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TRIANGLE ASSEMBLY

The basic assembly of all Deltic engines is the main triangle comprising three cylinder blocks and three crankcases "tied" together by a system of high tensile steel bolts which pass through the cylinder blocks and crankcases. 

The through bolts carry the combustion loads and unite the whole assembly into a structure of great inherent strength and rigidity

CRANKCASE AND MAIN

Each crankcase is a one-piece aluminum alloy casting, substantially webbed and carrying a crankshaft in thin-walled lead-bronze, lead plated, indium-infused main bearings.

Each bearing cap is secured by four studs, and additionally located by a tie-bolt which passes transversely through the cap and the crankcase walls on either side.

The two upper crankcases are identical, but the lower one is deepened in section to carry engine bearers, to provide effective oil drainage for the dry sump lubrication system, and to accommodate drives for the oil and water pumps.

CAMSHAFTS

The crankshafts have hollow crankpins, are nitrided all over and the bearing surfaces are finished by lapping. Each crankshaft is statically balanced and fitted with a viscous-type torsional vibration damper. The top crankshafts are identical and rotate in a clockwise direction; the bottom crankshaft has opposite-handed throws and rotates in an counter-clockwise direction to obtain the correct phase relationship.

CYLINDER BLOCKS

The three separate cylinder blocks are identical light allow castings of monoblock construction with integrally-cast coolant passages, exhaust ports, and air inlet manifolds.

CYLINDER BLOCK LINER

The cylinder liners are of the open-ended 'wet' type and are machined from hollow steel forgings, they are chromium-plated in the bore, honeychrome etched and finished by lapping.

Each liner is located longitudinally by a ring nut which clamps a flange on one end of the liner against a shoulder in the bore of the cylinder block. The liners are located radially by the injection nozzle adapters which are screwed through the cylinder block into the wall of the liner.

PISTON

Each piston consists of two separate parts, an outer piston body of cast aluminum which has an unbroken skirt and carries the two top compression rings in an austenitic iron insert bonded to the aluminum by the 'Alfin" process, and an inner member which is machined from a 'Y' alloy forging; the latter carrying a fully-floating, hardened-steel gudgeon pin. 

When assembled these parts form passages, beneath the piston crown and behind the piston rings, in which oil is shaken by the piston motion and assists cooling.

CONNECTING RODS AND BEARINGS

Each crankpin carries a pair of connecting rods, one plain and one forked, on thin-wall, lead-bronze, lead-plated, indium-infused bearings. 

The exhaust pistons are attached to the forked rods which are reinforced by a nitrided steel bearing shell, the inner surface of which carries the thin-wall bearing for the crankpin; the inlet pistons are attached to the plain rods, which carry a thin-wall bearing that moves on the outside of the steel bearing shell.

CAM SHAFTS

The injection pump camshafts are enclosed by light allow casings assembled to the outer face of the cylinder block. The camshafts are carried in phosphor-bronze bearings lined with white metal, and are driven through short quill-shafts which incorporate simple vernier timing adjustments.

PHASING GEAR

Power is transmitted from each crankshaft through coupling quill shafts to phasing gears which combine the three outputs into a single shaft, the direction of rotation of which is determined by the arrangement of the idler gears. 

The phasing gear also drives an ancillary power take-off shaft and the engine auxiliaries, except the fresh and sea-water pumps and oil pumps which are located on the bottom crankcase and driven through spur and bevel gears from the bottom crankshaft