A Report on Automatic Loading Gear (ALG) and Radio Communication in Tank T-72
By-
Name of Students ID nos.
Rudresh Gupta 2016A3PS0160G Jaskirat Singh Chhabra 2016A3PS0155G Vasu Gupta 2016A3PS0153G Dhruv Sharma 2016A8PS0371G Akanksha Singh 2016A8B30261G
AT 505 ARMY BASE WORKSHOP, NEW DELHI Practice School – I station of
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE, PILANI (MAY-JULY, 2018)
BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE PILANI (RAJASTHAN)
Practice School Division
Station: NEW DELHI Centre: 505 ARMY BASE WORKSHOP
Duration: 8 WEEKS Date of Start: 22/05/2018
Date of submission: 13/07/18
Title of the project: 1) Auto-Loading Gear (ALG) in tank T-72 2) Radio Communication in tank T-72
Name of Students ID nos. Discipline Rudresh Gupta 2016A3PS0160G EEE Jaskirat Singh Chhabra 2016A3PS0155G EEE Vasu Gupta 2016A3PS0153G EEE Dhruv Sharma 2016A8PS0371G ENI Akanksha Singh 2016A8B30261G ENI
Name and Designation of the expert: Sh. Kshitij Gupta, DGM (TEG)
Name of the PS faculty: Dr. Nirankush Dutta
Keywords: Tanks, ALG, KR-175, K1-M, Testing Jig, Amplifiers, Relays, Contactors.
Project Areas: Electronics of the ALG system
Abstract: The project is a detailed study and practical analysis of Auto-Loading Gear in tanks proposing improvements and possible changes, thereby reducing manual effort.
Signature of student(s) Signature of Supervisor Date : Date :
ACKNOWLEDGEMENT
We wish to express our sincere gratitude to Birla Institute of Technology and Science, Pilani for providing us the opportunity to do our internship and project work in “505 ARMY BASE WORKSHOP, New Delhi.”
We sincerely thank Sh. Kshitij Gupta, DGM (TEG) for his guidance and encouragement in carrying out this project work. We also wish to express our gratitude to Sh. Praveen Sharma who conferred his help during the period of our project work. We extend our gratitude to Mr. Rajbir and Mr. Ram Singh Sir for their continuous support. We would also like to thank all other officials and workers of 505 ARMY BASE WORKSHOP, New Delhi for their continuous support.
We also thank the Practice School Division of Birla Institute of Technology, Pilani and our instructor Dr. Nirankush Dutta for providing us the opportunity to embark on this project.
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TABLE OF CONTENTS
Main Battle Tanks…………………………………………………………………………………………….….8 Tanks……………………………….……………………………….……………………………….…….8 The T-72 Main Battle Tank……………………………….………………………………………9
Automatic Loading Gear System…………………………………………………………………….……11 Developments in Automatic Loading……………………………….………………………11 Advantages of ALG……………………………….……………………………….………………..12 Advantages and Challenges of New Autoloader………………………………………13
Components of ALG.…………………………………………………………………………………….……..14 Rotary conveyor……………………………….……………………………….……………..……14 Cassette lifting mechanism……………………………….……………………………………15 Cartridge base disposal mechanism……………………………….………………………17 Ramming mechanism……………………………….……………………………….…………..18 Memory unit……………………………….……………………………….………………………..19 Motor-operated gun lock……………………………….…………………………..… ...... 20 Distribution box KR-175……………………………….……………………………….…….…20 Control Unit……………………………….……………………………….………………………...20 Rounds indicator meter……………………………….……………………………….…….…20 Reduction gear……………………………….……………………………….………………….…21 Loading control unit……………………………….……………………………….………….…21
Project Map ...... 22
Detailed Explanation of Working of ALG System and Circuit Functions ...... 23 Rotation of Rotary Conveyor, Selection of Round, Stopping of Rotary Conveyor ...... 23 Cassette Lifting Mechanism (CLM) ...... 23 Ramming ...... 23 Returning of Cassette and Frame to Initial Position ...... 23
Safety Precautions ...... 24 Instructions While Testing/Operating During Firing ...... 24 Preventive Maintenance ...... 25
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Problems and Faults ...... 25 Electrical Faults ...... 25 Mechanical Faults ...... 26
Improvements Suggested ...... 26 Reduction of Rejects, Increase in Output ...... 27 Reduction of Waste ...... 27 Reduction of Consumption ...... 27 Improvement in Availability ...... 27
Radio Transmission ...... 28 Definition ...... 29 Different Steps in Radio Transmission ...... 29 Detailed Explanation of Different Processes Involved ...... 30
Communication in Tanks ...... 31 Types of ‘A’ Vehicles...... 31
Different Types of Radio Systems Used In Tanks ...... 32
