Main Air Compressor — Real Specification (TRC 1000)

The Elgi air compressor model TRC 1000 M/WK is a three-cylinder, two-stage, reciprocating, air-cooled, splash-lubricated compressor driven by an electric motor through a Bibby coupling. Its three cylinders are arranged in a 'W' form on a crank case. Oil-bath air filters sit on the suction side of the LP cylinder heads; the LP cylinder heads' discharge ports connect to a radiator called the inter-cooler for effective cooling, and the inter-cooler connects to the HP cylinder head's suction port. The HP cylinder head's discharge port carries a box-type after-cooler. Compressed air flows: LP cylinder delivery → inter-cooler → HP cylinder → after-cooler → delivered. The compressor is coupled to a 12.5 HP NGEF motor and mounted on a rigid, compact base; air filter and pipe fittings are all clamped to arrest vibration. A fan with a fan guard directs cool air onto the compressor unit, drawing air over the motor to cool it too. An eye bolt on the motor's terminal-belt side lets it be lifted (fix the eye bolt on top of the motor and lift).

Real Component Details

• Connecting rod & crankshaft assembly: precision-machined and dynamically balanced. The crankshaft has a single-row heavy-duty ball bearing at both ends; the main connecting rod's big end has a triple-row roller bearing, and its small end has a phosphor-bronze bearing.
• Piston & piston rings: automotive-type pistons of low-expansion silicon-aluminium alloy, fitted with plain compression rings, stepped rings, and slotted oil-control rings.
• Disc Valves: a special type of concentric disc valve used for both the LP and HP cylinders.
• Inter-cooler, safety valve & after-cooler: the inter-cooler is a radiator of copper tubes with wound fins, mounted above the motor, connecting LP-cylinder discharge to HP-cylinder suction; fitted with a safety valve set to lift at 6 kg/cm² and a drain valve. The after-cooler is similarly four finned copper tubes arranged together for better cooling, also with its own drain valve; both coolers are positioned for efficient cooling.

Bibby Coupling — Real Assembly Procedure

The flexible coupling connecting motor and compressor has 2 hubs (CP Hub and MCP Hub), each with grooves holding a grid spring that transmits rotation from motor to compressor. Care is needed in checking both parallel and angular alignment and in setting the correct gap (0.8mm). The coupling grooves must be completely packed with grease before the spring is inserted, with a further liberal grease application after insertion; after assembling the outer shell, the maximum possible quantity of grease must be forced in through the greasing nipple. This coupling needs no attention while running except periodic grease replenishment.

• Replacement rule: if any ring of the grid spring breaks in the middle, the grid spring must be replaced; if a tooth or number of teeth of the coupling hubs break, the hub must be replaced.
• Assembly steps: (1) check parallelism with a straight edge over the hub tops at each quarter point 90° apart, with a final check after foundation bolts are tightened; (2) check the hub-face gap is within 0.8-1mm, and check angular alignment with feelers in the gap at each quarter point 93° apart; (3) after thoroughly packing the grooves with grease, press the spring into position, apply grease liberally, draw the covers into position, tighten the bolts, and inject maximum grease through the grease nipple.

Compressor Details — Full Real Specification Table