque Wrench 0-3 Kg m range separate the piston, pin, and piston 2. Double End Spanner 24x27 mm trunk & piston rod assembly. across face (For M16) § Unscrew the brake cylinder plug at 3. Double End Spanner across face the rear end. 13x14 (For M12) Chapter 4, Page 6 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 409d Cleaning of Parts § Smear the piston head & inside the cylinder body with MP 2 grease or § Blow a jet of air to clean the dust equivalent. on the external surface. § Ease the packing into the cylinder § Clean the metallic parts using wire with a wooden spatula with a brush and kerosene oil. round nose and round edge to § Clean the internal parts with nylon avoid damage to the piston bristle brush. packing. § Clean piston packing, wear ring § Push the piston assembly and rubber parts with soap water approximately to the central solution. position of the cylinder. 409e Replacement of Parts § With the help of special fixture, bring down the dome cover on to § Replace return spring in case of the cylinder body and fasten the 8 crack, kinks or permanent set. Hex. HD bolt, nut and spring § Replace the brake cylinder body if washer with required torque. found with deep marks, heavily § Take out the φ 12x25 long pin corroded, or the bor e is worn from the piston trunk hole. uneven or having ovality. § Fit back the plug at the rear of the § Replace all rubber parts. cylinder. § If piston trunk is worn excessively it should be replaced. 409i Testing of Brake Cylinder (see 409f Inspection and Repairs of the Parts figure 4.6) § Examine visually that the internal i) Brake Cylinder Test Bench surface is free from scratches, rust. § Brake cylinder bore to be checked Test bench consists of the following for ovality with gauge. main parts § Check the characteristics of the a) 5 nos. of isolating cocks (1a, 1b, return spring. 1c, 1d, 1e and 1f). § Piston trunk to be checked for wear b) Pressure reducing valves as and tear. below § Pin, piston rod should be checked c) 2a - to be set on 10 Kg/cm2. for wear. d) 2b - to be set on 6 Kg/cm2. § Dome cover shall be checked for e) 2c - to be set on 0.8 Kg/cm2. excessive wear and if worn build up with welding and thereafter re- f) 2d - to be set on 3.8 Kg/cm2. bore to the required size. g) Pressure gauges § Gauge, bush bore of the piston rod, h) 6a - to measure supply pressure. replace it if worn. i) 6b- to measure brake cylinder pressure. 409g Testing of Brake Cylinder Body for Leakage j) Pipe line filter – Item no 3 k) Brake cylinder pressure Before assembly, put dummy plate on the mounting base with fixture –Item dome side and subject the brake cylinder no 4 for hydraulic pressur e of 10 kg/cm2 for 5 l) Air reservoir – Item no.5 minutes. No leakage is permitted. ii) Tools required during Testing 409h Assembly of Brake Cylinder § Assemble piston rod, pin, and piston a) Torque wrench range (2-3 kgm trunk on piston, tighten CSK screws capacity) – One number. to piston trunk and piston. b) Double ended spanner (M16) § Slide anti-rattler ring from the piston across face 24x27 – One number. front side. c) Socket wrench (M12) across face § Assemble piston return spring on the 19 – One Number. piston head and insert the dome d) Double ended spanner (M8) cover over the piston trunk. across face 13x14 – One number. e) Screw Driver – 300mm – One § Insert φ 12 x 25 mm long head pin number. into the hole provided in the extended portion of the trunk. Chapter 4, Page 7 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System Ref. No. of Description No. of Ref. No. of Description No. of Isolating cock Pressure Reducing valve 1a Supply angle cock 1 2a Set on 10 kg/cm 2 1 1b Angle cock 1 2b Set on 6 kg/cm2 1 1c Angle cock 1 2c Set on 0.8 kg/cm 2 1 1d Angle cock 1 2d Set on 3.8 kg/cm 2 1 1e Exhaust cock 1 3 Pipe line filter 1 1f Angle cock 1 4 Brake Cylinder pressure 1 mounting base 5 Air reservoir 1 Pressure Gauge 6a Supply Pressure 1 6b Brake Cylinder Pressure 1 Figure 4.6 – TEST BENCH FOR BRAKE CYLINDER After the overhauling of the brake § Check the brake cylinder piston cylinder, it is mounted on the test bench stroke at 0-5 kg/Cm2 pressure and tested. It should be operated a few for its jerk free smooth times on the test bench to ease the piston. movement. Each brake cylinder after its maintenance § Close the safety guar d. and overhaul shall be subjected to the § Close the cock (1b), (1c) and following tests on the test bench. (1d). § Open cock (1a) and (1f) and let a) Strength test the reservoir pressure increase. b) Pressure Tightness Test. § Set pressure regulator (2a) at iii) Strength Test 10Kg/cm2. § Monitor the pressure in the For strength test, procedure reservoir with the help of the MR described below should be follow: Gauge (6a). § Let the pressure reach upto 10 § Place the repaired/overhauled kg/cm2. brake cylinder body on mount ing § Open cock (1b) so that air base of the test stand. This collected in the reservoir is mounting base (4) is provided transferred to the brake cylinder. with a safety guard. § Adjust the pressure in the brake § Connect the air pressure