Radio System: R-174 ...... 32 Features of R-174 ...... 32 System Configuration of R-174 ...... 32
Digital Control Harness ...... 33 Features ...... 33
Vhf Radio Set Vrc-1465 M1-80/A-2-(5/50 W) ...... 33 Different Parts of Vhf Radio Set ...... 33
Limitations of Radio Communication System ...... 35
Recommendations ...... 35
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LIST OF FIGURES
1. T-72 Tank…………………………………………………………………………………………………7
2. Automatic Loading Gear.…………………………………………………………………………9
3. Rotary Conveyor……………………………………………………………………………………..13
4. Cassette………………………………………………………………………………………………….14
5. Cassette Lifting Mechanism…………………………………………………………………….14
6. Cartridge Disposal System………………………………………………………………………15
7. Ramming System……………………………………………………………………………………16
8. Memory Unit………………………………………………………………………………………….17
9. Project Map ...... 20
10. Different Steps In Radio Mechanism ...... 27
11. Antenna ...... 29
12. Types of Radio Systems Used in Tanks ...... 30
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P
PROJECT-1
AUTOMATIC LOADING
GEAR IN TANK T-72
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1. MAIN BATTLE TANKS
1.1 TANKS
1.1.1 Definition
Tanks are, in essence, mobile, protected, automotive, tracked, armored weapon platforms which carry heavy direct-fire weapons. In Modern combat tanks are expected to function in the following terrain: I. HAA’s (High Altitude Area) II. BUA’s (Urban Areas) III. Desserts
1.1.2 Combat tanks (MBT)
There are 3 main aims of a tank in combat: 1. Destruction of enemy tank with equivalent weight and caliber 2. Enhanced Range of combat 3. High FRHP (First Round Hit probability) 4. Enhanced SSKP (single shot kill probability)
1.1.3 Design Concept
There are 3 main factors kept in mind while designing a tank (according to combat requirements of the country):
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1.2 THE T-72 MAIN BATTLE TANK
Figure 1
1.2.1 History[1]
T-72 is Soviet second generation main battle tank. Second generation tanks can be used at nights and have Nuclear-Chemical-Biological (NCB) protection system in it. Its
production started in 1971. It comes after T-55 in the series. Different models of T-72 are T-72 (Ural), T-72A, T-72B, T-72M, T-72B3, T-72B3M. The differences in various models lies in the fact that different engines, ammunition, firing mechanisms, etc. are used but more or less they resemble to a great extent.
The T-72 is still in use today - and as yet being utilized by around 45 nations.
India acquired 500 T-72’s from Russia in 1978 and they are still the backbone of tanks for the Army’s armored core, despite indigenous new generation tanks like the Arjun
Mk-ii due to the core soviet technology and quality. The soviets made the T-72 to suit their own combat needs and not India, hence the army have had to adapt to aptly use the tank.
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1.2.2 Data and specifications
Unlike the previous T-series tank where the capacity was of 4 people, it has a capacity of 3 people namely the Commander, the driver and the Gunner. Gunner is responsible for laying the guns, Driver for driving the tank and as the day mechanic while the Commander synchronizes the crew.
The calibre uses a 125mm smooth bore. Various types of ammunitions used in T-72 are APFSDS (Armor piercing fin stabilized discarding sabot), HEF (High explosive fragmentation) and HEAT (High explosive anti-tank), they have projectile lengths of 4000m, 5000m and 4000m respectively. Maximum vertical height obtained by the projectile is 10,000m using the HEF. The highest muzzle velocity id of APFSDS which is 1800m/s. For HEAT and HEF it is 1200m/s. There is a gun stabilization mechanism which keeps it stabilized in both the axis and there is Delta D mechanism which maintains the gun on the target in spite of the movement of the tank.
It has 3 types of protection systems: 1. ERA Panels (explosive reactive panels) 2. Smoke Generation equipment – Grenade launchers and Engine smoke 3. NCB
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At the core of its machinery is the ALG which is the Auto Loading Gear system. The ALG was only responsible for the reduction of number of crew in the tank from 4 to 3. Earlier 1 person was required to load the gun. It is an electromechanical unit used to automatically load the main gun. The need of the 4th crew member (for loading) has been dispensed with it. It can load a maximum of 22 rounds automatically at one time.
