From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical description and cross-section diagram of the Bentley Mark V chassis and its 4¼-litre engine.
| Identifier | ExFiles\Box 160\5\ scan0329 | |
| Date | 1st May 1941 | |
| 144 AUTOMOBILE ENGINEER MAY, 1941 THE BENTLEY MARK V CHASSIS (Continued) As to riding qualities, excellent as were the previous models, experienced drivers have found the new car to be not merely more immune from road shocks but to possess improved control, stability and steering characteristics. This may be rightly attributed to the new front suspension combined with a scheme retained from the previous model, and consisting of an over-riding hand control for varying the effect exercised on the rear springs by the hydraulic shock absorbers. In this way a wide latitude is provided between the extremes of “soft” riding and slight roll at low speeds, or stiffer suspension giving stability at high speeds. which is a two-piece aluminium casting split on the centre line of the crankshaft. The joint between cylinder block and crankcase is just over 2in. above the bottom of each cylinder bore which depends into the crankcase. Special Aerolite pistons are fitted as standard. Of aluminium alloy, they have horizontal slits beneath the bottom ring to regulate the flow of heat from crown to skirt. They are fitted with three rings, the lower of which is a scraper, and diagonal oil holes are provided to lead excess oil on to the gudgeon pin. This is arranged to float in both piston bosses and small end. The gudgeon pins are increasing the main bearings which are of white metal. A seven-bearing crankshaft is employed, carefully heat-treated and hardened. It is a forging made from V.C.M. steel. All journals and crank pins are bored out with large-diameter holes, which are closed by two aluminium tapered washers drawn together by a light stud having a castel-lated nut and split pin at one end and a thin nut riveted over at the other. At the front end a particularly interesting form of vibration damper is fitted. The heavy central member is rigidly attached by taper and Woodruff key to the crankshaft. It is formed with a thin Fig. 3. General arrangement of six-cylinder 4¼-litre engine. Bore and stroke 3¼in. × 4½in. Engine The bore and stroke of the power unit are 3¼in. by 4½in. (approximately 89 mm. by 114 mm.), giving a swept volume for the six cylinders of 4,257 c.c. and an R.A.C. rating of 29.4 h.p., these dimensions being, of course, identical with the previous model. Maximum brake-horse-power is in the region of 130. The makers state that an engine speed of 4,500 r.p.m. should never be exceeded. As shown in Fig. 3, a one-piece cast-iron cylinder block is employed. It is fitted with a detachable cylinder head, which is also of cast-iron. It should be noted, however, that the cylinder block is not made in one piece with the crankcase, drilled out and fitted with two soft alu-minium plugs with rounded ends. A bronze bush forms the bearing for the little end. The special raised crown on the piston head is referred to in connection with the combustion chamber. Made from nickel steel forgings, the connecting rods are of I-section with the web thickened at the centre to enable the rod to be bored out to carry lubricating oil up to the pins from the big ends. Lightening recesses are forged in the big ends and their caps. For the big end bearings, a special light alloy developed at Derby is employed. It is known as A.C.9, and its use has made it possible to reduce the width of these bearings while flange in contact with two friction discs. On the front side of the friction element a presser plate holds the members in contact through the medium of a ring of coil springs each carried in a retainer screwed into the outer flanged member. The presser plate is riveted to a thin diaphragm slightly corrugated. The floating member of the damper consists of the fan pulley, the two flanged members enclosing the central friction element and the timing gear. This unit is free to revolve on two plain bushes, its movement being limited by long studs passing through the complete unit with clearance holes in the floating members. Though on the previous model a train | ||