line to cylinder with the help of the the brake cylinder. pressure regulator (2b). Chapter 4, Page 8 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System § Monitor the pressure in the brake This will discharge the brake cylinder with the help of the cylinder. pressure gauge (6b). § Remove the brake cylinder from § Close the cock 1(b) as soon as the test stand. pressure reaches 6 kg/cm2. § If operation is not correct or § Wait for 2 minutes. leakage rate is higher, dismantle § Brake cylinder should withstand the brake cylinder and examine this pressure. the piston packing wear ring for § Open cock (1e), this will proper fitment, examine the discharge the air pressure from fitment of the plug for leakage, the brake cylinder and the piston reassemble the components and assembly will come back. retest. v) Precautions during Testing iv) Pressure Tightness Test § Safety Guard should be used Brake cylinder when fully assembled during the strength test. must be tested for leakage. For § Assembled or dismantled brake pressure tightness test, procedure cylinder should be stored in such described below should be followed. a way to prevent the following: § Mount the brake cylinder on the i. Flange surface should be test stand and tighten the prevented from damage. mounting bolts and nuts. ii. Inlet port should be plugged § Set the brake cylinder, piston with a protective cap to stroke at 85+ 10 mm and the prevent the entry of dust and pressure regulator (2c) at 0.8 moisture inside the brake Kg/cm2. cylinder. § Open cock (1c) and let the air be transferred to the brake cylinder § Avoid damage to piston packing till the air pressure reaches upto by dull or sharp edged thin 0.8 kg/cm 2. Monitor this bladed tool. pressure with the help of the § Fit 12 dia, 25 mm long round pressure gauge (6b). headed pin on the hole provided § Close cock (1c) as soon as the in the extended portion of trunk pressure reaches upto 0.8 surface before loosening the kg/cm2. cover bolts. § Excessive lubrication of the § Wait for 1 minute till the cylinder must be avoided. pressure stabilizes in the gauge § Specified tools and fixtures (6b). Measure the final pressure should be used for handling, in the gauge (6b). mounting and removing the § Check for the pressure drop, brake cylinder from the test which should not be more than bench. 0.1 kg/cm2 in 10 minutes. § The small metal parts like § Open cock (1e). springs, washer, screws, nuts, bolts, washers should be kept in § Close cock (1c) and open cock (1d). a safe place and replaced in case found defective. § Repeat the test by setting the piston stroke at 130+10 mm. 410 DIRT COLLECTOR (See figure 4.7 & This time the air pressure is to be 4.8 ) (Ref. Drg. RDSO. SK-97005) maintained in the cylinder at 3.8 kg/cm2 with the help of the 410a Salient features of Dirt Collector pressure regulator (2d ) at 3.8 Kg/cm2. As above, the leakage Dirt Collector is placed in the brake pipe should not exceed 0.1 kg/cm2 in line and feed pipe line at a point from 10 minutes. where a branch is taken off to the § After the test is over, close the distributor valve and the auxiliary cock (1d) and the open cock (1e). reservoir. The air entering into the dirt Chapter 4, Page 9 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 410b Tools and Fixtures for overhauling The following tools and fixtures are required for overhauling: a) Spanner 19 x 22mm b) Vice. c) Screw Driver 410c Procedure for Overhauling i) Disassembly § Hold the dirt collector in vice. Figure 4.7 - COMPONENTS OF DIRT § Loosen drain plug and remove it COLLECTOR completely from housing. collector from the brake pipe and feed § Remove top cover and seal by pipe is guided through suitably shaped loosening four hexagonal nuts and passages in the dirt collector body to removing hexagonal bolts. produce centrifugal flow. The air is then § Remove filter from body. filtered through additional filter assembly before it is passed to outlet on branch pipe ii) Cleaning of Parts side to provide dust proof air to the distributor valve /auxiliary reservoir after § Clean all metallic parts using brush arresting fine dust particles. The dirt and kerosene oil. contained in the air descends down and § Clean filter with soap water. gets deposited in the dirt chamber. § Check all parts for any damage. However, fine particles are also arrested in the filter assembly. The dust particles iii) Replacement of Parts accumulated in the dirt chamber are removed by opening the drain plug. § Replace sealing ring and gasket. Rubber gasket is provided between the § Replace filter if found punctured cover and housing to prevent leakage. or damaged. Similarly leather washer is provided between the housing and the drain plug to Check spring washer and replace in prevent leakage. case defective or excessively corroded. The dirt collector is to be completely dismantled and overhauled in every POH. Fig. 4.8 - SECTIONAL VIEW OF DIRT COLLECTOR Chapter 4, Page 10 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System iv) Assembly § Keep cocks ( 1f), (1c) and 1(e) § Assemble body after