Following is the blueprint of the ALG
Figure 2
2. AUTOMATIC LOADING GEAR SYSTEM
At the core of its machinery is the ALG which is the Auto Loading Gear system. The ALG was only responsible for the reduction of number of members in the tank from 4 to 3. Earlier 1 person was required to load the gun. It is an electromechanical unit used to automatically load the main gun. The need of the 4thcrew member (for loading) has been dispensed with it. It can load a maximum of 22 rounds automatically at one time.
2.1 DEVELOPMENTS IN AUTOMATIC LOADING
2.1.1 Era of World War
Like other guns of their calibre, tank guns have been loaded manually but since the Second World War there has been a slowly growing interest in systems which would load them automatically. Development of automatic loading systems started during that
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conflict in Germany and in the United States, where one was actually built by 1945 for use with a 75mm gun in theT22El medium tank. Work on automatic loading systems continued in the United States during the late 1940s and throughout the 1950s but the next major step towards their use in tanks was taken in France with the development of the semi-automatic loading system for the 75mm gun of the AMX 13 light tank, the first prototype of which was completed in 1950.
[2] 2.1.2 Post World War Era
Little further progress was then made until the development in Sweden of the turretless S-tank, which was originally built in 1961 and which became the first tank with a fully automatic loading system to go into service. An automatic loading system was also incorporated in the MBT-70 which was developed by the United States and Germany during the late 1960s, but which was not put into service. However, at about the same time another system was developed in the Soviet Union for the T-64 and T-72 tanks, which became during the 1970s the first turreted tanks to go into service with automatic loading. Even earlier an automatic loading system was incorporated in the Soviet BMP infantry armored vehicle for its turret-mounted 73mm gun.
[3] 2.1.3 Cold War Era
Other automatic loading systems developed between the late 1960s and the early 1980s in Britain, Germany, Sweden and the United States did not advance beyond test rigs or experimental vehicles. But they embodied new concepts and were for the first time applied to guns mounted externally, on pedestals or in unmanned, remotely controlled turrets. The first of the vehicles with a pedestal mounted gun was the COMRES 75, which was built in Britain in 1968. In 1980 the first vehicle with an unmanned, remotely controlled turret was built in the United States. This was the Rapid Deployment Force Light Tank. In 1985 came the second experimental vehicle with an unmanned, remotely controlled Turret.
[4] 2.2 ADVANTAGES OF ALG
2.2.1 Higher Rate of Firing
One of the main advantages of automatic loading systems, which their developers sought to exploit from the start, has been a higher rate of fire than that possible with manual loading. Thus the original US system tried in the T22E1 medium tank provided a rate of fire of 20 rounds per minute and that incorporated in the Swedish S-tank enables its 105mm gun to be fired at the rate of 15 rounds per minute whereas the
12 highest rate of fire that can be achieved with manually loaded guns of the same calibre is 8 to 10 rounds per minute.
2.2.2 Handling Heavier Rounds
The second advantage of automatic loading systems is that they can handle heavy rounds which are difficult to load manually. This became important for the first time during the 1950s when guns of 120 or even 155mm firing full-calibre AP projectiles were being considered. The ability of automatic loading systems to handle heavy rounds then decreased in importance with the development of lighter ammunition with discarding sabot projectiles and combustible or semi combustible cartridge cases and with no increase in calibre beyond 120mm. But it will become important again if or when the calibre of tank guns increases further.
2.2.3 Increased Safety
The third and much more recently recognized advantage of automatic loading systems is that they allow the armament to be remote from the crews of tanks. This extends the range of possible configurations of tanks to designs which present smaller targets to enemy weapons, particularly in hull-down positions, or which reduce the danger to the crew from ammunition fires.
2.2.4 Better Design to Tank and Automation
Automatic loading systems also eliminate the need for a human loader and make it possible, therefore, to reduce the crew of a battle tank from four to three men, or even to two. In consequence, the internal volume of tanks and hence their size can be reduced, although it is more difficult to maintain and to operate a tank for a crew of three and even more of two men than for the customary crew of four.
2.3 ADVANTAGES AND CHALLENGES OF NEW AUTOLOADER
• Complete separation of the ammunition from the crew and therefore reduced the danger to the latter arising from ammunition fires. • But it required remote operation of the gun and posed other problems associated with externally mounted guns. • It also involved a relatively long loading path, almost all of which was outside the vehicle and therefore subject to various hazards.
