PROJECT

Study the pressurized water cooling system of WDM2 locomotive and study its

impact on performance of engine.

Prepared by-Manoj Kumar Katara

K.I.E.T., Gzb. Mechanical 2nd yr.

CONTENTS-

1. ACKNOWLEDGEMENT

2. HISTORY OF LOCOMPTIVE WORKSHOP, CHARBAGH

3. WDM2 LOCOMOTIVE

4. TECHNICAL SPECIFICATIONS

5. COOLING SYSTEM

5a.OBJECTIVE

5b.CONTENTS OF COOLING SYSTEM

6. SUMMARY

7. BIBLIOGRAPHY

ACKNOWLEDGEMENT

This project is result of the constant hard work of not just one people but a number of persons who guided me in making this project.

So first of all I am thankful to the principal sir of Supervisor Training Centre, who provided me the opportunity to study this project.

I am also thankful to the librarian sir, who provided the necessary details.

Then moving onto the workshop I am thankful to Mr. Yadav who explained the various parts of my project and also answered the various queries .

Also I am thankful to the staff members of the locomotive workshop Lucknow, who helped me a lot during the working days.

MANOJ KUMAR KATARA

History of Locomotive Charbagh Workshop

Construction for this workshop was started by the Oudh and Rohilkhand Rly. in 1867 to prepare for its needs of locomotive and carriage maintenance in the Lucknow area after it secured a contract to build a large BG railway system in the area north of the Ganga. 1867 was also the year that the company had finished construction of the light MG line between Lucknow and Kanpur.Originally almost all the staff of the Charbagh workshop was from Great Britain, however within a few years a large number of Indians were also employed, including many from Bihar and also the Jamalpur workshop.After Independence, the big locomotive overhauling facility in the north, at Moghulpura (belonging to the North-Western Railway), went to Pakistan. Charbagh workshops were therefore upgraded with manufacturing and major overhauling capabilities for locomotive. The workshop became the pre-eminent

steam loco maintenance and overhauling workshop of NR through the 1960s and 1970s, but thereafter lost ground with the ascent of diesel and electric traction. The workshop switched to diesel loco maintenance in 1975, and to electric loco maintenance in 1985.In recent years, the workshop has found an additional niche in restoring steam locomotives for various special runs and for preservation, exhibitions, etc. For instance, the WP locomotives at the NRM being used for special excursions on the occasion of IR's 150th anniversary were completely overhauled at Charbagh.

WDM2 LOCOMOTIVE(Class name unchanged after reclassification.) 2600 hp Alco models (RSD29 / DL560C). Co-

Co, 16-cylinder 4-stroke turbo-supercharged engine. Introduced in 1962. The first units were imported fully built from Alco. After DLW was set up, 12 of these were produced from kits imported from Alco (order no. D3389). After 1964, DLW produced this loco in vast numbers in lots of different configurations. This loco model was IR's workhorse for the second half of the 20th century, and perhaps the one loco that has an iconic association with IR for many people. These locos are found all over India hauling goods and passenger trains — the standard workhorse of IR. Many crack trains of IR used to be double-headed by WDM-2 locos; this has decreased now owing to the electrification of most important sections and the use of more powerful locos. A single WDM-2 can generally haul around 9 passenger coaches; twin WDM-2's were therefore used for 18-coach trains.

Jumbos – A few locos of the WDM-2 class produced in 1978-79 have a full-width short hood; these are unofficially termed 'Jumbos' by the crew. These range from serial numbers around 17796 or so to about 17895 or so (17899 and above are known to be 'normal' WDM-2s). These were apparently produced with the idea of improving the visibility for the drivers, but it was learned later that it did not make much of a difference under the typical operating conditions of these locos. Some of these were later modified to have narrower short hoods to look more like the other WDM-2's. Two locos, #17881 and #17882, were trial locos produced by DLW when they were considering shutting down Jumbo production; these look

like ordinary WDM-2 locos, even though there are other Jumbos with higher road numbers than them. Some Jumbos have undergone further modifications: Loco #17854 was a Jumbo based at Jhansi in 1981; now [6/04] it has been rebuilt as a WDM-3A locomotive (based at Pune) by DCW, Patiala.