smearing closed. grease. § Open cock (1a) and (1b). § Locate filter in position and § Charge the reservoir (5) to 10 assemble top cover with new kg/cm2. gasket. § Close two openings on the dirt § Fix hexagonal bolts/nuts along collector using dummy flanges. with the spring washer. § Open cock (1e), check the § Fix new sealing ring to the pressure at (6c). it should be bottom and assemble drain plug. equal to 10 kg/sq. cm. § If not develop pressure up to 10 410d Testing of Dirt Collector kg/cm2 by adjusting pressure Testing of dirt collector is needed after its regulator (2). overhauling. § Close cock ( 1e) § Check for leak over the body and i) Tools and Equipment joints with the help of soap § Test Bench solution, no leak is permitted. § Compressor, capable of building § Also check for pressure drop in air pressure up to 10 kg/sq. cm. gauge 6 (c)- for 3 minutes § Double ended spanner (Across § Pressure in the gauge 6c should Face 19x22) – One No. be maintained. § Dummy flange for dirt collector § Reduce the pressure in the main – 2 nos. reservoir (5) to 5 kg/cm2 by opening cock (1f) and adjusting ii) Test Procedure (refer figure 4.9) the pressure regulator (2). § Close cock (1f) as soon as § Mount the dirt collector on base pressure reaches upto 5 kg/cm2. of the test bench. Fig. 4.9 - TEST BENCH FOR ANGLE COCK, ISOLATING COCK, DIRT COLLECTOR, CHECK VALVE AND GUARD'S EMERGENCY VAN VALVE Chapter 4, Page 11 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System § Remove the dummy flange from 411c Procedure for Overhauling the outlet port (which feeds to the distributor valve). i) Dismantling § Check for free flow of air from the outlet port. (If air is not § Unscrew the drain plug and drain flowing freely it means that the cock. filter is choked). § Drain the water accumulated ni the § The pressure will soon exhaust tank. through the outlet port. ii) Cleaning of Parts § Remove the dirt collector from the test stand. § Examine the outer surface for any pitting, scales or rusting. 411 AUXILIARY RESERVOIR § Clean the exterior of the auxiliary (refer figure 4.10) reservoir with a wire brush. § Pour kerosene oil in to the auxiliary 411a SALIENT FEATURES reservoir and roll few times and drain the oil. The auxiliary reservoir is a cylindrical § Dry the interior of the reservoir with vessel made of sheet metal. On both the a jet of air. ends of the reservoir, flanges are provided § Rinse the reservoir with RUSTO- for pipe connections. One end of the LINE and then with ESSO-RUST auxiliary reservoir is connected to the 392 or equivalent. brake pipe through the distributor valve. § Clean the drain plug with a wire Auxiliary reservoir is charged through the brush. feed pipe to a pressure of 6kg/sq cm. At § Auxiliary reservoir shall be painted the bottom of the auxiliary reservoir, a on the exterior with two coats of zinc drain cock is provided for draining out the chromium prim er and two coats of condensate /moisture. The auxiliary black enamel. reservoir should be overhauled in every POH. iii) Replacement of Parts Note: The dimension & tolerances of the auxiliary reservoir shall be as § Replace the plug washer. indicated in latest revision of RDSO § Replace the plug if threads are rusted drawing number SK-96081. or damaged. 411b Tools and Equipment for overhauling iv) Assembly Spanner A/F 19x22. Assemble the drain plug with washer by Light hammer screwing it back into its position Figure 4.10 – AUXILIARY RESERVOIR Chapter 4, Page 12 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 411d Testing of Auxiliary Reservoir 412a Salient Features i) Air Pressure Test The guard’s emergency brake valve § Block one side passage of the consists of a housing in which a ball is auxiliary reservoir with dummy housed. The ball has a through hole flange. similar to the isolating cock. To the ball a § Admit air pressure from the other handle is fixed at the top. By operating the side passage at 10 Kg/cm2. handle the ball can be rotated along the § Check the leakage at the weld seams, vertical axis. When the hole in the ball with soap water solution. gets aligned with the inlet and the exhaust § No leakage is permitted. port the compressed air can pass through the valve. However, for restricting the ii) Hydraulic Test flow of air a choke of 5mm is fitted in the exhaust port for controlling the rate of BP § With a hydraulic pump, apply a exhaust. The inlet port of the valve is pressure of 16 Kg/cm2 from one connected to the brake pipe. In case of an flange end after blocking the emergency, the guard moves the handle of opposite end. the guard’s emergency brake valve so that § Hold the pressure for 5 minutes. it is placed parallel to the inlet pipe. This § Check for the leakage on the external action causes the air from the brake pipe surface of the reservoir by gently to be exhausted to the atmospher e through tapping on the weld seams with a a choke of 5 mm. The drop in pressure in light hammer. the brake pipe can also be observed in the § No leakage or bulging is permitted. air flow meter provided in the locomotive § Drain out