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• The latter problem did not exist with the system proposed for the NKPz in which the loading path was entirely within the vehicle but it was still relatively long as well as complex, which was bound to have an adverse effect on the rate of fire and reliability. • Although the ammunition was to be located in the NKPz where it was least likely to be hit, and although all of it was immediately available for the gun, which had been achieved previously only in the S-tank, it could not be separated completely from the crew because it had' to move, albeit rapidly, through the crew compartment.
3. COMPONENTS OF ALG
3.1. Rotary conveyor 3.2. Cassette lifting mechanism 3.3. Cartridge base disposal mechanism 3.4. Ramming mechanism 3.5. Motor-operated gun lock 3.6. Memory unit 3.7. Distribution box KR-175 3.8. Control Unit 3.9. Loading control unit 3.10. Rounds indicator meter 3.11. Reduction gear
3.1 ROTARY CONVEYOR:
Have 22 rounds of ammunition and brings the selected round to gate from where it can be lifted for loading /unloading. Driven by an electromechanical drive. It is covered by the deck and is actually the turntable in the fighting compartment. Rotary conveyor lock is provided to stop the RC after it turns through 1/22 of the circumference (one pitch) relative to turret.
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Figure 3
3.2 CASSETTE LIFTING MECHANISM:
Brings the cassette to the line of ramming or loading and subsequently returns the empty cassette to the initial position. The electromagnetic lock retainer, of the electromagnet lock of cassette lifting mechanism, enters the slots of the locking disc and stops the cassette in one of the four positions: a) Initial position in rotary conveyor b) Round loading line/conveyor filling c) Shell/projectile ramming/loading line d) Charge ramming/loading line
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Figure 4
Figure 5
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3.3 CARTRIDGE BASED DISPOSAL SYSTEM:
It is designed to trap the extracted spent cartridge base and to remove them from the tank. Consists of a trap, trap drive, cartridge base stop, disposal door and disposal door drive. This mechanism consists of contact point switches which after various actions/delivers signals to the ALG control.
Figure 6
17 3.4 THE RAMMING MECHANISM:
It is provided to ram the shell/projectile and charge into the chamber. It is installed on the turret bottom plate in the turret rear. It consists of reduction gear unit 1 with drive electric motor 2, the chain with folds 7, and snail 3. Contact unit 8 is used for actuation of the switches for sending signals to the ALG control circuits.
Figure 7
18 3.5 MEMORY UNIT:
Designed for the following purposes:
To store and issue information concerning the ammunition left in the cassette of the rotary conveyor. To give an electrical signal when the cassette with round is selected and empty cassette reaches the feed gate. To mark (memorize) the type of round in each cassette during loading/filling of the conveyor. To mark (memorize) the cassette in empty ones emptied or unloaded.
Figure 8
Important Features of Memory Unit:
It is mounted on the gear reduction unit of the RC. The mechanism for shifting the slide consist of three buttons: 1. HEAT: High explosive anti-tank. 2. APDS: Armor-piercing discarding sabot 3. HEF: High explosive fragmentation
It revolves in synchronization with RC. With RC locked one of the slides is arranged parallel to longitudinal axis of the tank.
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3.6 MOTOR OPERATED GUN LOCK:
It is present to reliably hold the gun at the loading angle. It is attached to the bracket on the front part of the turret roof to the right of the gun. The gun lock consists of cast frame 11 and electric motor 14. The frame houses a three stage tear down gear unit and 3 switches namely K1, K2, K3 which send signals to the control unit of the ALG.
3.7 DISTRIBUTION BOX KR – 175:
It is designed to accommodate various ALG CONTROL elements (relays, capacitors, resistors) which produce electrical signals that command the ALG to function in a certain sequence. The distribution box is mounted on the rotary conveyor deck under, and to the right of the gun.
3.8 CONTROL UNIT:
The control unit is designed to control the ALG. It is placed on the face panel of the range finding sight. Various parts of the ALG system send and receive electrical signals from the control unit.
The control unit consists of the following parts: - i. SHELL TYPE and LOADING MODE SELECTION SWITCH 1 ii. ALG ON BUTTON 6 to operate ALG in AUTO LOADING MODE
iii. PLUG 5 of the ROUND NUMBER INDICATOR adjusting potentiometer. iv. HAND pilot lamp 2 that indicates loading gear is in MANUAL OPERATION MODE. v. CART BASE pilot lamp 3 indicating a SPENT CARTRIDGE base in the trap. vi. AUTO-HAND Switch 4 that cuts in the armament stabilization system.
3.9 ROUNDS INDICATOR METER:
The rounds number indicator is used to indicate the number of rounds of each type of ammunition loaded in the rotary conveyor, as well as the number of empty cassettes in the rotary conveyor. In case any type of round of empty cassettes is greater than 11, the accurate value has to be determined by checking the number of rounds of other/all types of empty cassettes.
