ED.PC2.5 & PC2.6-2_Crankcase.E-00

 

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PC2.5 V engine ( Crankcase of « B » type ): The crankcase is machine-welded construction. The crankcase consists of partition walls, welded: - at the top part, to the roof ensuring the cylinder seating, - to the supporting plates ensuring the cylinder centring, - at the lower part, to the engine fixing bed-plates. Cylinder housings between supporting plates and roof are braced by reinforcing reinf orcing plates. The timing gear casing is at one end of the engine. The casings of the torsional vibration damper and of the turning gear are at the other end. Camshafts are housed in lateral tunnels. The engine lube oil is sucked from a sump fastened below the engine.

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PC2.6/2 V engine ( Crankcase of « C » type ): The crankcase is machine-welded construction. The crankcase consists of partition walls, the top part of which is welded to the cylinder supporting plate and their lower part to the engine fixing bed-plates. The top part is panelled ; each caisson houses one cylinder. The bearings are of suspended type, the top part of the bearing is integral with the crankcase. Each main bearing includes a body inserted in a crankcase housing and held by 2 vertical tie rods and 2 lateral screws.

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Each main bearing includes a body (1) and a cap (2). The body (1) is fastened to the crankcase partition wall by two vertical tie rods (3) and two lateral screws (19). A pin (24) ensures the positioning of the body bod y with respect to the crankcase. Each partition wall with its bearing is matched and numbered. Each bearing body is equipped with a temperature probe. The bearing cap is held against the body by a jack through which flows the oil towards the main bearing.

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A pin (25) ensures the positioning of the cap with respect to the body. The bearing shells (101) and (102) are tightened firm into their housings; lugs hold them in longitudinal position. The upper bearing shell includes a groove with a number of holes extending to the lower bearing shell. Lube oil coming from the distribution pipe, runs through the jack and the bearing cap, up to the bearing housing groove. Whereas some part of lube oil under pressure comes from this groove to the bearing surface, through bearing shell holes, some other part of lube oil enters the axial drilling of the crankshaft.

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The main bearings are of suspended type, the top part of the bearing is integral with the crankcase. Each main bearing includes a body (1) inserted (1) inserted in a crankcase housing and held by two vertical tie rods (2) and two lateral screws (3). (3). A pin (7) ensures (7) ensures the positioning of the body with respect to the crankcase. Each partition wall with its bearing body is matched and numbered.

The bearing shells (4) and (5) are tightened firm into their housings ; lugs hold them in longitudinal position. The upper bearing shell includes a groove with a number of holes extending to the lower bearing shell. Lube oil coming from the distribution pipe, runs through vertical drillings located in partition-walls of the crankcase, up to the bearing housing groove. Whereas some part of lube oil under pressure comes from this groove to the bearing surface, through bearing shell holes, some other part of lube oil enters the axial drilling of the crankshaft.

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In order to prevent misunderstandings, this bearing is often named bearing zero. This bearing is flanged outside the crankcase on the timing gear side. It is held in position on crankcase by means of bolts (14) adjusted after alignment with the main bearings. The upper casing (2) is tightened onto the crankcase by means of screws (11) and on the bearing body by means of screws (12); it is held in position on the bearing body by two fitted bolts (13). Both parts constitute a sealing unit on which the external thrust bearing casings are fastened.

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The external bearing is equipped with bearing shells (4 and 5) with collars to provide adequate longitudinal positioning of the crankshaft.

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The shaft oil seal is made of two half-casings (1) and (2) flanged on the external bearing. The tightness is ensured by a lip seal (7) on the crankshaft collar. The outer face of the crankshaft collar is used as a deflector for the possible oil leaks. In front of this face there is a recovery groove which is connected to the crankcase by a siphonshaped tube (21).

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The cap (3) is positioned an d tightened by two screws (6). positi oned on the casing (1) by means of pins (8) and The external bearing is equipped with bearing bearin g shells with collars (28) and (29) to provide adequate longitudinal positioning of the crankshaft.

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The external thrust bearing (403) which permits to take limi ting the crankshaft ta ke up high axial loads by limiting longitudinal displacement, is fastened to the crankshaft by means of screws (437).

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The upper and lower casings (102) (101) are fastened to the external bearing by screws (118 and 119); they receive two flanges (104 and 105) located on each side of the external thrust bearing. These flanges have an antifriction coating on the face in contact with the thrust collar ( lead  – tin, thickness = 0,025 mm ) The thrust bearing temperature is monitored by means of four sensors located on each side of the casings (not shown here).

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The shaft oil seal, which consists of a lower and upper flange (106) (107), is fastened onto the external thrust bearing casings (101) and (102) (102 ) by means of screws (115). (115).

The shaft oil seal includes the following : - a lip seal (113) ensuring tightness on main power take-off side, - a "scraper" gasket (112) tightened on the thrust bearing by a lock wire, which forms a deflector for oil leaks if any any.. Leak return to the crankcase is provided p rovided by a siphon shaped tube (136). The indication of T.D.C. is engraved on the coupling flange of timing gear side. A graduated sector which is fastened on the casing of the shaft oil seal, in front of the coupling flange allows precise settings.