the water completely and cabin and the driver applies the brakes for allow the reservoir to dry, by stopping the train. The handle of the directing a jet of air. guard’s emergency brake valve has to be reset manually to normal position before 411e SAFETY PRECAUTIONS the brake pipe pressure is recharged. § Specified tools and fixtures should Note: The general design and controlling be used for assembly and dimension of guard’s emergency dismantling operations. valve shall conform to the latest § Rubber / leather components should revision of RDSO drawing no SK- be stored in a safe place away from 73549. heat, alcohol & acids. All metal parts like washers should be kept in a safe The guard's emergency brake valve place. should be completely dismantled and overhauled in every POH. 412 GUARD'S EMERGENCY BRAKE VALVE (refer figure 4.11) Figure 4.11 – GUARD’S EMERGENCY BRAKE VALVE Chapter 4, Page 13 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 412b Tools and Fixtures for overhauling iv) Assembly The following tools and fixtures are § Place seat ring in its position in the required for overhauling bore of the body on one side. § Apply grease lightly on the ball. § Test rig/stand § Fit ‘O’ rings on the spindle. § Spanner A/F 19/22. § Insert the ball in the bore of the body § Special spanner for removing thread in such a way that the ball sits on the plug. seat ring and the groove seat for § Spanner for removing gland. spindle is in top position. § Light hammer § Insert the spindle with ‘O’ rings such § Vice. that the sp indle enters in to the groove. 412c Procedure for Overhauling § Screw the gland in to the body. § Insert the second seat ring through i) Dismantling the bore of the housing. § Fit ‘O’ ring on the threaded plug. § Hold the valve in the vice. With a special tool screw the § Unscrew the nut on the stem and threaded plug. remove the nut and the spring § Screw the threaded plug along with washer. the ‘O’ ring into the housing till the § Remove the handle. ball seat touches the ball. § Unscrew the gland and pull out the § The handle shall be put on the stem from the body. spindle and tightened with spring § Remove the two -gland packing on washer and nut. the stems. § Unscrew the threaded plug from the 412d Testing of Guard’s Emergency Brake body using a special spanner. Valve § Remove the ‘O’ ring and the ball seat from the body. § After overhauling, fix the valve to § Remove the ball and the second ball the test bench. (refer figure 4.9 & seat from the body. 4.11) § Put the handle of the valve in off ii) Cleaning of Parts position (close position). § Charge the inlet port with a pressure § Direct a jet of air on the valve body of 10 Kg./cm2. to remove the dust & dirt. § Check for leakage on the spindle § Clean the external parts of the valve portion and on the exhaust port with with wire brush. soap water solution. § All metal parts shall be washed with § No leakage is permitted. kerosene oil and wiped dry. § Operate guard’s emergency brake § Rubber parts shall be washed with valve, by putting the handle in open soap water solution. position. Air should escape through § Steel ball shall be handled carefully the vent of the valve. to avoid scratch marks or dent. 412e Safety Precautions iii) Replacement of Parts § Specified tools and fixtures should § Replace all the rubber parts such as be used for assembly and gland packing and ‘O’ ring. dismantling operations. § If spindle thread is corroded or § Rubber components should be stored damaged, the spindle shall be in a safe place away from heat, replaced with a new one. alcohol & acids. § If threads on the threaded plug are § All metal parts like nuts, washers damaged or corroded badly, the plug should be kept in a safe place. shall be replaced with a new one. § If ball of the valve has dent or scratch marks it should be replaced with a new one. Chapter 4, Page 14 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 413 SLACK ADJUSTER (see figure 4.12) adjuster does not pay out slack immediately, but indexes the amount of 413a Salient Features slack to be paid out. If the slack really is Slack adjuster (also known as brake too small, the slack adjuster will pay out regulator) is a device provided in the this indexed slack at the next brake brake rigging for automatic adjustment of application. Thus false payout will not clearance/slack between brake blocks and occur. wheel. It is fitted into the brake rigging as True Slack Adjuster i.e. The slack a part of mechanical pull rod. The slack adjuster adjusts incorrect slack only, thus adjuster is double acting and rapid giving the brake its best possible pre- working i.e. it quickly adjusts too large or adjusted limit of piston strokes, ensuring a too small clearance to a predetermined smooth and efficient braking force at all value known as `A’ dimension. The slack times. adjuster maintains this `A’ dimension throughout its operation. The slack Shock Resistant i.e. Train shocks will not adjuster, type IRSA-450 is used in cause false take-up or payout of slack. passenger coaches, It is composed of the