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3.10 REDUCTION GEAR UNIT:
The Reduction Gear Unit is a two stage assemble of spur gears and drive sprockets. The gear unit is driven by an electric motor. To drive the ROTARY CONVEYOR, an electro-mechanical system is provided. This drive is essentially a 4-STEP REDUCTION GEAR SYSTEM with external spur gear which meshes with the RC GEAR and an ELECTRIC MOTOR. The Memory Unit is mounted on the reduction gear unit. A small gear opposite to the external gear drives the shaft of memory unit. The Contact System 3 is built in the casing of reduction gear unit. The chains of the cassette lifting mechanism are driven by the sprockets of the reduction gear unit in a 3 step transfer mechanism.
3.11 LOADING CONTROL UNIT
It is designed to control the ALG in the loading unloading and the manual loading operations.
It is installed in the turret right part to the right of the commander. It consists of: - a. UNLOADED button 1, use to introduce information concerning the unloaded cassette into the memory unit. b. Auto-hand unloading switch 10 used to cut in the automatic operation of the ALG, automatic loading and loading and stabilizer interlocking. c. Pilot lamp 3 used to indicate that the manual operation is on. d. Lock button 4 used to release the gun from the motor operated lock. e. ALG READY pilot lamp 2 used to indicate that the ALG is ready for operation. f. ALG READY pilot lamp 2 used to indicate that the ALG is ready for operation. g. FRAME DISPOSAL-INITIAL Switch 5 used to eject the cartridge base and to lower the frame in manual loading h. CART BASE AUTO-HAND Switch 6 used to cut in the automatic and manual disposal of the cartridge base.
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4. PROJECT MAP
Figure 9
22 5. DETAILED EXPLANATION OF WORKING OF ALG SYSTEM AND CIRCUIT FUNCTIONS
5.1. ROTATION OF ROTARY CONVEYOR, SELECTION OF ROUND, STOPPING OF ROTARY ...... CONVEYOR:
Rotary conveyor houses 22 rounds for firing, inside T-72, below the turret. It is one of the main components of ALG. The number of rounds and the types of rounds on the rotary conveyor are stored in the memory unit. The type of round to be loaded is selected from the memory unit with the help of three micro-switches for the available 3 types of rounds. Once the round is selected the rotary conveyor halts, with the cassette holding the selected round directly below the turret ready for loading. The rotary conveyor is primarily mechanical with numerous gears and motors, all controlled by a single relay named as P11 on the confidential circuit diagram of the ALG control circuit.
5.2. CASSETTE LIFTING MECHANISM (CLM):
As the loading line is above the rotary conveyor a lifting mechanism is needed to bring the round up for ramming into the gun. This is carried out by the Cassette Lifting Mechanism (CLM) present inside the tank. The P11 relay controlling the rotary conveyor is turned off, and subsequently P16 and P17 are turned on to initiate the CLM. The sole purpose of the lifting mechanism is to first lift the cassette to the loading line, where the projectile/shell is rammed. After that the cassette is lifted a little bit further to bring the charge in front of the ramming line which is then rammed in. The last function of the CLM is to bring the cassette back to its initial position.
5.3. RAMMING:
Ramming is the mechanism by which the projectile and charge is pushed into the gun. The Ramming mechanism largely consists of the pushing hammer called the Rammer and the ramming chain. The ramming circuit is turned on when the relay P16 is switched off and the relay P20 is switched on. The rammer is run by ramming motor which is run by the circuit controlled by P21 First the projectile is rammed then the charge is rammed.
5.4. RETURNING OF CASSETTE AND FRAME TO INITIAL POSITION:
This process is initiated by the switching off of rammer motor which is carried out by switching off of P21. Subsequently P16 and P18 switch on to bring the cassette down. This ends one cycle of round loading. Further loading can now be done by going back to the first step.
23 6. SAFETY PRECAUTIONS
While operation the automatic loading gear, stick to the following “don’ts”
So not turn on the ALG CONTR circuit breaker on the ACB panel of the mains voltage is less than 22V. Do not leave the breech block open after the operation of automatic loading gear is over. Never change the position of the controls through the whole Automatic Loading gear operating cycle. Never manually load the gun with the ALG CONTR CIRCUIT BREAKER TURNED ON and switch AUTO-HAND-UNLOADING in position AUTO. Never open the breech block until switched AUTO HAND on the control unit and loading control unit are in position HAND.