The classification WDM-2A is applied to those that were re-fitted with air brakes (most of these therefore have dual braking capability), while WDM-2B is applied to more recent locos built with air brakes as the original equipment (these very rarely have vacuum braking capability in addition, especially if they have been rebuilt by Golden Rock). (However, in the past, before the widespread use of air-brakes, a few modified versions with a low short hood at one end like the WDS-6 were also classified WDM-2A.) A few WDM-2 locos of the Erode shed have been modified and sport a full-forward cab at one end, with the dynamic brake grid, blower, etc. moved between the cab and the traction alternator.

The original Alco designs had a 10-day, 3000km maintenance schedule, which was later extended by some modifications to a 14-day schedule. Now [1/02], the schedule is being extended to 30 days by increasing the capacities for various fluids (lubrication oil, etc.), and improving some bearings (mainly, using roller bearings for the suspension). The original WDM-2 bearings were very susceptible to failure. However, given the age of this model, unsurprisingly even locos that have been modified for a 14-day schedule do often require more frequent

maintenance or minor repair so they end up being put on a 7-day schedule anyway.

WDM-2 locos are accepted from the new mainline diesel classification scheme and will remain classified as WDM-2 and not 'WDM-2F' as they might be in the new scheme based on their horsepower.

The first one supplied by Alco was #18040. This one is no longer in use and is now preserved at the National Railway Museum at New Delhi. The second one from Alco, #18041, is currently [7/05] homed at Kalyan shed and is often seen hauling the Diva - Vasai DMU service. The first WDM-2 built by DLW, #18233, is now at Andal shed (not much in use). The last WDM-2's were in the 16000 series. The very last one is #16887.

The WDM-2 locos have a max. speed of 120km/h. There are generally speaking no restrictions for running with the long hood leading, although it's been reported that in some cases the practice was to limit it to 100km/h. The gear ratio is 65:18.

Some WDM-2 units are being converted [2/02] to have AC-DC transmission (alternator driving DC traction motors) by DCW, Patiala. Golden Rock workshops have also been renovating some WDM-2 locos with new features such as twin-beam headlamps.

Only one WDM-2 loco (#16859, Ernakulam shed) is known to have had cab air-conditioning fitted. This was the

first loco to have air-conditioning in India; this was done by the ERS shed in 1997 right after receiving the loco from DLW, but it was disabled later as the auxiliary alternator proved too weak to run the air-conditioner well.

A few WDM-2 locos downgraded for shunting duties have been seen marked with a WDM-2S class name; e.g., some at Itwari shed [2003] and some at Kurla. A few have also been spotted bearing the class name WDS-2, e.g., those at the Kalyan shed where they are used for shunting. These appear to be quirks of the local shed staff and not officially recognized classifications.

DCW Patiala has rebuilt some WDM-2 units to class WDM-3A/WDM-2C specifications. These are a little different from the normal WDM-2C from DLW. They look very similar to WDM-2's, except for a bulge on one of the doors of the hood; this is due to the presence of a centrifugal fuel filter which moved there because the model required larger aftercoolers. There are some other slight differences in appearance. These units have a GE turbocharger and a different expressor with integral air drying facility. They have a Woodwards governor which leads to even running and idling, and (to the great disappintment of Alco smoke fans) reduces the amount of black smoke during intense acceleration. These also have roller bearings for the suspension, improving on the longstanding problem of bearing failures on the regular WDM-2 model.

Following the new mainline diesel classification scheme, new WDM-2C's converted or overhauled by DCW, Patiala, are being labelled WDM-3A (new).