When brakes are released, the moving following parts parts of the slack adjuster are securely § Adjuster spindle with screw thread of locked. quick pitches (non self-locking). § Traction unit containing adjuster nut, 413b Overhauling of Slack Adjuster adjuster tube and adjuster ear etc. § i) Tools & Equipment Leader nut unit containing leader nut and barrel etc. The following tools and fixture are § Control rod with head. required for overhauling of slack adjuster; The out standing features of slack adjuster IRSA-450 are: (i) Jacking tool – for mass repair / Fully Automatic i.e. once initially set, no overhauling of Slack Adjuster manual adjustment is further necessary at pneumatically operated fixture is any time during its operation. used. (ii) Special Spanner Double-Acting i.e. The brake shoe clearance is adjusted to its correct value (iii) Straight Nose pliers (external) both ways, either when it has become too (spring type)18 mm to 25 mm- large (owing to wear of the brake shoes external and wheels) or when it has become too (iv) Bend nose pliers (internal) 25 -30 small (e.g. owing to renewal of `worn out mm –internal brake blocks’). (v) Screw driver Rapid working i.e. correct brake shoe (vi) Pipe vice & simple 6” vice clearance is automatically restored after (vii) Open end spanner 11-13 mm. one or two applications of the brake. (viii) Hand punches (ix) Kerosene oil bath Verification i.e. If resistance occurs early in the brake application, caused by heavy (x) Air jet gun brake rigging, e.g. an ice coating on the (xi) SAB test bench brake shoes, etc., in such cases the slack A1 A1 A A Note: The Slack Adjuster takes up100 mm per braking. Dimension A1 will be 98 + 1/-4 mm (refer G-92) Figure 4.12 – SLACK ADJUSTER Chapter 4, Page 15 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 413c Procedure for Overhauling 413e Safety Precautions The slack adjuster shall be overhauled at The following safety precautions should the time of POH of rolling stock. While be observed during overhauling of slack dimantaling or assembling it is essential to adjuster. use special tools. Each component of § The place of overhauling must be slack adjuster shall be examined. Worn clean and free from dust. out part shall be checked according to the § Ensure that no foreign limits. For details, refer RDSO Technical matter/particle remain inside the sub - pamphlet No. G -92(October-91). assemblies during re-assembly. § All rubber gasket, seal ring, washers The minimum desired characteristic of must be replaced during overhaul. each spring should be taken as under [Ref: § Specified tools and fixtures are used RDSO Technical pamphlet No. G-92 for disassembly and assembly (October -91)]: operations. Table 4.3 413f Testing of Slack Adjuster (refer figure 4.13) Sr. Description Part Spring Minimum No of spring No. length permiss- After overhauling, testing of slack compre- ible force adjuster in carried out in a test rack for :- ssion 1. Barrel spring 21 330 mm 140 kg i) Take up test & ii) Pay out test 2. Pay out 11 100 mm 58 Kg. a) Attach the adjuster ear to the free spring end of the cylinder lever of the test rack 3. Take out 37 21.5 mm 22 Kg. b) Screw the test rack spindle into the spring Slack Adjuster until the entire length of thread is covered by spindle 4. Clutch 39 38 mm 300 Kg. sleeve and attach the free end of the sprin g spindle to the test rack. i) Pay-in test Any spring, which does not conform, to the above characteristic should not be § Let down the control rod, so that the used. In addition any of the springs is fork of the rod clasps the adjuster badly rusted or having compressed coil tube of the Slack Adjuster turns should not be used. § Apply and release the brake a few times letting the slack Adjuster take The following parts must be replaced up until the correct piston stroke is during POH of the slack adjuster[Ref: obtained (until the indicator is within RDSO Technical pamphlet No. G-92 + 5 mm tolerance field of the scale). (October -91)]; ii) Pay-out test § Spring dowel sleeve part No. (18) § Lock washer part No. (27) § Turn up control rod and make two § Seal ring part No. (2) brake applications letting the slack § Seal ring part No. (43) adjuster pay out. § Rubber gasket part No. (4) § Repeat the above pay in and pay-out § Spring dowel sleeve part No. (25) tests a couple of times. § Dog pin part No. (6) § satisfactorily, dismantle it and check § Tab washer part No. (34) that the parts are placed correctly. § The slack adjuster must then be 413d Lubrication tested once more in the test rack in accordance with the above After cleaning and inspection all parts of instruction. slack adjuster should be coated with semi- § After the test is finished, remove the fluid grease SERVOGEM -RR3 or spindle from the slack adjuster. MALMEROL MULTIGREASE LL3 § Remove the slack adjuster from the (refer G-92) before undertaking re- test rack and unscrew adjuster ear. assembly. Chapter 4, Page 16 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System Figure 4.13 – TEST RACK FOR SLACK ADJUSTER installed in the brake rigging and