6.1. INSTRUCTIONS WHILE TESTING/OPERATING DURING FIRING
During the automatic loading gear operation, opening of the disposal door may be delayed. In this case the cartridge base is not ejected from the trap but remains inside. After the frame lowers, pilot lamps CART. Base on the control unit goes on. The firing circuit get interlocked; pilot lamps READY on the range finding sight fails to come on. To continue firing, priced as follows Interlock the gun and the turret by placing switch AUTO-HAND on the control unit or loading control unit in position HAND, and make sure that pilot lamp hand on control unit or loading control unit comes on.
Remove the cartridge base from the trap by releasing the retainer and raising the cartridge base stop (pilot lamp CART, BASE the control unit must go out). Set the cartridge base stop in its place. Put the cartridge base in the vacant charge storage rack or throw it out of the tank. Unlock the gun and the turret by returning switch AUTO-HAND to position AUTO as a result, pilot lamp HAND GOES OUT, PILOT LAMP ready on range-finding sight comes out, and a light spot appears in the field of view in eyepiece.
6.2. ROUTINE INSPECTION
In carrying out the routine inspection prior to a trip proceed as follows
Check the position of the circuit breaker on the turret left hand and right hand distributing board (ACB panel); all the circuit breakers must be in position on except for the EL TRIGGER and AZI LIGHT on the left-hand distributing board and the DOOR and ALG CONTR the right hand distributing board Check for foreign objects hindering the rotation of the rotary conveyers, and remove them if any. Check the serviceability of automatic loading gear. Check the condition of the cassettes and rotation of of the rotary conveyer, and also check the condition of cassettes letting mechanism. Clean the creating surface of the
24 cassettes lifting mechanism of dust and dirt, and clean the bottom under the rotary conveyer in compliance with requirements.
6.3. PREVENTIVE MAINTENANCE
Carry out the routine inspection of the automatic loading gear prior to a trip. Inspect and, if required, remove dust, dirt and foreign object from under the rotary conveyer whenever possible. Check the ramming mechanism friction clutch for torques slipping. Check licking of the bolts fastening the automatic loading gear units at accessible places. 7. PROBLEMS AND FAULTS
Under the following section, we discuss the problems and faults that may occur while operating the Automatic Loading Gear (ALG) in a T-72 tank. Broadly we can discuss these problems in two wide categories i.e. Electrical Faults Mechanical Faults
We know the ALG operates using an electrical system with its core element being the KR-175. This unit in turn operates the other parts and mechanisms. So, there has to be a perfect sync between both systems for the ALG to work perfectly. Even a single fault in the system can disrupt the whole working of ALG.
7.1. ELECTRICAL FAULTS
7.1.1. Delays during a step
In some cases, what happens in that a signal or a step is delayed which delays or corrupts the further working of the system. For example, consider a situation where the opening of the cartridge disposal door is delayed. In this case the cartridge base is not ejected from the remains inside. The firing circuits get interlocked and the READY light on the range finding sight fails to come on. Now there remain two choices, either to load the gun manually or to fix the fault manually. Both of these take lot of effort and time.
7.1.2. Circuit Breaker Faults
25 There are ACB panels inside the tank similar to MCB panels we have inside our homes. These panels have lights and switches and the circuit breakers operates such that the normal functioning of the tank is displayed by the lights. But the ACB panels displays if there are any faults or problems within the circuitry of the system (loose wires, short circuits etc.). In these cases, it is advised not to use the ALG till the cause of trouble is found and eliminated.
7.2. MECHANICAL FAULTS
The ALG system involves many mechanical components and wherever there are mechanical parts there comes friction. There has to be a routine inspection and cleaning of all the components. However there still may be some problems.
7.2.1. Rotary Conveyor (RC) RC holds 22 rounds of ammo and brings them to the gun loading line. It is the turntable covered by the deck of the tank. The regular cleaning under the RC is important as foreign particles often get stuck there and may hinder the working of the RC.
7.2.2. Ramming Mechanism In a few cases, the breech block closes spontaneously when the rammer chain is still in the barrel chamber. In other cases, the rammer does not slip properly. In this case, the Ramming mechanism friction clutch has to be thoroughly checked for slipping torque.
7.2.3. Cassette Lifting Mechanism It brings the cassette to the line of ramming/loading and subsequently returns the empty cassette to the initial position. The main problems with this component are errors in bringing the cassettes to the perfect positions. A slightest error will make the ramming/loading of the cassettes impossible. Then manual loading would have to be used.