TECHNICAL SPECIFICATIONS

Builders Alco, DLW

Engine

Alco 251-B, 16 cylinder, 2,600 hp (2,430 hp site rating) with Alco 710/720 turbo supercharged engine. 1,000 rpm max, 400 rpm idle; 228 mm x 266 mm bore/stroke; compression ratio 12.5:1. Direct fuel injection, centrifugal pump cooling system (2,457 l/min at 1,000 rpm), fan driven by eddy current clutch (86 hp at 1,000 rpm)

Governor GE 17MG8 / Woodwards 8574-650 / Medha MEG 601

Transmission Electric, with BHEL TG 10931 AZ generator (1,000 rpm, 770 V, 4,520 amperes)

Traction motorsGE752 (original Alco models) (405 hp), BHEL 4906 BZ (AZ?) (435 hp) and (newer) 4907 AZ (with roller bearings)

Axle load 18.8 tonnes, total weight 112.8 tBogies Alco design cast frame trimount (Co-Co) bogiesStarting TE 30.4 t, at adhesion 27%Length over buffer beams 15,862 mm

Distance between bogies 10,516 mm

.

COOLING SYSTEM

OBJECTIVE -To understand about

•the need for cooling system in a diesel engine

•the benefit of water cooling system

•harmful effects of natural water in cooling system

•the method of water treatment and the quality of treated water

• the water cooling system of WDM2 Locomotive

CONTENTS-1.STRUCTURE 2.Introduction 3.Cooling water and its treatment 4.Cooling water system of wdm2 locomotive engine 5.Water pump 6.Modifications in cooling system 7.Summary 

INTRODUCTION

After combustion of fuel in the engine, about 25-30 % of heat produced inside the cylinder is absorbed by the components surrounding the combustion chamber like piston , cylinder, cylinder head etc. Unless the heat is taken away from them and dispersed else where, the components are likely to fail under thermal stresses. All internal combustion engines are provided with a cooling system designed to cool the excessively hot components, distribute the heat to the other surrounding components to maintain uniform temperature throughout the engine, and finally dissipate the excess heat to atmosphere to keep the engine temperature within suitable limits. Different cooling systems, like air cooling, water cooling are adopted, depending on the engine design ,working conditions and service etc.. The advantage of having a water cooling system is that it maintains a uniform level of temperature throughout the engine and by controlling the water temperature, the engine temperature can be controlled effectively.

COOLING WATER AND ITS TREATMENT

Although natural water can meet the basic requirement, its use is prohibited for the cooling of the engine because it contains many dissolved solids and corrosive elements. Some of the dissolved solids may form scales on the heat exchanger surface and reduce the heat transfer coefficient. It also accelerates corrosion. Other minerals get collected in the form off sludge at an elevated temperature. This sludge may get deposited at the low-pressure zone and choke the passage of circulation. The insulation caused by the scale deposits results in unequal expansion and localized stress, which may eventually rupture the engine block, cylinder block, cylinder heads etc. to eliminate all of these, distilled or de-mineralized water is used in the cooling system of the diesel locomotive. The water sample is tested for chromate concentration, hardness, pH value, and chloride content. In case Chromate concentration is found lower than the required quantity, mixture is added. Water is changed if hardness and chloride is higher than the recommended limit. Water is also changed if found contaminated with oil etc.When water is changed due to contamination etc. the system is cleaned by adding Tri-Sodium Phosphate, and circulating water for 45min, this water is drained out, and fresh distilled water with chromate mixture is filled in the locomotive.

COOLING WATER SYSTEM

The WDM2 class locomotives have a closed circuit non-pressurized water cooling system for the engine. The system is filled in by 1210 liters. Of distilled water or Demineralised water treated with non chromate corrosion inhibitor (Borate nitrite treatment) to maintain a concentration of 4000 PPM. The pH value is '8.5-9.5'. The water circuit has two storage tanks in two segments known as expansion tanks on top of the locomotive. Apart from supplementing in case of shortage in the system, these interconnected tanks have some empty space left at the top to provide expansion to the water when it is hot. A centrifugal pump driven by the engine crankshaft through a gear sucks water from the system and delivers it through outlet under pressure. The outlet of the pump has three branch lines from a three-way elbow.