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The crankshaft is coupled on the timing gear side to the driven machine and on the timing gear opposite side to a vibration damper.

The main bearing alignment alignment is carried out when crankshaft is being installed and it is checked during the engine life by measuring the crank deflections and the clearances under the journals. Cranks are drilled to allow the lube oil to pass from the main bearings to the connecting rod big ends. Open ports are plugged. Crankshaft ends are axially drilled in order to allow oil to reach the torsional vibration damper.

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Each crank is equipped with 1 or 2 counterweights (1), hooked onto the web by recesses and tightened by means of a jack screw (2). Other parts : 3  – locking screw 4  – screw 5  – tab washer 202  – screw 206  – pad 207  – thrust

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2 and 16-cylinders engines are usually equipped with 1 counterweight per crank. 18-cylinders engines are fitted with 12 standard stand ard + 6 special counterweights (2 per crank).

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Example of a 16-cylinders engine, equipped equipp ed with one counterweight per crank.

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The doors closing the crankcase can be either plain (1) or bored (101) to receive the relief valve (102).

They are fastened onto the crankcase by six clamps (3) studs (4) and nuts (6). The gasket (2), stuck at the bottom of the door groove, provides sealing.

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Crankshaft vibration damper The vibration damper is fastened through tie bolts (3) and collared nuts (4) on the coupling flange, on coupling opposite side. It consists of a primary hub (1) on which the secondary second ary crown (14) is centered through rods (2). The assembly (1) - (14) delimitates cylindrical cells which accommodate springs (11) arranged around stop keys (12) which connect the hub h ub to the crown. The assembly is held by the th e flanges (15) fastened on the secondary secon dary crown by screws (18). Oil, supplied through the central hole of the crankshaft, is carried to the cells through radial drillings. The reduction of the torsional amplitudes results from the combined effect of the restoring forces of cylindrical spring packs and of the oil rolling.

The toothed crown fastened on the secondary crown of vibration damper allows the engine to be driven by the turning gear.

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The oil sump consisting of a casing of dry or wet type, is bolted to the underside of the bed-plates.

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Example of a 16V engines: The crankcase is fastened on the oil sump by means of 50 screws (section C-C). Positioning between these two elements is ensured by 20 taper pins (section B-B). The positioning of the assembly engine + oil sump is realized by 18 level adjusting screws (section A-A, on left hand side). 20 tie rods, fitted with spherical shaped nuts, tight the assembly on a reinforced concrete cast in place (section A-A, on right hand side). « Pagel » cement and resin chock fast are used to get a good horizontal setting between the oil sump and the concrete block.

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The crankcase bedplates rest and are held on metallic longitudinal beams (1-2-3-4), through a stuck resin chocking.

The bedplates are provided with reference marks, which allow the engine alignment to be checked. The engine is bolted on the support beams by means of free tie bolts (8) with nuts (10B) and spherical-shaped washers (9) and an d (11). It is positioned at each crankcase side by fitted tie bolts (12) with nuts (10A) and spherical-shaped washers (9) and an d (11). The support beams rest onto the foundation block by means of resin chocks cast on the spot. They are tightened onto the foundation block by tie rods (16) with nuts (19) and spherical-shaped washers (17) and (18).

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The crankcase bedplates rest and are held on metallic longitudinal beams (1-2-3-4), through a stuck resin chocking.

The bedplates are provided with reference marks, which allow the engine alignment to be checked. The engine is bolted on the support beams by means of free tie bolts (8) with nuts (10B) and spherical shaped washers (9) and an d (11). (11). It is positioned at each crankcase side by fitted tie bolts (12) with nuts (10A) and spherical-shaped washers (9) and an d (11). The support beams rest onto the foundation block by means of resin chocks cast on the spot. They are fixed on the foundation block by tie rods (16) with nuts (19) and spherical-shaped washers (17) and (18).

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Details of free tie bolt, fitted tie bolts and side stop.

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The crankcase bedplates rest and are held on the engine seating, through a stuck resin chocking. The bedplates are provided with reference marks, which allows the engine alignment to be checked. The engine is bolted to the engine seating by means of free tie bolts (1) and positioned by fitted tie bolts (2). The bedplates are held sidewise by stops sto ps (3).

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The crankcase is fastened on the frame-sump f rame-sump by means of screws (133). The frame-sump rests onto the foundation block by means of resin chocks cast on spot and is tightened onto the foundation block by tie rods with nuts and spherical-shaped washers.

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The engine is laid on resilient pads (1) via the bed plates of the sump. The crankcase is fastened on the oil sump by screws (14) with spherical-shaped washers (12 and 13), screws (15) as well as eight screws (19) under gear casings. The pads, which are fitted on the mechanism plates (3) by means of screws (4), are fixed first on the engine seating by screws (8), nuts (10) and then on the sump by screws (7). The central screw (2) enables pad compression to allow for its removal. The screw housing is protected by a closing plate (6).

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