Traction Rolling Stock - Indian Railways Institute of Electrical ...

6. AIR COMPRESSOR
6.0 INTRODUCTION
The Elgi air compressor model TRC 1000 M/WK is a three cylinder, two stage,
reciprocating, air cooled and splash lubricated compressor driven by an electric motor through a
bibby coupling. It consists of three cylinders arranged in a 'W' form on a crank case. Oil bath air
filers are fitted to the suction side of the LP cylinder heads. The discharge ports of the LP cylinder
heads are connected to the radiator called inter cooler for effective cooling. Inter cooler is
connected to the suction port of the HP cylinder head. The discharge port of the HP cylinder head
is fitted with a box type after cooler. The compressed air flows from delivery of LP cylinder through
inter cooler to HP cylinder and delivered after cooling in after cooler. The compressor is coupled
with a 12.5 HP NGEF motor and mounted on a rigid, compact base. The air filter and other pipe
fittings are all clamped properly to arrest vibration. A fan with a fan guard is provided to direct cool
air on to the compressor unit. The fan draws the air over the motor there-by cooling the motor also.
An eye bolt used to lift motor is provided at the terminal belt side of the motor. (Fix the eye bolt on
the top of the motor and lift the motor)
6.1 PARTS OF COMPRESSOR
6.1.1 Connecting rod and crank shaft assembly
The connecting rod and crankshaft assembly is precision machined and dynamically
balanced. The crank shaft is provided with a single row heavy duty ball bearing at both ends. The
main connecting rod big end is provided with a triple row roller bearing and small end consists of
phosphor bronze bearing.
6.1.2 Piston and piston rings
The pistons are of automotive type and are of low expansion silicon aluminum alloy.
They are provided with plain compression rings, stepped rings and slotted oil control rings.
6.1.3 Disc Valves
A special type of concentric disc valves have been used for the low pressure and high -
pressure cylinders.
6.1.4 Inter cooler, safety valve & after cooler
The inter cooler is a radiator, consists of a series of copper tubes, on which fins are wound for
effective cooling. It is mounted above the motor. It connects the discharge of the LP cylinders to
the suction of the HP cylinder. It is provided with a safety valve set to lift at 6 kg/cm² and a drain
valve. The after cooler is also, four copper tubes with fins wound on them, arranged together for
better cooling. A drain valve is provided with the after cooler. The inter cooler and after coolers are
positioned properly for efficient cooling.
6.2 BIBBY COUPLING