7.2.4. Improper Maintenance Improper maintenance of the mechanical components can cause troubles in its working. Dust and dirt has to be regularly cleaned of the moving surfaces. The bearing surfaces have to be cleaned and well lubricated to reduce friction. Check any loose bolts or joints.
8. IMPROVEMENTS SUGGESTED
Major parts for improvement of any process 8.1. Reduction of rejects, Increase in output 8.2. Reduction of waste 8.3. Reduction of Consumption 8.4. Improvement in availability
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8.1 REDUCTION OF REJECTS, INCREASE IN OUTPUT
We could reduce the time for loading and as a result number of rounds/minute would increase. We could do this by Changing the control system from electromechanical to electronic (computerized). The control unit used could be microprocessors instead of KR- 175. Microprocessor can be programmed to perform the same function as KR-175
8.2 REDUCTION OF WASTE
We could reduce the space occupied by the circuitry in the tank. Using PCBs (Printed Circuit Boards), Chips and Motherboards we could reduce the number of wires and hence more space would be available inside the tank. The increased space could be used to increase the fuel capacity of the tank.
8.3 REDUCTION OF CONSUMPTION
By changing the electrical components (wires) of the tank to electronic components (chips) the electrical power consumption could be reduced.
8.4 IMPROVEMENT IN AVAILABILITY
Since the space can be decreased, we can accumulate more ammunition and hence the number of rounds could be increased. Also since we have converted electrical components to electronic components which are quite cheaper and hence we have reduced the cost of production.
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PROJECT-2
RADIO COMMUNICATION
SYSTEM IN TANK T-72
28 1. RADIO TRANSMISSION
1.1 DEFINITION[5]
Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating properties of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.
1.2 DIFFERENT STEPS IN RADIO TRANSMISSION:
Figure 10
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1.3 DETAILED EXPLANATION OF DIFFERENT PROCESSES INVOLVED:
1.3.1 Transducer Converts sound energy to electrical energy.
1.3.2 Modulation
It is the process of varying one or more properties of a periodic waveform, called the carrier signal
(i) Frequency Modulator: Frequency modulation varies the frequency of the carrier. The instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal.
(ii) Amplitude Modulator: Amplitude modulation of a carrier wave works by varying the strength of the transmitted signal in proportion to the information being sent. For example, changes in the signal strength can be used to reflect the sounds to be reproduced by a speaker.
1.3.3 Transmitter
A transmitter is an electronic device used to generate and transmit electromagnetic waves carrying messages or signals.
1.3.4 Antenna
An antenna (or aerial) is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver.
30 Tank Antenna
Figure 11
1.3.5 Propagation
Electromagnetic waves travel through space either directly, or have their path altered by reflection, refraction or diffraction.
1.3.6 Receiver
The electromagnetic wave is intercepted by a tuned receiving antenna; this structure captures some of the energy of the wave and returns it to the form of oscillating electrical currents.
1.3.7 Demodulation
A radio receiver receives its input from an antenna, uses electronic filters to separate a wanted radio signal from all other signals picked up by this antenna, amplifies it to a level suitable for further processing, and finally converts through demodulation and decoding the signal into a suitable form.
2. COMMUNICATION IN TANKS
Tank is an ‘A’ type vehicle (tracked vehicles). Communication in ‘A’ type vehicles is mainly between commander, gunner and driver; it may sometimes include stick members as well.
2.1 TYPES OF ‘A’ VEHICLES:
There are two types of ‘A’ vehicles i. Command Tank: It receives orders from the control room and commands other tanks.
ii. Gunner Tank: It receives order from the command tank and operates accordingly.