The branching off leads water to the different places as follows- 1. To the turbo-supercharger through a flexible pipe to cool the intermediate casing, bearings on both sides of the rotor and the turbine casing. After cooling the components in the turbo-supercharger, water return to the inlet side of the pump through a bubble collector. The bubble collector with a vent line is a means to collect air bubbles formed due to evaporation and pass it onto the expansion tank, so that they cannot cause air lock in the water circulatory system. 2. The second line leads to the left bank of the cylinder block and water enter the engine block and circulates around the cylinder liners, cylinder heads on the left bank of the engine, and then passes onto the water outlet header. Individual inlet connections with water jumper pipes and outlet water riser pipes are provided to each cylinder head for entry and outlet of water from cylinder

head to the water outlet header. Cooling of cylinder liners, piston rings, cylinder heads, valves, and fuel injection nozzles are done in this process. Water then proceeds the left side radiator for circulation through it, and releases its heat into the atmosphere to cool itself down before recirculation through the engine once again. 

3. The third connection from the three-way elbow leads to the right side of the cylinder block. After cooling the cylinder liners, heads etc. on the Right Bank the water reaches the right side radiator for cooling itself. Before it enters the radiator, a connection is taken to the water temperature manifold where a thermometer is fitted to indicate the water temperature. Four other temperature switches are also provided here, out of whichT1 is for starting the movement of radiator fan at 60 degree C slowly through the eddy current clutch. The second switch T2 picks up at a water temperature of 64 degree C and accelerates the radiator fan to full speed. The third switch is the ETS3 (Engine Temperature Switch),set at90 degree Celsius protection against hot engine, which gives bell alarm and red lamp indication. The fourth switch is ETS4 (set at 95 degree Celsius) which brings the engine back to the idling speed and power cutoff also takes place to reduce load on the engine. In this situation the GF switch is cut off and engine is notched up to full notch. It helps in bringing down the cooling water temperature quickly with the radiator fan moving at full speed.

Water temperature is controlled by controlling the movement of the radiator fan .Cooling water from the left side radiator passes through the lube oil cooler, where water circulates inside a bunch of element tubes and lube oil circulates around the tubes. Thus passing through the lube oil cooler and cooling the lube oil, it unites with the suction pipe for recirculation through the cooling circuit. Cooling water from right side radiator passes through after cooler, where water circulates inside a bunch of element tubes and cooling the charge air, it unites with the suction pipe for recirculation. Apart from hot engine protection, another safety is also provided by way of low water switch (LWS). In the event of cooling water level falling below one inch from the bottom of the tank, the LWS shuts down the engine through the governor with warning bell and alarm indication to ensure the safety of the engine. Vent lines are provided from the after cooler, lube oil cooler, radiators. Turbo-supercharger vent box and bubble collectors etc.are provided to maintain uninterrupted circulation of cooling water by eliminating the hazards of air locks in the system. Cooling water is subjected to laboratory tests at regular intervals for quality controls. Contamination, chloride contents, and hardness etc.. are checked to reduce corrosion and scaling. The concentration of anti-corrosive mixture is also checked and laboratory advises corrective action in case of contamination. Proper quality control of cooling water and use of proper quantity

of no chromate corrosion inhibitor prevents scaling and corrosion in the system, and ensures longer life of the components. Normally 8.2kg is added for new water in WDM2 locomotive.

MODIFICATIONS PERTAINING TO COOLING WATER SYSTEM OF WDM2 LOCOMOTIVE (Louvered fin radiator)-

The radiator core has been redesigned by providing louvered fins thereby increasing the cooling capacity by 14% due to improved air flow pattern through the radiator.

1. High efficiency turbochargers:-

High efficiency turbochargers have been provided on the fuel efficient version of wdm2 locos. This has resulted in lowering of

the exhaust gas temperature by around 15% with modified after cooler.Large after cooler & water connection:-Large after cooler & water connection has-been provided on the fuel efficient locos. This has reduced the heat input to the cooling system.

2. Revision of ETS setting:-

The setting of ETS3 is raised to 90 deg.C from 85 deg.C in order to avoid frequent hot engine alarms. Subsequently, with the introduction of pressurized cooling water system, one more ETS is added with the idea of providing only hot engine alarm through ETS3 at 90 deg. C and bringing the engine to idle by ETS4 at 95deg. C. This change not only reduces the occurrences of hot engine alarm but also increases the heat transfer potential of the radiator at high temperature.