the Give adjuster spindle a final thorough correct piston stroke is obtained as inspection making sure that the threads follows:- are liberally greased, and screw it into the Slack Adjuster unt il its end protrudes § Place an iron object e.g. a hammer from Adjuster tube. Put the safety collar between the brake block and the and secure it with the spring dowel sleeve. wheel tread. Make two brake Make sure that the spring dowel sleeve applications after the second pin fits tightly and that its ends do not application the correct piston stroke protrude above the surface of the collar. should be obtained. Should there be any burrs on the collar, smooth off with a fine file and wipe clean. § Remove the iron object. Make two Then screw the adjuster spindle back into brake applications. After the first the Slack Adjuster enough to make room application the piston stroke is too for the adjuster ear. long, but after the second application Slide control rod head with control rod the correct piston stroke is recorded on to adjuster tube. Place lock washer on by the slack adjuster. thr eaded portion of adjuster ear and screw ear into threaded end of adjuster 413g Painting tube. The slack adjuster is given a coat of Note : Hold adjuster tube firmly with a anticorrosive paint, excluding the adjuster pipe wrench. Secure lock washer. Install tube. the Slack Adjuster in the brake rigging. iii) Testing of slack adjuster in brake Note : The unthreaded portion of the rigging with hand brake adjuster spindle should not have a thick coating. In case a test rack is not available in the work shop, a test of function of the slack adjuster ought to be carried out after the slack adjuster is Chapter 4, Page 17 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 413h Procedure for Brake Rigging setting such cases the `e' dimension can and measurement of “A” and “e” be restored by adjusting link dimensions:- provided on the bogie frame head stock. The procedure to be adopted for operating brake rigging setting and measuring ‘A’ (ii) Measure ‘e’ dimension i.e. and ‘e’ dimension is listed below:- distance between protection tube end and mark on adjuster spindle For ‘A’ dimension (16 +2/-0 mm for 13 using measuring stick after two t bogie and 22 +2/-0 mm for 16.25 t or three brake application. It bogie) (refer G-92) should be set to nearly to its maximum limit i.e. 375± 25mm. (i) Ensure the air brake is in fully released condition and all the 413i Safety Precautions brake rigging gears are in proper condition. § Always use wedge between wheel and rail before application and (ii) Apply brake three to four times release operations for setting and to ease the rigging, by dropping measuring A and e dimension to and re-charging the air pressure prevent rolling of coach. in the brake pipe § Ensure no part of the worker’s body (iii) Ensure once again that brake rigging is in fully released is in touch with moving brake condition. rigging gears during application and releasing of brakes. If ‘A’ dimension is not correct § Do not touch or hold slack adjuster barrel while it is in motion. 1. Remove pin securing the control rod in U bracket. § Before setting any dimension ensure wear of brake shoe does not exceed 2. Detach control rod and rotate it to its minimum permissible worn to adjust the gap between barrel limit (i.e. thickness of the shoe end face & control rod head as should not be less then 20 mm). specified in note above. Secure the control rod in U bracket. § There won't be any slack take up 3. Apply brakes two to three times. provision in the slack adjuster and slack adjuster will only act as 4. Check the ‘A’ dimension using strut/pull rod. This is because of the gauge. brake shoes and wheel wear reaching their condemning limit/near 5. Recheck dimension ‘A’ with brakes fully released after every condemning ilmit. In such cases the `e' dimension can be restored by brake release. adjusting link provided on the bogie 6. Lock the control rod head firmly frame head stock. with check nut and tooth lock washer. § Measure ‘e’ dimension i.e. distance between protection tube end and 7. Secure pin with split pin. mark on adjuster spindle using measuring stick after two or three For ‘e’ dimension brake application. It should be set to nearly to its maximum limit i.e. (i) If slack is in excess beyond the ± 25 mm. 375± capacity of slack adjuster (`e' dimension 375+25mm) there won't be any slack take up provision in the slack adjuster and slack adjuster will only act as strut/pull rod. This is because of brake shoes and wheel wear reaching their condemning limit/near condemning limit. In Chapter 4, Page 18 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System 414 DISTRIBUTOR VALVE 415 C3W DISTRIBUTOR VALVE (refer figure 4.14) Distributor valve is the most important functional component of the air brake The C3W Distributor Valve consists of: system and is also sometimes referred to i. Main body as the heart of the air brake system. The distributor valve senses drop and rise in ii. Quick Service valve brake pipe pressure for brake application iii. Main valve iv. Limiting device and release respectively. It is connected to the brake pipe through branch pipe. v. Double release valve Various other components connected to vi. Auxiliary reservoir check valve vii. Cut off valve the distributor valve are auxiliary reservoir, brake cylinders and control viii. Application choke ix. Release choke. reservoir. 