31 3. DIFFERENT TYPES OF RADIO SYSTEMS USED IN TANKS
a) ICSE R-174 b) Radio Set R-173 M/PM c) VHF Radio Set VRC-1465 d) VHF Radio Set VRC-745-50/A-2-(500) e) HF Radio Set 6100 M/MA
R-173 Head Gear
R-174
Figure 12
4. RADIO SYSTEM: R-174
4.1 FEATURES OF R-174 a) Internal 2-way communication between up-to 6 users b) External 2-way communication over any of the 3 Radio Sets c) Internal circular 2-way communication between all users d) Listening to Ring from Radio e) Ringing to external users over Radio
4.2 SYSTEM CONFIGURATION OF R-174 a) Main Control Unit- AC-34 b) Operator’s Control Unit – AC-35 c) Matching Amplifier Unit- AC-37 d) Chest Switch – MH1/unit MH1 e) Interconnecting cables
4.2.1 Main Control Unit – AC-34 Located at right side of commander Amplification of throat Microphone signals from communication helmet & feeding to all earphones Selection of appropriate radio station signals Enables mode selection by the commander i.e. IC, R/ST1, R/ST2 and R/ST3through four position Rotary Switch 32 Volume control for adjusting Audio output of IC model Selection of IC or R/ST1 for driver
4.2.2 Operator Switching Unit – AC-35 Mounted left to the Gunner Enables selection of modes for intercommunication as well as radio communication Operator’s mode switch (4 position Rotary Switch) for selection of IC, R/ST1, R/ST2 and R/ST3
4.2.3 Matching Unit This unit used by driver, does not have any control. However, depending on the position of drivers switch in AC-34, this unit is connected to intercom or external communication through radio station
4.2.4 Chest Switch MH1 All the above units are connected with the respective user’s communication helmet through this unit independently. This unit has 2 controls: Ring Knob, which brings in all the users into circular IC XMTR Knob, which enables entry into Radio Station Transmission 5. DIGITAL CONTROL HARNESS
5.1 FEATURES: 4 voice ports digitized at 64 kbps Data ports RS 232, USB and RJ-45 interface at the rate of minimum 48 kbps SMS capability within tank and also between Tank BMS Interface Stick Radio Interface Field Telephone Interface Fully Software Controlled Minimum 8 Alarm Signals 6. VHF RADIO SET VRC-1465 M1-80/A-2-(5/50 W)
6.1 DIFFERENT PARTS OF VHF RADIO SET Receiver Transmitter RT-7330 M Vehicular Adapter VA-9004 G Antenna AS-1288B H-250/V Mounting Tray MT-9004/1
33 Loud Speaker LS-454/V Other Connecting Cables
6.1.1 Vehicular Adapter VA-9004 G Vehicular adapter provides mechanical support, power and control functions for one or two RT-7330M installed unit. It provides the following: Protection of equipment against disturbance appearing on the DC power input line Distribution of power to the VA-9004 G internal circuits and RT-7330 M units installed in it. Routing of Audio and control signals between external equipment and RT-7330 M Audio power amplifier for RT-7330 M for external speakers Consists of one internal RF amplifier 50W The internal RF amplifier is seized by the first RT-7330 M that starts transmitting in high power
6.1.2 RT-7330 M
a) Performance Data: Frequency range – 30 to 87.975 Hz RF Channels- 23320 at 25 KHz spacing No. of present channels- 100 each programmable Modulation: Narrow band FM Power O/P: 5 to 50 W Operating Modes: 1. Receive only 2. Transmit & Receive 3. Scanning Hailing 4. Retransmit Break-in Signal protection: Clear, Secure, AJ, Authentication Selective Calling: Available in all modes except in CLR Types of traffic: 1. Analog voice 2. Digital voice
(16 Kbps CVSD or 2.4/4.8 Kbps Voc)
Data rate: Up-to 19.2 Kbps Asynchronous with or without error correction & up-to 32 Kbps Synchronous b) Clear Voice Communication
Clear Analog Simple FM with Fixed Frequency Clear Digital – 1. 16 Kbps & CVSD, 2.4/4.8 Kbps Vocoder 2. Essential for selective call break-in function 3. Adoptive 34 Whisper c) Secure Voice Communication 32 encryption keys Same keys should be used at both ends Voice override is available 2 key banks are available- Active and Reserve 7. LIMITATIONS OF RADIO COMMUNICATION SYSTEM
• Range of radio signals of tanks is limited, around 5 kilometres • Tank radio system is based on Amplitude Modulation. • Low voice quality, which may lead to misinterpretation of orders • Radio Communication System of tank T-72 is analogue based electronic device • Analogue System is unsecure as it can easily be tracked by enemy. •
8. RECOMMENDATION Radio Systems of tanks needs to be completely digitised. Radio Communication of tanks should be based on frequency modulation. It will have many benefits: 1. It will increase the range of radio signals. 2. It will improve the quality of voice signals. 3. It will have better signal to noise ratio.
REFERENCES
1. https://www.model-space.com/blog/2017/03/t-72-russian-tank-origin-and-history/ 2. https://en.wikipedia.org/wiki/T-72 3. https://en.wikipedia.org/wiki/T-72 4. https://www.armyrecognition.com/russia_russian_army_tank_heavy_armoured_vehicles_u/t- ....72a_t- ....72_a_main_battle_tank_technical_data_sheet_specifications_information_description_pictur. ....es.html 5. https://en.wikipedia.org/wiki/Radio All Images - www.google.com/images
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