3. Revised setting of OPS:-

The setting of low lube oil pressure switch on WDM2 locos used to be 1.8 kg/ cm2 with a view to obviate the problem of engine shutting down due to operation of OPS while suddenly easing throttle from higher notches to idle , particularly during summer season, the OPS setting has been revised to 1.3 kg/ cm2.

4. Pressurization of cooling water system:-

The cooling water circuit has been pressurized upto 7 psi thereby increasing the boiling point by 11 deg. C. This has not only increased the margin before the cooling water gets converted to

steam but has also increased the temperature differential across the radiators at peak engine temperature, thereby increasing the rate of cooling in radiators. This has been achieved by providing a pressure cap assembly on the water tank.

5. Flexible water inlet elbow:-

Rubber hose type flexible water inlet elbow has been developed in place of the rigid one piece metallic water inlet elbow for obtaining better leak proofness even in face of misalignments between the engine block and the cylinder head.

6. Digital water temperature indicator cum switch:-

This has been developed to replace the existing water temperature gauge as well as the four engine temperature switches whose performance was quite unreliable. This aims at ensuring operation of radiator fan and alarm at proper temperature.

7. Electronic water level indicator cum switch:-

This has been developed to replace the existing water level gauge as well as the low water switch. This indicator shall give precise and reliable information regarding the water level to the driver in the cab itself.

8. Improved type pipe joints:-

This has been improved to replace the existing pipe joints viz. dressers Victaulic’s by superior rubber hoses along with double wire stainless steel clamps and by stainless steel bellows.

9. Use of De Mineralized water:-

The modern devices have made the use of the de mineralized water in place of the TSP water. The main problem with the TSP water was the salt accumulation in the pipe and the tank of water which when used over the prolonged time causes the decrease in the efficiency.

SUMMARY

Builders: Alco, DLW

Engine: Alco 251-B, 16 cylinder, 2600hp (2430hp site rating) with Alco 710/720 Turbocharger. 1000rpm max, 400rpm idle; 228mm x 266mm bore/stroke; compression ratio 12.5:1. Direct fuel injection, centrifugal pump cooling system (2457l/min @ 1000rpm), fan driven by eddy current clutch (86hp @ engine rpm 1000).

Governor: GE 17MG8 / Woodward’s 8574-650. Transmission: Electric, with BHEL TG 10931 AZ

generator (1000rpm, 770V, 4520A). Traction motors: GE752 (original Alco models) (405hp),

BHEL 4906 BZ (AZ?) (435hp) and (newer) 4907 AZ (with roller bearings)

Axle Load: 18.8 tonnes, total weight 112.8t.

Bogies: Alco design asymmetric cast frame trimount (Co-Co) bogies (shared with WDS-6, WDM-7, WAM-4, WCAM-1, WCG-2).

Starting TE: 30.4t, at adhesion 27%. Length over buffer beams: 15862mm.

Distance between bogies: 10516mm.

In the process of combustion, about 25% to 30% of the total heat developed is absorbed by the components of the engine forming the combustion chamber. Hence an effective cooling system is essential to dissipate the accumulated heat. Amongst the various methods of cooling the water cooling system is the most effective method of cooling, as it maintains the uniformity of temperature through out the engine. In WDM2 type engine water cooling system is being used with 1200 liters system capacity. Demineralised water treated with chromium compound is used as coolant water. In this system a centrifugal pump, driven by engine crankshaft is being used to deliver water into the system with pressure. The outlet of the pump is being divided into main three heads- one for cooling turbo charger and after-cooler and the other two for cooling the engine components situated at left and right bank of the engine. Finally the water gets collected at headers and sent to radiator for cooling. An induced draft radiator fan is used to blow air through the radiators for cooling. The radiator fan takes drive from the engine crankshaft through ECC (EDDY CURRENT CLUTCH). A temperature switch controls the clutching effect of ECC

and hence radiator fan rpm. Safety devices are provided both for hot engine and low water conditions of the engine.

BIBLIOGRAPHY

Links:-

http://www.irfca.org/docs/wdm2-interactive.swf

http://en.wikipedia.org/wiki/Water_cooling

http://www.britannica.com/EBchecked/topic/136208/cooling-system

http://www.irfca.org/faq/faq-loco2d.html