415a Operation of C3w Distributor Valve 414a Function of Distributor Valve (Refer Fig 4.14) For application and release of brakes the For effective functioning of the air brake brake pipe pressure has to be reduced and system, the distributor valve has to increased respectively with the help of operate effectively during driver's brake valve. During these operations the distributor valve mainly i) Charging stage performs the following functions. ii) Application stage and iii) Release stage (i) Charges the air brake system to regime pressure during normal i) Charging Stage running condition. (ii) Helps in graduated brake During charging stage the compressed air application, when pressure in brake flows from the brake pipe and enters into pipe is reduced in steps. the brake pipe chamber of the main valve, (iii) Helps in graduated brake release, cut off valve and quick service valve. Due when pressure in brake pipe is to this pressure the various valves get, increased in steps. activated and perform as under. (iv) Quickly propagates reduction of pressure in brake pipe throughout the length of the train by arranging Main Valve : Due to brake pipe pressure acting on top face of the large diaphragm, additional air pressure reduction locally inside the distributor valve. differential pressure acts on the main (v) Limits maximum brake cylinder valve. As a result the hollow stem moves downwards there by connecting brake pressure for full service application/ emergency application. cylinder to atmosphere. (shown by arrow (vi) Controls the time for brake in figure 4.14) application and brake release In addition to this because of BP pressure depending on service conditions at top of large diaphragm it presses ring (vii) Facilitates complete discharge of and trigger. This action unlocks the CR air from the air brake system release valve by raising upward the manually with the help of operating locking rod. lever. (viii) Protects overcharging of control Cut Off Valve : As brake pipe pressure reservoir when the brake pipe enters into the cut off valve it flows pressure is quickly increased for through the solex jet and valve, (which is releasing the brakes. held open due to action of BP pressure on bottom side of the lower diaphragm) to Three designs of distributor the control reservoir. As the CR & BP valves are in use on coaches. These pressure equalises, diaphragm assembly are: come down and valve reach to lap i) C3W Type distributor valve position. The control reservoir pressure ii) KE type distributor valve. iii) P4aG type distributor valve. now also reaches to the upper portion of top diaphragm of quick service valve and the bottom portion of large diaphragm of main valve. Chapter 4,, Page 19 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System Simultaneously, the auxiliary reservoir is limiting device through the valve which is charged with BP pressure reaching from held open. From limiting device air cut off valve chamber - via auxiliary pressure now enter the brake cylinder. reservoir check valve. When the BC pressure rises to 3.8 kg/cm2 the upwards force on the diaphragm lifts ii) Application Stage the guide and the valve at the bottom of the limiting device gets closed. Thus EMERGENCY APPLICATION further entry of air into the brake cylinder stops. During emergency application the brake pipe pressure is reduced rapidly to When the brake cylinder pressure reaches 0 kg/cm2 by the driver's brake valve. 3.8 kg/cm2 this pressure i.e. BC pressure Because of this drop the position of the act on various valves will be as described below. § Top face of small diaphragm of main Main valve: With drop in BP valve pressure to 0 kg/cm2 differential pressure § Bottom face of upper diaphragm of acts across the large diaphragm. As a cut off valve result the hollow stem is moved in upward § Top (small chamber) of quick service direction and pushes the check valve there valve by opening the passage for entry of auxiliary reservoir pressure at top portion Now because of this BC pressure acting at of main valve. This pressure then gets a main valve small diaphragm, the hollow way to brake cylinder through limiting stem is pulled down. As a result the device. The brake cylinder thus gets check valve at top comes down to close charged with the compressed air. This stage and assume lap position with the pressure is known as BC-pressure. hollow stem closing further entry of AR pressure. Limiting Device: The auxiliary reservoir pressure which entered into the top Cut off valve : In cut off valve the position of main valve now enters the bottom face of the upper diaphragm is Fig. 4.14 C3W DISTRIBUTOR VALVE Chapter 4,, Page 20 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System subjected to BC pressure because of on top of the upper diaphragm and the which the guide is lifted. Also the upper hollow stem again lifts up to lap position. portion of lower diaphragm is subjected to It close the hollow stem top portion. The CR pressure, which pushes the total same cycle is repeated when BP is assembly downwards. This action closes increased during next stages. In this way the valve of cut off valve, there by graduated release effect is obtained. isolating it from control reservoir pressure. Cut off valve: As the BP pressure Quick Service Valve : In quick service increases the position of cut off valve valve BC pressure acts at the top of valve remains similar as in graduated and control reservoir pressure act at top application i.e. the cut off valve will face of upper diaphragm. As a result the remain closed, isolating CR pressure from stem is pushed down. The valve at the brake pipe pressure. bottom gets opened. Now as the BP pressure inside the DV is at "O" kg/cm2 Quick service valve : When the BP the residue BP pressure from the bulb of pressure is increased then as explained quick service valve will flow back and above for the main valve the BC pressure vent to atmosphere with the BP line. gets exhausted to atmosphere. This action gradually reduces the BC pressure. When GRADUATED APPLICATION BC pressure reduces to 0.8 kg/cm2 during brake release the force at the top of the During graduated brake application the quick service valve, becomes brake pipe pressure is dropped in steps by comparatively less than BP pressure driver's brake valve. The movement of present in Quick Service Valve. As a various valve assemblies is almost in the result the valve at top gets lifted thereby same direction as during emergency giving passage to blocked BP pressure to application, but their movement is atmosphere. With the exhaust of BP comparatively less. In the main valve pressure the Quick service valve of the however after each application the hollow distributor valve again gets ready for next stem assumes the lap position with the brake application. check valve. Manual release: Double release valve In addition to this during graduated provides for accelerated manual brake application the bottom valve of limiting release, which is particularly useful during device is held open to allow compressed shunting operation. A short pull on the air to enter into brake cylinder. lever of double release valve is all that is needed. This action opens the control When BC pressure reaches 3.8 kg/cm2 the reservoir release check valve, which is bottom valve in the limiting device gets then held open by the locking rod. closed. Similarly at the time of full service Venting of control reservoir through the application as the BC pressure reaches 3.8 open control reservoir release check valve + 0.1 kg/cm2 within specified time, the brings the main valve to release position position of various valve assemblies will and exhausts the brake cylinder pressure be the same as described above. through the hollow stem. iii) Release Stage 415b Periodicity of Overhauling When the brake pipe pressure is increased The overhauling of the distributor valve is in steps for graduated release of brakes the carried out once in five years or on position of the different valves is as completion of 8 lakh km whichever is described below; earlier or if there is some specific trouble. Main valve : At the top face of large 415c Overhauling diaphragm as the BP pressure increases, the hollow stem is moved downward C3W Distributor Valve consists of leaving its lap position with check valve. various sub-assemblies possessing highly The BC pressure thus finds a passage finished, accurate and sophisticated small from top of hollow stem to exhaust to the parts and therefore need a well arranged atmosphere. This action reduces pressure work-shop equipped with standard tools Chapter 4,, Page 21 of 50 Maintenance Manual for BG coaches of ICF design Air Brake System as well as specially designed tools and 415e Overhauling Procedure fixtures. It is also important to state that the work place (DV-overhauling section Before opening the distributor valve, it of the workshop) should be a clean, well needs to be dusted and cleaned externally. organized, dust & dirt free and a properly The disassembling and assembling of the developed space where the following distributor valve in the workshop is activities should be adjacently and facilitated by using a bench mounted DV- separately organized:- holding fixture, with facility to rotate a) dismantling and cleaning through 360 0 in the vertical plane and b) assembling and testing locking it after every 900 rotation. c) storage of assembled distributor valve & The distributor valve is mounted on d) storage of spare parts the fixture and can be locked in any including POH kits stocking desired position. The sub assemblies of store etc. different valve are dismantled in the sequence. It is imperative that The tools and fixtures required for the components of each sub assembly have to disassembly and assembly of